SystemUI: add circle page indicator for qs tiles

Change-Id: Ie6811657d3888e260b757a44f7535e6b6caec644
Signed-off-by: Roman Birg <roman@cyngn.com>

3 files changed, 595 insertions, 20 deletions

diff --git a/packages/SystemUI/src/com/android/systemui/qs/QSDragPanel.java b/packages/SystemUI/src/com/android/systemui/qs/QSDragPanel.java
index 7301525..26b6daa 100644
--- a/packages/SystemUI/src/com/android/systemui/qs/QSDragPanel.java
+++ b/packages/SystemUI/src/com/android/systemui/qs/QSDragPanel.java
@@ -18,21 +18,17 @@ package com.android.systemui.qs;
 
 import android.animation.Animator;
 import android.animation.AnimatorListenerAdapter;
-import android.app.ActivityManager;
 import android.app.AlertDialog;
-import android.content.BroadcastReceiver;
 import android.content.Context;
 import android.content.DialogInterface;
-import android.content.Intent;
-import android.content.IntentFilter;
 import android.graphics.Canvas;
 import android.graphics.PointF;
 import android.graphics.drawable.Drawable;
-import android.provider.Settings;
 import android.support.v4.view.PagerAdapter;
 import android.support.v4.view.ViewPager;
 import android.util.AttributeSet;
 import android.util.Log;
+import android.util.TypedValue;
 import android.view.DragEvent;
 import android.view.LayoutInflater;
 import android.view.View;
@@ -40,7 +36,6 @@ import android.view.ViewGroup;
 import android.widget.EditText;
 import android.widget.ImageView;
 import android.widget.TextView;
-import android.widget.Toast;
 import com.android.internal.logging.MetricsLogger;
 import com.android.systemui.R;
 import com.android.systemui.qs.tiles.EditTile;
@@ -50,7 +45,7 @@ import com.android.systemui.settings.ToggleSlider;
 import com.android.systemui.statusbar.phone.QSTileHost;
 import com.android.systemui.statusbar.phone.SystemUIDialog;
 import com.android.systemui.tuner.QsTuner;
-import cyanogenmod.providers.CMSettings;
+import com.viewpagerindicator.CirclePageIndicator;
 
 import java.util.ArrayList;
 import java.util.Arrays;
@@ -70,6 +65,7 @@ public class QSDragPanel extends QSPanel implements View.OnDragListener, View.On
     protected QSViewPager mViewPager;
     protected PagerAdapter mPagerAdapter;
     QSPanelTopView mQsPanelTop;
+    CirclePageIndicator mPageIndicator;
 
     private DragTileRecord mDraggingRecord;
     private boolean mEditing;
@@ -120,8 +116,10 @@ public class QSDragPanel extends QSPanel implements View.OnDragListener, View.On
                 });
         mViewPager = new QSViewPager(getContext());
 
+        mPageIndicator = new CirclePageIndicator(getContext());
         addView(mDetail);
         addView(mViewPager);
+        addView(mPageIndicator);
         addView(mFooter.getView());
 
         mClipper = new QSDetailClipper(mDetail);
@@ -178,7 +176,11 @@ public class QSDragPanel extends QSPanel implements View.OnDragListener, View.On
                 return view == object;
             }
         };
-        mViewPager.addOnPageChangeListener(new ViewPager.OnPageChangeListener() {
+        mViewPager.setAdapter(mPagerAdapter);
+        mViewPager.setCurrentItem(0);
+
+        mPageIndicator.setViewPager(mViewPager);
+        mPageIndicator.setOnPageChangeListener(new ViewPager.OnPageChangeListener() {
             @Override
             public void onPageScrolled(int position, float positionOffset,
                                        int positionOffsetPixels) {
@@ -210,8 +212,6 @@ public class QSDragPanel extends QSPanel implements View.OnDragListener, View.On
 
             }
         });
-        mViewPager.setAdapter(mPagerAdapter);
-        mViewPager.setCurrentItem(0);
 
         setClipChildren(false);
         updateResources();
@@ -470,14 +470,13 @@ public class QSDragPanel extends QSPanel implements View.OnDragListener, View.On
         final int width = MeasureSpec.getSize(widthMeasureSpec);
 
         mQsPanelTop.measure(exactly(width), MeasureSpec.UNSPECIFIED);
-
-        final int brightnessHeight = mQsPanelTop.getMeasuredHeight();
-
-        mFooter.getView().measure(exactly(width), MeasureSpec.UNSPECIFIED);
-
         mViewPager.measure(exactly(width), MeasureSpec.UNSPECIFIED);
+        mPageIndicator.measure(exactly(width), MeasureSpec.UNSPECIFIED);
+        mFooter.getView().measure(exactly(width), MeasureSpec.UNSPECIFIED);
 
-        int h = brightnessHeight + mViewPager.getMeasuredHeight();
+        int h = mQsPanelTop.getMeasuredHeight()
+                + mViewPager.getMeasuredHeight()
+                + mPageIndicator.getMeasuredHeight();
         if (mFooter.hasFooter()) {
             h += mFooter.getView().getMeasuredHeight();
         }
@@ -507,12 +506,20 @@ public class QSDragPanel extends QSPanel implements View.OnDragListener, View.On
         if (DEBUG_DRAG) Log.d(TAG, "onLayout()");
         final int w = getWidth();
 
-        mQsPanelTop.layout(0, t, mQsPanelTop.getMeasuredWidth(),
-                t + mQsPanelTop.getMeasuredHeight());
+        int top = 0;
+        mQsPanelTop.layout(0, top, w, top + mQsPanelTop.getMeasuredHeight());
+        top += mQsPanelTop.getMeasuredHeight();
 
+        mViewPager.layout(0, top, w, top + mViewPager.getMeasuredHeight());
+        top += mViewPager.getMeasuredHeight();
+
+        // layout page indicator below view pager
+        mPageIndicator.layout(0, top, w, top + mPageIndicator.getMeasuredHeight());
+
+        // detail takes up whole height
         final int dh = Math.max(mDetail.getMeasuredHeight(), mViewPager.getMeasuredHeight());
-        mViewPager.layout(0, t + mQsPanelTop.getMeasuredHeight(), w, t + dh);
-        mDetail.layout(0, t, mDetail.getMeasuredWidth(), t + dh);
+        mDetail.layout(0, 0, mDetail.getMeasuredWidth(), getMeasuredHeight());
+
         if (mFooter.hasFooter()) {
             View footer = mFooter.getView();
             footer.layout(0, getMeasuredHeight() - footer.getMeasuredHeight(),
diff --git a/packages/SystemUI/src/com/viewpagerindicator/CirclePageIndicator.java b/packages/SystemUI/src/com/viewpagerindicator/CirclePageIndicator.java
new file mode 100644
index 0000000..b1c08b98
--- /dev/null
+++ b/packages/SystemUI/src/com/viewpagerindicator/CirclePageIndicator.java
@@ -0,0 +1,505 @@
+/*
+ * Copyright (C) 2011 Patrik Akerfeldt
+ * Copyright (C) 2011 Jake Wharton
+ *
+ * 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.viewpagerindicator;
+
+import android.content.Context;
+import android.content.res.Resources;
+import android.content.res.TypedArray;
+import android.graphics.Canvas;
+import android.graphics.Paint;
+import android.graphics.Paint.Style;
+import android.graphics.drawable.Drawable;
+import android.support.v4.view.MotionEventCompat;
+import android.support.v4.view.ViewConfigurationCompat;
+import android.support.v4.view.ViewPager;
+import android.util.AttributeSet;
+import android.view.MotionEvent;
+import android.view.View;
+import android.view.ViewConfiguration;
+import com.android.systemui.R;
+
+import static android.graphics.Paint.ANTI_ALIAS_FLAG;
+import static android.widget.LinearLayout.HORIZONTAL;
+import static android.widget.LinearLayout.VERTICAL;
+
+/**
+ * Draws circles (one for each view). The current view position is filled and
+ * others are only stroked.
+ */
+public class CirclePageIndicator extends View implements PageIndicator {
+    private static final int INVALID_POINTER = -1;
+
+    private float mRadius;
+    private final Paint mPaintPageFill = new Paint(ANTI_ALIAS_FLAG);
+    private final Paint mPaintStroke = new Paint(ANTI_ALIAS_FLAG);
+    private final Paint mPaintFill = new Paint(ANTI_ALIAS_FLAG);
+    private ViewPager mViewPager;
+    private ViewPager.OnPageChangeListener mListener;
+    private int mCurrentPage;
+    private int mSnapPage;
+    private float mPageOffset;
+    private int mScrollState;
+    private int mOrientation;
+    private boolean mCentered;
+    private boolean mSnap;
+
+    private int mTouchSlop;
+    private float mLastMotionX = -1;
+    private int mActivePointerId = INVALID_POINTER;
+    private boolean mIsDragging;
+
+
+    public CirclePageIndicator(Context context) {
+        this(context, null);
+    }
+
+    public CirclePageIndicator(Context context, AttributeSet attrs) {
+        this(context, attrs, 0);
+    }
+
+    public CirclePageIndicator(Context context, AttributeSet attrs, int defStyle) {
+        super(context, attrs, defStyle);
+        if (isInEditMode()) return;
+
+        //Load defaults from resources
