Squashed commit of the following:

commit db1a75ffc2d5a811a8d983289dd4d0d9f2eeba5c
Author: Yang Li <liyang@google.com>
Date:   Fri May 1 17:49:29 2009 -0700

    Fixed a few more styles issues and made some methods package private

commit f9735c3f1bbe6183337df226aa730b4be1225d55
Author: Yang Li <liyang@google.com>
Date:   Fri May 1 16:38:16 2009 -0700

    - Refactored the code for Android coding styles and performance
    - Renamed GesturePad to GestureOverlay
    - Added GestureAdapter for default touch-through interactions of GestureOverlay
    - Added a new exmaple, ContactListGestureOverlay, to show how to gesture over an arbitary view

commit 31050183c6d85091612f53155126c2488b920e32
Author: Yang Li <liyang@google.com>
Date:   Wed Apr 29 18:41:54 2009 -0700

    Refactored the Gesture Library (An initial check-in).

23 files changed, 3028 insertions, 703 deletions

diff --git a/tests/sketch/src/com/android/gesture/Gesture.java b/tests/sketch/src/com/android/gesture/Gesture.java
index 29c07ad..a5e7a25 100755
--- a/tests/sketch/src/com/android/gesture/Gesture.java
+++ b/tests/sketch/src/com/android/gesture/Gesture.java
@@ -18,343 +18,290 @@ package com.android.gesture;
 
 import android.graphics.Bitmap;
 import android.graphics.Canvas;
-import android.graphics.Matrix;
 import android.graphics.Paint;
 import android.graphics.Path;
-import android.graphics.PointF;
 import android.graphics.RectF;
 import android.os.Parcel;
 import android.os.Parcelable;
 
-import com.android.gesture.recognizer.RecognitionUtil;
-
 import org.xmlpull.v1.XmlSerializer;
 
 import java.io.IOException;
 import java.util.ArrayList;
-import java.util.Iterator;
-import java.util.StringTokenizer;
 
 /**
- * A single stroke gesture.
+ * A gesture can have a single or multiple strokes
  */
 
 public class Gesture implements Parcelable {
 
-    private RectF mBBX;
-    private float mLength = 0;
-    private int mColor;
-    private float mWidth;
-    private ArrayList<PointF> mPtsBuffer = new ArrayList<PointF>();
-    private long mTimestamp = 0;
-    private long mID;
-    
-    private static final long systemStartupTime = System.currentTimeMillis();
-    private static int instanceCount = 0; 
+    private static final long GESTURE_ID_BASE = System.currentTimeMillis();
+
+    private static final int BITMAP_RENDERING_WIDTH = 2;
+
+    private static final boolean BITMAP_RENDERING_ANTIALIAS = true;
+
+    private static final boolean BITMAP_RENDERING_DITHER = true;
+
+    private static int sGestureCount = 0;
+
+    private RectF mBoundingBox;
+
+    // the same as its instance ID
+    private long mGestureID;
+
+    private ArrayList<GestureStroke> mStrokes = new ArrayList<GestureStroke>();
 
     public Gesture() {
-        mID = systemStartupTime + instanceCount++;
+        mGestureID = GESTURE_ID_BASE + sGestureCount++;
     }
 
-    public void setColor(int c) {
-        mColor = c;
-    }
-    
-    public void setStrokeWidth(float w) {
-        mWidth = w;
-    }
-    
-    public int getColor() {
-        return mColor;
-    }
-    
-    public float getStrokeWidth() {
-        return mWidth;
-    }
-  
-    public ArrayList<PointF> getPoints() {
-        return this.mPtsBuffer;
+    /**
+     * @return all the strokes of the gesture
+     */
+    public ArrayList<GestureStroke> getStrokes() {
+        return mStrokes;
     }
-  
-    public int numOfPoints() {
-        return this.mPtsBuffer.size();
+
+    /**
+     * @return the number of strokes included by this gesture
+     */
+    public int getStrokesCount() {
+        return mStrokes.size();
     }
 
-    public void addPoint(float x, float y) {
-        mPtsBuffer.add(new PointF(x, y));
-        if (mBBX == null) {
-            mBBX = new RectF();
-            mBBX.top = y;
-            mBBX.left = x;
-            mBBX.right = x;
-            mBBX.bottom = y;
-            mLength = 0;
-        }
-        else {
-            PointF lst = mPtsBuffer.get(mPtsBuffer.size()-2);
-            mLength += Math.sqrt(Math.pow(x-lst.x, 2)+Math.pow(y-lst.y, 2));
-            mBBX.union(x, y);
+    /**
+     * Add a stroke to the gesture
+     * 
+     * @param stroke
+     */
+    public void addStroke(GestureStroke stroke) {
+        mStrokes.add(stroke);
+
+        if (mBoundingBox == null) {
+            mBoundingBox = new RectF(stroke.boundingBox);
+        } else {
+            mBoundingBox.union(stroke.boundingBox);
         }
-        mTimestamp = System.currentTimeMillis();
     }
 
     /**
+     * Get the total length of the gesture. When there are multiple strokes in
+     * the gesture, this returns the sum of the lengths of all the strokes
+     * 
      * @return the length of the gesture
      */
     public float getLength() {
-        return this.mLength;
+        int len = 0;
+        ArrayList<GestureStroke> strokes = mStrokes;
+        int count = strokes.size();
+        for (int i = 0; i < count; i++) {
+            GestureStroke stroke = strokes.get(i);
+            len += stroke.length;
+        }
+        return len;
     }
-  
-    public RectF getBBX() {
-        return mBBX;
+
+    /**
+     * @return the bounding box of the gesture
+     */
+    public RectF getBoundingBox() {
+        return mBoundingBox;
     }
-  
-    public void setID(long id) {
-        mID = id;
+
+    /**
+     * Set the id of the gesture
+     * 
+     * @param id
+     */
+    void setID(long id) {
+        mGestureID = id;
     }
-    
+
+    /**
+     * @return the id of the gesture
+     */
     public long getID() {
-        return mID;
+        return mGestureID;
     }
-    
-    public long getTimeStamp() {
-        return mTimestamp;
-    }
-    
-    public void setTimestamp(long t) {
-  	    this.mTimestamp = t;
-    }
-    
+
     /**
      * draw the gesture
+     * 
      * @param canvas
      */
-    public void draw(Canvas canvas) {
-        Paint paint = new Paint();
-        paint.setAntiAlias(true);
-        paint.setDither(true);
-        paint.setColor(mColor);
-        paint.setStyle(Paint.Style.STROKE);
-        paint.setStrokeJoin(Paint.Join.ROUND);
-        paint.setStrokeCap(Paint.Cap.ROUND);
-        paint.setStrokeWidth(mWidth);
-        
-        Path path = null;
-        float mX = 0, mY = 0;
-        Iterator<PointF> it = mPtsBuffer.iterator();
-        while (it.hasNext()) {
-          PointF p = it.next();
-          float x = p.x;
-          float y = p.y;
-          if (path == null) {
-            path = new Path();
-            path.moveTo(x, y);
-            mX = x;
-            mY = y;
-          } else {
-            float dx = Math.abs(x - mX);
-            float dy = Math.abs(y - mY);
-            if (dx >= 3 || dy >= 3) {
-                path.quadTo(mX, mY, (x + mX)/2, (y + mY)/2);
-                mX = x;
-                mY = y;
-            }
-          }
+    void draw(Canvas canvas, Paint paint) {
+        ArrayList<GestureStroke> strokes = mStrokes;
+        int count = strokes.size();
+        for (int i = 0; i < count; i++) {
+            GestureStroke stroke = strokes.get(i);
+            stroke.draw(canvas, paint);
         }
-        
-        canvas.drawPath(path, paint);
     }
-    
+
     /**
-     * convert the gesture to a Path
-     * @param width the width of the bounding box of the target path
-     * @param height the height of the bounding box of the target path
-     * @param numSample the num of points needed
-     * @return the path
+     * Create a bitmap of the gesture with a transparent background
+     * 
+     * @param width width of the target bitmap
+     * @param height height of the target bitmap
+     * @param edge the edge
+     * @param numSample
+     * @param color
+     * @return the bitmap
      */
-    public Path toPath(float width, float height, int numSample) {
-        float[] pts = RecognitionUtil.resample(this, numSample);
-        RectF rect = this.getBBX();
-        float scale = height / rect.height();
-        Matrix matrix = new Matrix();
-        matrix.setTranslate(-rect.left, -rect.top);
-        Matrix scalem = new Matrix();
-        scalem.setScale(scale, scale);
-        matrix.postConcat(scalem);
-        Matrix translate = new Matrix();
-        matrix.postConcat(translate);
-        matrix.mapPoints(pts);
-        
-        Path path = null;
-        float mX = 0, mY = 0;
-        for (int i=0; i<pts.length-1; i+=2) {
-          float x = pts[i];
-          float y = pts[i+1];
-          if (path == null) {
-            path = new Path();
-            path.moveTo(x, y);
-            mX = x;
-            mY = y;
-          } else {
-            float dx = Math.abs(x - mX);
-            float dy = Math.abs(y - mY);
-            if (dx >= 3 || dy >= 3) {
-                path.quadTo(mX, mY, (x + mX)/2, (y + mY)/2);
-                mX = x;
-                mY = y;
-            }
-          }
+    public Bitmap toBitmap(int width, int height, int edge, int numSample, int color) {
+        RectF bbx = getBoundingBox();
+        Bitmap bitmap = Bitmap.createBitmap(width, height, Bitmap.Config.ARGB_8888);
+        Canvas canvas = new Canvas(bitmap);
+        canvas.translate(edge, edge);
+        Paint paint = new Paint();
+        paint.setAntiAlias(BITMAP_RENDERING_ANTIALIAS);
+        paint.setDither(BITMAP_RENDERING_DITHER);
+        paint.setColor(color);
+        paint.setStyle(Paint.Style.STROKE);
+        paint.setStrokeJoin(Paint.Join.ROUND);
+        paint.setStrokeCap(Paint.Cap.ROUND);
+        paint.setStrokeWidth(BITMAP_RENDERING_WIDTH);
+        ArrayList<GestureStroke> strokes = mStrokes;
+        int count = strokes.size();
+        for (int i = 0; i < count; i++) {
+            GestureStroke stroke = strokes.get(i);
+            Path path = stroke.toPath(width - 2 * edge, height - 2 * edge, numSample);
+            canvas.drawPath(path, paint);
         }
-        return path;
+
+        return bitmap;
     }
-  
+
     /**
-     * get a bitmap thumbnail of the gesture with a transparent background
-     * @param w
-     * @param h
+     * Create a bitmap of the gesture with a transparent background
+     * 
+     * @param width
+     * @param height
      * @param edge
-     * @param numSample
-     * @param foreground
-     * @return
+     * @param color
+     * @return the bitmap
      */
-    public Bitmap toBitmap(int w, int h, 
-        int edge, int numSample) {
-        RectF bbx = this.getBBX();
-        Bitmap bitmap = Bitmap.createBitmap(w, h, Bitmap.Config.ARGB_8888);
-        Path path = this.toPath(w - 2 * edge, h - 2 * edge, numSample);
-        Canvas c = new Canvas(bitmap);
-        //c.drawColor(background);
-        c.translate(edge, edge);
+    public Bitmap toBitmap(int width, int height, int edge, int color) {
+        RectF bbx = getBoundingBox();
+        Bitmap bitmap = Bitmap.createBitmap(width, height, Bitmap.Config.ARGB_8888);
+        Canvas canvas = new Canvas(bitmap);
+        canvas.translate(edge, edge);
         Paint paint = new Paint();
-        paint.setAntiAlias(true);
-        paint.setDither(true);
-        paint.setColor(mColor);
+        paint.setAntiAlias(BITMAP_RENDERING_ANTIALIAS);
+        paint.setDither(BITMAP_RENDERING_DITHER);
+        paint.setColor(color);
         paint.setStyle(Paint.Style.STROKE);
         paint.setStrokeJoin(Paint.Join.ROUND);
         paint.setStrokeCap(Paint.Cap.ROUND);
-        paint.setStrokeWidth(2);
-        c.drawPath(path, paint);
+        paint.setStrokeWidth(BITMAP_RENDERING_WIDTH);
+        ArrayList<GestureStroke> strokes = mStrokes;
+        int count = strokes.size();
+        for (int i = 0; i < count; i++) {
+            GestureStroke stroke = strokes.get(i);
+            stroke.draw(canvas, paint);
+        }
+
         return bitmap;
     }
-    
+
     /**
-     * save the gesture as XML
+     * Save the gesture as XML
+     * 
      * @param namespace
      * @param serializer
      * @throws IOException
      */
-    public void toXML(String namespace, XmlSerializer serializer) throws IOException {
-        serializer.startTag(namespace, "stroke");
-        serializer.attribute(namespace, "timestamp", Long.toString(mTimestamp));
-        serializer.attribute(namespace, "id", Long.toString(mID));
-        serializer.attribute(namespace, "color", Integer.toString(mColor));
-        serializer.attribute(namespace, "width", Float.toString(mWidth));
-        Iterator it = this.mPtsBuffer.iterator();
-        String pts = "";
-        while (it.hasNext()) {
-        	PointF fp = (PointF)it.next();
-        	if (pts.length() > 0)
-        		pts += ",";
-        	pts += fp.x + "," + fp.y;
+    void toXML(String namespace, XmlSerializer serializer) throws IOException {
+        serializer.startTag(namespace, GestureConstants.XML_TAG_GESTURE);
+        serializer.attribute(namespace, GestureConstants.XML_TAG_ID, Long.toString(mGestureID));
+        ArrayList<GestureStroke> strokes = mStrokes;
+        int count = strokes.size();
+        for (int i = 0; i < count; i++) {
+            GestureStroke stroke = strokes.get(i);
+            stroke.toXML(namespace, serializer);
         }
-        serializer.text(pts);
-        serializer.endTag(namespace, "stroke");
+        serializer.endTag(namespace, GestureConstants.XML_TAG_GESTURE);
     }
-    
-    
+
+    /**
+     * Create the gesture from a string
+     * 
+     * @param str
+     */
     public void createFromString(String str) {
-        StringTokenizer st = new StringTokenizer(str, "#");
-        
-        String para = st.nextToken();
-        StringTokenizer innerst = new StringTokenizer(para, ",");
-        this.mBBX = new RectF();
-        this.mBBX.left = Float.parseFloat(innerst.nextToken());
-        this.mBBX.top = Float.parseFloat(innerst.nextToken());
-        this.mBBX.right = Float.parseFloat(innerst.nextToken());
-        this.mBBX.bottom = Float.parseFloat(innerst.nextToken());
-        
-        para = st.nextToken();
-        innerst = new StringTokenizer(para, ",");
-        while (innerst.hasMoreTokens()) {
-          String s = innerst.nextToken().trim();
-          if (s.length()==0)
-            break;
-          float x = Float.parseFloat(s);
-          float y = Float.parseFloat(innerst.nextToken());
-          this.mPtsBuffer.add(new PointF(x, y));
+        int startIndex = 0;
+        int endIndex;
+        while ((endIndex = str.indexOf(GestureConstants.STRING_GESTURE_DELIIMITER, startIndex + 1)) != -1) {
+            String token = str.substring(startIndex, endIndex);
+            if (startIndex > 0) { // stroke tokens
+                addStroke(GestureStroke.createFromString(token));
+            } else { // id token
+                mGestureID = Long.parseLong(token);
+            }
+            startIndex = endIndex + 1;
         }
-  
-        para = st.nextToken();
-        this.mColor = Integer.parseInt(para);
-        
-        para = st.nextToken();
-        this.mWidth = Float.parseFloat(para);
-        
-        para = st.nextToken();
-        this.mLength = Float.parseFloat(para);
-        
-        para = st.nextToken();
-        this.mTimestamp = Long.parseLong(para);
     }
-    
+
+    /**
+     * Convert the gesture to string
+     */
     @Override
     public String toString() {
-        String str = "";
-        
-        str += "#" + this.mBBX.left + "," + this.mBBX.top + "," +
-               this.mBBX.right + "," + this.mBBX.bottom;
-        
-        str += "#";
-        Iterator<PointF> it = this.mPtsBuffer.iterator();
-        while (it.hasNext()) {
-          PointF fp = it.next();
-          str += fp.x + "," + fp.y + ","; 
+        StringBuilder str = new StringBuilder();
+        str.append(mGestureID);
+        ArrayList<GestureStroke> strokes = mStrokes;
+        int count = strokes.size();
+        for (int i = 0; i < count; i++) {
+            GestureStroke stroke = strokes.get(i);
+            str.append(GestureConstants.STRING_GESTURE_DELIIMITER);
+            str.append(stroke.toString());
         }
 
