Android example source code file (GestureOverlayView.java)

This example Android source code file (GestureOverlayView.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Android by Example" ^TM.

Java - Android tags/keywords

acceleratedecelerateinterpolator, android, arraylist, attributeset, drawing, fade_animation_rate, fadeoutrunnable, gesture, gesture_stroke_type_single, gestureoverlayview, gesturepoint, graphics, motionevent, orientation_vertical, override, paint, path, rect, ui, view

The GestureOverlayView.java Android example source code

/*
 * 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 android.gesture;

import android.content.Context;
import android.content.res.TypedArray;
import android.graphics.Canvas;
import android.graphics.Paint;
import android.graphics.Path;
import android.graphics.Rect;
import android.graphics.RectF;
import android.util.AttributeSet;
import android.view.MotionEvent;
import android.view.animation.AnimationUtils;
import android.view.animation.AccelerateDecelerateInterpolator;
import android.widget.FrameLayout;
import android.os.SystemClock;
import android.annotation.Widget;
import com.android.internal.R;

import java.util.ArrayList;

/**
 * A transparent overlay for gesture input that can be placed on top of other
 * widgets or contain other widgets.
 *
 * @attr ref android.R.styleable#GestureOverlayView_eventsInterceptionEnabled
 * @attr ref android.R.styleable#GestureOverlayView_fadeDuration
 * @attr ref android.R.styleable#GestureOverlayView_fadeOffset
 * @attr ref android.R.styleable#GestureOverlayView_fadeEnabled
 * @attr ref android.R.styleable#GestureOverlayView_gestureStrokeWidth
 * @attr ref android.R.styleable#GestureOverlayView_gestureStrokeAngleThreshold
 * @attr ref android.R.styleable#GestureOverlayView_gestureStrokeLengthThreshold
 * @attr ref android.R.styleable#GestureOverlayView_gestureStrokeSquarenessThreshold
 * @attr ref android.R.styleable#GestureOverlayView_gestureStrokeType
 * @attr ref android.R.styleable#GestureOverlayView_gestureColor
 * @attr ref android.R.styleable#GestureOverlayView_orientation
 * @attr ref android.R.styleable#GestureOverlayView_uncertainGestureColor
 */
@Widget
public class GestureOverlayView extends FrameLayout {
    public static final int GESTURE_STROKE_TYPE_SINGLE = 0;
    public static final int GESTURE_STROKE_TYPE_MULTIPLE = 1;

    public static final int ORIENTATION_HORIZONTAL = 0;
    public static final int ORIENTATION_VERTICAL = 1;

    private static final int FADE_ANIMATION_RATE = 16;
    private static final boolean GESTURE_RENDERING_ANTIALIAS = true;
    private static final boolean DITHER_FLAG = true;

    private final Paint mGesturePaint = new Paint();

    private long mFadeDuration = 150;
    private long mFadeOffset = 420;
    private long mFadingStart;
    private boolean mFadingHasStarted;
    private boolean mFadeEnabled = true;

    private int mCurrentColor;
    private int mCertainGestureColor = 0xFFFFFF00;
    private int mUncertainGestureColor = 0x48FFFF00;
    private float mGestureStrokeWidth = 12.0f;
    private int mInvalidateExtraBorder = 10;

    private int mGestureStrokeType = GESTURE_STROKE_TYPE_SINGLE;
    private float mGestureStrokeLengthThreshold = 50.0f;
    private float mGestureStrokeSquarenessTreshold = 0.275f;
    private float mGestureStrokeAngleThreshold = 40.0f;

    private int mOrientation = ORIENTATION_VERTICAL;

    private final Rect mInvalidRect = new Rect();
    private final Path mPath = new Path();
    private boolean mGestureVisible = true;

    private float mX;
    private float mY;

    private float mCurveEndX;
    private float mCurveEndY;

    private float mTotalLength;
    private boolean mIsGesturing = false;
    private boolean mPreviousWasGesturing = false;
    private boolean mInterceptEvents = true;
    private boolean mIsListeningForGestures;
    private boolean mResetGesture;

    // current gesture
    private Gesture mCurrentGesture;
    private final ArrayList<GesturePoint> mStrokeBuffer = new ArrayList(100);

