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默认情况下事件分发会按照由Activity到ViewGroup再到View的顺序进行分发
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事件的传递流程是从PhoneWindow->DecorView(mDecor是getWindow().getDecorView()返回的View，通过setContentView设置的View是该View的子View)，再传递到Activity的View树。
[](
)1.View的事件分发的重要的方法：diapatchTouchEvent和touchEvent,onClick
================================================================================================================
|---View
| |---boolean dispatchTouchEvent(MotionEvent event)
| |--- boolean onTouchEvent(MotionEvent event)
[](
)1.1 dispatchTouchEvent: 如果事件由视图处理，则为true，否则为false。
===========================================================================================================
public boolean dispatchTouchEvent(MotionEvent event) {
// If the event should be handled by accessibility focus first.
if (event.isTargetAccessibilityFocus()) {
// We don't have focus or no virtual descendant has it, do not handle the event.
if (!isAccessibilityFocusedViewOrHost()) {
return false;
}
// We have focus and got the event, then use normal event dispatch.
event.setTargetAccessibilityFocus(false);
}
boolean result = false;
if (mInputEventConsistencyVerifier != null) {
mInputEventConsistencyVerifier.onTouchEvent(event, 0);
}
final int actionMasked = event.getActionMasked();
if (actionMasked == MotionEvent.ACTION_DOWN) {
// Defensive cleanup for new gesture
stopNestedScroll();
}
if (onFilterTouchEventForSecurity(event)) {
if ((mViewFlags & ENABLED_MASK) == ENABLED && handleScrollBarDragging(event)) {
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;
}
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dispatchTouchEvent中final int actionMasked = event.getActionMasked();
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ListenerInfo :将view所有的listener信息封装到一个对象中。
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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
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boolean onTouchEvent
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MotionEvent.ACTION_UP:调用了PerformClick()
[](
)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);
}
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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;
}
}