get dragged shadow location on View.OnDragListener

问题

I am using drag and drop functionality in my application. It works fine. Now i am facing issue while animating view when view comes back to it's original position if it is not placed on dropped view.

I have created my shadow view by

  View.DragShadowBuilder shadowBuilder = new MyDragShadowBuilder(view);
                                view.startDrag(data, shadowBuilder, view, 0);

And my shadowbuilder class is,

private static class MyDragShadowBuilder extends View.DragShadowBuilder {
    private static Drawable shadow;

    public MyDragShadowBuilder(View v) {
        // Stores the View parameter passed to myDragShadowBuilder.
        super(v);
        v.buildDrawingCache();
        shadow =  new BitmapDrawable(v.getDrawingCache());
    }

    @Override
    public void onProvideShadowMetrics (Point size, Point touch){
        // Defines local variables
        int width, height;
        width = (int)(getView().getWidth() * 1.1);
        height =(int)(getView().getHeight() * 1.1);
        shadow.setBounds(0, 0, width, height);
        size.set(width, height);
        touch.set(width / 2, height / 2);
    }

    @Override
    public void onDrawShadow(Canvas canvas) {
        // Draws the ColorDrawable in the Canvas passed in from the system.
        shadow.draw(canvas);
    }
}

Now, when i found unsuccessful drop, then i want my view to get animated and go back to it's original position.

   case DragEvent.ACTION_DRAG_ENDED:
                if (!event.getResult()) {
                      if (dragged.getTag() == v.getTag()){
                         int[] location={0,0};
                         v.getLocationOnScreen(location);
                         Log.v("values::", "x:" + x + "  - y:" +x);
                         addViewRemoveViewFromWindow(dragged, location);
                    }
                }

                break;

I am able to get my view's original position in location array i.e. my end position. And i want my that dragged view(shadow view) position on screen. But i am not able to get it in any cases. Have tried to get it on DragEvent.ACTION_DRAG_LOCATION: case but with no luck. It always returns position of either original view's position or dropped view position. I want dragged shadow images's location. I want to apply translation animation in window between two locations. That animating view in window between 2 locations works fine when i tried by using 2 static locations.

回答1:

To animate your shadow to initial view you can use this snippet.

private void animateDragToStart(View initialView, float fromX, float fromY) {
    float topMargin = fromY - initialView.getTop();
    float leftMargin = fromX - initialView.getLeft();

    Animation translateAnimation = new TranslateAnimation(leftMargin - (initialView.getWidth() / 2), 0, topMargin - (initialView.getHeight() / 2), 0);
    translateAnimation.setDuration(500);
    translateAnimation.setInterpolator(new AccelerateInterpolator());
    initialView.startAnimation(translateAnimation);
    initialView.setVisibility(View.VISIBLE);
}

In my case I called method from the DROP case

case DragEvent.ACTION_DROP:
View initialView = (View) event.getLocalState();//get your initial view
initialView.setVisibility(View.VISIBLE);
animateDragToStart(initialView, event.getX(), event.getY());

// Returns true. DragEvent.getResult() will return true.
return true;

And when the shadow is created you should hide the original view.

View.DragShadowBuilder shadowBuilder = new MyDragShadowBuilder(view);
view.startDrag(data, shadowBuilder, view, 0);
view.setVisibility(View.INVISIBLE);

The question is old, but I answered because could help to somebody.

来源：https://stackoverflow.com/questions/34760518/get-dragged-shadow-location-on-view-ondraglistener

标签

android

drag-and-drop