GestureDetector裏onLongPress方法的回調來自
private void dispatchLongPress() {
mHandler.removeMessages(TAP);
mDeferConfirmSingleTap = false;
mInLongPress = true;
mListener.onLongPress(mCurrentDownEvent); //這裏
}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: //就是這個message控制了啦
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
}
}Come on！ 進入正題OnTouchEvent的手勢處理
這個LONG_PRESS的message發送的地方有且只有一個
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); //喏喏 就是這裏是一個delayMessage
}
mHandler.sendEmptyMessageAtTime(SHOW_PRESS, mCurrentDownEvent.getDownTime() + TAP_TIMEOUT);
handled |= mListener.onDown(ev);
break;它們分別是多少呢？
private static final int LONGPRESS_TIMEOUT = ViewConfiguration.getLongPressTimeout(); //缺省500毫秒 Settings.Secure可設置
private static final int TAP_TIMEOUT = ViewConfiguration.getTapTimeout(); //100毫秒也就是說缺省總共0.6秒。
主題是解決了，那爲什麼要發一個延遲message哪？
因爲如果不符合長按條件 咱可以取消啊
場景1： MOVE的時候
case MotionEvent.ACTION_MOVE:
if (mInLongPress || mInContextClick) {
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) { //這個前提條件看字面意思是所有區域都視爲tap區域？
final int deltaX = (int) (focusX - mDownFocusX);
final int deltaY = (int) (focusY - mDownFocusY);
int distance = (deltaX * deltaX) + (deltaY * deltaY);
if (distance > mTouchSlopSquare) { //如果還沒longPress就超出TouchSlop了
handled = mListener.onScroll(mCurrentDownEvent, ev, scrollX, scrollY);
mLastFocusX = focusX;
mLastFocusY = focusY;
mAlwaysInTapRegion = false;
mHandler.removeMessages(TAP);
mHandler.removeMessages(SHOW_PRESS);
mHandler.removeMessages(LONG_PRESS);//那你就沒機會longPress了？ 待驗證前提條件
}
if (distance > mDoubleTapTouchSlopSquare) {
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 && !mIgnoreNextUpEvent) {
handled = mListener.onSingleTapUp(ev);
if (mDeferConfirmSingleTap && mDoubleTapListener != null) {
mDoubleTapListener.onSingleTapConfirmed(ev);
}
} else if (!mIgnoreNextUpEvent) {
// A fling must travel the minimum tap distance
final VelocityTracker velocityTracker = mVelocityTracker;
final int pointerId = ev.getPointerId(0);
velocityTracker.computeCurrentVelocity(1000, mMaximumFlingVelocity);
final float velocityY = velocityTracker.getYVelocity(pointerId);
final float velocityX = velocityTracker.getXVelocity(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;
mIgnoreNextUpEvent = false;
mHandler.removeMessages(SHOW_PRESS);
mHandler.removeMessages(LONG_PRESS); //這是必然的
break; /**
* Analyzes the given generic 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 onGenericMotionEvent(MotionEvent ev) {
if (mInputEventConsistencyVerifier != null) {
mInputEventConsistencyVerifier.onGenericMotionEvent(ev, 0);
}
final int actionButton = ev.getActionButton();
switch (ev.getActionMasked()) {
case MotionEvent.ACTION_BUTTON_PRESS:
if (mContextClickListener != null && !mInContextClick && !mInLongPress
&& (actionButton == MotionEvent.BUTTON_STYLUS_PRIMARY
|| actionButton == MotionEvent.BUTTON_SECONDARY)) {
if (mContextClickListener.onContextClick(ev)) {
mInContextClick = true;
mHandler.removeMessages(LONG_PRESS);
mHandler.removeMessages(TAP);
return true;
}
}
break;
case MotionEvent.ACTION_BUTTON_RELEASE:
if (mInContextClick && (actionButton == MotionEvent.BUTTON_STYLUS_PRIMARY
|| actionButton == MotionEvent.BUTTON_SECONDARY)) {
mInContextClick = false;
mIgnoreNextUpEvent = true;
}
break;
}
return false;
}場景4 5 手勢cancel和tap cancel的時候
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;
mInLongPress = false;
mInContextClick = false;
mIgnoreNextUpEvent = false;
}
private void cancelTaps() {
mHandler.removeMessages(SHOW_PRESS);
mHandler.removeMessages(LONG_PRESS);
mHandler.removeMessages(TAP);
mIsDoubleTapping = false;
mAlwaysInTapRegion = false;
mAlwaysInBiggerTapRegion = false;
mDeferConfirmSingleTap = false;
mInLongPress = false;
mInContextClick = false;
mIgnoreNextUpEvent = false;
}