Question

我正在使用此代码创建拖放：

private final class MyTouchListener implements OnTouchListener {
    public boolean onTouch(View view, MotionEvent motionEvent) {
      if (motionEvent.getAction() == MotionEvent.ACTION_DOWN) {
        ClipData data = ClipData.newPlainText("", "");

        GlobalTouchX = (int) motionEvent.getX();
        GlobalTouchY = (int) motionEvent.getY();

        shadowBuilder = new MyDragShadowBuilder(view);       

        view.startDrag(data, shadowBuilder, null, 0);

        CurrentDragImage = (ImageView)view;
        view.setVisibility(View.GONE);

        return true;
      } else {
      return false;
      }
    }
  }

如何在不等待丢弃的情况下中断拖放方法，还是可以以编程方式调用drop事件？我尝试了很多方法，但没有运气。例如，如果我可以在这里打断它会很棒：

MainRelative.setOnDragListener(new OnDragListener() {                  
  public boolean onDrag(View v, DragEvent event) {

  int action = event.getAction();

  switch (event.getAction()) {

  case DragEvent.ACTION_DRAG_LOCATION:    

        //!!!!!!!!!!!!!!!
        //HERE I WANT TO INTERRUPT DRAG EVENT ON SOME CONDITION
        //!!!!!!!!!!!!!!!

       break;

  case DragEvent.ACTION_DROP:

       MyOnDrop(v, event, true);                  

       break;
  }

return true;}
});

Answer 1

拦截动作的一种方法是覆盖ViewGroup类中的onInterceptTouchEvent（MotionEvent me）方法，如果要拖动到View，则调用此方法。因此，如果需要拦截，则必须放置逻辑在这种方法中。

例如，如果您想使用FrameLayout来保存您的子视图。然后你将不得不创建一个扩展这个FrameLayout类的新类并覆盖onInterceptTouchEvent（MotionEvent me）方法：

class NewFrameLayout extends FrameLayout{


    @Override
    public boolean onInterceptTouchEvent(MotionEvent ev) {

     ///Place your logic here to intercept the dragging event


        /*
         * This method JUST determines whether we want to intercept the motion.
         * If we return true, onMotionEvent will be called and we do the actual
         * work here.
         */

        /*
        * Shortcut the most recurring case: the user is in the dragging
        * state and he is moving his finger.  We want to intercept this
        * motion.
        */
    }
}

Android系统。如何中断拖动？

1 个答案: