TransformGestureDetector is now ScaleGestureDetector - scope reduced.

N1 screen can't reliably handle translation and scaling at the same time.

2 files changed, 360 insertions, 316 deletions

diff --git a/core/java/android/view/ScaleGestureDetector.java b/core/java/android/view/ScaleGestureDetector.java
new file mode 100644
index 0000000..2da8f14
--- /dev/null
+++ b/core/java/android/view/ScaleGestureDetector.java
@@ -0,0 +1,360 @@
+/*
+ * Copyright (C) 2010 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 android.view;
+
+import android.content.Context;
+
+/**
+ * Detects transformation gestures involving more than one pointer ("multitouch")
+ * using the supplied {@link MotionEvent}s. The {@link OnScaleGestureListener}
+ * callback will notify users when a particular gesture event has occurred.
+ * This class should only be used with {@link MotionEvent}s reported via touch.
+ * 
+ * To use this class:
+ * <ul>
+ *  <li>Create an instance of the {@code ScaleGestureDetector} for your
+ *      {@link View}
+ *  <li>In the {@link View#onTouchEvent(MotionEvent)} method ensure you call
+ *          {@link #onTouchEvent(MotionEvent)}. The methods defined in your
+ *          callback will be executed when the events occur.
+ * </ul>
+ * @hide Pending API approval
+ */
+public class ScaleGestureDetector {
+    /**
+     * The listener for receiving notifications when gestures occur.
+     * If you want to listen for all the different gestures then implement
+     * this interface. If you only want to listen for a subset it might
+     * be easier to extend {@link SimpleOnScaleGestureListener}.
+     * 
+     * An application will receive events in the following order:
+     * <ul>
+     *  <li>One {@link OnScaleGestureListener#onScaleBegin()}
+     *  <li>Zero or more {@link OnScaleGestureListener#onScale()}
+     *  <li>One {@link OnScaleGestureListener#onTransformEnd()}
+     * </ul>
+     */
+    public interface OnScaleGestureListener {
+        /**
+         * Responds to scaling events for a gesture in progress.
+         * Reported by pointer motion.
+         * 
+         * @param detector The detector reporting the event - use this to
+         *          retrieve extended info about event state.
+         * @return Whether or not the detector should consider this event
+         *          as handled. If an event was not handled, the detector
+         *          will continue to accumulate movement until an event is
+         *          handled. This can be useful if an application, for example,
+         *          only wants to update scaling factors if the change is
+         *          greater than 0.01.
+         */
+        public boolean onScale(ScaleGestureDetector detector);
+
+        /**
+         * Responds to the beginning of a scaling gesture. Reported by
+         * new pointers going down.
+         * 
+         * @param detector The detector reporting the event - use this to
+         *          retrieve extended info about event state.
+         * @return Whether or not the detector should continue recognizing
+         *          this gesture. For example, if a gesture is beginning
+         *          with a focal point outside of a region where it makes
+         *          sense, onScaleBegin() may return false to ignore the
+         *          rest of the gesture.
+         */
+        public boolean onScaleBegin(ScaleGestureDetector detector);
+
+        /**
+         * Responds to the end of a scale gesture. Reported by existing
+         * pointers going up. If the end of a gesture would result in a fling,
+         * {@link onTransformFling()} is called instead.
+         * 
+         * Once a scale has ended, {@link ScaleGestureDetector#getFocusX()}
+         * and {@link ScaleGestureDetector#getFocusY()} will return the location
+         * of the pointer remaining on the screen.
+         * 
+         * @param detector The detector reporting the event - use this to
+         *          retrieve extended info about event state.
+         */
+        public void onScaleEnd(ScaleGestureDetector detector);
+    }
+    
+    /**
+     * A convenience class to extend when you only want to listen for a subset
+     * of scaling-related events. This implements all methods in
+     * {@link OnScaleGestureListener} but does nothing.
