/*
* Copyright (C) 2012 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.support.v4.view;
import android.content.Context;
import android.os.Build;
import android.os.Handler;
import android.os.Message;
import android.view.GestureDetector;
import android.view.GestureDetector.OnDoubleTapListener;
import android.view.GestureDetector.OnGestureListener;
import android.view.MotionEvent;
import android.view.VelocityTracker;
import android.view.View;
import android.view.ViewConfiguration;
/**
* Detects various gestures and events using the supplied {@link MotionEvent}s.
* The {@link OnGestureListener} callback will notify users when a particular
* motion event has occurred. This class should only be used with {@link MotionEvent}s
* reported via touch (don't use for trackball events).
*
* <p>This compatibility implementation of the framework's GestureDetector guarantees
* the newer focal point scrolling behavior from Jellybean MR1 on all platform versions.</p>
*
* To use this class:
* <ul>
* <li>Create an instance of the {@code GestureDetectorCompat} 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>
*/
public class GestureDetectorCompat {
interface GestureDetectorCompatImpl {
boolean isLongpressEnabled();
boolean onTouchEvent(MotionEvent ev);
void setIsLongpressEnabled(boolean enabled);
void setOnDoubleTapListener(OnDoubleTapListener listener);
}
static class GestureDetectorCompatImplBase implements GestureDetectorCompatImpl {
private int mTouchSlopSquare;
private int mDoubleTapSlopSquare;
private int mMinimumFlingVelocity;
private int mMaximumFlingVelocity;
private static final int LONGPRESS_TIMEOUT = ViewConfiguration.getLongPressTimeout();
private static final int TAP_TIMEOUT = ViewConfiguration.getTapTimeout();
private static final int DOUBLE_TAP_TIMEOUT = ViewConfiguration.getDoubleTapTimeout();
// constants for Message.what used by GestureHandler below
private static final int SHOW_PRESS = 1;
private static final int LONG_PRESS = 2;
private static final int TAP = 3;
private final Handler mHandler;
private final OnGestureListener mListener;
private OnDoubleTapListener mDoubleTapListener;
private boolean mStillDown;
private boolean mDeferConfirmSingleTap;
private boolean mInLongPress;
private boolean mAlwaysInTapRegion;
private boolean mAlwaysInBiggerTapRegion;
private MotionEvent mCurrentDownEvent;
private MotionEvent mPreviousUpEvent;
/**
* True when the user is still touching for the second tap (down, move, and
* up events). Can only be true if there is a double tap listener attached.
*/
private boolean mIsDoubleTapping;
private float mLastFocusX;
private float mLastFocusY;
private float mDownFocusX;
private float mDownFocusY;
private boolean mIsLongpressEnabled;
/**
* Determines speed during touch scrolling
*/
private VelocityTracker mVelocityTracker;
private class GestureHandler extends Handler {
GestureHandler() {
super();
}
GestureHandler(Handler handler) {
super(handler.getLooper());
}
@Override
public void handleMessage(Message msg) {
switch (msg.what) {
case SHOW_PRESS:
mListener.onShowPress(mCurrentDownEvent);
break;
case LONG_PRESS:
dispatchLongPress();
break;
case TAP:
// If the user's finger is still down, do not count it as a tap
if (mDoubleTapListener != null) {
if (!mStillDown) {
mDoubleTapListener.onSingleTapConfirmed(mCurrentDownEvent);
} else {
mDeferConfirmSingleTap = true;
}
}
break;
default:
throw new RuntimeException("Unknown message " + msg); //never
}
}
}
/**
* Creates a GestureDetector with the supplied listener.
* You may only use this constructor from a UI thread (this is the usual situation).
* @see android.os.Handler#Handler()
*
* @param context the application's context
* @param listener the listener invoked for all the callbacks, this must
* not be null.
* @param handler the handler to use
*
* @throws NullPointerException if {@code listener} is null.
*/
public GestureDetectorCompatImplBase(Context context, OnGestureListener listener,
Handler handler) {
if (handler != null) {
mHandler = new GestureHandler(handler);
} else {
mHandler = new GestureHandler();
}
mListener = listener;
if (listener instanceof OnDoubleTapListener) {
setOnDoubleTapListener((OnDoubleTapListener) listener);
}
init(context);
}
private void init(Context context) {
if (context == null) {
throw new IllegalArgumentException("Context must not be null");
}
if (mListener == null) {
throw new IllegalArgumentException("OnGestureListener must not be null");
}
mIsLongpressEnabled = true;
final ViewConfiguration configuration = ViewConfiguration.get(context);
final int touchSlop = configuration.getScaledTouchSlop();
final int doubleTapSlop = configuration.getScaledDoubleTapSlop();
mMinimumFlingVelocity = configuration.getScaledMinimumFlingVelocity();
mMaximumFlingVelocity = configuration.getScaledMaximumFlingVelocity();
mTouchSlopSquare = touchSlop * touchSlop;
mDoubleTapSlopSquare = doubleTapSlop * doubleTapSlop;
}
/**
* Sets the listener which will be called for double-tap and related
* gestures.
