|
result = true;
}
// 重点 判断listenerInfo 中是否有事件listenter 并且mOnTouchListener.onTouc 返回true
ListenerInfo li = mListenerInfo;
if (li != null && li.mOnTouchListener != null
&& (mViewFlags & ENABLED_MASK) == ENABLED
&& li.mOnTouchListener.onTouch(this, event)) {
result = true;
}
// 第二个重点，如果上述判断为false,并且 onTouchEventr返回为true,消耗事件
if (!result && onTouchEvent(event)) {
result = true;
}
}
if (!result && mInputEventConsistencyVerifier != null) {
mInputEventConsistencyVerifier.onUnhandledEvent(event, 0);
}
// Clean up after nested scrolls if this is the end of a gesture;
// also cancel it if we tried an ACTION_DOWN but we didn’t want the rest
// of the gesture.
if (actionMasked == MotionEvent.ACTION_UP ||
actionMasked == MotionEvent.ACTION_CANCEL ||
(actionMasked == MotionEvent.ACTION_DOWN && !result)) {
stopNestedScroll();
}
return result;
}
-
dispatchTouchEvent中final int actionMasked = event.getActionMasked(); -
ListenerInfo :将view所有的listener信息封装到一个对象中。 -
在该方法中有两个判断：
ListenerInfo li = mListenerInfo;
if (li != null && li.mOnTouchListener != null
&& (mViewFlags & ENABLED_MASK) == ENABLED
&& li.mOnTouchListener.onTouch(this, event)) {
result = true;
}
if (!result && onTouchEvent(event)) {
result = true;
}
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如果onTouchEvent或者是onTouchListenner是true的话，会消费此事件，同时，在这里也走了onTouchEvent
三个问题：
==============================================================
1. 在activity中调用了
==========================================================================
mTouchView.setOnTouchListener(new View.OnTouchListener() {
@Override
public boolean onTouch(View v, MotionEvent event) {
Log.e(“TAG”, "onTouch: " + event.getAction());
return false;
}
});
mTouchView.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
Log.e(“TAG”, "onClick: " );
}
});
/TabLayout*/
@Override
public boolean onTouchEvent(MotionEvent event) {
Log.e(“TAG”, "onTouchEvent: "+event.getAction());
return super.onTouchEvent(event);
}
复制代码
执行顺序：
2. 如果是Tablyout中直接return ture呢？
========================================================================================
不执行onClick,因为onClick在View.OntouchEvent中的ACTION_UP中，若直接return true 就不会走super中的方法。
3. 如果是dispatchEvent return true呢？
===========================================================================================
什么都不执行
分发流程
=============================================================
super.dispatchEvent->ListenerInfo->super.onTouchEvent(event)->ACTION_UP->performListener().
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2. ViewGroup的事件分发：
============================================================================
首先是actionDown:
if (actionMasked == MotionEvent.ACTION_DOWN
|| mFirstTouchTarget != null) { //
final boolean disallowIntercept = (mGroupFlags & FLAG_DISALLOW_INTERCEPT) != 0;
if (!disallowIntercept) {
intercepted = onInterceptTouchEvent(ev);
ev.setAction(action); // restore action in case it was changed
} else {
intercepted = false;
}
}
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- mFirstTouchTarget: 这个很重要,只有在第一次按下的时候才会调用disallowIntercept,如果之后想要改变效果的时候，这是一个坑。
|—ViewGroup
| |—dispatchTouchEvent
| | |—onInterceptTouchEvent(ev)
有View会消耗时间的情况（比如点击，onTouchListener）
-
第一次按下进来（down）—>ViewGroup.dispatchTouchEvent—>ViewGroup.onInterceptTouchEvent(ev)–>view.dispatchEvent—(view的那一套) -
第二次进来（move）ViewGroup.dispatchTouchEvent—>ViewGroup.onInterceptTouchEvent(ev)–>view.dispatchEvent—(view的那一套) -
第三次（up）ViewGroup.dispatchTouchEvent—>ViewGroup.onInterceptTouchEvent(ev)–>view.dispatchEvent—(view的那一套)–>view.onClick
子****View中没有消费事件的情况。只走一遍
- 第一次进来(down)ViewGroup.dispatchTouchEvent—>ViewGroup.onInterceptTouchEvent(ev)–>view.dispatchEvent—view.onTouch–>onTouch Event
viewGroup的源码分析
=======================================================================
actionDown
/**
- Clears all touch targets.
*/
private void clearTouchTargets() {
TouchTarget target = mFirstTouchTarget;
if (target != null) {
do {
TouchTarget next = target.next;
target.recycle();
target = next;
} while (target != null);
mFirstTouchTarget = null; //清除target
}
}
if (!canceled && !intercepted) // intercepted 默认是没有拦截
{
if (newTouchTarget == null && childrenCount != 0) {
for
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(int i = childrenCount - 1; i >= 0; i–) {//反序列的for循环 先拿最上面的layout
if (dispatchTransformedTouchEvent(ev, false, child, idBitsToAssign)) {
}
}
}
}
/**
-
Transforms a motion event into the coordinate space of a particular child view, -
filters out irrelevant pointer ids, and overrides its action if necessary. -
If child is null, assumes the MotionEvent will be sent to this ViewGroup instead.
*/
private boolean dispatchTransformedTouchEvent(MotionEvent event, boolean cancel,
View child, int desiredPointerIdBits) {
final boolean handled;
final int oldAction = event.getAction();
if (cancel || oldAction == MotionEvent.ACTION_CANCEL) {
event.setAction(MotionEvent.ACTION_CANCEL);
if (child == null) {
handled = super.dispatchTouchEvent(event);
} else {
handled = child.dispatchTouchEvent(event);
}
event.setAction(oldAction);
return handled;
}
// Calculate the number of pointers to deliver.
final int oldPointerIdBits = event.getPointerIdBits();
final int newPointerIdBits = oldPointerIdBits & desiredPointerIdBits;
// If for some reason we ended up in an inconsistent state where it looks like we
// might produce a motion event with no pointers in it, then drop the event.
if (newPointerIdBits == 0) {
return false;
}
final MotionEvent transformedEvent;
if (newPointerIdBits == oldPointerIdBits) {
if (child == null || child.hasIdentityMatrix()) {
if (child == null) {
handled = super.dispatchTouchEvent(event);
} else {
final float offsetX = mScrollX - child.mLeft;
final float offsetY = mScrollY - child.mTop;
|