View事件传递机制

最新推荐文章于 2023-07-20 13:00:00 发布

EllisMiao

最新推荐文章于 2023-07-20 13:00:00 发布

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分类专栏： Android

本文链接：https://blog.youkuaiyun.com/qwiwuqo/article/details/84112668

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Activity,ViewGroup,View

1.默认情况

Activity->dispatchTouchEvent

MyLinearLayout->dispatchTouchEvent

MyLinearLayout->onInterceptTouchEvent

customview->dispatchTouchEvent

customview->onTouchEvent

MyLinearLayout->onTouchEvent

Activity->onTouchEvent

Activity->dispatchTouchEvent

Activity->onTouchEvent

为什么dispatchTouchEvent会调用两次？

因为有ACTION_DOWN(按下)和ACTION_UP(抬起)两个操作。

2.ViewGroup调用onInterceptTouchEvent拦截，返回true

Activity->dispatchTouchEvent

MyLinearLayout->dispatchTouchEvent

MyLinearLayout->onInterceptTouchEvent

MyLinearLayout->onTouchEvent

Activity->onTouchEvent

Activity->dispatchTouchEvent

Activity->onTouchEvent

3.ViewGroup调用onInterceptTouchEvent拦截，返回true,并消费onTouchEvent,返回true

Activity->dispatchTouchEvent

MyLinearLayout->dispatchTouchEvent

MyLinearLayout->onInterceptTouchEvent

MyLinearLayout->onTouchEvent

Activity->dispatchTouchEvent

MyLinearLayout->dispatchTouchEvent

MyLinearLayout->onTouchEvent

4.在View消费onTouchEvent,返回true

Activity->dispatchTouchEvent

MyLinearLayout->dispatchTouchEvent

MyLinearLayout->onInterceptTouchEvent

customview->dispatchTouchEvent

customview->onTouchEvent

Activity->dispatchTouchEvent

MyLinearLayout->dispatchTouchEvent

MyLinearLayout->onInterceptTouchEvent

customview->dispatchTouchEvent

总结：

a.屏幕按下，先调用activity的dispatchEvent，然后调用viewgroup的dispatchEvent,最后调用view的dispatchEvent

b.dispatchEvent在内部会调用onTouchEvent

c.先调用onTouch，再调用onClick。onTouch默认返回false,如果返回true的话，onTouchEvent不会调用

d.在activity中dispatchTouchEvent如果不调用父类的方法，例如返回false或者true，会拦截所有事件。

f.onTouchEvent中父类会调用onClick

g.onLongClick的返回值，返回fasle,会继续传递最后调用onClick,返回true,最后不会调用onClick