+        final Resources res = getResources();
+        final int defaultPageColor = res.getColor(R.color.default_circle_indicator_page_color);
+        final int defaultFillColor = res.getColor(R.color.default_circle_indicator_fill_color);
+        final int defaultOrientation = res.getInteger(R.integer.default_circle_indicator_orientation);
+        final int defaultStrokeColor = res.getColor(R.color.default_circle_indicator_stroke_color);
+        final float defaultStrokeWidth = res.getDimension(R.dimen.default_circle_indicator_stroke_width);
+        final float defaultRadius = res.getDimension(R.dimen.default_circle_indicator_radius);
+        final boolean defaultCentered = res.getBoolean(R.bool.default_circle_indicator_centered);
+        final boolean defaultSnap = res.getBoolean(R.bool.default_circle_indicator_snap);
+
+        //Retrieve styles attributes
+        TypedArray a = context.obtainStyledAttributes(attrs, R.styleable.CirclePageIndicator, defStyle, 0);
+
+        mCentered = a.getBoolean(R.styleable.CirclePageIndicator_centered, defaultCentered);
+        mOrientation = a.getInt(R.styleable.CirclePageIndicator_android_orientation, defaultOrientation);
+        mPaintPageFill.setStyle(Style.FILL);
+        mPaintPageFill.setColor(a.getColor(R.styleable.CirclePageIndicator_pageColor, defaultPageColor));
+        mPaintStroke.setStyle(Style.STROKE);
+        mPaintStroke.setColor(a.getColor(R.styleable.CirclePageIndicator_strokeColor, defaultStrokeColor));
+        mPaintStroke.setStrokeWidth(a.getDimension(R.styleable.CirclePageIndicator_strokeWidth, defaultStrokeWidth));
+        mPaintFill.setStyle(Style.FILL);
+        mPaintFill.setColor(a.getColor(R.styleable.CirclePageIndicator_indicatorFillColor, defaultFillColor));
+        mRadius = a.getDimension(R.styleable.CirclePageIndicator_radius, defaultRadius);
+        mSnap = a.getBoolean(R.styleable.CirclePageIndicator_snap, defaultSnap);
+
+        Drawable background = a.getDrawable(R.styleable.CirclePageIndicator_android_background);
+        if (background != null) {
+            setBackgroundDrawable(background);
+        }
+
+        a.recycle();
+
+        final ViewConfiguration configuration = ViewConfiguration.get(context);
+        mTouchSlop = ViewConfigurationCompat.getScaledPagingTouchSlop(configuration);
+    }
+
+
+    public void setCentered(boolean centered) {
+        mCentered = centered;
+        invalidate();
+    }
+
+    public boolean isCentered() {
+        return mCentered;
+    }
+
+    public void setPageColor(int pageColor) {
+        mPaintPageFill.setColor(pageColor);
+        invalidate();
+    }
+
+    public int getPageColor() {
+        return mPaintPageFill.getColor();
+    }
+
+    public void setFillColor(int fillColor) {
+        mPaintFill.setColor(fillColor);
+        invalidate();
+    }
+
+    public int getFillColor() {
+        return mPaintFill.getColor();
+    }
+
+    public void setOrientation(int orientation) {
+        switch (orientation) {
+            case HORIZONTAL:
+            case VERTICAL:
+                mOrientation = orientation;
+                requestLayout();
+                break;
+
+            default:
+                throw new IllegalArgumentException("Orientation must be either HORIZONTAL or VERTICAL.");
+        }
+    }
+
+    public int getOrientation() {
+        return mOrientation;
+    }
+
+    public void setStrokeColor(int strokeColor) {
+        mPaintStroke.setColor(strokeColor);
+        invalidate();
+    }
+
+    public int getStrokeColor() {
+        return mPaintStroke.getColor();
+    }
+
+    public void setStrokeWidth(float strokeWidth) {
+        mPaintStroke.setStrokeWidth(strokeWidth);
+        invalidate();
+    }
+
+    public float getStrokeWidth() {
+        return mPaintStroke.getStrokeWidth();
+    }
+
+    public void setRadius(float radius) {
+        mRadius = radius;
+        invalidate();
+    }
+
+    public float getRadius() {
+        return mRadius;
+    }
+
+    public void setSnap(boolean snap) {
+        mSnap = snap;
+        invalidate();
+    }
+
+    public boolean isSnap() {
+        return mSnap;
