android 事件传递

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假如dispatchTouchEvent返回false，那么在响应了ACTION_DOWN之后，后续的ACTION_MOVE和ACTION_UP均忽略，因此ACTION_MOVE和ACTION_UP永远不会有得到处理的机会。

类ViewGroup －－View

ViewGroup

dispatchTransformedTouchEvent

if (child == null) {
handled = super.dispatchTouchEvent(event);
} else {
handled = child.dispatchTouchEvent(event);
}

View

dispatchTouchEvent

if (!result && onTouchEvent(event)) {
result = true;
}

onTouchEvent

switch (action) {
case MotionEvent.ACTION_UP:

if (!focusTaken) {
// Use a Runnable and post this rather than calling
// performClick directly. This lets other visual state
// of the view update before click actions start.
if (mPerformClick == null) {
mPerformClick = new PerformClick();
}
if (!post(mPerformClick)) {
performClick();//调用liseten的clickli 代码：mOnClickListener.onClick(this);

}
}

case MotionEvent.ACTION_Down:

….

layout1包含layout2，layout2包含view

layout1:

public boolean dispatchTouchEvent(MotionEvent ev)
{
   boolean b= super.dispatchTouchEvent(ev);
   SyncLog.log("layout1 ","" + b+" "+ev.getAction());
   return true;
}
public boolean onInterceptTouchEvent(MotionEvent ev)
{
return false;
}

layout2:

public boolean dispatchTouchEvent(MotionEvent ev)
{
boolean b = super.dispatchTouchEvent(ev);
SyncLog.log("layout2 ", b + " " + ev.getAction());
return false;
}
public boolean onInterceptTouchEvent(MotionEvent ev)
{
SyncLog.log("layout1 onInterceptTouchEvent "," "+ev.getAction());
return false;
}

layout1的onInterceptTouchEvent 返回false

结果：

05-06 03:41:06.598 1255-1255/? E/layout1 onInterceptTouchEvent﹕ 0

05-06 03:41:06.598 1255-1255/? E/layout2﹕ true 0 motion down

05-06 03:41:06.598 1255-1255/? E/layout1﹕ true 0

05-06 03:41:08.058 1255-1255/? E/layout1﹕ true 1 motion up

05-06 03:41:08.062 1255-1255/? E/layout1=-------﹕ asdf1 触发layout1的onclick

layout1的onInterceptTouchEvent 返回true

结果：

05-06 03:42:35.058 3704-3704/com.event.tessssss E/layout1﹕ true 0

05-06 03:42:36.594 3704-3704/com.event.tessssss E/layout1﹕ true 1

05-06 03:42:36.598 3704-3704/com.event.tessssss E/layout1=-------﹕ asdf1

结论 onInterceptTouchEvent如果是true就不会再往下派发。这个只影响是否分发出去，是否消费事件是由dispatchTouchEvent返回决定，true是消费，false不消费

public boolean dispatchTouchEvent(MotionEvent ev)
{
   boolean b= super.dispatchTouchEvent(ev);
   SyncLog.log("layout1 ","" + b+" "+ev.getAction());
   return false;
}
public boolean onInterceptTouchEvent(MotionEvent ev)
{
return true;
}

结果：

05-06 03:59:28.170 11444-11444/com.event.tessssss E/layout1﹕ true 0 down

如果onInterceptTouchEvent为false，dispatchTouchEvent不管返回什么都会往下分发。

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