*
* @param onDoubleTapListener the listener invoked for all the callbacks, or
* null to stop listening for double-tap gestures.
*/
public void setOnDoubleTapListener(OnDoubleTapListener onDoubleTapListener) {
mDoubleTapListener = onDoubleTapListener;
}
/**
* Set whether longpress is enabled, if this is enabled when a user
* presses and holds down you get a longpress event and nothing further.
* If it's disabled the user can press and hold down and then later
* moved their finger and you will get scroll events. By default
* longpress is enabled.
*
* @param isLongpressEnabled whether longpress should be enabled.
*/
public void setIsLongpressEnabled(boolean isLongpressEnabled) {
mIsLongpressEnabled = isLongpressEnabled;
}
/**
* @return true if longpress is enabled, else false.
*/
public boolean isLongpressEnabled() {
return mIsLongpressEnabled;
}
/**
* Analyzes the given motion event and if applicable triggers the
* appropriate callbacks on the {@link OnGestureListener} supplied.
*
* @param ev The current motion event.
* @return true if the {@link OnGestureListener} consumed the event,
* else false.
*/
public boolean onTouchEvent(MotionEvent ev) {
final int action = ev.getAction();
if (mVelocityTracker == null) {
mVelocityTracker = VelocityTracker.obtain();
}
mVelocityTracker.addMovement(ev);
final boolean pointerUp =
(action & MotionEventCompat.ACTION_MASK) == MotionEventCompat.ACTION_POINTER_UP;
final int skipIndex = pointerUp ? MotionEventCompat.getActionIndex(ev) : -1;
// Determine focal point
float sumX = 0, sumY = 0;
final int count = MotionEventCompat.getPointerCount(ev);
for (int i = 0; i < count; i++) {
if (skipIndex == i) continue;
sumX += MotionEventCompat.getX(ev, i);
sumY += MotionEventCompat.getY(ev, i);
}
final int div = pointerUp ? count - 1 : count;
final float focusX = sumX / div;
final float focusY = sumY / div;
boolean handled = false;
switch (action & MotionEventCompat.ACTION_MASK) {
case MotionEventCompat.ACTION_POINTER_DOWN:
mDownFocusX = mLastFocusX = focusX;
mDownFocusY = mLastFocusY = focusY;
// Cancel long press and taps
cancelTaps();
break;
case MotionEventCompat.ACTION_POINTER_UP:
mDownFocusX = mLastFocusX = focusX;
mDownFocusY = mLastFocusY = focusY;
// Check the dot product of current velocities.
// If the pointer that left was opposing another velocity vector, clear.
mVelocityTracker.computeCurrentVelocity(1000, mMaximumFlingVelocity);
final int upIndex = MotionEventCompat.getActionIndex(ev);
final int id1 = MotionEventCompat.getPointerId(ev, upIndex);
final float x1 = VelocityTrackerCompat.getXVelocity(mVelocityTracker, id1);
final float y1 = VelocityTrackerCompat.getYVelocity(mVelocityTracker, id1);
for (int i = 0; i < count; i++) {
if (i == upIndex) continue;
final int id2 = MotionEventCompat.getPointerId(ev, i);
final float x = x1 * VelocityTrackerCompat.getXVelocity(mVelocityTracker, id2);
final float y = y1 * VelocityTrackerCompat.getYVelocity(mVelocityTracker, id2);
final float dot = x + y;
if (dot < 0) {
mVelocityTracker.clear();
break;
}
}
break;
case MotionEvent.ACTION_DOWN:
if (mDoubleTapListener != null) {
boolean hadTapMessage = mHandler.hasMessages(TAP);
if (hadTapMessage) mHandler.removeMessages(TAP);
if ((mCurrentDownEvent != null) && (mPreviousUpEvent != null) && hadTapMessage &&
isConsideredDoubleTap(mCurrentDownEvent, mPreviousUpEvent, ev)) {