+     * {@link OnScaleGestureListener#onScale(ScaleGestureDetector)} and
+     * {@link OnScaleGestureListener#onScaleBegin(ScaleGestureDetector)} return
+     * {@code true}. 
+     */
+    public class SimpleOnScaleGestureListener implements OnScaleGestureListener {
+
+        public boolean onScale(ScaleGestureDetector detector) {
+            return true;
+        }
+
+        public boolean onScaleBegin(ScaleGestureDetector detector) {
+            return true;
+        }
+
+        public void onScaleEnd(ScaleGestureDetector detector) {
+            // Intentionally empty
+        }
+    }
+
+    private static final float PRESSURE_THRESHOLD = 0.67f;
+
+    private Context mContext;
+    private OnScaleGestureListener mListener;
+    private boolean mGestureInProgress;
+
+    private MotionEvent mPrevEvent;
+    private MotionEvent mCurrEvent;
+
+    private float mFocusX;
+    private float mFocusY;
+    private float mPrevFingerDiffX;
+    private float mPrevFingerDiffY;
+    private float mCurrFingerDiffX;
+    private float mCurrFingerDiffY;
+    private float mCurrLen;
+    private float mPrevLen;
+    private float mScaleFactor;
+    private float mCurrPressure;
+    private float mPrevPressure;
+    private long mTimeDelta;
+
+    public ScaleGestureDetector(Context context, OnScaleGestureListener listener) {
+        mContext = context;
+        mListener = listener;
+    }
+
+    public boolean onTouchEvent(MotionEvent event) {
+        final int action = event.getAction();
+        boolean handled = true;
+
+        if (!mGestureInProgress) {
+            if ((action == MotionEvent.ACTION_POINTER_1_DOWN ||
+                    action == MotionEvent.ACTION_POINTER_2_DOWN) &&
+                    event.getPointerCount() >= 2) {
+                // We have a new multi-finger gesture
+                
+                // Be paranoid in case we missed an event
+                reset();
+                
+                mPrevEvent = MotionEvent.obtain(event);
+                mTimeDelta = 0;
+                
+                setContext(event);
+                mGestureInProgress = mListener.onScaleBegin(this);
+            }
+        } else {
+            // Transform gesture in progress - attempt to handle it
+            switch (action) {
+                case MotionEvent.ACTION_POINTER_1_UP:
+                case MotionEvent.ACTION_POINTER_2_UP:
+                    // Gesture ended
+                    setContext(event);
+                    
+                    // Set focus point to the remaining finger
+                    int id = (((action & MotionEvent.ACTION_POINTER_ID_MASK)
+                            >> MotionEvent.ACTION_POINTER_ID_SHIFT) == 0) ? 1 : 0;
+                    mFocusX = event.getX(id);
+                    mFocusY = event.getY(id);
+                    
+                    mListener.onScaleEnd(this);
+                    mGestureInProgress = false;
+
+                    reset();
+                    break;
+
+                case MotionEvent.ACTION_CANCEL:
+                    mListener.onScaleEnd(this);
+                    mGestureInProgress = false;
+
+                    reset();
+                    break;
+
+                case MotionEvent.ACTION_MOVE:
+                    setContext(event);
+
+                    // Only accept the event if our relative pressure is within
+                    // a certain limit - this can help filter shaky data as a
+                    // finger is lifted.
+                    if (mCurrPressure / mPrevPressure > PRESSURE_THRESHOLD) {
+                        final boolean updatePrevious = mListener.onScale(this);
+
+                        if (updatePrevious) {
+                            mPrevEvent.recycle();
+                            mPrevEvent = MotionEvent.obtain(event);
+                        }
+                    }
+                    break;
+            }
+        }
+        return handled;
+    }
+
+    private void setContext(MotionEvent curr) {
+        if (mCurrEvent != null) {
+            mCurrEvent.recycle();
+        }
+        mCurrEvent = MotionEvent.obtain(curr);
+
+        mCurrLen = -1;
+        mPrevLen = -1;
+        mScaleFactor = -1;
+
+        final MotionEvent prev = mPrevEvent;
+
+        final float px0 = prev.getX(0);
+        final float py0 = prev.getY(0);
+        final float px1 = prev.getX(1);
+        final float py1 = prev.getY(1);
+        final float cx0 = curr.getX(0);
+        final float cy0 = curr.getY(0);
+        final float cx1 = curr.getX(1);
+        final float cy1 = curr.getY(1);
+
+        final float pvx = px1 - px0;
+        final float pvy = py1 - py0;
+        final float cvx = cx1 - cx0;
+        final float cvy = cy1 - cy0;
+        mPrevFingerDiffX = pvx;
+        mPrevFingerDiffY = pvy;
+        mCurrFingerDiffX = cvx;
+        mCurrFingerDiffY = cvy;
+
+        mFocusX = cx0 + cvx * 0.5f;
+        mFocusY = cy0 + cvy * 0.5f;
+        mTimeDelta = curr.getEventTime() - prev.getEventTime();
+        mCurrPressure = curr.getPressure(0) + curr.getPressure(1);
+        mPrevPressure = prev.getPressure(0) + prev.getPressure(1);
+    }
+
+    private void reset() {
+        if (mPrevEvent != null) {
+            mPrevEvent.recycle();
+            mPrevEvent = null;
+        }
+        if (mCurrEvent != null) {
+            mCurrEvent.recycle();
+            mCurrEvent = null;
+        }
+    }
+
+    /**
+     * Returns {@code true} if a two-finger scale gesture is in progress.
+     * @return {@code true} if a scale gesture is in progress, {@code false} otherwise.
+     */
+    public boolean isInProgress() {
+        return mGestureInProgress;
+    }
+
+    /**
+     * Get the X coordinate of the current gesture's focal point.
+     * If a gesture is in progress, the focal point is directly between
+     * the two pointers forming the gesture.
+     * If a gesture is ending, the focal point is the location of the
+     * remaining pointer on the screen.
+     * If {@link isInProgress()} would return false, the result of this
+     * function is undefined.
+     * 
+     * @return X coordinate of the focal point in pixels.
+     */
+    public float getFocusX() {
+        return mFocusX;
+    }
+
+    /**
+     * Get the Y coordinate of the current gesture's focal point.
+     * If a gesture is in progress, the focal point is directly between
+     * the two pointers forming the gesture.
+     * If a gesture is ending, the focal point is the location of the
+     * remaining pointer on the screen.
+     * If {@link isInProgress()} would return false, the result of this
+     * function is undefined.
+     * 
+     * @return Y coordinate of the focal point in pixels.
+     */
+    public float getFocusY() {
+        return mFocusY;
+    }
+
+    /**
+     * Return the current distance between the two pointers forming the
+     * gesture in progress.
+     * 
+     * @return Distance between pointers in pixels.
+     */
+    public float getCurrentSpan() {
+        if (mCurrLen == -1) {
+            final float cvx = mCurrFingerDiffX;
+            final float cvy = mCurrFingerDiffY;
+            mCurrLen = (float)Math.sqrt(cvx*cvx + cvy*cvy);
+        }
+        return mCurrLen;
+    }
+
+    /**
+     * Return the previous distance between the two pointers forming the
+     * gesture in progress.
+     * 
+     * @return Previous distance between pointers in pixels.
+     */
+    public float getPreviousSpan() {
+        if (mPrevLen == -1) {
+            final float pvx = mPrevFingerDiffX;
+            final float pvy = mPrevFingerDiffY;
+            mPrevLen = (float)Math.sqrt(pvx*pvx + pvy*pvy);
+        }
+        return mPrevLen;
+    }
+
+    /**
+     * Return the scaling factor from the previous scale event to the current
+     * event. This value is defined as
+     * ({@link getCurrentSpan()} / {@link getPreviousSpan()}).
+     * 
+     * @return The current scaling factor.
+     */
+    public float getScaleFactor() {
+        if (mScaleFactor == -1) {
+            mScaleFactor = getCurrentSpan() / getPreviousSpan();
+        }
+        return mScaleFactor;
+    }
+    
+    /**
+     * Return the time difference in milliseconds between the previous
+     * accepted scaling event and the current scaling event.
+     * 
+     * @return Time difference since the last scaling event in milliseconds.
+     */
+    public long getTimeDelta() {
+        return mTimeDelta;
+    }
+    
+    /**
+     * Return the event time of the current event being processed.
+     * 
+     * @return Current event time in milliseconds.
+     */
+    public long getEventTime() {
+        return mCurrEvent.getEventTime();
+    }
+}
diff --git a/core/java/android/view/TransformGestureDetector.java b/core/java/android/view/TransformGestureDetector.java
deleted file mode 100644
index 196716a..0000000
--- a/core/java/android/view/TransformGestureDetector.java
+++ /dev/null
@@ -1,316 +0,0 @@
-/*
- * Copyright (C) 2010 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 android.view;
-
-import android.content.Context;
-import android.util.Log;
-import android.view.GestureDetector.SimpleOnGestureListener;
-
-/**
- * Detects transformation gestures involving more than one pointer ("multitouch")
- * using the supplied {@link MotionEvent}s. The {@link OnGestureListener} callback
- * will notify users when a particular gesture event has occurred. This class
- * should only be used with {@link MotionEvent}s reported via touch.
- * 
- * To use this class:
- * <ul>
- *  <li>Create an instance of the {@code TransformGestureDetector} for your
- *      {@link View}
- *  <li>In the {@link View#onTouchEvent(MotionEvent)} method ensure you call
- *          {@link #onTouchEvent(MotionEvent)}. The methods defined in your
- *          callback will be executed when the events occur.
- * </ul>
- * @hide Pending API approval
- */
-public class TransformGestureDetector {
-    /**
-     * The listener for receiving notifications when gestures occur.
-     * If you want to listen for all the different gestures then implement
-     * this interface. If you only want to listen for a subset it might
-     * be easier to extend {@link SimpleOnGestureListener}.
-     * 
-     * An application will receive events in the following order:
-     * One onTransformBegin()
-     * Zero or more onTransform()
-     * One onTransformEnd() or onTransformFling()
-     */
-    public interface OnTransformGestureListener {
-        /**
-         * Responds to transformation events for a gesture in progress.
-         * Reported by pointer motion.
-         * 
-         * @param detector The detector reporting the event - use this to
-         *          retrieve extended info about event state.
-         * @return true if the event was handled, false otherwise.
-         */
-        public boolean onTransform(TransformGestureDetector detector);
-        
-        /**
-         * Responds to the beginning of a transformation gesture. Reported by
-         * new pointers going down.
-         * 
-         * @param detector The detector reporting the event - use this to
-         *          retrieve extended info about event state.
-         * @return true if the event was handled, false otherwise.
-         */
-        public boolean onTransformBegin(TransformGestureDetector detector);
- 
-        /**
-         * Responds to the end of a transformation gesture. Reported by existing
-         * pointers going up. If the end of a gesture would result in a fling,
-         * onTransformFling is called instead.
-         * 
-         * @param detector The detector reporting the event - use this to
-         *          retrieve extended info about event state.
-         * @return true if the event was handled, false otherwise.
-         */
-        public boolean onTransformEnd(TransformGestureDetector detector);
-
-        /**
-         * Responds to the end of a transformation gesture that begins a fling.
-         * Reported by existing pointers going up. If the end of a gesture 
-         * would not result in a fling, onTransformEnd is called instead.
-         * 
-         * @param detector The detector reporting the event - use this to
-         *          retrieve extended info about event state.
-         * @return true if the event was handled, false otherwise.
-         */
-        public boolean onTransformFling(TransformGestureDetector detector);
-    }
-    
-    private static final boolean DEBUG = false;
-    
-    private static final int INITIAL_EVENT_IGNORES = 2;
-    
-    private Context mContext;
-    private float mTouchSizeScale;
-    private OnTransformGestureListener mListener;
-    private int mVelocityTimeUnits;
-    private MotionEvent mInitialEvent;
-    
-    private MotionEvent mPrevEvent;
-    private MotionEvent mCurrEvent;
-    private VelocityTracker mVelocityTracker;
-
-    private float mCenterX;
-    private float mCenterY;
-    private float mTransX;
-    private float mTransY;
-    private float mPrevFingerDiffX;
-    private float mPrevFingerDiffY;
-    private float mCurrFingerDiffX;
-    private float mCurrFingerDiffY;
-    private float mRotateDegrees;
-    private float mCurrLen;
-    private float mPrevLen;
-    private float mScaleFactor;
-    
-    // Units in pixels. Current value is pulled out of thin air for debugging only.
-    private float mPointerJumpLimit = 30;
-    
-    private int mEventIgnoreCount;
-    
-   public TransformGestureDetector(Context context, OnTransformGestureListener listener,
-            int velocityTimeUnits) {
-        mContext = context;
-        mListener = listener;
-        mTouchSizeScale = context.getResources().getDisplayMetrics().widthPixels/3;
-        mVelocityTimeUnits = velocityTimeUnits;
-        mEventIgnoreCount = INITIAL_EVENT_IGNORES;
-    }
-    
-    public TransformGestureDetector(Context context, OnTransformGestureListener listener) {
-        this(context, listener, 1000);
-    }
-    
-    public boolean onTouchEvent(MotionEvent event) {
-        final int action = event.getAction();
-        boolean handled = true;
-
-        if (mInitialEvent == null) {
-            // No transform gesture in progress
-            if ((action == MotionEvent.ACTION_POINTER_1_DOWN ||
-                    action == MotionEvent.ACTION_POINTER_2_DOWN) &&
-                    event.getPointerCount() >= 2) {
-                // We have a new multi-finger gesture
-                mInitialEvent = MotionEvent.obtain(event);
-                mPrevEvent = MotionEvent.obtain(event);
-                mVelocityTracker = VelocityTracker.obtain();
-                handled = mListener.onTransformBegin(this);
-            }
-        } else {
-            // Transform gesture in progress - attempt to handle it
-            switch (action) {
-                case MotionEvent.ACTION_POINTER_1_UP:
-                case MotionEvent.ACTION_POINTER_2_UP:
-                    // Gesture ended
-                    handled = mListener.onTransformEnd(this);
-
-                    reset();
-                    break;
-                    
-                case MotionEvent.ACTION_CANCEL:
-                    handled = mListener.onTransformEnd(this);
-                    
-                    reset();
-                    break;
-                    
-                case MotionEvent.ACTION_MOVE:
-                    setContext(event);
-
-                    // Our first few events can be crazy from some touchscreens - drop them.
-                    if (mEventIgnoreCount == 0) {
-                        mVelocityTracker.addMovement(event);
-                        handled = mListener.onTransform(this);
-                    } else {
-                        mEventIgnoreCount--;
-                    }
-                    
-                    mPrevEvent.recycle();
-                    mPrevEvent = MotionEvent.obtain(event);
-                    break;
-            }
-        }
-        return handled;
-    }
-    
-    private void setContext(MotionEvent curr) {
-        mCurrEvent = MotionEvent.obtain(curr);
-
-        mRotateDegrees = -1;
-        mCurrLen = -1;
-        mPrevLen = -1;
-        mScaleFactor = -1;
-
-        final MotionEvent prev = mPrevEvent;
-        
-        float px0 = prev.getX(0);
-        float py0 = prev.getY(0);
-        float px1 = prev.getX(1);
-        float py1 = prev.getY(1);
-        float cx0 = curr.getX(0);
-        float cy0 = curr.getY(0);
-        float cx1 = curr.getX(1);
-        float cy1 = curr.getY(1);
-
-        // Some touchscreens do weird things with pointer values where points are
-        // too close along one axis. Try to detect this here and smooth things out.