-        str += "#";
-        str += this.mColor;
-        
-        str += "#";
-        str += this.mWidth;
-        
-        str += "#";
-        str += this.mLength;
-        
-        str += "#";
-        str += this.mTimestamp;
-  
-        return str;
+        return str.toString();
     }
-    
-    public static final Parcelable.Creator CREATOR = new Parcelable.Creator() {
+
+    public static final Parcelable.Creator<Gesture> CREATOR = new Parcelable.Creator<Gesture>() {
         public Gesture createFromParcel(Parcel in) {
             String str = in.readString();
-            Gesture stk = new Gesture();
-            stk.createFromString(str);
-            return stk;
+            Gesture gesture = new Gesture();
+            gesture.createFromString(str);
+            return gesture;
         }
-    
+
         public Gesture[] newArray(int size) {
             return new Gesture[size];
         }
     };
-    
-    public static Gesture buildFromArray(byte[] bytes) {
+
+    /**
+     * Build a gesture from a byte array
+     * 
+     * @param bytes
+     * @return the gesture
+     */
+    static Gesture buildFromArray(byte[] bytes) {
         String str = new String(bytes);
-        Gesture stk = new Gesture();
-        stk.createFromString(str);
-        return stk;
+        Gesture gesture = new Gesture();
+        gesture.createFromString(str);
+        return gesture;
     }
-    
-    public static byte[] saveToArray(Gesture stk) {
-        String str = stk.toString();   
+
+    /**
+     * Save a gesture to a byte array
+     * 
+     * @param stroke
+     * @return the byte array
+     */
+    static byte[] saveToArray(Gesture stroke) {
+        String str = stroke.toString();
         return str.getBytes();
     }
-    
+
     public void writeToParcel(Parcel out, int flags) {
-        out.writeString(this.toString());
+        out.writeString(toString());
     }
-      
+
     public int describeContents() {
         return CONTENTS_FILE_DESCRIPTOR;
     }
diff --git a/tests/sketch/src/com/android/gesture/GestureActionListener.java b/tests/sketch/src/com/android/gesture/GestureActionListener.java
new file mode 100644
index 0000000..130ac19
--- /dev/null
+++ b/tests/sketch/src/com/android/gesture/GestureActionListener.java
@@ -0,0 +1,22 @@
+/*
+ * Copyright (C) 2008-2009 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.gesture;
+
+
+public interface GestureActionListener {
+    public void onGesturePerformed(GestureOverlay overlay, Gesture gesture);
+}
diff --git a/tests/sketch/src/com/android/gesture/GestureAdapter.java b/tests/sketch/src/com/android/gesture/GestureAdapter.java
new file mode 100644
index 0000000..3cf9b4c
--- /dev/null
+++ b/tests/sketch/src/com/android/gesture/GestureAdapter.java
@@ -0,0 +1,124 @@
+/*
+ * Copyright (C) 2008-2009 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.gesture;
+
+import android.graphics.Color;
+import android.view.MotionEvent;
+import android.view.View;
+
+import java.util.ArrayList;
+
+public class GestureAdapter implements GestureListener {
+
+    public static final int SINGLE_STROKE = 0;
+
+    public static final int MULTIPLE_STROKE = 1;
+
+    private static final float STROKE_LENGTH_THRESHOLD = 100;
+
+    private static final float SQUARENESS_THRESHOLD = 0.24f;
+
+    private static final int UNCERTAIN_GESTURE_COLOR = Color.argb(60, 255, 255, 0);
+
+    private boolean mIsGesturing = false;
+
+    private float mTotalLength;
+
+    private float mX, mY;
+
+    private View mModel;
+
+    private int mGestureType = SINGLE_STROKE;
+
+    private ArrayList<GestureActionListener> mActionListeners = new ArrayList<GestureActionListener>();
+
+    public GestureAdapter(View model) {
+        mModel = model;
+    }
+
+    public void setGestureType(int type) {
+        mGestureType = type;
+    }
+
+    public void onStartGesture(GestureOverlay overlay, MotionEvent event) {
+        if (mGestureType == MULTIPLE_STROKE) {
+            overlay.cancelFadingOut();
+        }
+        mX = event.getX();
+        mY = event.getY();
+        mTotalLength = 0;
+        mIsGesturing = false;
+        if (mGestureType == SINGLE_STROKE || overlay.getCurrentGesture() == null
+                || overlay.getCurrentGesture().getStrokesCount() == 0) {
+            overlay.setGestureColor(UNCERTAIN_GESTURE_COLOR);
+        }
+        mModel.dispatchTouchEvent(event);
+    }
+
+    public void onGesture(GestureOverlay overlay, MotionEvent event) {
+        if (mIsGesturing) {
+            return;
+        }
+        float x = event.getX();
+        float y = event.getY();
+        float dx = x - mX;
+        float dy = y - mY;
+        mTotalLength += (float)Math.sqrt(dx * dx + dy * dy);
+        mX = x;
+        mY = y;
+
+        if (mTotalLength > STROKE_LENGTH_THRESHOLD) {
+            OrientedBoundingBox bbx = GestureUtils.computeOrientedBBX(overlay.getCurrentStroke());
+            if (bbx.squareness > SQUARENESS_THRESHOLD) {
+                mIsGesturing = true;
+                overlay.setGestureColor(GestureOverlay.DEFAULT_GESTURE_COLOR);
+                event = MotionEvent.obtain(event.getDownTime(), System.currentTimeMillis(),
+                        MotionEvent.ACTION_UP, x, y, event.getPressure(), event.getSize(), event
+                                .getMetaState(), event.getXPrecision(), event.getYPrecision(),
+                        event.getDeviceId(), event.getEdgeFlags());
+            }
+        }
+        mModel.dispatchTouchEvent(event);
+    }
+
+    public void onFinishGesture(GestureOverlay overlay, MotionEvent event) {
+        if (mIsGesturing) {
+            overlay.clear(true);
+            ArrayList<GestureActionListener> listeners = mActionListeners;
+            int count = listeners.size();
+            for (int i = 0; i < count; i++) {
+                GestureActionListener listener = listeners.get(i);
+                listener.onGesturePerformed(overlay, overlay.getCurrentGesture());
+            }
+        } else {
+            mModel.dispatchTouchEvent(event);
+            overlay.clear(false);
+        }
+    }
+
+    public void addGestureActionListener(GestureActionListener listener) {
+        mActionListeners.add(listener);
+    }
+
+    public void removeGestureActionListener(GestureActionListener listener) {
+        mActionListeners.remove(listener);
+    }
+
+    public boolean isGesturing() {
+        return mIsGesturing;
+    }
+}
diff --git a/tests/sketch/src/com/android/gesture/GestureConstants.java b/tests/sketch/src/com/android/gesture/GestureConstants.java
new file mode 100644
index 0000000..0e17c8a
--- /dev/null
+++ b/tests/sketch/src/com/android/gesture/GestureConstants.java
@@ -0,0 +1,31 @@
+/*
+ * Copyright (C) 2009 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.gesture;
+
+interface GestureConstants {
+    static final String XML_TAG_LIBRARY = "library";
+    static final String XML_TAG_ENTRY = "entry";
+    static final String XML_TAG_GESTURE = "gesture";
+    static final String XML_TAG_STROKE = "stroke";
+    static final String XML_TAG_ID = "id";
+    static final String XML_TAG_NAME = "name";
+    static final String STRING_GESTURE_DELIIMITER = "#";
+    static final String STRING_STROKE_DELIIMITER = ",";
+    static final int STROKE_STRING_BUFFER_SIZE = 1024;
+    static final int STROKE_POINT_BUFFER_SIZE = 100; // number of points
+    static final int IO_BUFFER_SIZE = 8 * 1024; // 8K
+}
diff --git a/tests/sketch/src/com/android/gesture/GestureLibrary.java b/tests/sketch/src/com/android/gesture/GestureLibrary.java
new file mode 100644
index 0000000..32c1ac4
--- /dev/null
+++ b/tests/sketch/src/com/android/gesture/GestureLibrary.java
@@ -0,0 +1,332 @@
+/*
+ * Copyright (C) 2008-2009 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.gesture;
+
+import android.util.Config;
+import android.util.Log;
+import android.util.Xml;
+import android.util.Xml.Encoding;
+
+import org.xml.sax.Attributes;
+import org.xml.sax.ContentHandler;
+import org.xml.sax.Locator;
+import org.xml.sax.SAXException;
+import org.xmlpull.v1.XmlSerializer;
+
+import java.io.BufferedInputStream;
+import java.io.BufferedOutputStream;
+import java.io.File;
+import java.io.FileInputStream;
+import java.io.FileOutputStream;
+import java.io.IOException;
+import java.io.PrintWriter;
+import java.util.ArrayList;
+import java.util.HashMap;
+import java.util.Iterator;
+import java.util.Set;
+
+/**
+ * GestureLibrary maintains gesture examples and makes predictions on a new
+ * gesture
+ */
+public class GestureLibrary {
+
+    public static final int SEQUENCE_INVARIANT = 1;
+
+    public static final int SEQUENCE_SENSITIVE = 2;
+
+    private int mSequenceType = SEQUENCE_SENSITIVE;
+
+    public static final int ORIENTATION_INVARIANT = 1;
+
+    public static final int ORIENTATION_SENSITIVE = 2;
+
+    private int mOrientationStyle = ORIENTATION_SENSITIVE;
+
+    private static final String LOGTAG = "GestureLibrary";
+
+    private static final String NAMESPACE = "";
+
+    private final String mGestureFileName;
+
+    private HashMap<String, ArrayList<Gesture>> mEntryName2gestures = new HashMap<String, ArrayList<Gesture>>();
+
+    private Learner mClassifier;
+
+    private boolean mChanged = false;
+
+    /**
+     * @param path where gesture data is stored
+     */
+    public GestureLibrary(String path) {
+        mGestureFileName = path;
+        mClassifier = new InstanceLearner();
+    }
+
+    /**
+     * Specify whether the gesture library will handle orientation sensitive
+     * gestures. Use ORIENTATION_INVARIANT or ORIENTATION_SENSITIVE
+     * 
+     * @param style
+     */
+    public void setOrientationStyle(int style) {
+        mOrientationStyle = style;
+    }
+
+    public int getOrientationStyle() {
+        return mOrientationStyle;
+    }
+
+    public void setGestureType(int type) {
+        mSequenceType = type;
+    }
+
+    public int getGestureType() {
+        return mSequenceType;
+    }
+
+    /**
+     * Get all the gesture entry names in the library
+     * 
+     * @return a set of strings
+     */
+    public Set<String> getGestureEntries() {
+        return mEntryName2gestures.keySet();
+    }
+
+    /**
+     * Recognize a gesture
+     * 
+     * @param gesture the query
+     * @return a list of predictions of possible entries for a given gesture
+     */
+    public ArrayList<Prediction> recognize(Gesture gesture) {
+        Instance instance = Instance.createInstance(this, gesture, null);
+        return mClassifier.classify(this, instance);
+    }
+
+    /**
+     * Add a gesture for the entry
+     * 
+     * @param entryName entry name
+     * @param gesture
+     */
+    public void addGesture(String entryName, Gesture gesture) {
+        if (Config.DEBUG) {
+            Log.v(LOGTAG, "Add an example for gesture: " + entryName);
+        }
+        ArrayList<Gesture> gestures = mEntryName2gestures.get(entryName);
+        if (gestures == null) {
+            gestures = new ArrayList<Gesture>();
+            mEntryName2gestures.put(entryName, gestures);
+        }
+        gestures.add(gesture);
+        mClassifier.addInstance(Instance.createInstance(this, gesture, entryName));
+        mChanged = true;
+    }
+
+    /**
+     * Remove a gesture from the library. If there are no more gestures for the
+     * given entry, the gesture entry will be removed.
+     * 
+     * @param entryName entry name
+     * @param gesture
+     */
+    public void removeGesture(String entryName, Gesture gesture) {
+        ArrayList<Gesture> gestures = mEntryName2gestures.get(entryName);
+        if (gestures == null) {
+            return;
+        }
+
+        gestures.remove(gesture);
+
+        // if there are no more samples, remove the entry automatically
+        if (gestures.isEmpty()) {
+            mEntryName2gestures.remove(entryName);
+        }
+
+        mClassifier.removeInstance(gesture.getID());
+
+        mChanged = true;
+    }
+
+    /**
+     * Remove a entry of gestures
+     * 
+     * @param entryName the entry name
+     */
+    public void removeEntireEntry(String entryName) {
+        mEntryName2gestures.remove(entryName);
+        mClassifier.removeInstances(entryName);
+        mChanged = true;
+    }
+
+    /**
+     * Get all the gestures of an entry
+     * 
+     * @param entryName
+     * @return the list of gestures that is under this name
+     */
+    @SuppressWarnings("unchecked")
+    public ArrayList<Gesture> getGestures(String entryName) {
+        ArrayList<Gesture> gestures = mEntryName2gestures.get(entryName);
+        if (gestures != null) {
+            return (ArrayList<Gesture>)gestures.clone();
+        } else {
+            return null;
+        }
+    }
+
+    /**
+     * Save the gesture library
+     */
+    public void save() {
+        if (!mChanged)
+            return;
+
+        try {
+            File file = new File(mGestureFileName);
+            if (!file.getParentFile().exists()) {
+                file.getParentFile().mkdirs();
+            }
+            if (Config.DEBUG) {
+                Log.v(LOGTAG, "Save to " + mGestureFileName);
+            }
+            BufferedOutputStream outputStream = new BufferedOutputStream(new FileOutputStream(
+                    mGestureFileName), GestureConstants.IO_BUFFER_SIZE);
+
+            PrintWriter writer = new PrintWriter(outputStream);
+            XmlSerializer serializer = Xml.newSerializer();
+            serializer.setOutput(writer);
+            serializer.startDocument(Encoding.ISO_8859_1.name(), null);
+            serializer.startTag(NAMESPACE, GestureConstants.XML_TAG_LIBRARY);
+            HashMap<String, ArrayList<Gesture>> maps = mEntryName2gestures;
+            Iterator<String> it = maps.keySet().iterator();
+            while (it.hasNext()) {
+                String key = it.next();
+                ArrayList<Gesture> examples = maps.get(key);
+                // save an entry
+                serializer.startTag(NAMESPACE, GestureConstants.XML_TAG_ENTRY);
+                serializer.attribute(NAMESPACE, GestureConstants.XML_TAG_NAME, key);
+                int count = examples.size();
+                for (int i = 0; i < count; i++) {
+                    Gesture gesture = examples.get(i);
+                    // save each gesture in the entry
+                    gesture.toXML(NAMESPACE, serializer);
+                }
+                serializer.endTag(NAMESPACE, GestureConstants.XML_TAG_ENTRY);
+            }
+            serializer.endTag(NAMESPACE, GestureConstants.XML_TAG_LIBRARY);
+            serializer.endDocument();
+            serializer.flush();
+            writer.close();
+            outputStream.close();
+            mChanged = false;
+        } catch (IOException ex) {
+            Log.d(LOGTAG, "Failed to save gestures:", ex);
+        }
+    }
+
+    /**
+     * Load the gesture library
+     */
+    public void load() {
+        File file = new File(mGestureFileName);
+        if (file.exists()) {
+            try {
+                if (Config.DEBUG) {
+                    Log.v(LOGTAG, "Load from " + mGestureFileName);
+                }
+                BufferedInputStream in = new BufferedInputStream(new FileInputStream(
+                        mGestureFileName), GestureConstants.IO_BUFFER_SIZE);
+                Xml.parse(in, Encoding.ISO_8859_1, new CompactInkHandler());
+                in.close();
+            } catch (SAXException ex) {
+                Log.d(LOGTAG, "Failed to load gestures:", ex);
+            } catch (IOException ex) {
+                Log.d(LOGTAG, "Failed to load gestures:", ex);
+            }
+        }
+    }
+
+    private class CompactInkHandler implements ContentHandler {
+        Gesture currentGesture = null;
+
+        StringBuilder buffer = new StringBuilder(GestureConstants.STROKE_STRING_BUFFER_SIZE);
+
+        String entryName;
+
+        ArrayList<Gesture> gestures;
+
+        CompactInkHandler() {
+        }
+
+        public void characters(char[] ch, int start, int length) {
+            buffer.append(ch, start, length);
+        }
+
+        public void endDocument() {
+        }
+
+        public void endElement(String uri, String localName, String qName) {
+            if (localName.equals(GestureConstants.XML_TAG_ENTRY)) {
+                mEntryName2gestures.put(entryName, gestures);
+                gestures = null;
+            } else if (localName.equals(GestureConstants.XML_TAG_GESTURE)) {
+                gestures.add(currentGesture);
+                mClassifier.addInstance(Instance.createInstance(GestureLibrary.this,
+                        currentGesture, entryName));
+                currentGesture = null;
+            } else if (localName.equals(GestureConstants.XML_TAG_STROKE)) {
+                currentGesture.addStroke(GestureStroke.createFromString(buffer.toString()));
+                buffer.setLength(0);
+            }
+        }
+
+        public void endPrefixMapping(String prefix) {
+        }
+
+        public void ignorableWhitespace(char[] ch, int start, int length) {
+        }
+
+        public void processingInstruction(String target, String data) {
+        }
+
+        public void setDocumentLocator(Locator locator) {
+        }
+
+        public void skippedEntity(String name) {
+        }
+
+        public void startDocument() {
+        }
+
+        public void startElement(String uri, String localName, String qName, Attributes attributes) {
+            if (localName.equals(GestureConstants.XML_TAG_ENTRY)) {
+                gestures = new ArrayList<Gesture>();
+                entryName = attributes.getValue(NAMESPACE, GestureConstants.XML_TAG_NAME);
+            } else if (localName.equals(GestureConstants.XML_TAG_GESTURE)) {
+                currentGesture = new Gesture();
+                currentGesture.setID(Long.parseLong(attributes.getValue(NAMESPACE,
+                        GestureConstants.XML_TAG_ID)));
+            }
+        }
+
+        public void startPrefixMapping(String prefix, String uri) {
+        }
+    }
+}
diff --git a/tests/sketch/src/com/android/gesture/GestureListener.java b/tests/sketch/src/com/android/gesture/GestureListener.java
index ebb4149..9b50714 100755
--- a/tests/sketch/src/com/android/gesture/GestureListener.java
+++ b/tests/sketch/src/com/android/gesture/GestureListener.java
@@ -18,8 +18,13 @@ package com.android.gesture;
 
 import android.view.MotionEvent;
 