// This is a second tap
mIsDoubleTapping = true;
// Give a callback with the first tap of the double-tap
handled |= mDoubleTapListener.onDoubleTap(mCurrentDownEvent);
// Give a callback with down event of the double-tap
handled |= mDoubleTapListener.onDoubleTapEvent(ev);
} else {
// This is a first tap
mHandler.sendEmptyMessageDelayed(TAP, DOUBLE_TAP_TIMEOUT);
}
}
mDownFocusX = mLastFocusX = focusX;
mDownFocusY = mLastFocusY = focusY;
if (mCurrentDownEvent != null) {
mCurrentDownEvent.recycle();
}
mCurrentDownEvent = MotionEvent.obtain(ev);
mAlwaysInTapRegion = true;
mAlwaysInBiggerTapRegion = true;
mStillDown = true;
mInLongPress = false;
mDeferConfirmSingleTap = false;
if (mIsLongpressEnabled) {
mHandler.removeMessages(LONG_PRESS);
mHandler.sendEmptyMessageAtTime(LONG_PRESS, mCurrentDownEvent.getDownTime()
+ TAP_TIMEOUT + LONGPRESS_TIMEOUT);
}
mHandler.sendEmptyMessageAtTime(SHOW_PRESS, mCurrentDownEvent.getDownTime() + TAP_TIMEOUT);
handled |= mListener.onDown(ev);
break;
case MotionEvent.ACTION_MOVE:
if (mInLongPress) {
break;
}
final float scrollX = mLastFocusX - focusX;
final float scrollY = mLastFocusY - focusY;
if (mIsDoubleTapping) {
// Give the move events of the double-tap
handled |= mDoubleTapListener.onDoubleTapEvent(ev);
} else if (mAlwaysInTapRegion) {
final int deltaX = (int) (focusX - mDownFocusX);
final int deltaY = (int) (focusY - mDownFocusY);
int distance = (deltaX * deltaX) + (deltaY * deltaY);
if (distance > mTouchSlopSquare) {
handled = mListener.onScroll(mCurrentDownEvent, ev, scrollX, scrollY);
mLastFocusX = focusX;
mLastFocusY = focusY;
mAlwaysInTapRegion = false;
mHandler.removeMessages(TAP);
mHandler.removeMessages(SHOW_PRESS);
mHandler.removeMessages(LONG_PRESS);
}
if (distance > mTouchSlopSquare) {
mAlwaysInBiggerTapRegion = false;
}
} else if ((Math.abs(scrollX) >= 1) || (Math.abs(scrollY) >= 1)) {
handled = mListener.onScroll(mCurrentDownEvent, ev, scrollX, scrollY);
mLastFocusX = focusX;
mLastFocusY = focusY;
}
break;
case MotionEvent.ACTION_UP:
mStillDown = false;
MotionEvent currentUpEvent = MotionEvent.obtain(ev);
if (mIsDoubleTapping) {
// Finally, give the up event of the double-tap
handled |= mDoubleTapListener.onDoubleTapEvent(ev);
} else if (mInLongPress) {
mHandler.removeMessages(TAP);
mInLongPress = false;
} else if (mAlwaysInTapRegion) {
handled = mListener.onSingleTapUp(ev);
if (mDeferConfirmSingleTap && mDoubleTapListener != null) {
mDoubleTapListener.onSingleTapConfirmed(ev);
}
} else {
// A fling must travel the minimum tap distance
final VelocityTracker velocityTracker = mVelocityTracker;
final int pointerId = MotionEventCompat.getPointerId(ev, 0);
velocityTracker.computeCurrentVelocity(1000, mMaximumFlingVelocity);
final float velocityY = VelocityTrackerCompat.getYVelocity(
velocityTracker, pointerId);
final float velocityX = VelocityTrackerCompat.getXVelocity(
velocityTracker, pointerId);
if ((Math.abs(velocityY) > mMinimumFlingVelocity)
|| (Math.abs(velocityX) > mMinimumFlingVelocity)){
handled = mListener.onFling(mCurrentDownEvent, ev, velocityX, velocityY);
}
}
if (mPreviousUpEvent != null) {
mPreviousUpEvent.recycle();
}
// Hold the event we obtained above - listeners may have changed the original.
mPreviousUpEvent = currentUpEvent;
if (mVelocityTracker != null) {
// This may have been cleared when we called out to the
// application above.
