拖动侦听器上视图的位置更改

Question

我在父布局上放置视图。我想通过长按 L1 来拖动整个视图。当我长按 L1 时，视图进入拖动模式，但将触摸位置更改为视图中心 (x,y)。 我想按住布局（L1）的上栏拖动视图。

View:
    ______________
   |______L1______|
   |              |
y  |      L2      |
   |              |
   |______________|
           x


    @Override
    public boolean onDrag(View v, DragEvent event) {

        // Handles each of the expected events
        switch (event.getAction()) {

        //signal for the start of a drag and drop operation.
        case DragEvent.ACTION_DRAG_STARTED:
            // do nothing

            break;

        //the drag point has entered the bounding box of the View
        case DragEvent.ACTION_DRAG_ENTERED:
            v.setBackground(targetShape);   //change the shape of the view
            break;

        //the user has moved the drag shadow outside the bounding box of the View
        case DragEvent.ACTION_DRAG_EXITED:
            v.setBackground(normalShape);   //change the shape of the view back to normal
            break;

        //drag shadow has been released,the drag point is within the bounding box of the View
        case DragEvent.ACTION_DROP:
             doStuff();
              break;

        //the drag and drop operation has concluded.
        case DragEvent.ACTION_DRAG_ENDED:
            v.setBackground(normalShape);   //go back to normal shape

        default:
            break;
        }
        return true;
    }

Answer 1

您可以使用View.DragShadowBuilder 设置图像中的拖动点：

view.onProvideShadowMetrics(/* size of shadow */,
/* provide Point object with x cordinate equal to whole
 width of L1 and y cordinate equal to height of L1*/);

这样您就可以将阴影触摸点设置为 L1

可以参考Developer page for DragShadowBuilder