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2016-06-17 10:00 555 查看

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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