java - 通过 ACTION_DRAG_LOCATION 滚动 GridView 并在 ACTION_DROP 上交换 Gridview 的 ArrayAdapter 中的项目

Question

我希望用户能够在 a 中交换项目（aImageView中的一个RelativeLayout）GridView，但我也希望他们能够在GridView将图像拖动到相应的顶部或底部时向上或向下滚动GridView。

如果我在 backing 中实现拖动侦听ArrayAdapter器，则无法进行滚动。如果我GridView按如下所示实现它，我将无法获得我放置的数组项的位置。

有没有办法做到这一点？请注意我遇到问题的评论。谢谢！

我有一个GridView实现OnDragListener，但我不知道如何获得我想要交换的位置。

这是长按监听器：

gv.setOnItemLongClickListener(new OnItemLongClickListener() {

        @Override
        public boolean onItemLongClick(AdapterView<?> grv, View v,
                int position, long row) {
            mVibrator.vibrate(VIBRATE_DURATION);
            ClipData cd = ClipData.newPlainText("position", String.valueOf(position));
            v.startDrag(cd, new View.DragShadowBuilder(v), v, 0);
            return true;
        }
    });

这是我的拖动监听器：

 gv.setOnDragListener(new OnDragListener() {

        Drawable enterShape = getResources().getDrawable(R.drawable.shape_droptarget);
        Drawable normalShape = getResources().getDrawable(R.drawable.shape);

        private static final int THRESHHOLD = 200;

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

            int height = v.getMeasuredHeight();

            switch (event.getAction()) {
            case DragEvent.ACTION_DRAG_STARTED:
                v.setBackground(enterShape);
                break;
            case DragEvent.ACTION_DRAG_ENTERED:
                v.setBackground(enterShape);
                break;
            case DragEvent.ACTION_DRAG_EXITED:
                v.setBackground(normalShape);
                break;
            case DragEvent.ACTION_DRAG_LOCATION:

                float y = event.getY();
                if (height - y < THRESHHOLD) {
                    gv.smoothScrollBy(200, 300);
                    Log.i(TAG, "Scrolling DOWN");
                } else if (height - y > height - THRESHHOLD) {
                    gv.smoothScrollBy(-200, 300);
                    Log.i(TAG, "Scrolling UP");
                }
                break;
            case DragEvent.ACTION_DROP:
                //Gridview position to swap with.
                // HOW DO I GET THIS?
                int i = position;
                int j = Integer.parseInt(event.getClipData().getItemAt(0).getText().toString());
                Collections.swap(mUriList, i, j);
                Log.i(TAG, "Swapped " + i+ " with " + j);
                break;
            case DragEvent.ACTION_DRAG_ENDED:
                v.setBackground(null);
                mAdapter.notifyDataSetChanged();
            default:
                break;
            }
            return true;
        }

    });

Answer 1

答案是使 GridView 最终并用于gv.pointToPosition((int)event.getX(), (int)event.getY());获取位置。

case DragEvent.ACTION_DROP:
    //Gridview position to swap with.
    int i =gv.pointToPosition((int)event.getX(), (int)event.getY());
    int j = Integer.parseInt(event.getClipData().getItemAt(0).getText().toString());
    Collections.swap(mUriList, i, j);
    Log.i(TAG, "Swapped " + i+ " with " + j);
    break;