    // TODO: Make this a list of WeakReferences
    private final ArrayList<OnGestureListener> mOnGestureListeners =
            new ArrayList<OnGestureListener>();
    // TODO: Make this a list of WeakReferences
    private final ArrayList<OnGesturePerformedListener> mOnGesturePerformedListeners =
            new ArrayList<OnGesturePerformedListener>();
    // TODO: Make this a list of WeakReferences
    private final ArrayList<OnGesturingListener> mOnGesturingListeners =
            new ArrayList<OnGesturingListener>();

    private boolean mHandleGestureActions;

    // fading out effect
    private boolean mIsFadingOut = false;
    private float mFadingAlpha = 1.0f;
    private final AccelerateDecelerateInterpolator mInterpolator =
            new AccelerateDecelerateInterpolator();

    private final FadeOutRunnable mFadingOut = new FadeOutRunnable();

    public GestureOverlayView(Context context) {
        super(context);
        init();
    }

    public GestureOverlayView(Context context, AttributeSet attrs) {
        this(context, attrs, com.android.internal.R.attr.gestureOverlayViewStyle);
    }

    public GestureOverlayView(Context context, AttributeSet attrs, int defStyle) {
        super(context, attrs, defStyle);

        TypedArray a = context.obtainStyledAttributes(attrs,
                R.styleable.GestureOverlayView, defStyle, 0);

        mGestureStrokeWidth = a.getFloat(R.styleable.GestureOverlayView_gestureStrokeWidth,
                mGestureStrokeWidth);
        mInvalidateExtraBorder = Math.max(1, ((int) mGestureStrokeWidth) - 1);
        mCertainGestureColor = a.getColor(R.styleable.GestureOverlayView_gestureColor,
                mCertainGestureColor);
        mUncertainGestureColor = a.getColor(R.styleable.GestureOverlayView_uncertainGestureColor,
                mUncertainGestureColor);
        mFadeDuration = a.getInt(R.styleable.GestureOverlayView_fadeDuration, (int) mFadeDuration);
        mFadeOffset = a.getInt(R.styleable.GestureOverlayView_fadeOffset, (int) mFadeOffset);
        mGestureStrokeType = a.getInt(R.styleable.GestureOverlayView_gestureStrokeType,
                mGestureStrokeType);
        mGestureStrokeLengthThreshold = a.getFloat(
                R.styleable.GestureOverlayView_gestureStrokeLengthThreshold,
                mGestureStrokeLengthThreshold);
        mGestureStrokeAngleThreshold = a.getFloat(
                R.styleable.GestureOverlayView_gestureStrokeAngleThreshold,
                mGestureStrokeAngleThreshold);
        mGestureStrokeSquarenessTreshold = a.getFloat(
                R.styleable.GestureOverlayView_gestureStrokeSquarenessThreshold,
                mGestureStrokeSquarenessTreshold);
        mInterceptEvents = a.getBoolean(R.styleable.GestureOverlayView_eventsInterceptionEnabled,
                mInterceptEvents);
        mFadeEnabled = a.getBoolean(R.styleable.GestureOverlayView_fadeEnabled,
                mFadeEnabled);
        mOrientation = a.getInt(R.styleable.GestureOverlayView_orientation, mOrientation);

        a.recycle();

        init();
    }

    private void init() {
        setWillNotDraw(false);

        final Paint gesturePaint = mGesturePaint;
        gesturePaint.setAntiAlias(GESTURE_RENDERING_ANTIALIAS);
        gesturePaint.setColor(mCertainGestureColor);
        gesturePaint.setStyle(Paint.Style.STROKE);
        gesturePaint.setStrokeJoin(Paint.Join.ROUND);
        gesturePaint.setStrokeCap(Paint.Cap.ROUND);
        gesturePaint.setStrokeWidth(mGestureStrokeWidth);
        gesturePaint.setDither(DITHER_FLAG);

        mCurrentColor = mCertainGestureColor;
        setPaintAlpha(255);
    }

    public ArrayList<GesturePoint> getCurrentStroke() {
        return mStrokeBuffer;
    }

    public int getOrientation() {
        return mOrientation;
    }

    public void setOrientation(int orientation) {
        mOrientation = orientation;
    }

    public void setGestureColor(int color) {
        mCertainGestureColor = color;
    }

    public void setUncertainGestureColor(int color) {
        mUncertainGestureColor = color;
    }

    public int getUncertainGestureColor() {
        return mUncertainGestureColor;
    }