+/**
+ * An interface for processing gesture events
+ */
 public interface GestureListener {
-    public void onStartGesture(GesturePad pad, MotionEvent event);
-    public void onGesture(GesturePad pad, MotionEvent event);
-    public void onFinishGesture(GesturePad pad, MotionEvent event);
+    public void onStartGesture(GestureOverlay overlay, MotionEvent event);
+
+    public void onGesture(GestureOverlay overlay, MotionEvent event);
+
+    public void onFinishGesture(GestureOverlay overlay, MotionEvent event);
 }
diff --git a/tests/sketch/src/com/android/gesture/GestureOverlay.java b/tests/sketch/src/com/android/gesture/GestureOverlay.java
new file mode 100755
index 0000000..5cef8c8
--- /dev/null
+++ b/tests/sketch/src/com/android/gesture/GestureOverlay.java
@@ -0,0 +1,340 @@
+/*
+ * Copyright (C) 2008-2009 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.gesture;
+
+import android.content.Context;
+import android.graphics.Bitmap;
+import android.graphics.BlurMaskFilter;
+import android.graphics.Canvas;
+import android.graphics.Color;
+import android.graphics.Paint;
+import android.graphics.Path;
+import android.os.Handler;
+import android.util.AttributeSet;
+import android.view.MotionEvent;
+import android.view.View;
+import java.util.ArrayList;
+
+/**
+ * A (transparent) overlay for gesture input that can be placed on top of other
+ * widgets. The view can also be opaque.
+ */
+
+public class GestureOverlay extends View {
+
+    static final float TOUCH_TOLERANCE = 3;
+
+    private static final int TRANSPARENT_BACKGROUND = Color.argb(0, 0, 0, 0);
+
+    private static final float FADING_ALPHA_CHANGE = 0.03f;
+
+    private static final long FADING_REFRESHING_RATE = 100;
+
+    private static final int GESTURE_STROKE_WIDTH = 12;
+
+    private static final boolean GESTURE_RENDERING_ANTIALIAS = true;
+
+    private static final int BLUR_MASK_RADIUS = 1;
+
+    public static final int DEFAULT_GESTURE_COLOR = Color.argb(255, 255, 255, 0);
+
+    // double buffering
+    private Paint mGesturePaint;
+
+    private Bitmap mBitmap; // with transparent background
+
+    private Canvas mBitmapCanvas;
+
+    // for rendering immediate ink feedback
+    private Path mPath;
+
+    private float mX;
+
+    private float mY;
+
+    // current gesture
+    private Gesture mCurrentGesture = null;
+
+    // gesture event handlers
+    ArrayList<GestureListener> mGestureListeners = new ArrayList<GestureListener>();
+
+    private ArrayList<GesturePoint> mPointBuffer = null;
+
+    // fading out effect
+    private boolean mIsFadingOut = false;
+
+    private float mFadingAlpha = 1;
+
+    private Handler mHandler = new Handler();
+    
+    private Paint mBitmapPaint = new Paint(Paint.DITHER_FLAG);
+
+    private Runnable mFadingOut = new Runnable() {
+        public void run() {
+            if (mIsFadingOut) {
+                mFadingAlpha -= FADING_ALPHA_CHANGE;
+                if (mFadingAlpha <= 0) {
+                    mIsFadingOut = false;
+                    mPath = null;
+                    mCurrentGesture = null;
+                    mBitmap.eraseColor(TRANSPARENT_BACKGROUND);
+                } else {
+                    mHandler.postDelayed(this, FADING_REFRESHING_RATE);
+                }
+                invalidate();
+            }
+        }
+    };
+
+    public GestureOverlay(Context context) {
+        super(context);
+        init();
+    }
+
+    public GestureOverlay(Context context, AttributeSet attrs) {
+        super(context, attrs);
+        init();
+    }
+
+    public ArrayList<GesturePoint> getCurrentStroke() {
+        return mPointBuffer;
+    }
+
+    public Gesture getCurrentGesture() {
+        return mCurrentGesture;
+    }
+
+    /**
+     * Set Gesture color
+     * 
+     * @param color
+     */
+    public void setGestureColor(int color) {
+        mGesturePaint.setColor(color);
+        if (mCurrentGesture != null) {
+            mBitmap.eraseColor(TRANSPARENT_BACKGROUND);
+            mCurrentGesture.draw(mBitmapCanvas, mGesturePaint);
+        }
+    }
+
+    /**
+     * Set the gesture to be shown in the view
+     * 
+     * @param gesture
+     */
+    public void setCurrentGesture(Gesture gesture) {
+        if (mCurrentGesture != null) {
+            clear(false);
+        }
+
+        mCurrentGesture = gesture;
+
+        if (gesture != null) {
+            if (mBitmapCanvas != null) {
+                gesture.draw(mBitmapCanvas, mGesturePaint);
+                invalidate();
+            }
+        }
+    }
+
+    private void init() {
+        mGesturePaint = new Paint();
+        mGesturePaint.setAntiAlias(GESTURE_RENDERING_ANTIALIAS);
+        mGesturePaint.setColor(DEFAULT_GESTURE_COLOR);
+        mGesturePaint.setStyle(Paint.Style.STROKE);
+        mGesturePaint.setStrokeJoin(Paint.Join.ROUND);
+        mGesturePaint.setStrokeCap(Paint.Cap.ROUND);
+        mGesturePaint.setStrokeWidth(GESTURE_STROKE_WIDTH);
+        mGesturePaint
+                .setMaskFilter(new BlurMaskFilter(BLUR_MASK_RADIUS, BlurMaskFilter.Blur.NORMAL));
+
+        mPath = null;
+    }
+
+    @Override
+    protected void onSizeChanged(int width, int height, int oldWidth, int oldHeight) {
+        super.onSizeChanged(width, height, oldWidth, oldHeight);
+        if (width <= 0 || height <= 0) {
+            return;
+        }
+        int targetWidth = width > oldWidth ? width : oldWidth;
+        int targetHeight = height > oldHeight ? height : oldHeight;
+        mBitmap = Bitmap.createBitmap(targetWidth, targetHeight, Bitmap.Config.ARGB_8888);
+        mBitmapCanvas = new Canvas(mBitmap);
+        mBitmapCanvas.drawColor(TRANSPARENT_BACKGROUND);
+        if (mCurrentGesture != null) {
+            mCurrentGesture.draw(mBitmapCanvas, mGesturePaint);
+        }
+    }
+
+    public void addGestureListener(GestureListener listener) {
+        mGestureListeners.add(listener);
+    }
+
+    public void removeGestureListener(GestureListener listener) {
+        mGestureListeners.remove(listener);
+    }
+
+    @Override
+    protected void onDraw(Canvas canvas) {
+        super.onDraw(canvas);
+
+        // draw double buffer
+        if (mIsFadingOut) {
+            mBitmapPaint.setAlpha((int) (255 * mFadingAlpha));
+            canvas.drawBitmap(mBitmap, 0, 0, mBitmapPaint);
+        } else {
+            mBitmapPaint.setAlpha(255);
+            canvas.drawBitmap(mBitmap, 0, 0, mBitmapPaint);
+        }
+
+        // draw the current stroke
+        if (mPath != null) {
+            canvas.drawPath(mPath, mGesturePaint);
+        }
+    }
+
+    /**
+     * Clear up the overlay
+     * 
+     * @param fadeOut whether the gesture on the overlay should fade out
+     *            gradually or disappear immediately
+     */
+    public void clear(boolean fadeOut) {
+        if (fadeOut) {
+            mFadingAlpha = 1;
+            mIsFadingOut = true;
+            mHandler.removeCallbacks(mFadingOut);
+            mHandler.postDelayed(mFadingOut, FADING_REFRESHING_RATE);
+        } else {
+            mPath = null;
+            mCurrentGesture = null;
+            if (mBitmap != null) {
+                mBitmap.eraseColor(TRANSPARENT_BACKGROUND);
+                invalidate();
+            }
+        }
+    }
+    
+    public void cancelFadingOut() {
+        mIsFadingOut = false;
+        mHandler.removeCallbacks(mFadingOut);
+    }
+
+    @Override
+    public boolean onTouchEvent(MotionEvent event) {
+
+        if (!isEnabled()) {
+            return true;
+        }
+
+        switch (event.getAction()) {
+            case MotionEvent.ACTION_DOWN:
+                touch_start(event);
+                invalidate();
+                break;
+            case MotionEvent.ACTION_MOVE:
+                touch_move(event);
+                invalidate();
+                break;
+            case MotionEvent.ACTION_UP:
+                touch_up(event);
+                invalidate();
+                break;
+        }
+
+        return true;
+    }
+
+    private void touch_start(MotionEvent event) {
+        // pass the event to handlers
+        ArrayList<GestureListener> listeners = mGestureListeners;
+        int count = listeners.size();
+        for (int i = 0; i < count; i++) {
+            GestureListener listener = listeners.get(i);
+            listener.onStartGesture(this, event);
+        }
+        
+        // if there is fading out going on, stop it.
+        if (mIsFadingOut) {
+            mIsFadingOut = false;
+            mHandler.removeCallbacks(mFadingOut);
+            mBitmap.eraseColor(TRANSPARENT_BACKGROUND);
+            mCurrentGesture = null;
+        }
+
+        float x = event.getX();
+        float y = event.getY();
+
+        mX = x;
+        mY = y;
+
+        if (mCurrentGesture == null) {
+            mCurrentGesture = new Gesture();
+        }
+
+        mPointBuffer = new ArrayList<GesturePoint>();
+        mPointBuffer.add(new GesturePoint(x, y, event.getEventTime()));
+
+        mPath = new Path();
+        mPath.moveTo(x, y);
+    }
+
+    private void touch_move(MotionEvent event) {
+        float x = event.getX();
+        float y = event.getY();
+
+        float dx = Math.abs(x - mX);
+        float dy = Math.abs(y - mY);
+        if (dx >= TOUCH_TOLERANCE || dy >= TOUCH_TOLERANCE) {
+            mPath.quadTo(mX, mY, (x + mX) / 2, (y + mY) / 2);
+            mX = x;
+            mY = y;
+        }
+
+        mPointBuffer.add(new GesturePoint(x, y, event.getEventTime()));
+
+        // pass the event to handlers
+        ArrayList<GestureListener> listeners = mGestureListeners;
+        int count = listeners.size();
+        for (int i = 0; i < count; i++) {
+            GestureListener listener = listeners.get(i);
+            listener.onGesture(this, event);
+        }
+    }
+
+    private void touch_up(MotionEvent event) {
+        // add the stroke to the current gesture
+        mCurrentGesture.addStroke(new GestureStroke(mPointBuffer));
+        mPointBuffer = null;
+
+        // add the stroke to the double buffer
+        mGesturePaint.setDither(true);
+        mBitmapCanvas.drawPath(mPath, mGesturePaint);
+        mGesturePaint.setDither(false);
+        mPath = null;
+
+        // pass the event to handlers
+        ArrayList<GestureListener> listeners = mGestureListeners;
+        int count = listeners.size();
+        for (int i = 0; i < count; i++) {
+            GestureListener listener = listeners.get(i);
+            listener.onFinishGesture(this, event);
+        }
+    }
+
+}
diff --git a/tests/sketch/src/com/android/gesture/GesturePad.java b/tests/sketch/src/com/android/gesture/GesturePad.java
index 45a09e6..04dbe3a 100755
--- a/tests/sketch/src/com/android/gesture/GesturePad.java
+++ b/tests/sketch/src/com/android/gesture/GesturePad.java
@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2008 The Android Open Source Project
+ * Copyright (C) 2008-2009 Google Inc.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -18,64 +18,67 @@ package com.android.gesture;
 
 import android.content.Context;
 import android.graphics.Bitmap;
+import android.graphics.BlurMaskFilter;
 import android.graphics.Canvas;
 import android.graphics.Color;
-import android.graphics.Matrix;
 import android.graphics.Paint;
 import android.graphics.Path;
-import android.graphics.PointF;
 import android.os.Handler;
 import android.util.AttributeSet;
 import android.view.MotionEvent;
 import android.view.View;
 import java.util.ArrayList;
-import java.util.Iterator;
+
 
 /**
- * A view for rendering and processing gestures
+ * A (transparent) view for gesture input that can be placed on top of other
+ * widgets. The background of the view is customizable. 
+ * 
+ * @author liyang@google.com (Yang Li)
+ *
  */
 
 public class GesturePad extends View {
 
-    public static final float TOUCH_TOLERANCE = 4;
-    public static final int default_foreground = Color.argb(255, 255, 255, 0);
-    private int         background = Color.argb(0, 0, 0, 0);
-    private int         foreground = default_foreground;
-    private int         uncertain_foreground = Color.argb(55, 255, 255, 0);
-    private Bitmap      mBitmap;
-    private Canvas      mCanvas;
-    private Path        mPath;
-    private Paint       mBitmapPaint;
-    private Paint       mPaint;
-    private Paint       mDebugPaint;
-    private float       mX, mY;
-    private boolean     mEnableInput = true; 
-    private boolean     mEnableRendering = true;
-    private boolean     mCacheGesture = true;
-    private Gesture       mCurrentGesture = null;
-    ArrayList<GestureListener> mGestureListeners = new ArrayList<GestureListener>();
-
-    private boolean     mShouldFadingOut = true;
-    private boolean     mIsFadingOut = false;
-    private float       mFadingAlpha = 1;
+    private static final float TOUCH_TOLERANCE = 4;
+    public static final int DEFAULT_GESTURE_COLOR = Color.argb(255, 255, 255, 0);
     
-    private boolean     reconstruct = false;
+    // double buffering 
+    private Paint mGesturePaint;
+    private Bitmap mBitmap; // with transparent background
+    private Canvas mBitmapCanvas;
+
+    // for rendering immediate ink feedback
+    private Path mPath;
+    private float mX;
+    private float mY;
+
+    // current gesture
+    private Gesture mCurrentGesture = null;
     
-    private ArrayList<Path> debug = new ArrayList<Path>();
+    // gesture event handlers
+    ArrayList<GestureListener> mGestureListeners =
+                                new ArrayList<GestureListener>();
+    private ArrayList<GesturePoint> mPointBuffer = null;
+
+    // fading out effect
+    private boolean mIsFadingOut = false;
+    private float mFadingAlpha = 1;
     private Handler mHandler = new Handler();
-    
     private Runnable mFadingOut = new Runnable() {
-      public void run() {
-          mFadingAlpha -= 0.03f;
-          if (mFadingAlpha <= 0) {
-              mIsFadingOut = false;
-              mPath.reset();
-          } else {
-              mHandler.postDelayed(this, 100);
-          }
-          invalidate();
-      }
-   };
+        public void run() {
+            mFadingAlpha -= 0.03f;
+            if (mFadingAlpha <= 0) {
+                mIsFadingOut = false;
+                mPath = null;
+                mCurrentGesture = null;
+                mBitmap.eraseColor(Color.argb(0, 0, 0, 0));
+            } else {
+                mHandler.postDelayed(this, 100);
+            }
+            invalidate();
+        }
+    };
 
     public GesturePad(Context context) {
         super(context);
@@ -87,82 +90,76 @@ public class GesturePad extends View {
         init();
     }
     
