onInterceptTouchEvent只得到ACTION_DOWN [英] onInterceptTouchEvent only gets ACTION_DOWN

问题描述

为什么ViewGroup中唯一获得ACTION_DOWN在onInterceptTouchEvent？根据文档，只要返回false应接收所有的事件类型。 <一href="http://developer.android.com/reference/android/view/ViewGroup.html#onInterceptTouchEvent%28android.view.MotionEvent%29">http://developer.android.com/reference/android/view/ViewGroup.html#onInterceptTouchEvent%28android.view.MotionEvent%29 点＃3。

样品code：

 公共类MainActivity延伸活动{

私有静态最后字符串变量= MainActivity.class.getSimpleName（）;

@覆盖
保护无效的onCreate（包savedInstanceState）{
    super.onCreate（savedInstanceState）;
    的setContentView（新容器（本））;
}

私有类容器扩展的LinearLayout {

    公共集装箱（上下文的背景下）{
        超（上下文）;
        setBackgroundColor（0xFF0000FF）;
    }

    @覆盖
    公共布尔onInterceptTouchEvent（MotionEvent EV）{
        Log.i（TAG，onInterceptTouchEvent）;
        INT行动= ev.getActionMasked（）;
        开关（动作）{
        案例MotionEvent.ACTION_DOWN：
            Log.i（TAG，onInterceptTouchEvent.ACTION_DOWN）;
            打破;
        案例MotionEvent.ACTION_MOVE：
            Log.i（TAG，onInterceptTouchEvent.ACTION_MOVE）;
            打破;
        案例MotionEvent.ACTION_CANCEL：
        案例MotionEvent.ACTION_UP：
            Log.i（TAG，onInterceptTouchEvent.ACTION_UP）;
            打破;
    }
        返回super.onInterceptTouchEvent（EV）;
    }

}
}
 

解决方案

我会回答我的问题：onInterceptTouchEvent只被调用，如果父母有从的onTouchEvent返回true子视图。一旦孩子返回true，家长现在有机会截获该事件。

Why do ViewGroup's only get ACTION_DOWN in the onInterceptTouchEvent? According to the docs, as long as false is returned it should receive all the event types. http://developer.android.com/reference/android/view/ViewGroup.html#onInterceptTouchEvent%28android.view.MotionEvent%29 Point #3.

sample code:

public class MainActivity extends Activity {

private static final String TAG = MainActivity.class.getSimpleName();

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(new Container(this));
}

private class Container extends LinearLayout {

    public Container(Context context) {
        super(context);
        setBackgroundColor(0xFF0000FF);
    }

    @Override
    public boolean onInterceptTouchEvent(MotionEvent ev) {
        Log.i(TAG, "onInterceptTouchEvent");
        int action = ev.getActionMasked();
        switch (action) {
        case MotionEvent.ACTION_DOWN:
            Log.i(TAG, "onInterceptTouchEvent.ACTION_DOWN");
            break;
        case MotionEvent.ACTION_MOVE:
            Log.i(TAG, "onInterceptTouchEvent.ACTION_MOVE");
            break;
        case MotionEvent.ACTION_CANCEL:
        case MotionEvent.ACTION_UP:
            Log.i(TAG, "onInterceptTouchEvent.ACTION_UP");
            break;
    }
        return super.onInterceptTouchEvent(ev);
    }

}
}

解决方案

I'll answer my own question: onInterceptTouchEvent only get called if the parent has a child view which returns "true" from onTouchEvent. Once the child returns true, the parent now has a chance to intercept that event.

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