    public int getGestureColor() {
        return mCertainGestureColor;
    }

    public float getGestureStrokeWidth() {
        return mGestureStrokeWidth;
    }

    public void setGestureStrokeWidth(float gestureStrokeWidth) {
        mGestureStrokeWidth = gestureStrokeWidth;
        mInvalidateExtraBorder = Math.max(1, ((int) gestureStrokeWidth) - 1);
        mGesturePaint.setStrokeWidth(gestureStrokeWidth);
    }

    public int getGestureStrokeType() {
        return mGestureStrokeType;
    }

    public void setGestureStrokeType(int gestureStrokeType) {
        mGestureStrokeType = gestureStrokeType;
    }

    public float getGestureStrokeLengthThreshold() {
        return mGestureStrokeLengthThreshold;
    }

    public void setGestureStrokeLengthThreshold(float gestureStrokeLengthThreshold) {
        mGestureStrokeLengthThreshold = gestureStrokeLengthThreshold;
    }

    public float getGestureStrokeSquarenessTreshold() {
        return mGestureStrokeSquarenessTreshold;
    }

    public void setGestureStrokeSquarenessTreshold(float gestureStrokeSquarenessTreshold) {
        mGestureStrokeSquarenessTreshold = gestureStrokeSquarenessTreshold;
    }

    public float getGestureStrokeAngleThreshold() {
        return mGestureStrokeAngleThreshold;
    }

    public void setGestureStrokeAngleThreshold(float gestureStrokeAngleThreshold) {
        mGestureStrokeAngleThreshold = gestureStrokeAngleThreshold;
    }

    public boolean isEventsInterceptionEnabled() {
        return mInterceptEvents;
    }

    public void setEventsInterceptionEnabled(boolean enabled) {
        mInterceptEvents = enabled;
    }

    public boolean isFadeEnabled() {
        return mFadeEnabled;
    }

    public void setFadeEnabled(boolean fadeEnabled) {
        mFadeEnabled = fadeEnabled;
    }

    public Gesture getGesture() {
        return mCurrentGesture;
    }

    public void setGesture(Gesture gesture) {
        if (mCurrentGesture != null) {
            clear(false);
        }

        setCurrentColor(mCertainGestureColor);
        mCurrentGesture = gesture;

        final Path path = mCurrentGesture.toPath();
        final RectF bounds = new RectF();
        path.computeBounds(bounds, true);

        // TODO: The path should also be scaled to fit inside this view
        mPath.rewind();
        mPath.addPath(path, -bounds.left + (getWidth() - bounds.width()) / 2.0f,
                -bounds.top + (getHeight() - bounds.height()) / 2.0f);

        mResetGesture = true;

        invalidate();
    }

    public Path getGesturePath() {
        return mPath;
    }

    public Path getGesturePath(Path path) {
        path.set(mPath);
        return path;
    }

    public boolean isGestureVisible() {
        return mGestureVisible;
    }

    public void setGestureVisible(boolean visible) {
        mGestureVisible = visible;
    }

    public long getFadeOffset() {
        return mFadeOffset;
    }

    public void setFadeOffset(long fadeOffset) {
        mFadeOffset = fadeOffset;
    }

    public void addOnGestureListener(OnGestureListener listener) {
        mOnGestureListeners.add(listener);
    }

    public void removeOnGestureListener(OnGestureListener listener) {
        mOnGestureListeners.remove(listener);
    }

    public void removeAllOnGestureListeners() {
        mOnGestureListeners.clear();
    }

    public void addOnGesturePerformedListener(OnGesturePerformedListener listener) {
        mOnGesturePerformedListeners.add(listener);
        if (mOnGesturePerformedListeners.size() > 0) {
            mHandleGestureActions = true;
        }
    }

    public void removeOnGesturePerformedListener(OnGesturePerformedListener listener) {
        mOnGesturePerformedListeners.remove(listener);
        if (mOnGesturePerformedListeners.size() <= 0) {
            mHandleGestureActions = false;
        }
    }

    public void removeAllOnGesturePerformedListeners() {
        mOnGesturePerformedListeners.clear();
        mHandleGestureActions = false;
    }

    public void addOnGesturingListener(OnGesturingListener listener) {
        mOnGesturingListeners.add(listener);
    }

    public void removeOnGesturingListener(OnGesturingListener listener) {
        mOnGesturingListeners.remove(listener);
    }

    public void removeAllOnGesturingListeners() {
        mOnGesturingListeners.clear();
    }

    public boolean isGesturing() {
        return mIsGesturing;
    }

    private void setCurrentColor(int color) {
        mCurrentColor = color;
        if (mFadingHasStarted) {
            setPaintAlpha((int) (255 * mFadingAlpha));
        } else {
            setPaintAlpha(255);
        }
        invalidate();
    }