-    public boolean isEnableRendering() {
-        return this.mEnableRendering;
+    public ArrayList<GesturePoint> getCurrentStroke() {
+        return this.mPointBuffer;
     }
     
     public Gesture getCurrentGesture() {
         return mCurrentGesture;
     }
     
-    public Paint getPaint() {
-        return mPaint;
-    }
-    
-    public void setColor(int c) {
-        this.foreground = c;
-    }
-    
-    public void setFadingAlpha(float f) {
-        mFadingAlpha = f;
+    /**
+     * Set Gesture color
+     * @param c
+     */
+    public void setGestureColor(int c) {
+        this.mGesturePaint.setColor(c);
+        if (mCurrentGesture != null) {
+            mBitmap.eraseColor(Color.argb(0, 0, 0, 0));
+            mCurrentGesture.draw(mBitmapCanvas, mGesturePaint);
+        }
     }
     
-    public void setCurrentGesture(Gesture stk) {
-        this.mCurrentGesture = stk;
-        reconstruct = true;
+    /**
+     * Set the gesture to be shown in the view
+     * @param gesture
+     */
+    public void setCurrentGesture(Gesture gesture) {
+        if (this.mCurrentGesture != null) {
+            clear(false);
+        }
+        
+        this.mCurrentGesture = gesture;
+        
+        if (this.mCurrentGesture != null) {
+            if (mBitmapCanvas != null) {
+                this.mCurrentGesture.draw(mBitmapCanvas, mGesturePaint);
+                this.invalidate();
+            }
+        }
     }
     
     private void init() {
-        mDebugPaint = new Paint();
-        mDebugPaint.setColor(Color.WHITE);
-        mDebugPaint.setStrokeWidth(4);
-        mDebugPaint.setAntiAlias(true);
-        mDebugPaint.setStyle(Paint.Style.STROKE);
-        
-        mPaint = new Paint();
-        mPaint.setAntiAlias(true);
-        mPaint.setDither(true);
-        mPaint.setColor(foreground);
-        mPaint.setStyle(Paint.Style.STROKE);
-        mPaint.setStrokeJoin(Paint.Join.ROUND);
-        mPaint.setStrokeCap(Paint.Cap.ROUND);
-        mPaint.setStrokeWidth(12);
+        mGesturePaint = new Paint();
+        mGesturePaint.setAntiAlias(true);
+        mGesturePaint.setDither(true);
+        mGesturePaint.setColor(DEFAULT_GESTURE_COLOR);
+        mGesturePaint.setStyle(Paint.Style.STROKE);
+        mGesturePaint.setStrokeJoin(Paint.Join.ROUND);
+        mGesturePaint.setStrokeCap(Paint.Cap.ROUND);
+        mGesturePaint.setStrokeWidth(12);
+        mGesturePaint.setMaskFilter(
+            new BlurMaskFilter(1, BlurMaskFilter.Blur.NORMAL));
         
-        mBitmapPaint = new Paint(Paint.DITHER_FLAG);
-        mPath = new Path();
-        
-        reconstruct = false;
-    }
-
-    public void cacheGesture(boolean b) {
-        mCacheGesture = b;
-    }
-      
-    public void enableRendering(boolean b) {
-        mEnableRendering = b;
+        mPath = null;
     }
-  
     
     @Override
     protected void onSizeChanged(int w, int h, int oldw, int oldh) {
         // TODO Auto-generated method stub
         super.onSizeChanged(w, h, oldw, oldh);
-        
-        if (w <=0 || h <=0)
+        if (w <= 0 || h <= 0) {
             return;
-        
-        int width = w>oldw? w : oldw;
-        int height = h>oldh? h : oldh;
-        Bitmap newBitmap = Bitmap.createBitmap(width, height, Bitmap.Config.ARGB_8888);
-        mCanvas = new Canvas(newBitmap);
-        
-        if (mBitmap != null) {
-            mCanvas.drawColor(background);
-            mCanvas.drawBitmap(mBitmap, 0, 0, mBitmapPaint);
-            mCanvas.drawPath(mPath, mPaint);
         }
-        
-        mBitmap = newBitmap;
+        int width = w > oldw? w : oldw;
+        int height = h > oldh? h : oldh;
+        mBitmap = Bitmap.createBitmap(
+            width, height, Bitmap.Config.ARGB_8888);
+        mBitmapCanvas = new Canvas(mBitmap);
+        mBitmapCanvas.drawColor(Color.argb(0, 0, 0, 0));
+        if (mCurrentGesture != null) {
+            mCurrentGesture.draw(mBitmapCanvas, mGesturePaint);
+        }
     }
 
     public void addGestureListener(GestureListener l) {
@@ -175,111 +172,50 @@ public class GesturePad extends View {
   
     @Override
     protected void onDraw(Canvas canvas) {
-        canvas.drawColor(background);
-        
-        if (mCacheGesture)
-            canvas.drawBitmap(mBitmap, 0, 0, mBitmapPaint);
-        
+        super.onDraw(canvas);
+
+        // draw double buffer
+        Paint paint = new Paint(Paint.DITHER_FLAG);
         if (mIsFadingOut) {
-            int color = foreground;
-            int alpha = (int)(Color.alpha(color) * mFadingAlpha);
-            mPaint.setColor(Color.argb(alpha, 
-                Color.red(color), 
-                Color.green(color), 
-                Color.blue(color)));
-        } else if (mEnableRendering == false) {
-            mPaint.setColor(uncertain_foreground);
+            paint.setAlpha((int)(255 * mFadingAlpha));
+            canvas.drawBitmap(mBitmap, 0, 0, paint);
         } else {
-            mPaint.setColor(foreground);
-        }
-        
-        if (reconstruct) {
-            
-            if (this.mCurrentGesture != null) {
-                float xedge = 30;
-                float yedge = 30;
-                float w = this.getWidth() - 2 * xedge;
-                float h = this.getHeight() - 2 * yedge;
-                float sx =  w / this.mCurrentGesture.getBBX().width();
-                float sy = h / mCurrentGesture.getBBX().height();
-                float scale = sx>sy?sy:sx;
-                convertFromStroke(mCurrentGesture);
-                Matrix matrix = new Matrix();
-                matrix.preTranslate(-mCurrentGesture.getBBX().centerX(), -mCurrentGesture.getBBX().centerY());
-                matrix.postScale(scale, scale);
-                matrix.postTranslate(this.getWidth()/2, this.getHeight()/2);
-                this.mPath.transform(matrix);
-            } else {
-                mPath.reset();
-            }
-            
-            reconstruct = false;
+            canvas.drawBitmap(mBitmap, 0, 0, paint);
         }
         
-        canvas.drawPath(mPath, mPaint);
-        
-        Iterator<Path> it = debug.iterator();
-        while (it.hasNext()) {
-            Path path = it.next();
-            canvas.drawPath(path, mDebugPaint);
+        // draw the current stroke
+        if (mPath != null) {
+            canvas.drawPath(mPath, mGesturePaint);
         }
     }
-    
-    public void clearDebugPath() {
-        debug.clear();
-    }
-    
-    public void addDebugPath(Path path) {
-        debug.add(path);
-    }
-    
-    public void addDebugPath(ArrayList<Path> paths) {
-        debug.addAll(paths);
-    }
-    
-    public void clear() {
-        mPath = new Path();
-        this.mCurrentGesture = null;
-        mCanvas.drawColor(background);
-        this.invalidate();
-    }
-    
-    private void convertFromStroke(Gesture stk) {
-        mPath = null;
-        Iterator it = stk.getPoints().iterator();
-        while (it.hasNext()) {
-            PointF p = (PointF) it.next();
-            if (mPath == null) {
-                mPath = new Path();
-                mPath.moveTo(p.x, p.y);
-                mX = p.x;
-                mY = p.y;
-            } else {
-                float dx = Math.abs(p.x - mX);
-                float dy = Math.abs(p.y - mY);
-                if (dx >= TOUCH_TOLERANCE || dy >= TOUCH_TOLERANCE) {
-                    mPath.quadTo(mX, mY, (p.x + mX)/2, (p.y + mY)/2);
-                    mX = p.x;
-                    mY = p.y;
-                }
+
+    /**
+     * Clear up the gesture pad
+     * @param fadeOut whether the gesture on the pad should fade out gradually
+     * or disappear immediately
+     */
+    public void clear(boolean fadeOut) {
+        if (fadeOut) {
+            mFadingAlpha = 1;
+            mIsFadingOut = true;
+            mHandler.removeCallbacks(mFadingOut);
+            mHandler.postDelayed(mFadingOut, 100);
+        } else {
+            mPath = null;
+            this.mCurrentGesture = null;
+            if (mBitmap != null) {
+                mBitmap.eraseColor(Color.argb(0, 0, 0, 0));
+                this.invalidate();
             }
         }
-        mPath.lineTo(mX, mY);
-    }
-    
-    public void setEnableInput(boolean b) {
-        mEnableInput = b;
-    }
-    
-    public boolean isEnableInput() {
-        return mEnableInput;
     }
     
     @Override
     public boolean onTouchEvent(MotionEvent event) {
       
-        if(mEnableInput == false) 
+        if(this.isEnabled() == false) { 
             return true;
+        }
         
         switch (event.getAction()) {
             case MotionEvent.ACTION_DOWN:
@@ -295,28 +231,41 @@ public class GesturePad extends View {
                 invalidate();
                 break;
         }
+        
         return true;
     }
     
     private void touch_start(MotionEvent event) {
-        mIsFadingOut = false;
-        mHandler.removeCallbacks(mFadingOut);
+        // if there is fading-out effect, stop it.
+        if (mIsFadingOut) {
+            mIsFadingOut = false;
+            mHandler.removeCallbacks(mFadingOut);
+            mBitmap.eraseColor(Color.argb(0, 0, 0, 0));
+            this.mCurrentGesture = null;
+        }
       
         float x = event.getX();
         float y = event.getY();
 
-        mCurrentGesture = new Gesture();
-        mCurrentGesture.addPoint(x, y);
-        
-        mPath.reset();
-        mPath.moveTo(x, y);
         mX = x;
         mY = y;
         
-        Iterator<GestureListener> it = mGestureListeners.iterator();
-        while (it.hasNext()) {
-            it.next().onStartGesture(this, event);
+        // pass the event to handlers
+        int count = mGestureListeners.size();
+        for (int i = 0; i < count; i++) {
+            GestureListener listener = mGestureListeners.get(i);
+            listener.onStartGesture(this, event);
         }
+
+        if (mCurrentGesture == null) {
+            mCurrentGesture = new Gesture();
+        }
+        
+        mPointBuffer = new ArrayList<GesturePoint>();
+        mPointBuffer.add(new GesturePoint(x, y, event.getEventTime()));
+
+        mPath = new Path();
+        mPath.moveTo(x, y);
     }
     
     private void touch_move(MotionEvent event) {
@@ -331,41 +280,32 @@ public class GesturePad extends View {
             mY = y;
         }
         
-        mCurrentGesture.addPoint(x, y);
-        
-        Iterator<GestureListener> it = mGestureListeners.iterator();
-        while (it.hasNext()) {
-            it.next().onGesture(this, event);
+        mPointBuffer.add(new GesturePoint(x, y, event.getEventTime()));
+
+        // pass the event to handlers
+        int count = mGestureListeners.size();
+        for (int i = 0; i < count; i++) {
+            GestureListener listener = mGestureListeners.get(i);
+            listener.onGesture(this, event);
         }
     }
-    
-    public void setFadingOut(boolean b) {
-        mShouldFadingOut = b;
-        mIsFadingOut = false;
-    }
-    
-    public boolean shouldFadingOut() {
-        return mShouldFadingOut;
-    }
+
     
     private void touch_up(MotionEvent event) {
-        mPath.lineTo(mX, mY);
-        
-        if (mCacheGesture)
-            mCanvas.drawPath(mPath, mPaint);
-        
-        // kill this so we don't double draw
-        if (shouldFadingOut()) {
-            mFadingAlpha = 1;
-            mIsFadingOut = true;
-            mHandler.removeCallbacks(mFadingOut);
-            mHandler.postDelayed(mFadingOut, 100);
-        }
+        // add the stroke to the current gesture
+        mCurrentGesture.addStroke(new GestureStroke(mPointBuffer));
+        mPointBuffer = null;
+
+        // add the stroke to the double buffer
+        mBitmapCanvas.drawPath(mPath, mGesturePaint);
+        mPath = null;
         
