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Android开发——浅谈onInterceptTouchEvent、onTouchEvent与onTouch

2010-08-18 16:50  HalZhang  阅读(12390)  评论(4编辑  收藏  举报

一、onTouch

onTouch是View中OnTouchListener接口中的方法,处理View及其子类被touch是的事件处理。当然,前提是touch时间能够传递到指定的view。Q1:为什么会传递不到呢?

   1:   /**
   2:      * Interface definition for a callback to be invoked when a touch event is
   3:      * dispatched to this view. The callback will be invoked before the touch
   4:      * event is given to the view.
   5:      */
   6:     public interface OnTouchListener {
   7:         /**
   8:          * Called when a touch event is dispatched to a view. This allows listeners to
   9:          * get a chance to respond before the target view.
  10:          *
  11:          * @param v The view the touch event has been dispatched to.
  12:          * @param event The MotionEvent object containing full information about
  13:          *        the event.
  14:          * @return True if the listener has consumed the event, false otherwise.
  15:          */
  16:         boolean onTouch(View v, MotionEvent event);
  17:     }

二、onTouchEvent

onTouchEvent同样也是在view中定义的一个方法。处理传递到view 的手势事件。手势事件类型包括ACTION_DOWN,ACTION_MOVE,ACTION_UP,ACTION_CANCEL四种事件。

   1: /**
   2:  * Implement this method to handle touch screen motion events.
   3:  *
   4:  * @param event The motion event.
   5:  * @return True if the event was handled, false otherwise.
   6:  */
   7: public boolean onTouchEvent(MotionEvent event) {
   8:  ……
   9:  ……
  10: }

一旦onTouchEvent方法被调用,并返回true则这个手势事件就结束了,并不会向下传递到子控件Q2:onTouchEvent什么时候被调用呢?

三、onInterceptTouchEvent

onInterceptTouchEvent是在ViewGroup里面定义的。Android中的layout布局类一般都是继承此类的。onInterceptTouchEvent是用于拦截手势事件的,每个手势事件都会先调用onInterceptTouchEvent。

   1: public boolean onInterceptTouchEvent(MotionEvent ev) {
   2:         return false;
   3: }

此方法返回false,则手势事件会向子控件传递;返回true,则调用onTouchEvent方法。

以上纯属个人见解,如有不同看法欢迎交流。

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