+    }
+
+    @Override
+    protected void onDraw(Canvas canvas) {
+        super.onDraw(canvas);
+
+        if (mViewPager == null) {
+            return;
+        }
+        final int count = mViewPager.getAdapter().getCount();
+        if (count == 0) {
+            return;
+        }
+
+        if (mCurrentPage >= count) {
+            setCurrentItem(count - 1);
+            return;
+        }
+
+        int longSize;
+        int longPaddingBefore;
+        int longPaddingAfter;
+        int shortPaddingBefore;
+        if (mOrientation == HORIZONTAL) {
+            longSize = getWidth();
+            longPaddingBefore = getPaddingLeft();
+            longPaddingAfter = getPaddingRight();
+            shortPaddingBefore = getPaddingTop();
+        } else {
+            longSize = getHeight();
+            longPaddingBefore = getPaddingTop();
+            longPaddingAfter = getPaddingBottom();
+            shortPaddingBefore = getPaddingLeft();
+        }
+
+        final float threeRadius = mRadius * 3;
+        final float shortOffset = shortPaddingBefore + mRadius;
+        float longOffset = longPaddingBefore + mRadius;
+        if (mCentered) {
+            longOffset += ((longSize - longPaddingBefore - longPaddingAfter) / 2.0f) - ((count * threeRadius) / 2.0f);
+        }
+
+        float dX;
+        float dY;
+
+        float pageFillRadius = mRadius;
+        if (mPaintStroke.getStrokeWidth() > 0) {
+            pageFillRadius -= mPaintStroke.getStrokeWidth() / 2.0f;
+        }
+
+        //Draw stroked circles
+        for (int iLoop = 0; iLoop < count; iLoop++) {
+            float drawLong = longOffset + (iLoop * threeRadius);
+            if (mOrientation == HORIZONTAL) {
+                dX = drawLong;
+                dY = shortOffset;
+            } else {
+                dX = shortOffset;
+                dY = drawLong;
+            }
+            // Only paint fill if not completely transparent
+            if (mPaintPageFill.getAlpha() > 0) {
+                canvas.drawCircle(dX, dY, (float) (pageFillRadius/1.5f), mPaintPageFill);
+            }
+
+            // Only paint stroke if a stroke width was non-zero
+            if (pageFillRadius != mRadius) {
+                canvas.drawCircle(dX, dY, mRadius, mPaintStroke);
+            }
+        }
+
+        //Draw the filled circle according to the current scroll
+        float cx = (mSnap ? mSnapPage : mCurrentPage) * threeRadius;
+        if (!mSnap) {
+            cx += mPageOffset * threeRadius;
+        }
+        if (mOrientation == HORIZONTAL) {
+            dX = longOffset + cx;
+            dY = shortOffset;
+        } else {
+            dX = shortOffset;
+            dY = longOffset + cx;
+        }
+        canvas.drawCircle(dX, dY, mRadius, mPaintFill);
+    }
+
+    public boolean onTouchEvent(MotionEvent ev) {
+        if (super.onTouchEvent(ev)) {
+            return true;
+        }
+        if ((mViewPager == null) || (mViewPager.getAdapter().getCount() == 0)) {
+            return false;
+        }
+
+        final int action = ev.getAction() & MotionEventCompat.ACTION_MASK;
+        switch (action) {
+            case MotionEvent.ACTION_DOWN:
+                mActivePointerId = MotionEventCompat.getPointerId(ev, 0);
+                mLastMotionX = ev.getX();
+                break;
+
+            case MotionEvent.ACTION_MOVE: {
+                final int activePointerIndex = MotionEventCompat.findPointerIndex(ev, mActivePointerId);
+                final float x = MotionEventCompat.getX(ev, activePointerIndex);
+                final float deltaX = x - mLastMotionX;
+
+                if (!mIsDragging) {
+                    if (Math.abs(deltaX) > mTouchSlop) {
+                        mIsDragging = true;
+                    }
+                }
+
+                if (mIsDragging) {
+                    mLastMotionX = x;
+                    if (mViewPager.isFakeDragging() || mViewPager.beginFakeDrag()) {
+                        mViewPager.fakeDragBy(deltaX);
+                    }
+                }
+
+                break;
+            }
+
+            case MotionEvent.ACTION_CANCEL:
+            case MotionEvent.ACTION_UP:
+                if (!mIsDragging) {
+                    final int count = mViewPager.getAdapter().getCount();
+                    final int width = getWidth();
+                    final float halfWidth = width / 2f;
+                    final float sixthWidth = width / 6f;
+
+                    if ((mCurrentPage > 0) && (ev.getX() < halfWidth - sixthWidth)) {
+                        if (action != MotionEvent.ACTION_CANCEL) {
+                            mViewPager.setCurrentItem(mCurrentPage - 1);
+                        }
+                        return true;
+                    } else if ((mCurrentPage < count - 1) && (ev.getX() > halfWidth + sixthWidth)) {
+                        if (action != MotionEvent.ACTION_CANCEL) {
+                            mViewPager.setCurrentItem(mCurrentPage + 1);
+                        }
+                        return true;
+                    }
+                }
+
+                mIsDragging = false;
+                mActivePointerId = INVALID_POINTER;
+                if (mViewPager.isFakeDragging()) mViewPager.endFakeDrag();
+                break;
+
+            case MotionEventCompat.ACTION_POINTER_DOWN: {
+                final int index = MotionEventCompat.getActionIndex(ev);
+                mLastMotionX = MotionEventCompat.getX(ev, index);
+                mActivePointerId = MotionEventCompat.getPointerId(ev, index);
+                break;
+            }
+
+            case MotionEventCompat.ACTION_POINTER_UP:
+                final int pointerIndex = MotionEventCompat.getActionIndex(ev);
+                final int pointerId = MotionEventCompat.getPointerId(ev, pointerIndex);
+                if (pointerId == mActivePointerId) {
+                    final int newPointerIndex = pointerIndex == 0 ? 1 : 0;
+                    mActivePointerId = MotionEventCompat.getPointerId(ev, newPointerIndex);
+                }
+                mLastMotionX = MotionEventCompat.getX(ev, MotionEventCompat.findPointerIndex(ev, mActivePointerId));
+                break;
+        }
+
+        return true;
+    }
+
+    @Override
+    public void setViewPager(ViewPager view) {
+        if (mViewPager == view) {
+            return;
+        }
+        if (mViewPager != null) {
+            mViewPager.setOnPageChangeListener(null);
+        }
+        if (view.getAdapter() == null) {
+            throw new IllegalStateException("ViewPager does not have adapter instance.");
+        }
+        mViewPager = view;
+        mViewPager.setOnPageChangeListener(this);
+        invalidate();
+    }
+
+    @Override
+    public void setViewPager(ViewPager view, int initialPosition) {
+        setViewPager(view);
+        setCurrentItem(initialPosition);
+    }
+
+    @Override
+    public void setCurrentItem(int item) {
+        if (mViewPager == null) {
+            throw new IllegalStateException("ViewPager has not been bound.");
+        }
+        mViewPager.setCurrentItem(item);
+        mCurrentPage = item;
+        invalidate();
+    }
+
+    @Override
+    public void notifyDataSetChanged() {
+        invalidate();
+    }
+
+    @Override
+    public void onPageScrollStateChanged(int state) {
+        mScrollState = state;
+
+        if (mListener != null) {
+            mListener.onPageScrollStateChanged(state);
+        }
+    }
+
+    @Override
+    public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {
+        mCurrentPage = position;
+        mPageOffset = positionOffset;
+        invalidate();
+
+        if (mListener != null) {
+            mListener.onPageScrolled(position, positionOffset, positionOffsetPixels);
+        }
+    }
+
+    @Override
+    public void onPageSelected(int position) {
+        if (mSnap || mScrollState == ViewPager.SCROLL_STATE_IDLE) {
+            mCurrentPage = position;
+            mSnapPage = position;
+            invalidate();
+        }
+
+        if (mListener != null) {
+            mListener.onPageSelected(position);
+        }
+    }
+
+    @Override
+    public void setOnPageChangeListener(ViewPager.OnPageChangeListener listener) {