-        Iterator<GestureListener> it = mGestureListeners.iterator();
-        while (it.hasNext()) {
-            it.next().onFinishGesture(this, event);
+        // pass the event to handlers
+        int count = mGestureListeners.size();
+        for (int i = 0; i < count; i++) {
+            GestureListener listener = mGestureListeners.get(i);
+            listener.onFinishGesture(this, event);
         }
     }
-
+    
 }
diff --git a/tests/sketch/src/com/android/gesture/GesturePoint.java b/tests/sketch/src/com/android/gesture/GesturePoint.java
new file mode 100644
index 0000000..d06eff47
--- /dev/null
+++ b/tests/sketch/src/com/android/gesture/GesturePoint.java
@@ -0,0 +1,35 @@
+/*
+ * Copyright (C) 2008-2009 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.gesture;
+
+/**
+ * A timed point of a gesture stroke
+ */
+
+public class GesturePoint {
+    public final float xpos;
+
+    public final float ypos;
+
+    public final long timestamp;
+
+    public GesturePoint(float x, float y, long t) {
+        xpos = x;
+        ypos = y;
+        timestamp = t;
+    }
+}
diff --git a/tests/sketch/src/com/android/gesture/GestureProcessor.java b/tests/sketch/src/com/android/gesture/GestureProcessor.java
new file mode 100644
index 0000000..feddead
--- /dev/null
+++ b/tests/sketch/src/com/android/gesture/GestureProcessor.java
@@ -0,0 +1,128 @@
+/*
+ * Copyright (C) 2008-2009 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.gesture;
+
+import android.graphics.Color;
+import android.view.MotionEvent;
+import android.view.View;
+
+import java.util.ArrayList;
+
+public class GestureProcessor implements GestureListener {
+
+    public static final int SINGLE_STROKE = 0;
+
+    public static final int MULTIPLE_STROKE = 1;
+
+    private static final float STROKE_LENGTH_THRESHOLD = 100;
+
+    private static final float SQUARENESS_THRESHOLD = 0.24f;
+
+    private static final int UNCERTAIN_GESTURE_COLOR = Color.argb(60, 255, 255, 0);
+
+    private boolean mIsGesturing = false;
+
+    private float mTotalLength;
+
+    private float mX, mY;
+
+    private View mModel;
+
+    private int mGestureType = SINGLE_STROKE;
+
+    private ArrayList<GestureActionListener> mActionListeners = new ArrayList<GestureActionListener>();
+
+    public GestureProcessor(View model) {
+        mModel = model;
+    }
+
+    /**
+     * 
+     * @param type SINGLE_STROKE or MULTIPLE_STROKE
+     */
+    public void setGestureType(int type) {
+        mGestureType = type;
+    }
+
+    public void onStartGesture(GestureOverlay overlay, MotionEvent event) {
+        if (mGestureType == MULTIPLE_STROKE) {
+            overlay.cancelFadingOut();
+        }
+        mX = event.getX();
+        mY = event.getY();
+        mTotalLength = 0;
+        mIsGesturing = false;
+        if (mGestureType == SINGLE_STROKE || overlay.getCurrentGesture() == null
+                || overlay.getCurrentGesture().getStrokesCount() == 0) {
+            overlay.setGestureColor(UNCERTAIN_GESTURE_COLOR);
+        }
+        mModel.dispatchTouchEvent(event);
+    }
+
+    public void onGesture(GestureOverlay overlay, MotionEvent event) {
+        if (mIsGesturing) {
+            return;
+        }
+        float x = event.getX();
+        float y = event.getY();
+        float dx = x - mX;
+        float dy = y - mY;
+        mTotalLength += (float)Math.sqrt(dx * dx + dy * dy);
+        mX = x;
+        mY = y;
+
+        if (mTotalLength > STROKE_LENGTH_THRESHOLD) {
+            OrientedBoundingBox bbx = GestureUtils.computeOrientedBBX(overlay.getCurrentStroke());
+            if (bbx.squareness > SQUARENESS_THRESHOLD) {
+                mIsGesturing = true;
+                overlay.setGestureColor(GestureOverlay.DEFAULT_GESTURE_COLOR);
+                event = MotionEvent.obtain(event.getDownTime(), System.currentTimeMillis(),
+                        MotionEvent.ACTION_UP, x, y, event.getPressure(), event.getSize(), event
+                                .getMetaState(), event.getXPrecision(), event.getYPrecision(),
+                        event.getDeviceId(), event.getEdgeFlags());
+            }
+        }
+        mModel.dispatchTouchEvent(event);
+    }
+
+    public void onFinishGesture(GestureOverlay overlay, MotionEvent event) {
+        if (mIsGesturing) {
+            overlay.clear(true);
+            ArrayList<GestureActionListener> listeners = mActionListeners;
+            int count = listeners.size();
+            for (int i = 0; i < count; i++) {
+                GestureActionListener listener = listeners.get(i);
+                listener.onGesturePerformed(overlay, overlay.getCurrentGesture());
+            }
+        } else {
+            mModel.dispatchTouchEvent(event);
+            overlay.clear(false);
+        }
+    }
+
+    public void addGestureActionListener(GestureActionListener listener) {
+        mActionListeners.add(listener);
+    }
+
+    public void removeGestureActionListener(GestureActionListener listener) {
+        mActionListeners.remove(listener);
+    }
+
+    public boolean isGesturing() {
+        return mIsGesturing;
+    }
+}
diff --git a/tests/sketch/src/com/android/gesture/GestureStroke.java b/tests/sketch/src/com/android/gesture/GestureStroke.java
new file mode 100644
index 0000000..b1081e5
--- /dev/null
+++ b/tests/sketch/src/com/android/gesture/GestureStroke.java
@@ -0,0 +1,244 @@
+/*
+ * Copyright (C) 2008-2009 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.gesture;
+
+import android.graphics.Canvas;
+import android.graphics.Matrix;
+import android.graphics.Paint;
+import android.graphics.Path;
+import android.graphics.RectF;
+
+import org.xmlpull.v1.XmlSerializer;
+
+import java.io.IOException;
+import java.util.ArrayList;
+
+/**
+ * A gesture stroke started on a touch down and ended on a touch up.
+ */
+public class GestureStroke {
+    public final RectF boundingBox;
+
+    public final float length;
+
+    public final float[] xPoints;
+
+    public final float[] yPoints;
+
+    public final long[] timestamps;
+
+    private Path mCachedPath;
+
+    /**
+     * Construct a gesture stroke from a list of gesture points
+     * 
+     * @param pts
+     */
+    public GestureStroke(ArrayList<GesturePoint> pts) {
+        xPoints = new float[pts.size()];
+        yPoints = new float[pts.size()];
+        timestamps = new long[pts.size()];
+
+        RectF bx = null;
+        float len = 0;
+        int index = 0;
+        int count = pts.size();
+        float[] xpts = xPoints;
+        float[] ypts = yPoints;
+        long[] times = timestamps;
+
+        for (int i = 0; i < count; i++) {
+            GesturePoint p = pts.get(i);
+            xpts[index] = p.xpos;
+            ypts[index] = p.ypos;
+            times[index] = p.timestamp;
+
+            if (bx == null) {
+                bx = new RectF();
+                bx.top = p.ypos;
+                bx.left = p.xpos;
+                bx.right = p.xpos;
+                bx.bottom = p.ypos;
+                len = 0;
+            } else {
+                len += Math.sqrt(Math.pow(p.xpos - xpts[index - 1], 2)
+                        + Math.pow(p.ypos - ypts[index - 1], 2));
+                bx.union(p.xpos, p.ypos);
+            }
+            index++;
+        }
+
+        boundingBox = bx;
+        length = len;
+    }
+
+    /**
+     * Draw the gesture with a given canvas and paint
+     * 
+     * @param canvas
+     */
+    void draw(Canvas canvas, Paint paint) {
+        if (mCachedPath == null) {
+            float[] xpts = xPoints;
+            float[] ypts = yPoints;
+            int count = xpts.length;
+            Path path = null;
+            float mX = 0, mY = 0;
+            for (int i = 0; i < count; i++) {
+                float x = xpts[i];
+                float y = ypts[i];
+                if (path == null) {
+                    path = new Path();
+                    path.moveTo(x, y);
+                    mX = x;
+                    mY = y;
+                } else {
+                    float dx = Math.abs(x - mX);
+                    float dy = Math.abs(y - mY);
+                    if (dx >= 3 || dy >= 3) {
+                        path.quadTo(mX, mY, (x + mX) / 2, (y + mY) / 2);
+                        mX = x;
+                        mY = y;
+                    }
+                }
+            }
+
+            mCachedPath = path;
+        }
+
+        canvas.drawPath(mCachedPath, paint);
+    }
+
+    /**
+     * Convert the stroke to a Path based on the number of points
+     * 
+     * @param width the width of the bounding box of the target path
+     * @param height the height of the bounding box of the target path
+     * @param numSample the number of points needed
+     * @return the path
+     */
+    public Path toPath(float width, float height, int numSample) {
+        float[] pts = GestureUtils.sequentialFeaturize(this, numSample);
+        RectF rect = boundingBox;
+        float scale = height / rect.height();
+        Matrix matrix = new Matrix();
+        matrix.setTranslate(-rect.left, -rect.top);
+        Matrix scaleMatrix = new Matrix();
+        scaleMatrix.setScale(scale, scale);
+        matrix.postConcat(scaleMatrix);
+        Matrix translate = new Matrix();
+        matrix.postConcat(translate);
+        matrix.mapPoints(pts);
+
+        Path path = null;
+        float mX = 0;
+        float mY = 0;
+        int count = pts.length;
+        for (int i = 0; i < count; i += 2) {
+            float x = pts[i];
+            float y = pts[i + 1];
+            if (path == null) {
+                path = new Path();
+                path.moveTo(x, y);
+                mX = x;
+                mY = y;
+            } else {
+                float dx = Math.abs(x - mX);
+                float dy = Math.abs(y - mY);
+                if (dx >= GestureOverlay.TOUCH_TOLERANCE || dy >= GestureOverlay.TOUCH_TOLERANCE) {
+                    path.quadTo(mX, mY, (x + mX) / 2, (y + mY) / 2);
+                    mX = x;
+                    mY = y;
+                }
+            }
+        }
+        return path;
+    }
+
+    /**
+     * Save the gesture stroke as XML
+     * 
+     * @param namespace
+     * @param serializer
+     * @throws IOException
+     */
+    void toXML(String namespace, XmlSerializer serializer) throws IOException {
+        serializer.startTag(namespace, GestureConstants.XML_TAG_STROKE);
+        serializer.text(toString());
+        serializer.endTag(namespace, GestureConstants.XML_TAG_STROKE);
+    }
+
+    /**
+     * Create a gesture stroke from a string
+     * 
+     * @param str
+     * @return the gesture stroke
+     */
+    public static GestureStroke createFromString(String str) {
+        ArrayList<GesturePoint> points = new ArrayList<GesturePoint>(
+                GestureConstants.STROKE_POINT_BUFFER_SIZE);
+        int endIndex;
+        int startIndex = 0;
+        while ((endIndex = str.indexOf(GestureConstants.STRING_STROKE_DELIIMITER, startIndex + 1)) != -1) {
+
+            // parse x
+            String token = str.substring(startIndex, endIndex);
+            float x = Float.parseFloat(token);
+            startIndex = endIndex + 1;
+
+            // parse y
+            endIndex = str.indexOf(GestureConstants.STRING_STROKE_DELIIMITER, startIndex + 1);
+            token = str.substring(startIndex, endIndex);
+            float y = Float.parseFloat(token);
+            startIndex = endIndex + 1;
+
+            // parse t
+            endIndex = str.indexOf(GestureConstants.STRING_STROKE_DELIIMITER, startIndex + 1);
+            token = str.substring(startIndex, endIndex);
+            long time = Long.parseLong(token);
+            startIndex = endIndex + 1;
+
+            points.add(new GesturePoint(x, y, time));
+        }
+        return new GestureStroke(points);
+    }
+
+    /**
+     * Convert the stroke to string
+     */
+    @Override
+    public String toString() {
+        StringBuilder str = new StringBuilder(GestureConstants.STROKE_STRING_BUFFER_SIZE);
+        float[] xpts = xPoints;
+        float[] ypts = yPoints;
+        long[] times = timestamps;
+        int count = xpts.length;
+        for (int i = 0; i < count; i++) {
+            str.append(xpts[i] + GestureConstants.STRING_STROKE_DELIIMITER + ypts[i]
+                    + GestureConstants.STRING_STROKE_DELIIMITER + times[i]
+                    + GestureConstants.STRING_STROKE_DELIIMITER);
+        }
+        return str.toString();
+    }
+
+    /**
+     * Invalidate the cached path that is used for rendering the stroke
+     */
+    public void invalidate() {
+        mCachedPath = null;
+    }
+}
diff --git a/tests/sketch/src/com/android/gesture/GestureUtils.java b/tests/sketch/src/com/android/gesture/GestureUtils.java
new file mode 100755
index 0000000..7c3237a
--- /dev/null
+++ b/tests/sketch/src/com/android/gesture/GestureUtils.java
@@ -0,0 +1,358 @@
+/*
+ * Copyright (C) 2008-2009 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.gesture;
+
+import android.graphics.RectF;
+
+import java.util.ArrayList;
+import java.util.Arrays;
+
+public class GestureUtils {
+
+    private static final int SEQUENCE_SAMPLE_SIZE = 16;
+
+    protected static float[] spatialFeaturize(Gesture gesture, int sampleSize) {
+        float[] sample = new float[sampleSize * sampleSize];
+        Arrays.fill(sample, 0);
+
+        RectF rect = gesture.getBoundingBox();
+        float sx = sampleSize / rect.width();
+        float sy = sampleSize / rect.height();
+        float scale = sx < sy ? sx : sy;
+        android.graphics.Matrix trans = new android.graphics.Matrix();
+        trans.setScale(scale, scale);
+        android.graphics.Matrix translate1 = new android.graphics.Matrix();
+        translate1.setTranslate(-rect.centerX(), -rect.centerY());
+        trans.preConcat(translate1);
+        android.graphics.Matrix translate2 = new android.graphics.Matrix();
+        translate2.setTranslate(sampleSize / 2, sampleSize / 2);
+        trans.postConcat(translate2);
+
+        ArrayList<GestureStroke> strokes = gesture.getStrokes();
+        int count = strokes.size();
+        int size;
+        for (int index = 0; index < count; index++) {
+            GestureStroke stroke = strokes.get(index);
+            float[] pts = sequentialFeaturize(stroke, SEQUENCE_SAMPLE_SIZE);
+            trans.mapPoints(pts);
+
+            size = pts.length;
+            for (int i = 0; i < size; i += 2) {
+                float x = pts[i];
+                int xFloor = (int) Math.floor(x);
+                int xCeiling = (int) Math.ceil(x);
+                float y = pts[i + 1];
+                int yFloor = (int) Math.floor(y);
+                int yCeiling = (int) Math.ceil(y);
+
+                if (yFloor >= 0 && yFloor < sampleSize && xFloor >= 0 && xFloor < sampleSize) {
+                    int pos = yFloor * sampleSize + xFloor;
+                    float value = (1 - x + xFloor) * (1 - y + yFloor);
+                    if (sample[pos] < value) {
+                        sample[pos] = value;
+                    }
+                }
+
+                if (yFloor >= 0 && yFloor < sampleSize && xCeiling >= 0 && xCeiling < sampleSize) {
+                    int pos = yFloor * sampleSize + xCeiling;
+                    float value = (1 - xCeiling + x) * (1 - y + yFloor);
+                    if (sample[pos] < value) {
+                        sample[pos] = value;
+                    }
+                }
+
+                if (yCeiling >= 0 && yCeiling < sampleSize && xFloor >= 0 && xFloor < sampleSize) {
+                    int pos = yCeiling * sampleSize + xFloor;
+                    float value = (1 - x + xFloor) * (1 - yCeiling + y);
+                    if (sample[pos] < value) {
+                        sample[pos] = value;
+                    }
+
+                }
+
+                if (yCeiling >= 0 && yCeiling < sampleSize && xCeiling >= 0
+                        && xCeiling < sampleSize) {
+                    int pos = yCeiling * sampleSize + xCeiling;
+                    float value = (1 - xCeiling + x) * (1 - yCeiling + y);
+                    if (sample[pos] < value) {
+                        sample[pos] = value;
+                    }
+                }
+            }
+        }
+
+        return sample;
+    }
+
+    /**
+     * Featurize a stroke into a vector of a given number of elements
+     * 
+     * @param stroke
+     * @param sampleSize
+     * @return a float array
+     */
+    protected static float[] sequentialFeaturize(GestureStroke stroke, int sampleSize) {
+        final float increment = stroke.length / (sampleSize - 1);
+        int vectorLength = sampleSize * 2;
+        float[] vector = new float[vectorLength];
+        float distanceSoFar = 0;
+        float[] xpts = stroke.xPoints;
+        float[] ypts = stroke.yPoints;
+        float lstPointX = xpts[0];
+        float lstPointY = ypts[0];
+        int index = 0;
+        float currentPointX = Float.MIN_VALUE;
+        float currentPointY = Float.MIN_VALUE;
+        vector[index] = lstPointX;
+        index++;
+        vector[index] = lstPointY;
+        index++;
+        int i = 0;
+        int count = xpts.length;
+        while (i < count) {
+            if (currentPointX == Float.MIN_VALUE) {
+                i++;
+                if (i >= count) {
+                    break;
+                }
+                currentPointX = xpts[i];
+                currentPointY = ypts[i];
+            }
+            float deltaX = currentPointX - lstPointX;
+            float deltaY = currentPointY - lstPointY;
+            float distance = (float) Math.sqrt(deltaX * deltaX + deltaY * deltaY);
+            if (distanceSoFar + distance >= increment) {
+                float ratio = (increment - distanceSoFar) / distance;
+                float nx = lstPointX + ratio * deltaX;
+                float ny = lstPointY + ratio * deltaY;
+                vector[index] = nx;
+                index++;
+                vector[index] = ny;
+                index++;
+                lstPointX = nx;
+                lstPointY = ny;
+                distanceSoFar = 0;
+            } else {
+                lstPointX = currentPointX;
+                lstPointY = currentPointY;
+                currentPointX = Float.MIN_VALUE;
+                currentPointY = Float.MIN_VALUE;
+                distanceSoFar += distance;
+            }
+        }
+
+        for (i = index; i < vectorLength; i += 2) {
+            vector[i] = lstPointX;
+            vector[i + 1] = lstPointY;
+        }
+        return vector;
+    }
+
+    /**
+     * Calculate the centroid 
+     * 
+     * @param points
+     * @return the centroid
+     */
+    public static float[] computeCentroid(float[] points) {
+        float centerX = 0;
+        float centerY = 0;
+        int count = points.length;
+        for (int i = 0; i < count; i++) {
+            centerX += points[i];
+            i++;
+            centerY += points[i];
+        }
+        float[] center = new float[2];
+        center[0] = 2 * centerX / count;
+        center[1] = 2 * centerY / count;
+
+        return center;
+    }
+
+    /**
+     * calculate the variance-covariance matrix, treat each point as a sample
+     * 
+     * @param points
+     * @return the covariance matrix
+     */
+    protected static double[][] computeCoVariance(float[] points) {
+        double[][] array = new double[2][2];
+        array[0][0] = 0;
+        array[0][1] = 0;
+        array[1][0] = 0;
+        array[1][1] = 0;
+        int count = points.length;
+        for (int i = 0; i < count; i++) {
+            float x = points[i];
+            i++;
+            float y = points[i];
+            array[0][0] += x * x;
+            array[0][1] += x * y;
+            array[1][0] = array[0][1];
+            array[1][1] += y * y;
+        }
+        array[0][0] /= (count / 2);
+        array[0][1] /= (count / 2);
+        array[1][0] /= (count / 2);
+        array[1][1] /= (count / 2);
+
+        return array;
+    }
+
+    public static float computeTotalLength(float[] points) {
+        float sum = 0;
+        int count = points.length - 4;
+        for (int i = 0; i < count; i += 2) {
+            float dx = points[i + 2] - points[i];
+            float dy = points[i + 3] - points[i + 1];
+            sum += Math.sqrt(dx * dx + dy * dy);
+        }
+        return sum;
+    }
+
+    public static double computeStraightness(float[] points) {
+        float totalLen = computeTotalLength(points);
+        float dx = points[2] - points[0];
+        float dy = points[3] - points[1];
+        return Math.sqrt(dx * dx + dy * dy) / totalLen;
+    }
+
+    public static double computeStraightness(float[] points, float totalLen) {
+        float dx = points[2] - points[0];
+        float dy = points[3] - points[1];
+        return Math.sqrt(dx * dx + dy * dy) / totalLen;
+    }
+
+    /**
+     * Calculate the squared Euclidean distance between two vectors
+     * 
+     * @param vector1
+     * @param vector2
+     * @return the distance
+     */
+    protected static double euclideanDistance(float[] vector1, float[] vector2) {
+        double squaredDistance = 0;
+        int size = vector1.length;
+        for (int i = 0; i < size; i++) {
+            float difference = vector1[i] - vector2[i];
+            squaredDistance += difference * difference;
+        }
+        return squaredDistance / size;
+    }
+
+    /**
+     * Calculate the cosine distance between two instances
+     * 
+     * @param in1
+     * @param in2
+     * @return the distance between 0 and Math.PI
+     */
+    protected static double cosineDistance(Instance in1, Instance in2) {
+        float sum = 0;
+        float[] vector1 = in1.vector;
+        float[] vector2 = in2.vector;
+        int len = vector1.length;
+        for (int i = 0; i < len; i++) {
+            sum += vector1[i] * vector2[i];
+        }
+        return Math.acos(sum / (in1.magnitude * in2.magnitude));
+    }
+
+    public static OrientedBoundingBox computeOrientedBBX(ArrayList<GesturePoint> pts) {
+        GestureStroke stroke = new GestureStroke(pts);
+        float[] points = sequentialFeaturize(stroke, SEQUENCE_SAMPLE_SIZE);
+        return computeOrientedBBX(points);
+    }
+
+    public static OrientedBoundingBox computeOrientedBBX(float[] points) {
+        float[] meanVector = computeCentroid(points);
+        return computeOrientedBBX(points, meanVector);
+    }
+
+    public static OrientedBoundingBox computeOrientedBBX(float[] points, float[] centroid) {
+
+        android.graphics.Matrix tr = new android.graphics.Matrix();
+        tr.setTranslate(-centroid[0], -centroid[1]);
+        tr.mapPoints(points);
+
+        double[][] array = computeCoVariance(points);
+        double[] targetVector = computeOrientation(array);
+
+        float angle;
+        if (targetVector[0] == 0 && targetVector[1] == 0) {
+            angle = -90;
+        } else { // -PI<alpha<PI
+            angle = (float) Math.atan2(targetVector[1], targetVector[0]);
+            angle = (float) (180 * angle / Math.PI);
+            android.graphics.Matrix trans = new android.graphics.Matrix();
+            trans.setRotate(-angle);
+            trans.mapPoints(points);
+        }
+
+        float minx = Float.MAX_VALUE;
+        float miny = Float.MAX_VALUE;
+        float maxx = Float.MIN_VALUE;
+        float maxy = Float.MIN_VALUE;
+        int count = points.length;
+        for (int i = 0; i < count; i++) {
+            if (points[i] < minx) {
+                minx = points[i];
+            }
+            if (points[i] > maxx) {
+                maxx = points[i];
+            }
+            i++;
+            if (points[i] < miny) {
+                miny = points[i];
+            }
+            if (points[i] > maxy) {
+                maxy = points[i];
+            }
+        }
+
+        OrientedBoundingBox bbx = new OrientedBoundingBox(angle, centroid[0], centroid[1], maxx
+                - minx, maxy - miny);
+        return bbx;
+    }
+
+    private static double[] computeOrientation(double[][] covarianceMatrix) {
+        double[] targetVector = new double[2];
+        if (covarianceMatrix[0][1] == 0 || covarianceMatrix[1][0] == 0) {
+            targetVector[0] = 1;
+            targetVector[1] = 0;
+        }
+
+        // lamda^2 + a * lamda + b = 0
+        double a = -covarianceMatrix[0][0] - covarianceMatrix[1][1];
+        double b = covarianceMatrix[0][0] * covarianceMatrix[1][1] - covarianceMatrix[0][1]
+                * covarianceMatrix[1][0];
+        double value = a / 2;
+        double rightside = Math.sqrt(Math.pow(value, 2) - b);
+        double lambda1 = -value + rightside;
+        double lambda2 = -value - rightside;
+        if (lambda1 == lambda2) {
+            targetVector[0] = 0;
+            targetVector[1] = 0;
+        } else {
+            double lambda = lambda1 > lambda2 ? lambda1 : lambda2;
+            targetVector[0] = 1;
+            targetVector[1] = (lambda - covarianceMatrix[0][0]) / covarianceMatrix[0][1];
+        }
+        return targetVector;
+    }
+}
diff --git a/tests/sketch/src/com/android/gesture/Instance.java b/tests/sketch/src/com/android/gesture/Instance.java
new file mode 100755
index 0000000..4eb10f9
--- /dev/null
+++ b/tests/sketch/src/com/android/gesture/Instance.java
@@ -0,0 +1,106 @@
+/*
+ * Copyright (C) 2008-2009 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.gesture;
+
+/**
+ * An instance represents a sample if the label is available or a query if the
+ * label is null.
+ */
+public class Instance {
+
+    private static final int SEQUENCE_SAMPLE_SIZE = 16;
+
+    private static final int PATCH_SAMPLE_SIZE = 8;
+
+    private final static float[] ORIENTATIONS = {
+            0, 45, 90, 135, 180, -0, -45, -90, -135, -180
+    };
+
+    // the feature vector
+    public final float[] vector;
+
+    // the label can be null
+    public final String label;
+
+    // the length of the vector
+    public final float magnitude;
+
+    // the id of the instance
+    public final long instanceID;
+
+    private Instance(long id, float[] sample, String sampleName) {
+        instanceID = id;
+        vector = sample;
+        label = sampleName;
+        float sum = 0;
+        int size = sample.length;
+        for (int i = 0; i < size; i++) {
+            sum += sample[i] * sample[i];
+        }