    /**
     * @hide
     */
    public Paint getGesturePaint() {
        return mGesturePaint;
    }

    @Override
    public void draw(Canvas canvas) {
        super.draw(canvas);

        if (mCurrentGesture != null && mGestureVisible) {
            canvas.drawPath(mPath, mGesturePaint);
        }
    }

    private void setPaintAlpha(int alpha) {
        alpha += alpha >> 7;
        final int baseAlpha = mCurrentColor >>> 24;
        final int useAlpha = baseAlpha * alpha >> 8;
        mGesturePaint.setColor((mCurrentColor << 8 >>> 8) | (useAlpha << 24));
    }

    public void clear(boolean animated) {
        clear(animated, false, true);
    }

    private void clear(boolean animated, boolean fireActionPerformed, boolean immediate) {
        setPaintAlpha(255);
        removeCallbacks(mFadingOut);
        mResetGesture = false;
        mFadingOut.fireActionPerformed = fireActionPerformed;
        mFadingOut.resetMultipleStrokes = false;

        if (animated && mCurrentGesture != null) {
            mFadingAlpha = 1.0f;
            mIsFadingOut = true;
            mFadingHasStarted = false;
            mFadingStart = AnimationUtils.currentAnimationTimeMillis() + mFadeOffset;

            postDelayed(mFadingOut, mFadeOffset);
        } else {
            mFadingAlpha = 1.0f;
            mIsFadingOut = false;
            mFadingHasStarted = false;

            if (immediate) {
                mCurrentGesture = null;
                mPath.rewind();
                invalidate();
            } else if (fireActionPerformed) {
                postDelayed(mFadingOut, mFadeOffset);
            } else if (mGestureStrokeType == GESTURE_STROKE_TYPE_MULTIPLE) {
                mFadingOut.resetMultipleStrokes = true;
                postDelayed(mFadingOut, mFadeOffset);
            } else {
                mCurrentGesture = null;
                mPath.rewind();
                invalidate();
            }
        }
    }

    public void cancelClearAnimation() {
        setPaintAlpha(255);
        mIsFadingOut = false;
        mFadingHasStarted = false;
        removeCallbacks(mFadingOut);
        mPath.rewind();
        mCurrentGesture = null;
    }

    public void cancelGesture() {
        mIsListeningForGestures = false;

        // add the stroke to the current gesture
        mCurrentGesture.addStroke(new GestureStroke(mStrokeBuffer));

        // pass the event to handlers
        final long now = SystemClock.uptimeMillis();
        final MotionEvent event = MotionEvent.obtain(now, now,
                MotionEvent.ACTION_CANCEL, 0.0f, 0.0f, 0);

        final ArrayList<OnGestureListener> listeners = mOnGestureListeners;
        int count = listeners.size();
        for (int i = 0; i < count; i++) {
            listeners.get(i).onGestureCancelled(this, event);
        }

        event.recycle();

        clear(false);
        mIsGesturing = false;
        mPreviousWasGesturing = false;
        mStrokeBuffer.clear();

        final ArrayList<OnGesturingListener> otherListeners = mOnGesturingListeners;
        count = otherListeners.size();
        for (int i = 0; i < count; i++) {
            otherListeners.get(i).onGesturingEnded(this);
        }
    }

    @Override
    protected void onDetachedFromWindow() {
        cancelClearAnimation();
    }

    @Override
    public boolean dispatchTouchEvent(MotionEvent event) {
        if (isEnabled()) {
            final boolean cancelDispatch = (mIsGesturing || (mCurrentGesture != null &&
                    mCurrentGesture.getStrokesCount() > 0 && mPreviousWasGesturing)) &&
                    mInterceptEvents;

            processEvent(event);

            if (cancelDispatch) {
                event.setAction(MotionEvent.ACTION_CANCEL);
            }

            super.dispatchTouchEvent(event);