+        mListener = listener;
+    }
+
+    /*
+     * (non-Javadoc)
+     *
+     * @see android.view.View#onMeasure(int, int)
+     */
+    @Override
+    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
+        if (mOrientation == HORIZONTAL) {
+            setMeasuredDimension(measureLong(widthMeasureSpec), measureShort(heightMeasureSpec));
+        } else {
+            setMeasuredDimension(measureShort(widthMeasureSpec), measureLong(heightMeasureSpec));
+        }
+    }
+
+    /**
+     * Determines the width of this view
+     *
+     * @param measureSpec
+     *            A measureSpec packed into an int
+     * @return The width of the view, honoring constraints from measureSpec
+     */
+    private int measureLong(int measureSpec) {
+        int result;
+        int specMode = MeasureSpec.getMode(measureSpec);
+        int specSize = MeasureSpec.getSize(measureSpec);
+
+        if ((specMode == MeasureSpec.EXACTLY) || (mViewPager == null)) {
+            //We were told how big to be
+            result = specSize;
+        } else {
+            //Calculate the width according the views count
+            final int count = mViewPager.getAdapter().getCount();
+            result = (int)(getPaddingLeft() + getPaddingRight()
+                    + (count * 2 * mRadius) + (count - 1) * mRadius + 1);
+            //Respect AT_MOST value if that was what is called for by measureSpec
+            if (specMode == MeasureSpec.AT_MOST) {
+                result = Math.min(result, specSize);
+            }
+        }
+        return result;
+    }
+
+    /**
+     * Determines the height of this view
+     *
+     * @param measureSpec
+     *            A measureSpec packed into an int
+     * @return The height of the view, honoring constraints from measureSpec
+     */
+    private int measureShort(int measureSpec) {
+        int result;
+        int specMode = MeasureSpec.getMode(measureSpec);
+        int specSize = MeasureSpec.getSize(measureSpec);
+
+        if (specMode == MeasureSpec.EXACTLY) {
+            //We were told how big to be
+            result = specSize;
+        } else {
+            //Measure the height
+            result = (int)(2 * mRadius + getPaddingTop() + getPaddingBottom() + 1);
+            //Respect AT_MOST value if that was what is called for by measureSpec
+            if (specMode == MeasureSpec.AT_MOST) {
+                result = Math.min(result, specSize);
+            }
+        }
+        return result;
+    }
+}
diff --git a/packages/SystemUI/src/com/viewpagerindicator/PageIndicator.java b/packages/SystemUI/src/com/viewpagerindicator/PageIndicator.java
new file mode 100644
index 0000000..c08c00a
--- /dev/null
+++ b/packages/SystemUI/src/com/viewpagerindicator/PageIndicator.java
@@ -0,0 +1,63 @@
+/*
+ * Copyright (C) 2011 Patrik Akerfeldt
+ * Copyright (C) 2011 Jake Wharton
+ *
+ * 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.viewpagerindicator;
+
+import android.support.v4.view.ViewPager;
+
+/**
+ * A PageIndicator is responsible to show an visual indicator on the total views
+ * number and the current visible view.
+ */
+public interface PageIndicator extends ViewPager.OnPageChangeListener {
+    /**
+     * Bind the indicator to a ViewPager.
+     *
+     * @param view
+     */
+    void setViewPager(ViewPager view);
+
+    /**
+     * Bind the indicator to a ViewPager.
+     *
+     * @param view
+     * @param initialPosition
+     */
+    void setViewPager(ViewPager view, int initialPosition);
+
+    /**
+     * <p>Set the current page of both the ViewPager and indicator.</p>
+     *
+     * <p>This <strong>must</strong> be used if you need to set the page before
+     * the views are drawn on screen (e.g., default start page).</p>
+     *
+     * @param item
+     */
+    void setCurrentItem(int item);
+
+    /**
+     * Set a page change listener which will receive forwarded events.
+     *
+     * @param listener
+     */
+    void setOnPageChangeListener(ViewPager.OnPageChangeListener listener);
+
+    /**
+     * Notify the indicator that the fragment list has changed.
+     */
+    void notifyDataSetChanged();
+}