mVelocityTracker.recycle();
mVelocityTracker = null;
}
mIsDoubleTapping = false;
mDeferConfirmSingleTap = false;
mHandler.removeMessages(SHOW_PRESS);
mHandler.removeMessages(LONG_PRESS);
break;
case MotionEvent.ACTION_CANCEL:
cancel();
break;
}
return handled;
}
private void cancel() {
mHandler.removeMessages(SHOW_PRESS);
mHandler.removeMessages(LONG_PRESS);
mHandler.removeMessages(TAP);
mVelocityTracker.recycle();
mVelocityTracker = null;
mIsDoubleTapping = false;
mStillDown = false;
mAlwaysInTapRegion = false;
mAlwaysInBiggerTapRegion = false;
mDeferConfirmSingleTap = false;
if (mInLongPress) {
mInLongPress = false;
}
}
private void cancelTaps() {
mHandler.removeMessages(SHOW_PRESS);
mHandler.removeMessages(LONG_PRESS);
mHandler.removeMessages(TAP);
mIsDoubleTapping = false;
mAlwaysInTapRegion = false;
mAlwaysInBiggerTapRegion = false;
mDeferConfirmSingleTap = false;
if (mInLongPress) {
mInLongPress = false;
}
}
private boolean isConsideredDoubleTap(MotionEvent firstDown, MotionEvent firstUp,
MotionEvent secondDown) {
if (!mAlwaysInBiggerTapRegion) {
return false;
}
if (secondDown.getEventTime() - firstUp.getEventTime() > DOUBLE_TAP_TIMEOUT) {
return false;
}
int deltaX = (int) firstDown.getX() - (int) secondDown.getX();
int deltaY = (int) firstDown.getY() - (int) secondDown.getY();
return (deltaX * deltaX + deltaY * deltaY < mDoubleTapSlopSquare);
}
private void dispatchLongPress() {
mHandler.removeMessages(TAP);
mDeferConfirmSingleTap = false;
mInLongPress = true;
mListener.onLongPress(mCurrentDownEvent);
}
}
static class GestureDetectorCompatImplJellybeanMr2 implements GestureDetectorCompatImpl {
private final GestureDetector mDetector;
public GestureDetectorCompatImplJellybeanMr2(Context context, OnGestureListener listener,
Handler handler) {
mDetector = new GestureDetector(context, listener, handler);
}
@Override
public boolean isLongpressEnabled() {
return mDetector.isLongpressEnabled();
}
@Override
public boolean onTouchEvent(MotionEvent ev) {
return mDetector.onTouchEvent(ev);
}
@Override
public void setIsLongpressEnabled(boolean enabled) {
mDetector.setIsLongpressEnabled(enabled);
}
@Override
public void setOnDoubleTapListener(OnDoubleTapListener listener) {
mDetector.setOnDoubleTapListener(listener);
}
}
private final GestureDetectorCompatImpl mImpl;
/**
* Creates a GestureDetectorCompat with the supplied listener.
* As usual, you may only use this constructor from a UI thread.
* @see android.os.Handler#Handler()
*
* @param context the application's context
* @param listener the listener invoked for all the callbacks, this must
* not be null.
*/
public GestureDetectorCompat(Context context, OnGestureListener listener) {
this(context, listener, null);
}
/**
* Creates a GestureDetectorCompat with the supplied listener.
* As usual, you may only use this constructor from a UI thread.
* @see android.os.Handler#Handler()
*
* @param context the application's context
* @param listener the listener invoked for all the callbacks, this must
* not be null.
* @param handler the handler that will be used for posting deferred messages
*/
public GestureDetectorCompat(Context context, OnGestureListener listener, Handler handler) {
if (Build.VERSION.SDK_INT > 17) {
mImpl = new GestureDetectorCompatImplJellybeanMr2(context, listener, handler);
} else {
mImpl = new GestureDetectorCompatImplBase(context, listener, handler);
}
}
/**
* @return true if longpress is enabled, else false.
*/
public boolean isLongpressEnabled() {
return mImpl.isLongpressEnabled();
}
/**
* Analyzes the given motion event and if applicable triggers the
* appropriate callbacks on the {@link OnGestureListener} supplied.
*
* @param event The current motion event.
* @return true if the {@link OnGestureListener} consumed the event,
* else false.
*/
public boolean onTouchEvent(MotionEvent event) {
return mImpl.onTouchEvent(event);
}
/**
* Set whether longpress is enabled, if this is enabled when a user
* presses and holds down you get a longpress event and nothing further.
* If it's disabled the user can press and hold down and then later
* moved their finger and you will get scroll events. By default
* longpress is enabled.
*
* @param enabled whether longpress should be enabled.
*/
public void setIsLongpressEnabled(boolean enabled) {
mImpl.setIsLongpressEnabled(enabled);
}
/**
* Sets the listener which will be called for double-tap and related
* gestures.
*
* @param listener the listener invoked for all the callbacks, or
* null to stop listening for double-tap gestures.
*/
public void setOnDoubleTapListener(OnDoubleTapListener listener) {
mImpl.setOnDoubleTapListener(listener);
}
}