            return true;
        }

        return super.dispatchTouchEvent(event);
    }

    private boolean processEvent(MotionEvent event) {
        switch (event.getAction()) {
            case MotionEvent.ACTION_DOWN:
                touchDown(event);
                invalidate();
                return true;
            case MotionEvent.ACTION_MOVE:
                if (mIsListeningForGestures) {
                    Rect rect = touchMove(event);
                    if (rect != null) {
                        invalidate(rect);
                    }
                    return true;
                }
                break;
            case MotionEvent.ACTION_UP:
                if (mIsListeningForGestures) {
                    touchUp(event, false);
                    invalidate();
                    return true;
                }
                break;
            case MotionEvent.ACTION_CANCEL:
                if (mIsListeningForGestures) {
                    touchUp(event, true);
                    invalidate();
                    return true;
                }
        }

        return false;
    }

    private void touchDown(MotionEvent event) {
        mIsListeningForGestures = true;

        float x = event.getX();
        float y = event.getY();

        mX = x;
        mY = y;

        mTotalLength = 0;
        mIsGesturing = false;

        if (mGestureStrokeType == GESTURE_STROKE_TYPE_SINGLE || mResetGesture) {
            if (mHandleGestureActions) setCurrentColor(mUncertainGestureColor);
            mResetGesture = false;
            mCurrentGesture = null;
            mPath.rewind();
        } else if (mCurrentGesture == null || mCurrentGesture.getStrokesCount() == 0) {
            if (mHandleGestureActions) setCurrentColor(mUncertainGestureColor);
        }

        // if there is fading out going on, stop it.
        if (mFadingHasStarted) {
            cancelClearAnimation();
        } else if (mIsFadingOut) {
            setPaintAlpha(255);
            mIsFadingOut = false;
            mFadingHasStarted = false;
            removeCallbacks(mFadingOut);
        }

        if (mCurrentGesture == null) {
            mCurrentGesture = new Gesture();
        }

        mStrokeBuffer.add(new GesturePoint(x, y, event.getEventTime()));
        mPath.moveTo(x, y);

        final int border = mInvalidateExtraBorder;
        mInvalidRect.set((int) x - border, (int) y - border, (int) x + border, (int) y + border);

        mCurveEndX = x;
        mCurveEndY = y;

        // pass the event to handlers
        final ArrayList<OnGestureListener> listeners = mOnGestureListeners;
        final int count = listeners.size();
        for (int i = 0; i < count; i++) {
            listeners.get(i).onGestureStarted(this, event);
        }
    }

    private Rect touchMove(MotionEvent event) {
        Rect areaToRefresh = null;

        final float x = event.getX();
        final float y = event.getY();

        final float previousX = mX;
        final float previousY = mY;

        final float dx = Math.abs(x - previousX);
        final float dy = Math.abs(y - previousY);

        if (dx >= GestureStroke.TOUCH_TOLERANCE || dy >= GestureStroke.TOUCH_TOLERANCE) {
            areaToRefresh = mInvalidRect;

            // start with the curve end
            final int border = mInvalidateExtraBorder;
            areaToRefresh.set((int) mCurveEndX - border, (int) mCurveEndY - border,
                    (int) mCurveEndX + border, (int) mCurveEndY + border);

            float cX = mCurveEndX = (x + previousX) / 2;
            float cY = mCurveEndY = (y + previousY) / 2;

            mPath.quadTo(previousX, previousY, cX, cY);

            // union with the control point of the new curve
            areaToRefresh.union((int) previousX - border, (int) previousY - border,
                    (int) previousX + border, (int) previousY + border);

            // union with the end point of the new curve
            areaToRefresh.union((int) cX - border, (int) cY - border,
                    (int) cX + border, (int) cY + border);

            mX = x;
            mY = y;

            mStrokeBuffer.add(new GesturePoint(x, y, event.getEventTime()));

            if (mHandleGestureActions && !mIsGesturing) {
                mTotalLength += (float) Math.sqrt(dx * dx + dy * dy);

                if (mTotalLength > mGestureStrokeLengthThreshold) {
                    final OrientedBoundingBox box =
                            GestureUtils.computeOrientedBoundingBox(mStrokeBuffer);

                    float angle = Math.abs(box.orientation);
                    if (angle > 90) {
                        angle = 180 - angle;
                    }

                    if (box.squareness > mGestureStrokeSquarenessTreshold ||
                            (mOrientation == ORIENTATION_VERTICAL ?
                                    angle < mGestureStrokeAngleThreshold :
                                    angle > mGestureStrokeAngleThreshold)) {

                        mIsGesturing = true;
                        setCurrentColor(mCertainGestureColor);