+        magnitude = (float) Math.sqrt(sum);
+    }
+
+    /**
+     * create a learning instance for a single stroke gesture
+     * 
+     * @param gesture
+     * @param label
+     * @return the instance
+     */
+    public static Instance createInstance(GestureLibrary gesturelib, Gesture gesture, String label) {
+        float[] pts;
+        if (gesturelib.getGestureType() == GestureLibrary.SEQUENCE_SENSITIVE) {
+            pts = sequenceSampler(gesturelib, gesture);
+        } else {
+            pts = spatialSampler(gesture);
+        }
+        return new Instance(gesture.getID(), pts, label);
+    }
+
+    private static float[] spatialSampler(Gesture gesture) {
+        float[] pts = GestureUtils.spatialFeaturize(gesture, PATCH_SAMPLE_SIZE);
+        return pts;
+    }
+
+    private static float[] sequenceSampler(GestureLibrary gesturelib, Gesture gesture) {
+        float[] pts = GestureUtils.sequentialFeaturize(gesture.getStrokes().get(0),
+                SEQUENCE_SAMPLE_SIZE);
+        float[] center = GestureUtils.computeCentroid(pts);
+        float orientation = (float) Math.atan2(pts[1] - center[1], pts[0] - center[0]);
+        orientation *= 180 / Math.PI;
+
+        float adjustment = -orientation;
+        if (gesturelib.getOrientationStyle() == GestureLibrary.ORIENTATION_SENSITIVE) {
+            int count = ORIENTATIONS.length;
+            for (int i = 0; i < count; i++) {
+                float delta = ORIENTATIONS[i] - orientation;
+                if (Math.abs(delta) < Math.abs(adjustment)) {
+                    adjustment = delta;
+                }
+            }
+        }
+
+        android.graphics.Matrix m = new android.graphics.Matrix();
+        m.setTranslate(-center[0], -center[1]);
+        android.graphics.Matrix rotation = new android.graphics.Matrix();
+        rotation.setRotate(adjustment);
+        m.postConcat(rotation);
+        m.mapPoints(pts);
+        return pts;
+    }
+
+}
diff --git a/tests/sketch/src/com/android/gesture/InstanceLearner.java b/tests/sketch/src/com/android/gesture/InstanceLearner.java
new file mode 100644
index 0000000..3bd875b
--- /dev/null
+++ b/tests/sketch/src/com/android/gesture/InstanceLearner.java
@@ -0,0 +1,105 @@
+/*
+ * Copyright (C) 2008-2009 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.gesture;
+
+import android.util.Config;
+import android.util.Log;
+
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.Comparator;
+import java.util.Iterator;
+import java.util.TreeMap;
+
+/**
+ * An implementation of an instance-based learner
+ */
+
+class InstanceLearner extends Learner {
+
+    private static final String LOGTAG = "InstanceLearner";
+
+    @Override
+    ArrayList<Prediction> classify(GestureLibrary lib, Instance instance) {
+        ArrayList<Prediction> predictions = new ArrayList<Prediction>();
+        ArrayList<Instance> instances = getInstances();
+        int count = instances.size();
+        TreeMap<String, Double> label2score = new TreeMap<String, Double>();
+        for (int i = 0; i < count; i++) {
+            Instance sample = instances.get(i);
+            if (sample.vector.length != instance.vector.length) {
+                continue;
+            }
+            double distance;
+            if (lib.getGestureType() == GestureLibrary.SEQUENCE_SENSITIVE) {
+                distance = GestureUtils.cosineDistance(sample, instance);
+            } else {
+                distance = GestureUtils.euclideanDistance(sample.vector, instance.vector);
+            }
+            double weight;
+            if (distance == 0) {
+                weight = Double.MAX_VALUE;
+            } else {
+                weight = 1 / distance;
+            }
+            Double score = label2score.get(sample.label);
+            if (score == null || weight > score) {
+                label2score.put(sample.label, weight);
+            }
+        }
+
+        double sum = 0;
+        Iterator<String> lableIterator = label2score.keySet().iterator();
+        while (lableIterator.hasNext()) {
+            String name = lableIterator.next();
+            double score = label2score.get(name);
+            sum += score;
+            predictions.add(new Prediction(name, score));
+        }
+
+        // normalize
+        Iterator<Prediction> predictionIterator = predictions.iterator();
+        while (predictionIterator.hasNext()) {
+            Prediction name = predictionIterator.next();
+            name.predictionScore /= sum;
+        }
+
+        Collections.sort(predictions, new Comparator<Prediction>() {
+            public int compare(Prediction object1, Prediction object2) {
+                double score1 = object1.predictionScore;
+                double score2 = object2.predictionScore;
+                if (score1 > score2) {
+                    return -1;
+                } else if (score1 < score2) {
+                    return 1;
+                } else {
+                    return 0;
+                }
+            }
+        });
+
+        if (Config.DEBUG) {
+            predictionIterator = predictions.iterator();
+            while (predictionIterator.hasNext()) {
+                Prediction name = predictionIterator.next();
+                Log.v(LOGTAG, "prediction [" + name.gestureName + " = " + name.predictionScore + "]");
+            }
+        }
+
+        return predictions;
+    }
+}
diff --git a/tests/sketch/src/com/android/gesture/Learner.java b/tests/sketch/src/com/android/gesture/Learner.java
new file mode 100755
index 0000000..63f3156
--- /dev/null
+++ b/tests/sketch/src/com/android/gesture/Learner.java
@@ -0,0 +1,82 @@
+/*
+ * Copyright (C) 2008-2009 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.gesture;
+
+import java.util.ArrayList;
+
+/**
+ * The abstract class of a gesture learner
+ */
+abstract class Learner {
+
+    private final ArrayList<Instance> mInstances = new ArrayList<Instance>();
+
+    /**
+     * Add an instance to the learner
+     * 
+     * @param instance
+     */
+    void addInstance(Instance instance) {
+        mInstances.add(instance);
+    }
+
+    /**
+     * Retrieve all the instances
+     * 
+     * @return instances
+     */
+    ArrayList<Instance> getInstances() {
+        return mInstances;
+    }
+
+    /**
+     * Remove an instance based on its id
+     * 
+     * @param id
+     */
+    void removeInstance(long id) {
+        ArrayList<Instance> instances = mInstances;
+        int count = instances.size();
+        for (int i = 0; i < count; i++) {
+            Instance instance = instances.get(i);
+            if (id == instance.instanceID) {
+                instances.remove(instance);
+                return;
+            }
+        }
+    }
+
+    /**
+     * Remove all the instances of a category
+     * 
+     * @param name the category name
+     */
+    void removeInstances(String name) {
+        ArrayList<Instance> toDelete = new ArrayList<Instance>();
+        ArrayList<Instance> instances = mInstances;
+        int count = instances.size();
+        for (int i = 0; i < count; i++) {
+            Instance instance = instances.get(i);
+            if (instance.label.equals(name)) {
+                toDelete.add(instance);
+            }
+        }
+        mInstances.removeAll(toDelete);
+    }
+
+    abstract ArrayList<Prediction> classify(GestureLibrary library, Instance instance);
+}
diff --git a/tests/sketch/src/com/android/gesture/OrientedBoundingBox.java b/tests/sketch/src/com/android/gesture/OrientedBoundingBox.java
new file mode 100644
index 0000000..fe1984c
--- /dev/null
+++ b/tests/sketch/src/com/android/gesture/OrientedBoundingBox.java
@@ -0,0 +1,81 @@
+/*
+ * Copyright (C) 2008-2009 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.gesture;
+
+import android.graphics.Matrix;
+import android.graphics.Path;
+
+/**
+ * An oriented bounding box
+ */
+public class OrientedBoundingBox {
+
+    public final float squareness;
+
+    public final float width;
+    public final float height;
+
+    public final float orientation; // -PI<alpha<PI
+
+    public final float centerX;
+    public final float centerY;
+
+    OrientedBoundingBox(float angle, float cx, float cy, float w, float h) {
+        orientation = angle;
+        width = w;
+        height = h;
+        centerX = cx;
+        centerY = cy;
+        float ratio = w / h;
+        if (ratio > 1) {
+            squareness = 1 / ratio;
+        } else {
+            squareness = ratio;
+        }
+    }
+
+    public Path toPath() {
+        Path path = new Path();
+        float[] point = new float[2];
+        point[0] = -width / 2;
+        point[1] = height / 2;
+        Matrix matrix = new Matrix();
+        matrix.setRotate(orientation);
+        matrix.postTranslate(centerX, centerY);
+        matrix.mapPoints(point);
+        path.moveTo(point[0], point[1]);
+
+        point[0] = -width / 2;
+        point[1] = -height / 2;
+        matrix.mapPoints(point);
+        path.lineTo(point[0], point[1]);
+
+        point[0] = width / 2;
+        point[1] = -height / 2;
+        matrix.mapPoints(point);
+        path.lineTo(point[0], point[1]);
+
+        point[0] = width / 2;
+        point[1] = height / 2;
+        matrix.mapPoints(point);
+        path.lineTo(point[0], point[1]);
+
+        path.close();
+
+        return path;
+    }
+}
diff --git a/tests/sketch/src/com/android/gesture/Prediction.java b/tests/sketch/src/com/android/gesture/Prediction.java
new file mode 100755
index 0000000..60cca8b
--- /dev/null
+++ b/tests/sketch/src/com/android/gesture/Prediction.java
@@ -0,0 +1,33 @@
+/*
+ * Copyright (C) 2008-2009 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.gesture;
+
+public class Prediction {
+    public final String gestureName;
+
+    public double predictionScore;
+
+    Prediction(String label, double score) {
+        gestureName = label;
+        predictionScore = score;
+    }
+
+    @Override
+    public String toString() {
+        return gestureName;
+    }
+}
diff --git a/tests/sketch/src/com/android/gesture/example/ContactAdapter.java b/tests/sketch/src/com/android/gesture/example/ContactAdapter.java
new file mode 100644
index 0000000..008a972
--- /dev/null
+++ b/tests/sketch/src/com/android/gesture/example/ContactAdapter.java
@@ -0,0 +1,100 @@
+/*
+ * Copyright (C) 2008-2009 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.gesture.example;
+
+import android.app.Activity;
+import android.view.LayoutInflater;
+import android.view.View;
+import android.view.ViewGroup;
+import android.widget.ArrayAdapter;
+import android.widget.TextView;
+
+import java.util.ArrayList;
+
+class ContactAdapter extends ArrayAdapter<ContactItem> {
+
+    private LayoutInflater mInflater;
+
+    public ContactAdapter(Activity activity, ArrayList<ContactItem> contacts) {
+        super(activity, 0, contacts);
+        mInflater = activity.getLayoutInflater();
+    }
+
+    @Override
+    public ContactItem getItem(int position) {
+        return super.getItem(position);
+    }
+
+    @Override
+    public long getItemId(int position) {
+        return getItem(position).itemID;
+    }
+
+    @Override
+    public View getView(int position, View convertView, ViewGroup parent) {
+        final ContactItem info = getItem(position);
+
+        View view = convertView;
+        if (view == null) {
+            view = mInflater.inflate(android.R.layout.simple_list_item_1, parent, false);
+            view.setTag(view.findViewById(android.R.id.text1));
+        }
+
+        final TextView textView = (TextView)view.getTag();
+        textView.setText(info.toString());
+
+        return view;
+    }
+
+    public int search(String query) {
+        if (query != null && query.length() > 0) {
+            int start = 0;
+            int end = getCount() - 1;
+            int index = binarySearch(query, start, end);
+            for (index = index - 1; index >= 0; index--) {
+                String str = getItem(index).toString().toLowerCase();
+                if (!str.startsWith(query)) {
+                    return index + 1;
+                }
+                if (index == 0) {
+                    return 0;
+                }
+            }
+            return -1;
+        } else {
+            return -1;
+        }
+    }
+
+    private int binarySearch(String prefix, int start, int end) {
+        if (start > end) {
+            return -1;
+        }
+        int mid = (start + end) / 2;
+        String str = getItem(mid).toString().toLowerCase();
+        if (prefix.compareTo(str) <= 0) {
+            if (str.startsWith(prefix)) {
+                return mid;
+            } else {
+                return binarySearch(prefix, start, mid - 1);
+            }
+        } else {
+            return binarySearch(prefix, mid + 1, end);
+        }
+    }
+
+}
diff --git a/tests/sketch/src/com/android/gesture/example/ContactItem.java b/tests/sketch/src/com/android/gesture/example/ContactItem.java
new file mode 100644
index 0000000..557c4d9
--- /dev/null
+++ b/tests/sketch/src/com/android/gesture/example/ContactItem.java
@@ -0,0 +1,34 @@
+/*
+ * Copyright (C) 2008-2009 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.gesture.example;
+
+
+class ContactItem {
+    final String itemName;
+
+    final long itemID;
+
+    public ContactItem(long id, String name) {
+        itemID = id;
+        itemName = name;
+    }
+
+    @Override
+    public String toString() {
+        return itemName;
+    }
+}
diff --git a/tests/sketch/src/com/android/gesture/example/ContactListGestureOverlay.java b/tests/sketch/src/com/android/gesture/example/ContactListGestureOverlay.java
new file mode 100644
index 0000000..50d349a
--- /dev/null
+++ b/tests/sketch/src/com/android/gesture/example/ContactListGestureOverlay.java
@@ -0,0 +1,122 @@
+/*
+ * Copyright (C) 2008-2009 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.gesture.example;
+
+import android.app.Activity;
+import android.content.ContentResolver;
+import android.content.ContentUris;
+import android.content.Intent;
+import android.database.Cursor;
+import android.os.Bundle;
+import android.os.Environment;
+import android.provider.Contacts.People;
+import android.view.View;
+import android.view.ViewGroup;
+import android.view.Window;
+import android.widget.AdapterView;
+import android.widget.ListView;
+
+import com.android.gesture.Gesture;
+import com.android.gesture.GestureActionListener;
+import com.android.gesture.GestureProcessor;
+import com.android.gesture.GestureLibrary;
+import com.android.gesture.GestureOverlay;
+import com.android.gesture.Prediction;
+
+import java.io.File;
+import java.util.ArrayList;
+
+public class ContactListGestureOverlay extends Activity {
+
+    static final String GESTURE_FILE_NAME = Environment.getExternalStorageDirectory().getAbsolutePath()
+            + File.separator + "gestureOverlay.xml";
+
+    private static final String SORT_ORDER = People.DISPLAY_NAME + " COLLATE LOCALIZED ASC";
+
+    private static final String[] CONTACTS_PROJECTION = new String[] {
+            People._ID, // 0
+            People.DISPLAY_NAME, // 1
+    };
+
+    private GestureOverlay mOverlay;
+
+    private ContactAdapter mContactAdapter;
+
+    private GestureProcessor mGestureProcessor;
+
+    private GestureLibrary mLibrary;
+
+    private ListView mContactList;
+
+    @Override
+    public void onCreate(Bundle savedInstanceState) {
+        super.onCreate(savedInstanceState);
+        requestWindowFeature(Window.FEATURE_INDETERMINATE_PROGRESS);
+        setContentView(R.layout.overlaydemo);
+
+        setProgressBarIndeterminateVisibility(true);
+
+        // load the gesture library
+        mLibrary = new GestureLibrary(GESTURE_FILE_NAME);
+        mLibrary.load();
+
+        // load the contact list
+        mContactList = (ListView)this.findViewById(R.id.list);
+        registerForContextMenu(mContactList);
+        mContactList.setTextFilterEnabled(true);
+        mContactList.setVerticalScrollBarEnabled(true);
+        mContactList.setOnItemClickListener(new AdapterView.OnItemClickListener() {
+            public void onItemClick(AdapterView<?> parent, View v, int position, long id) {
+                if (!mGestureProcessor.isGesturing()) {
+                    Intent intent = new Intent(Intent.ACTION_VIEW, ContentUris.withAppendedId(
+                            People.CONTENT_URI, id));
+                    startActivity(intent);
+                }
+            }
+        });
+        ContentResolver resolver = getContentResolver();
+        Cursor cursor = resolver.query(People.CONTENT_URI, CONTACTS_PROJECTION, null, null,
+                SORT_ORDER);
+        ArrayList<ContactItem> list = new ArrayList<ContactItem>();
+        while (cursor.moveToNext()) {
+            list.add(new ContactItem(cursor.getLong(0), cursor.getString(1)));
+        }
+        mContactAdapter = new ContactAdapter(this, list);
+        mContactList.setAdapter(mContactAdapter);
+
+        setProgressBarIndeterminateVisibility(false);
+
+        // add a gesture overlay on top of the ListView
+        mOverlay = new GestureOverlay(this);
+        mGestureProcessor = new GestureProcessor(mContactList);
+        mGestureProcessor.addGestureActionListener(new GestureActionListener() {
+            public void onGesturePerformed(GestureOverlay overlay, Gesture gesture) {
+                ArrayList<Prediction> predictions = mLibrary.recognize(gesture);
+                if (!predictions.isEmpty()) {
+                    int index = mContactAdapter.search(predictions.get(0).gestureName);
+                    if (index != -1) {
+                        mContactList.setSelection(index);
+                    }
+                }
+            }
+        });
+        mOverlay.addGestureListener(mGestureProcessor);
+        ViewGroup.LayoutParams params = new ViewGroup.LayoutParams(
+                ViewGroup.LayoutParams.FILL_PARENT, ViewGroup.LayoutParams.FILL_PARENT);
+        this.addContentView(mOverlay, params);
+    }
+}
diff --git a/tests/sketch/src/com/android/gesture/example/GestureEntry.java b/tests/sketch/src/com/android/gesture/example/GestureEntry.java
new file mode 100644
index 0000000..6a54b49
--- /dev/null
+++ b/tests/sketch/src/com/android/gesture/example/GestureEntry.java
@@ -0,0 +1,209 @@
+/*
+ * Copyright (C) 2008-2009 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.gesture.example;
+
+import android.app.Activity;
+import android.app.AlertDialog;
+import android.app.Dialog;
+import android.content.DialogInterface;
+import android.content.Intent;
+import android.graphics.Color;
+import android.os.Bundle;
+import android.os.Environment;
+import android.view.LayoutInflater;
+import android.view.Menu;
+import android.view.MenuItem;
+import android.view.MotionEvent;
+import android.view.View;
+import android.view.View.OnClickListener;
+import android.widget.AdapterView;
+import android.widget.ArrayAdapter;
+import android.widget.Button;
+import android.widget.EditText;
+import android.widget.Spinner;
+import android.widget.AdapterView.OnItemSelectedListener;
+
+import com.android.gesture.Gesture;
+import com.android.gesture.GestureLibrary;
+import com.android.gesture.GestureListener;
+import com.android.gesture.GestureOverlay;
+import com.android.gesture.Prediction;
+
+import java.io.File;
+import java.util.ArrayList;
+
+public class GestureEntry extends Activity {
+
+    private static final String PARCEL_KEY = "gesture";
+
+    static final String GESTURE_FILE_NAME = Environment.getExternalStorageDirectory().getAbsolutePath()
+            + File.separator + "gestureEntry.xml";
+
+    private static final int DIALOG_NEW_ENTRY = 1;
+
+    private static final int NEW_ID = Menu.FIRST;
+
+    private static final int VIEW_ID = Menu.FIRST + 1;
+
+    private GestureOverlay mGesturePad;
+
+    private Spinner mRecognitionResult;
+
+    private GestureLibrary mGestureLibrary;
+
+    private boolean mChangedByRecognizer = false;
+
+    @Override
+    public void onCreate(Bundle savedInstanceState) {
+        super.onCreate(savedInstanceState);
+        setContentView(R.layout.demo);
+
+        // init the gesture library
+        mGestureLibrary = new GestureLibrary(GESTURE_FILE_NAME);
+        mGestureLibrary.load();
+
+        // create the spinner for showing the recognition results
+        // the spinner also allows a user to correct a prediction
+        mRecognitionResult = (Spinner) findViewById(R.id.spinner);
+        mRecognitionResult.setOnItemSelectedListener(new OnItemSelectedListener() {
+
+            public void onItemSelected(AdapterView<?> parent, View view, int position, long id) {
+                // correct the recognition result by adding the new example
+                if (!mChangedByRecognizer) {
+                    mGestureLibrary.addGesture(parent.getSelectedItem().toString(), mGesturePad
+                            .getCurrentGesture());
+                } else {
+                    mChangedByRecognizer = false;
+                }
+            }
+
+            public void onNothingSelected(AdapterView<?> parent) {
+
+            }
+
+        });
+
+        // create the area for drawing a gesture
+        mGesturePad = (GestureOverlay) findViewById(R.id.drawingpad);
+        mGesturePad.setBackgroundColor(Color.BLACK);
+        mGesturePad.addGestureListener(new GestureListener() {
+            public void onFinishGesture(GestureOverlay pad, MotionEvent event) {
+                recognize(pad.getCurrentGesture());
+                pad.clear(true);
+            }
+
+            public void onGesture(GestureOverlay pad, MotionEvent event) {
+            }
+
+            public void onStartGesture(GestureOverlay pad, MotionEvent event) {
+            }
+        });
+
+        if (savedInstanceState != null) {
+            Gesture g = (Gesture) savedInstanceState.getParcelable(PARCEL_KEY);
+            if (g != null) {
+                mGesturePad.setCurrentGesture(g);
+            }
+        }
+    }
+
+    @Override
+    protected Dialog onCreateDialog(int id) {
+        LayoutInflater factory = LayoutInflater.from(this);
+        final View textEntryView = factory.inflate(R.layout.newgesture_dialog, null);
+        return new AlertDialog.Builder(GestureEntry.this).setTitle(
+                R.string.newgesture_text_entry).setView(textEntryView).setPositiveButton(
+                R.string.newgesture_dialog_ok, new DialogInterface.OnClickListener() {
+                    public void onClick(DialogInterface dialog, int whichButton) {
+                        EditText edittext = (EditText) ((AlertDialog) dialog)
+                                .findViewById(R.id.gesturename_edit);
+                        String text = edittext.getText().toString().trim();
+                        if (text.length() > 0) {
+                            mGestureLibrary.addGesture(text, mGesturePad.getCurrentGesture());
+                        }
+                    }
+                }).setNegativeButton(R.string.newgesture_dialog_cancel,
+                new DialogInterface.OnClickListener() {
+                    public void onClick(DialogInterface dialog, int whichButton) {
+                    }
+                }).create();
+    }
+
+    @Override
+    public boolean onCreateOptionsMenu(Menu menu) {
+        super.onCreateOptionsMenu(menu);
+        menu.add(0, NEW_ID, 0, R.string.newgesture).setShortcut('0', 'n').setIcon(
+                android.R.drawable.ic_menu_add);
+        menu.add(0, VIEW_ID, 0, R.string.viewgesture).setShortcut('1', 'v').setIcon(
+                android.R.drawable.ic_menu_view);
+        return true;
+    }
+
+    @Override
+    public boolean onOptionsItemSelected(MenuItem item) {
+        switch (item.getItemId()) {
+            case NEW_ID:
+                if (mGesturePad.getCurrentGesture() != null) {
+                    showDialog(DIALOG_NEW_ENTRY);
+                }
+                break;
+
+            case VIEW_ID:
+                startActivityForResult(new Intent(this, GestureLibViewer.class), VIEW_ID);
+                break;
+        }
+
+        return super.onOptionsItemSelected(item);
+    }
+
+    @Override
+    protected void onActivityResult(int requestCode, int resultCode, Intent data) {
+        mGestureLibrary.load();
+        mGesturePad.clear(false);
+    }
+
+    @Override
+    protected void onPause() {
+        super.onPause();
+        mGestureLibrary.save();
+    }
+
+    @Override
+    protected void onPrepareDialog(int id, Dialog dialog) {
+        super.onPrepareDialog(id, dialog);
+    }
+
+    @Override
+    protected void onSaveInstanceState(Bundle outState) {
+        super.onSaveInstanceState(outState);
+        Gesture gesture = mGesturePad.getCurrentGesture();
+        if (gesture != null) {
+            outState.putParcelable(PARCEL_KEY, gesture);
+        }
+        mGestureLibrary.save();
+    }
+
+    private void recognize(Gesture ink) {
+        mChangedByRecognizer = true;
+        ArrayList<Prediction> predictions = mGestureLibrary.recognize(ink);
+        ArrayAdapter<Prediction> adapter = new ArrayAdapter<Prediction>(this,
+                android.R.layout.simple_spinner_item, predictions);
+        adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
+        mRecognitionResult.setAdapter(adapter);
+    }
+
+}
diff --git a/tests/sketch/src/com/android/gesture/example/GestureEntryDemo.java b/tests/sketch/src/com/android/gesture/example/GestureEntryDemo.java
index 8fee21a..52a2ba8 100755..100644
--- a/tests/sketch/src/com/android/gesture/example/GestureEntryDemo.java
+++ b/tests/sketch/src/com/android/gesture/example/GestureEntryDemo.java
@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2008 The Android Open Source Project
+ * Copyright (C) 2009 Google Inc.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -21,29 +21,34 @@ import android.app.AlertDialog;
 import android.app.Dialog;
 import android.content.DialogInterface;
 import android.content.Intent;
+import android.graphics.Color;
 import android.os.Bundle;
 import android.view.LayoutInflater;
 import android.view.Menu;
 import android.view.MenuItem;
 import android.view.MotionEvent;
 import android.view.View;
+import android.view.View.OnClickListener;
 import android.widget.AdapterView;
 import android.widget.ArrayAdapter;
+import android.widget.Button;
 import android.widget.EditText;
 import android.widget.Spinner;
 import android.widget.AdapterView.OnItemSelectedListener;
 
