view,viewGroup 的onTouchEvent返回值的作用

最新推荐文章于 2021-05-26 04:27:37 发布

原创最新推荐文章于 2021-05-26 04:27:37 发布 · 1k 阅读

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#view #viewGroup #onTouchEvent返回值的作用

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本文详细解析了Android事件处理机制中return true和return false的用法，阐述了它们如何影响事件的传递和处理流程，帮助开发者更深入地理解Android事件系统的工作原理。

注意如果返回的是true，自己处理的话，当执行完了后还需要再执行一次cancel，这个也是按照顺序一层一层的。

http://blog.youkuaiyun.com/huangbiao86/article/details/6743861

 
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关于返回值的问题，基本规则很清楚，如果return true,那么表示该方法消费了此次事件，如果return false，那么表示该方法并未处理完全，该事件仍然需要以某种方式传递下去继续等待处理。

SDK给出的说明如下：

· You will receive the down event here.

· The down event will be handled either by a child of this view group, or given to your own onTouchEvent() method to handle; this means you should implement onTouchEvent() to return true, so you will continue to see the rest of the gesture (instead of looking for a parent view to handle it). Also, by returning true from onTouchEvent(), you will not receive any following events in onInterceptTouchEvent() and all touch processing must happen in onTouchEvent() like normal.

· For as long as you return false from this function, each following event (up to and including the final up) will be delivered first here and then to the target's onTouchEvent().

· If you return true from here, you will not receive any following events: the target view will receive the same event but with the action ACTION_CANCEL, and all further events will be delivered to your onTouchEvent() method and no longer appear here.