                        final ArrayList<OnGesturingListener> listeners = mOnGesturingListeners;
                        int count = listeners.size();
                        for (int i = 0; i < count; i++) {
                            listeners.get(i).onGesturingStarted(this);
                        }
                    }
                }
            }

            // pass the event to handlers
            final ArrayList<OnGestureListener> listeners = mOnGestureListeners;
            final int count = listeners.size();
            for (int i = 0; i < count; i++) {
                listeners.get(i).onGesture(this, event);
            }
        }

        return areaToRefresh;
    }

    private void touchUp(MotionEvent event, boolean cancel) {
        mIsListeningForGestures = false;

        // A gesture wasn't started or was cancelled
        if (mCurrentGesture != null) {
            // add the stroke to the current gesture
            mCurrentGesture.addStroke(new GestureStroke(mStrokeBuffer));

            if (!cancel) {
                // pass the event to handlers
                final ArrayList<OnGestureListener> listeners = mOnGestureListeners;
                int count = listeners.size();
                for (int i = 0; i < count; i++) {
                    listeners.get(i).onGestureEnded(this, event);
                }

                clear(mHandleGestureActions && mFadeEnabled, mHandleGestureActions && mIsGesturing,
                        false);
            } else {
                cancelGesture(event);

            }
        } else {
            cancelGesture(event);
        }

        mStrokeBuffer.clear();
        mPreviousWasGesturing = mIsGesturing;
        mIsGesturing = false;

        final ArrayList<OnGesturingListener> listeners = mOnGesturingListeners;
        int count = listeners.size();
        for (int i = 0; i < count; i++) {
            listeners.get(i).onGesturingEnded(this);
        }
    }

    private void cancelGesture(MotionEvent event) {
        // pass the event to handlers
        final ArrayList<OnGestureListener> listeners = mOnGestureListeners;
        final int count = listeners.size();
        for (int i = 0; i < count; i++) {
            listeners.get(i).onGestureCancelled(this, event);
        }

        clear(false);
    }

    private void fireOnGesturePerformed() {
        final ArrayList<OnGesturePerformedListener> actionListeners = mOnGesturePerformedListeners;
        final int count = actionListeners.size();
        for (int i = 0; i < count; i++) {
            actionListeners.get(i).onGesturePerformed(GestureOverlayView.this, mCurrentGesture);
        }
    }

    private class FadeOutRunnable implements Runnable {
        boolean fireActionPerformed;
        boolean resetMultipleStrokes;

        public void run() {
            if (mIsFadingOut) {
                final long now = AnimationUtils.currentAnimationTimeMillis();
                final long duration = now - mFadingStart;

                if (duration > mFadeDuration) {
                    if (fireActionPerformed) {
                        fireOnGesturePerformed();
                    }

                    mPreviousWasGesturing = false;
                    mIsFadingOut = false;
                    mFadingHasStarted = false;
                    mPath.rewind();
                    mCurrentGesture = null;
                    setPaintAlpha(255);
                } else {
                    mFadingHasStarted = true;
                    float interpolatedTime = Math.max(0.0f,
                            Math.min(1.0f, duration / (float) mFadeDuration));
                    mFadingAlpha = 1.0f - mInterpolator.getInterpolation(interpolatedTime);
                    setPaintAlpha((int) (255 * mFadingAlpha));
                    postDelayed(this, FADE_ANIMATION_RATE);
                }
            } else if (resetMultipleStrokes) {
                mResetGesture = true;
            } else {
                fireOnGesturePerformed();

                mFadingHasStarted = false;
                mPath.rewind();
                mCurrentGesture = null;
                mPreviousWasGesturing = false;
                setPaintAlpha(255);
            }

            invalidate();
        }
    }

    public static interface OnGesturingListener {
        void onGesturingStarted(GestureOverlayView overlay);

        void onGesturingEnded(GestureOverlayView overlay);
    }

    public static interface OnGestureListener {
        void onGestureStarted(GestureOverlayView overlay, MotionEvent event);

        void onGesture(GestureOverlayView overlay, MotionEvent event);

        void onGestureEnded(GestureOverlayView overlay, MotionEvent event);

        void onGestureCancelled(GestureOverlayView overlay, MotionEvent event);
    }

    public static interface OnGesturePerformedListener {
        void onGesturePerformed(GestureOverlayView overlay, Gesture gesture);
    }
}