 import com.android.gesture.Gesture;
-import com.android.gesture.GestureLib;
+import com.android.gesture.GestureLibrary;
 import com.android.gesture.GestureListener;
 import com.android.gesture.GesturePad;
-import com.android.gesture.R;
-import com.android.gesture.recognizer.Prediction;
+import com.android.gesture.Prediction;
 
 import java.util.ArrayList;
 
 /**
  * The demo shows how to construct a gesture-based user interface on Android.
+ * 
+ * @author liyang@google.com (Yang Li)
+ *
  */
 
 public class GestureEntryDemo extends Activity {
@@ -52,31 +57,35 @@ public class GestureEntryDemo extends Activity {
     private static final int NEW_ID = Menu.FIRST;
     private static final int VIEW_ID = Menu.FIRST + 1;
 
-    GesturePad  mView;
-    Spinner     mResult;
-    GestureLib  mRecognizer;
-    boolean     mChangedByRecognizer = false;
+    private GesturePad mGesturePad;
+    private Spinner mRecognitionResult;
+    private GestureLibrary mGestureLibrary;
+    private boolean mChangedByRecognizer = false;
     
     @Override
     public void onCreate(Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
         setContentView(R.layout.demo);
         
-        // init the recognizer
-        mRecognizer = new GestureLib("/sdcard/gestureentry");
-        mRecognizer.load();
+        // init the gesture library
+        mGestureLibrary = new GestureLibrary(
+            "/sdcard/gestureentry/gestures.xml");
+        mGestureLibrary.load();
         
         // create the spinner for showing the recognition results
         // the spinner also allows a user to correct a prediction
-        mResult = (Spinner) findViewById(R.id.spinner);
-        mResult.setOnItemSelectedListener(new OnItemSelectedListener() {
+        mRecognitionResult = (Spinner) findViewById(R.id.spinner);
+        mRecognitionResult.setOnItemSelectedListener(
+            new OnItemSelectedListener() {
 
-            public void onItemSelected(AdapterView<?> parent, View view, int position, long id) {
+            public void onItemSelected(
+                AdapterView<?> parent, View view, int position, long id) {
                 // TODO Auto-generated method stub
                 // correct the recognition result by adding the new example
                 if (mChangedByRecognizer == false) {
-                    mRecognizer.addGesture(parent.getSelectedItem().toString(), 
-                      mView.getCurrentGesture());
+                    mGestureLibrary.addGesture(
+                        parent.getSelectedItem().toString(), 
+                        mGesturePad.getCurrentGesture());
                 } else {
                     mChangedByRecognizer = false;
                 }
@@ -90,28 +99,35 @@ public class GestureEntryDemo extends Activity {
         });
         
         // create the area for drawing a gesture
-        mView = (GesturePad)this.findViewById(R.id.drawingpad);
-        mView.cacheGesture(false);
-        mView.setFadingOut(false);
-        mView.addGestureListener(new GestureListener() {
-            public void onFinishGesture(GesturePad patch, MotionEvent event) {
+        mGesturePad = (GesturePad)this.findViewById(R.id.drawingpad);
+        mGesturePad.setBackgroundColor(Color.BLACK);
+        mGesturePad.addGestureListener(new GestureListener() {
+            public void onFinishGesture(GesturePad pad, MotionEvent event) {
                 // TODO Auto-generated method stub
-                recognize(patch.getCurrentGesture());
+                recognize(pad.getCurrentGesture());
             }
-            public void onGesture(GesturePad patch, MotionEvent event) {
+            public void onGesture(GesturePad pad, MotionEvent event) {
               // TODO Auto-generated method stub
-              
             }
-            public void onStartGesture(GesturePad patch, MotionEvent event) {
-              // TODO Auto-generated method stub
-              
+            public void onStartGesture(GesturePad pad, MotionEvent event) {
+                // TODO Auto-generated method stub
             }
         });
         