-        // The main indicator is that we get the X or Y value from the other pointer.
-        final float dx0 = cx0 - px0;
-        final float dy0 = cy0 - py0;
-        final float dx1 = cx1 - px1;
-        final float dy1 = cy1 - py1;
-
-        if (cx0 == cx1) {
-            if (Math.abs(dx0) > mPointerJumpLimit) {
-                 cx0 = px0;
-            } else if (Math.abs(dx1) > mPointerJumpLimit) {
-                cx1 = px1;
-            }
-        } else if (cy0 == cy1) {
-            if (Math.abs(dy0) > mPointerJumpLimit) {
-                cy0 = py0;
-            } else if (Math.abs(dy1) > mPointerJumpLimit) {
-                cy1 = py1;
-            }
-        }
-        
-        final float pvx = px1 - px0;
-        final float pvy = py1 - py0;
-        final float cvx = cx1 - cx0;
-        final float cvy = cy1 - cy0;
-        mPrevFingerDiffX = pvx;
-        mPrevFingerDiffY = pvy;
-        mCurrFingerDiffX = cvx;
-        mCurrFingerDiffY = cvy;
-
-        final float pmidx = px0 + pvx * 0.5f;
-        final float pmidy = py0 + pvy * 0.5f;
-        final float cmidx = cx0 + cvx * 0.5f;
-        final float cmidy = cy0 + cvy * 0.5f;
-
-        mCenterX = cmidx;
-        mCenterY = cmidy;
-        mTransX = cmidx - pmidx;
-        mTransY = cmidy - pmidy;
-    }
-    
-    private void reset() {
-        if (mInitialEvent != null) {
-            mInitialEvent.recycle();
-            mInitialEvent = null;
-        }
-        if (mPrevEvent != null) {
-            mPrevEvent.recycle();
-            mPrevEvent = null;
-        }
-        if (mCurrEvent != null) {
-            mCurrEvent.recycle();
-            mCurrEvent = null;
-        }
-        if (mVelocityTracker != null) {
-            mVelocityTracker.recycle();
-            mVelocityTracker = null;
-        }
-        mEventIgnoreCount = INITIAL_EVENT_IGNORES;
-    }
-    
-    public float getCenterX() {
-        return mCenterX;
-    }
-
-    public float getCenterY() {
-        return mCenterY;
-    }
-
-    public float getTranslateX() {
-        return mTransX;
-    }
-
-    public float getTranslateY() {
-        return mTransY;
-    }
-
-    public float getCurrentSpan() {
-        if (mCurrLen == -1) {
-            final float cvx = mCurrFingerDiffX;
-            final float cvy = mCurrFingerDiffY;
-            mCurrLen = (float)Math.sqrt(cvx*cvx + cvy*cvy);
-        }
-        return mCurrLen;
-    }
-
-    public float getPreviousSpan() {
-        if (mPrevLen == -1) {
-            final float pvx = mPrevFingerDiffX;
-            final float pvy = mPrevFingerDiffY;
-            mPrevLen = (float)Math.sqrt(pvx*pvx + pvy*pvy);
-        }
-        return mPrevLen;
-    }
-
-    public float getScaleFactor() {
-        if (mScaleFactor == -1) {
-            mScaleFactor = getCurrentSpan() / getPreviousSpan();
-        }
-        return mScaleFactor;
-    }
-
-    public float getRotation() {
-        throw new UnsupportedOperationException();
-    }
-}