我有Gallery个ImageView个，ImageView是可缩放的，可翻译的。我的目标是，ImageView无法再转换为左/右，Gallery将滚动。因此有时ImageView需要处理触摸事件，有时Gallery需要处理触摸事件。我在ImageView的{{1}}方法中有逻辑，因为当我希望发生切换时，我会得到意想不到的结果。我在展示代码后会解释这个问题：
onTouchEvent这是我的// PinchZoomImageView.java
@Override
public boolean onTouchEvent( MotionEvent event ) {
Log.i( "PinchZoomImageView", "IM GETTING TOUCHED!" );
if ( isPassThroughTouchEvent() ) {
Log.i( "PinchZoomImageView", "IM RETURNING FALSE!" );
return false;
}
getScaleDetector().onTouchEvent( event );
switch (event.getAction() & MotionEvent.ACTION_MASK) {
case MotionEvent.ACTION_DOWN: {
final float x = event.getX();
final float y = event.getY();
setLastTouchX( x );
setLastTouchY( y );
setActivePointerId( event.getPointerId( 0 ) );
break;
}
case MotionEvent.ACTION_MOVE: {
final int pointerIndex = event.findPointerIndex( getActivePointerId() );
final float x = event.getX( pointerIndex );
final float y = event.getY( pointerIndex );
// Only move if the ScaleGestureDetector isn't processing a gesture.
if ( !getScaleDetector().isInProgress() ) {
if ( isDetectMovementX() ) {
final float dx = x - getLastTouchX();
setPosX( getPosX() + dx );
}
if ( isDetectMovementY() ) {
final float dy = y - getLastTouchY();
setPosY( getPosY() + dy );
}
invalidate();
}
setLastTouchX( x );
setLastTouchY( y );
if ( isAtXBound() && !isPassThroughTouchEvent() ) {
setPassThroughTouchEvent( true );
}
break;
}
case MotionEvent.ACTION_UP: {
setActivePointerId( INVALID_POINTER_ID );
break;
}
case MotionEvent.ACTION_CANCEL: {
setActivePointerId( INVALID_POINTER_ID );
break;
}
case MotionEvent.ACTION_POINTER_UP: {
final int pointerIndex = ( event.getAction() & MotionEvent.ACTION_POINTER_INDEX_MASK ) >> MotionEvent.ACTION_POINTER_INDEX_SHIFT;
final int pointerId = event.getPointerId( pointerIndex );
if ( pointerId == getActivePointerId() ) {
// This was our active pointer going up. Choose a new
// active pointer and adjust accordingly.
final int newPointerIndex = pointerIndex == 0 ? 1 : 0;
setLastTouchX( event.getX( newPointerIndex ) );
setLastTouchY( event.getY( newPointerIndex ) );
setActivePointerId( event.getPointerId( newPointerIndex ) );
}
break;
}
}
return true;
}
。我覆盖了Gallery只是为了表明接收触摸事件的时间。
onTouchEvent所以当我加载活动时，我会尝试从右向左滑动。传递动作事件的逻辑立即被触发，但这是我的日志输出。
// SwipeGallery.java
@Override
public boolean onTouchEvent( MotionEvent event ) {
Log.i( "SwipeGallery", "IM GETTING TOUCHED!" );
return super.onTouchEvent( event );
}
第二次我从右向左滑动，我明白了：
08-02 10:04:47.097: INFO/PinchZoomImageView(17189): IM GETTING TOUCHED!
08-02 10:04:47.179: INFO/PinchZoomImageView(17189): IM GETTING TOUCHED!
08-02 10:04:47.179: INFO/PinchZoomImageView(17189): IM GETTING TOUCHED!
08-02 10:04:47.179: INFO/PinchZoomImageView(17189): IM RETURNING FALSE!
08-02 10:04:47.230: INFO/PinchZoomImageView(17189): IM GETTING TOUCHED!
08-02 10:04:47.230: INFO/PinchZoomImageView(17189): IM RETURNING FALSE!
08-02 10:04:47.230: INFO/PinchZoomImageView(17189): IM GETTING TOUCHED!
08-02 10:04:47.230: INFO/PinchZoomImageView(17189): IM RETURNING FALSE!