+        Button clear = (Button)this.findViewById(R.id.clear);
+        clear.setOnClickListener(new OnClickListener() {
+            public void onClick(View v) {
+                // TODO Auto-generated method stub
+                mGesturePad.clear(false);
+                mGesturePad.invalidate();
+            }
+        });
         
         if (savedInstanceState != null) {
-            mView.setCurrentGesture(
-                (Gesture)savedInstanceState.getParcelable("gesture"));
+            Gesture g = (Gesture)savedInstanceState.getParcelable("gesture");
+            if (g != null) {
+                mGesturePad.setCurrentGesture(g);
+            }
         }
     }
     
@@ -129,10 +145,12 @@ public class GestureEntryDemo extends Activity {
                 public void onClick(DialogInterface dialog, int whichButton) {
                     /* User clicked OK so do some stuff */
                     EditText edittext =
-                      (EditText)((AlertDialog)dialog).findViewById(R.id.gesturename_edit);
+                      (EditText)((AlertDialog)dialog).findViewById(
+                          R.id.gesturename_edit);
                     String text = edittext.getText().toString().trim();
                     if (text.length() > 0) {
-                        mRecognizer.addGesture(text, mView.getCurrentGesture());
+                        mGestureLibrary.addGesture(
+                            text, mGesturePad.getCurrentGesture());
                     }
                 }
             })
@@ -164,7 +182,7 @@ public class GestureEntryDemo extends Activity {
         switch (item.getItemId()) {
             case NEW_ID:
                 // if there has been a gesture on the canvas
-                if (mView.getCurrentGesture() != null) {
+                if (mGesturePad.getCurrentGesture() != null) {
                     showDialog(DIALOG_NEW_ENTRY);
                 }
                 break;
@@ -180,16 +198,17 @@ public class GestureEntryDemo extends Activity {
     
     
     @Override
-    protected void onActivityResult(int requestCode, int resultCode, Intent data) {
-        mRecognizer.load();
-        mView.clear();
+    protected void onActivityResult(
+        int requestCode, int resultCode, Intent data) {
+        mGestureLibrary.load();
+        mGesturePad.clear(false);
     }
     
     @Override
     protected void onPause() {
         // TODO Auto-generated method stub
         super.onPause();
-        mRecognizer.save();
+        mGestureLibrary.save();
     }
     
     
@@ -203,18 +222,20 @@ public class GestureEntryDemo extends Activity {
     protected void onSaveInstanceState(Bundle outState) {
         // TODO Auto-generated method stub
         super.onSaveInstanceState(outState);
-        outState.putParcelable("gesture", mView.getCurrentGesture());
-        mRecognizer.save();
+        Gesture gesture = mGesturePad.getCurrentGesture();
+        if (gesture != null)
+            outState.putParcelable("gesture", gesture);
+        mGestureLibrary.save();
     }
 
     public void recognize(Gesture ink) {
         mChangedByRecognizer = true;
-        ArrayList<Prediction> predictions = mRecognizer.recognize(ink);
-        ArrayAdapter adapter = new ArrayAdapter(this, 
+        ArrayList<Prediction> predictions = mGestureLibrary.recognize(ink);
+        ArrayAdapter<Prediction> adapter = new ArrayAdapter<Prediction>(this, 
                     android.R.layout.simple_spinner_item, predictions);
         adapter.setDropDownViewResource(
                     android.R.layout.simple_spinner_dropdown_item);
-        mResult.setAdapter(adapter);
+        mRecognitionResult.setAdapter(adapter);
     }
 
 }
diff --git a/tests/sketch/src/com/android/gesture/example/GestureLibViewer.java b/tests/sketch/src/com/android/gesture/example/GestureLibViewer.java
index 7ae7fc5..ca54110 100755..100644
--- a/tests/sketch/src/com/android/gesture/example/GestureLibViewer.java
+++ b/tests/sketch/src/com/android/gesture/example/GestureLibViewer.java
@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2008 The Android Open Source Project
+ * Copyright (C) 2008-2009 The Android Open Source Project
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -17,8 +17,6 @@
 package com.android.gesture.example;
 
 import android.app.Activity;
-import android.graphics.Matrix;
-import android.graphics.Path;
 import android.os.Bundle;
 import android.view.KeyEvent;
 import android.view.View;
@@ -30,228 +28,156 @@ import android.widget.Spinner;
 import android.widget.AdapterView.OnItemSelectedListener;
 
 import com.android.gesture.Gesture;
-import com.android.gesture.GestureLib;
-import com.android.gesture.GesturePad;
-import com.android.gesture.R;
-import com.android.gesture.recognizer.Instance;
+import com.android.gesture.GestureLibrary;
+import com.android.gesture.GestureOverlay;
 
 import java.util.ArrayList;
 import java.util.Collections;
 
 /**
- * GestureLibViewer is for viewing existing gestures and 
+ * GestureLibViewer gives an example on how to browse existing gestures and
  * removing unwanted gestures.
  */
 
-public class GestureLibViewer  extends Activity {
-  
-    GesturePad          mView;
-    Spinner             mResult;
-    GestureLib          mRecognizer;
-    ArrayList<Gesture>  mSamples;
-    int                 mCurrentGestureIndex;
+public class GestureLibViewer extends Activity {
+
+    private GestureOverlay mGesturePad;
+
+    private Spinner mGestureCategory;
+
+    private GestureLibrary mGesureLibrary;
+
+    private ArrayList<Gesture> mGestures;
+
+    private int mCurrentGestureIndex;
+
+    private class RemoveGestureListener implements OnClickListener {
+        public void onClick(View v) {
+            if (mGestures.isEmpty()) {
+                return;
+            }
+
+            String name = (String) mGestureCategory.getSelectedItem();
+            Gesture gesture = mGestures.get(mCurrentGestureIndex);
+            mGesureLibrary.removeGesture(name, gesture);
+
+            mGestures = mGesureLibrary.getGestures(name);
+
+            if (mGestures == null) {
+                // delete the entire entry
+                mCurrentGestureIndex = 0;
+                ArrayList<String> list = new ArrayList<String>();
+                list.addAll(mGesureLibrary.getGestureEntries());
+                Collections.sort(list);
+                ArrayAdapter<String> adapter = new ArrayAdapter<String>(GestureLibViewer.this,
+                        android.R.layout.simple_spinner_item, list);
+                adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
+                mGestureCategory.setAdapter(adapter);
+            } else {
+                if (mCurrentGestureIndex > mGestures.size() - 1) {
+                    mCurrentGestureIndex--;
+                }
+                gesture = mGestures.get(mCurrentGestureIndex);
+                mGesturePad.setCurrentGesture(gesture);
+                mGesturePad.invalidate();
+            }
+        }
+    }
     
     @Override
     public void onCreate(Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
         setContentView(R.layout.gestureviewer);
-        
-        // create the area for drawing a glyph
-        mView = (GesturePad)this.findViewById(R.id.drawingpad);
-        mView.cacheGesture(false);
-        mView.setFadingOut(false);
-        mView.setEnableInput(false);
-        
-        // init the recognizer
-        mRecognizer = new GestureLib("/sdcard/gestureentry");
-        mRecognizer.load();
 
-        mResult = (Spinner) findViewById(R.id.spinner);
+        // create the area for drawing a gesture
+        mGesturePad = (GestureOverlay) findViewById(R.id.drawingpad);
+        mGesturePad.setEnabled(false);
+
+        // init the gesture library
+        mGesureLibrary = new GestureLibrary(GestureEntry.GESTURE_FILE_NAME);
+        mGesureLibrary.load();
+
+        mGestureCategory = (Spinner) findViewById(R.id.spinner);
         ArrayList<String> list = new ArrayList<String>();
-        list.addAll(mRecognizer.getLabels());
-        Collections.sort(list);
-        ArrayAdapter<String> adapter = new ArrayAdapter<String>(this, 
-                    android.R.layout.simple_spinner_item, 
-                    list);
-        adapter.setDropDownViewResource(
-                    android.R.layout.simple_spinner_dropdown_item);
-        mResult.setAdapter(adapter);
-        mSamples = mRecognizer.getGestures(list.get(0));
-        if (mSamples.isEmpty() == false) {
+        if (!mGesureLibrary.getGestureEntries().isEmpty()) {
+            list.addAll(mGesureLibrary.getGestureEntries());
+            Collections.sort(list);
+            ArrayAdapter<String> adapter = new ArrayAdapter<String>(this,
+                    android.R.layout.simple_spinner_item, list);
+            adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
+            mGestureCategory.setAdapter(adapter);
+            mGestures = mGesureLibrary.getGestures(list.get(0));
             mCurrentGestureIndex = 0;
-            Gesture gesture = mSamples.get(mCurrentGestureIndex);
-            mView.setCurrentGesture(gesture);
-            mView.clearDebugPath();
-            mView.addDebugPath(
-                toPath(mRecognizer.getClassifier().getInstance(gesture.getID())));
+            Gesture gesture = mGestures.get(mCurrentGestureIndex);
+            mGesturePad.setCurrentGesture(gesture);
         }
-        
-        mResult.setOnItemSelectedListener(new OnItemSelectedListener() {
+
+        mGestureCategory.setOnItemSelectedListener(new OnItemSelectedListener() {
             public void onItemSelected(AdapterView<?> parent, View view, int position, long id) {
-                // TODO Auto-generated method stub
-                mSamples = mRecognizer.getGestures(
-                    (String)mResult.getSelectedItem());
-                if (mSamples.isEmpty() == false) {
+                mGestures = mGesureLibrary.getGestures((String) mGestureCategory.getSelectedItem());
+                if (!mGestures.isEmpty()) {
                     mCurrentGestureIndex = 0;
-                    Gesture gesture = mSamples.get(mCurrentGestureIndex);
-                    mView.setCurrentGesture(gesture);
-                    mView.clearDebugPath();
-                    mView.addDebugPath(
-                        toPath(mRecognizer.getClassifier().getInstance(gesture.getID())));
+                    Gesture gesture = mGestures.get(mCurrentGestureIndex);
+                    mGesturePad.setCurrentGesture(gesture);
                 }
-                mView.invalidate();
+                mGesturePad.invalidate();
             }
-  
+
             public void onNothingSelected(AdapterView<?> parent) {
-              // TODO Auto-generated method stub
-              
-            }
-          
-        });
-        
-        Button remove = (Button)this.findViewById(R.id.remove);
-        remove.setOnClickListener(new OnClickListener() {
-            public void onClick(View v) {
-                // TODO Auto-generated method stub
-                if (mSamples.isEmpty())
-                    return;
-                
-                String name = (String)mResult.getSelectedItem();
-                Gesture gesture = mSamples.get(mCurrentGestureIndex);
-                mRecognizer.removeGesture(name, gesture);
-                
-                mSamples = mRecognizer.getGestures(name);
-                
-                if (mSamples == null) {
-                    // delete the entire entry
-                    mCurrentGestureIndex = 0;
-                    ArrayList<String> list = new ArrayList<String>();
-                    list.addAll(mRecognizer.getLabels());
-                    Collections.sort(list);
-                    ArrayAdapter<String> adapter = new ArrayAdapter<String>(
-                                GestureLibViewer.this, 
-                                android.R.layout.simple_spinner_item, 
-                                list);
-                    adapter.setDropDownViewResource(
-                                android.R.layout.simple_spinner_dropdown_item);
-                    mResult.setAdapter(adapter);
-                } else {
-                    if (mCurrentGestureIndex > mSamples.size()-1) {
-                        mCurrentGestureIndex--;
-                    }
-                    gesture = mSamples.get(mCurrentGestureIndex);
-                    mView.setCurrentGesture(gesture);
-                    mView.clearDebugPath();
-                    mView.addDebugPath(
-                        toPath(mRecognizer.getClassifier().getInstance(gesture.getID())));
-                    mView.invalidate();
-                }
             }
+
         });
-        
-        Button next = (Button)this.findViewById(R.id.next);
+
+        Button remove = (Button) findViewById(R.id.remove);
+        remove.setOnClickListener(new RemoveGestureListener());
+
+        Button next = (Button) findViewById(R.id.next);
         next.setOnClickListener(new OnClickListener() {
             public void onClick(View v) {
-                // TODO Auto-generated method stub
-                if (mCurrentGestureIndex >= mSamples.size()-1)
+                if (mCurrentGestureIndex >= mGestures.size() - 1) {
                     return;
-                
+                }
                 mCurrentGestureIndex++;
-                Gesture gesture = mSamples.get(mCurrentGestureIndex);
-                mView.setCurrentGesture(gesture);
-                mView.clearDebugPath();
-                mView.addDebugPath(
-                    toPath(mRecognizer.getClassifier().getInstance(gesture.getID())));
-                mView.invalidate();
+                Gesture gesture = mGestures.get(mCurrentGestureIndex);
+                mGesturePad.setCurrentGesture(gesture);
+                mGesturePad.invalidate();
             }
         });
 
-        Button previous = (Button)this.findViewById(R.id.previous);
+        Button previous = (Button) findViewById(R.id.previous);
         previous.setOnClickListener(new OnClickListener() {
             public void onClick(View v) {
-                // TODO Auto-generated method stub
-                if (mCurrentGestureIndex >= 1 &&
-                    mSamples.isEmpty() == false) {
+                if (mCurrentGestureIndex >= 1 && !mGestures.isEmpty()) {
                     mCurrentGestureIndex--;
-                    Gesture gesture = mSamples.get(mCurrentGestureIndex);
-                    mView.setCurrentGesture(gesture);
-                    mView.clearDebugPath();
-                    mView.addDebugPath(
-                        toPath(mRecognizer.getClassifier().getInstance(gesture.getID())));
-                    mView.invalidate();
+                    Gesture gesture = mGestures.get(mCurrentGestureIndex);
+                    mGesturePad.setCurrentGesture(gesture);
+                    mGesturePad.invalidate();
                 }
             }
         });
     }
-    
-    public static ArrayList<Path> toPath(Instance instance) {
-        ArrayList<Path> paths = new ArrayList();
-        Path path = null;
-        float minx = 0, miny = 0;
-        float mX = 0, mY = 0;
-        for (int i=0; i<instance.vector.length; i+=2) {
-            float x = instance.vector[i];
-            float y = instance.vector[i+1];
-            if (x < minx)
-                minx = x;
-            if (y < miny)
-                miny = y;
-            if (path == null) {
-              path = new Path();
-              path.moveTo(x, y);
-              mX = x;
-              mY = y;
-            } else {
-              float dx = Math.abs(x - mX);
-              float dy = Math.abs(y - mY);
-              if (dx >= 3 || dy >= 3) {
-                  path.quadTo(mX, mY, (x + mX)/2, (y + mY)/2);
-                  mX = x;
-                  mY = y;
-              }
-            }
-        }
-        Matrix matrix = new Matrix();
-        matrix.setTranslate(-minx + 10, -miny + 10);
-        path.transform(matrix);
-        paths.add(path);
-        
-        path = new Path();
-        path.moveTo(instance.vector[0]-5, instance.vector[1]-5);
-        path.lineTo(instance.vector[0]-5, instance.vector[1]+5);
-        path.lineTo(instance.vector[0]+5, instance.vector[1]+5);
-        path.lineTo(instance.vector[0]+5, instance.vector[1]-5);
-        path.close();
-        path.transform(matrix);
-        paths.add(path);
-        
-        return paths;
-    }
-    
+
     @Override
     public boolean onKeyUp(int keyCode, KeyEvent event) {
-      // TODO Auto-generated method stub
-      if (keyCode == KeyEvent.KEYCODE_BACK) {
-          mRecognizer.save();
-          this.setResult(RESULT_OK);
-          finish();
-          return true;
-      }
-      else
-        return false;
+        if (keyCode == KeyEvent.KEYCODE_BACK) {
+            mGesureLibrary.save();
+            setResult(RESULT_OK);
+            finish();
+            return true;
+        } else {
+            return false;
+        }
     }
-    
+
     @Override
     protected void onPause() {
-        // TODO Auto-generated method stub
         super.onPause();
-        mRecognizer.save();
+        mGesureLibrary.save();
     }
 
     @Override
     protected void onSaveInstanceState(Bundle outState) {
-        // TODO Auto-generated method stub
         super.onSaveInstanceState(outState);
-        mRecognizer.save();
+        mGesureLibrary.save();
     }
 }