08-02 10:04:47.245: INFO/PinchZoomImageView(17189): IM GETTING TOUCHED!
08-02 10:04:47.245: INFO/PinchZoomImageView(17189): IM RETURNING FALSE!
08-02 10:04:47.261: INFO/PinchZoomImageView(17189): IM GETTING TOUCHED!
08-02 10:04:47.261: INFO/PinchZoomImageView(17189): IM RETURNING FALSE!
08-02 10:04:47.277: INFO/PinchZoomImageView(17189): IM GETTING TOUCHED!
08-02 10:04:47.277: INFO/PinchZoomImageView(17189): IM RETURNING FALSE!
08-02 10:04:47.296: INFO/PinchZoomImageView(17189): IM GETTING TOUCHED!
08-02 10:04:47.296: INFO/PinchZoomImageView(17189): IM RETURNING FALSE!
08-02 10:04:47.312: INFO/PinchZoomImageView(17189): IM GETTING TOUCHED!
08-02 10:04:47.312: INFO/PinchZoomImageView(17189): IM RETURNING FALSE!
08-02 10:04:47.327: INFO/PinchZoomImageView(17189): IM GETTING TOUCHED!
08-02 10:04:47.327: INFO/PinchZoomImageView(17189): IM RETURNING FALSE!
08-02 10:04:47.343: INFO/PinchZoomImageView(17189): IM GETTING TOUCHED!
08-02 10:04:47.343: INFO/PinchZoomImageView(17189): IM RETURNING FALSE!
08-02 10:04:47.360: INFO/PinchZoomImageView(17189): IM GETTING TOUCHED!
08-02 10:04:47.360: INFO/PinchZoomImageView(17189): IM RETURNING FALSE!
....etc.
“imageview始终处理的第一个动作事件，画廊始终处理的第二个动作事件”的这种模式将永远持续下去（为图库中的每个位置创建一个新的imageview，这就是08-02 10:27:31.573: INFO/PinchZoomImageView(17189): IM GETTING TOUCHED!
08-02 10:27:31.573: INFO/PinchZoomImageView(17189): IM RETURNING FALSE!
08-02 10:27:31.573: INFO/SwipeGallery(17189): IM GETTING TOUCHED!
08-02 10:27:31.636: INFO/SwipeGallery(17189): IM GETTING TOUCHED!
08-02 10:27:31.636: INFO/SwipeGallery(17189): IM GETTING TOUCHED!
08-02 10:27:31.683: INFO/SwipeGallery(17189): IM GETTING TOUCHED!
08-02 10:27:31.933: INFO/SwipeGallery(17189): IM GETTING TOUCHED!
08-02 10:27:31.964: INFO/SwipeGallery(17189): IM GETTING TOUCHED!
08-02 10:27:31.999: INFO/SwipeGallery(17189): IM GETTING TOUCHED!
08-02 10:27:32.034: INFO/SwipeGallery(17189): IM GETTING TOUCHED!
返回false的原因，第5等时间）。那么我到底错过了什么？我认为返回false会传播触摸事件直到它被处理，但是isPassThroughTouchEvent()不会第一次接受它，但它会在第二次执行吗？这对我来说毫无意义。有人有主意吗？感谢。
答案 0 :(得分：3)
当视图在向下（ACTION_DOWN）运动事件中返回true时，该视图将“锁定”为触摸运动目标。这意味着，无论屏幕在屏幕上发生什么，它都会收到后续动作事件（请参阅此thread），除非其父级wants和allowed为拦截事件。
解释你的情况：
在第一次滑动时，ImageView处理了向下运动，使其成为运动目标（请参阅日志）。这意味着所有后续动作事件都将被传递给它，并且由于您的Gallery不拦截事件，因此不会调用其onTouchEvent处理程序。
在第二次滑动时，ImageView不处理向下运动（在日志中显示“IM GETTING TOUCH！”+“IM RETURNING FALSE！”）并将事件传递给下一个处理程序，在这种情况下是Gallery，它将运行其onTouchEvent处理程序。默认情况下，Gallery始终处理向下事件，该事件将其锁定为运动目标。