Question

当我按住ImageView并将其拖动到屏幕上时，ImageView变得不可见，并且ImageView的可拖动版本将以屏幕的中心出现在屏幕上指尖下方的生成的视图；这不是有机的。我希望视图的可拖动版本直接在ImageView上方产生，而不是直接在指尖下方产生。

例如，如果我的ImageView是卡片组顶部的钻石王牌，并且我想将卡片拖离卡片组，则卡片应平稳地拖离卡片组，而不要将其自身重新放置在下面我的手指，然后拖动（如果有道理的话）。

这是我的可拖动ImageView代码；我不确定如何使拖动动画如上所述更平滑。

public class DragView2 extends AppCompatImageView
implements View.OnDragListener, View.OnTouchListener{

    private static final String TAG = DragView2.class.getSimpleName();

    public DragView2(Context context) 
    {
        super(context, null);
        this.setOnTouchListener(this);
        this.setOnDragListener(this);
    }

    public DragView2(Context context, AttributeSet attrs) 
    {
        super(context, attrs, 0);
        this.setOnTouchListener(this);
        this.setOnDragListener(this);
    }

    @Override
    public boolean onTouch(View view, MotionEvent motionEvent) 
    {
        switch (motionEvent.getAction())
        {
            case ACTION_DOWN:
                Log.d(TAG, "ACTION_DOWN");
                ClipData data = ClipData.newPlainText("", "");
                DragShadowBuilder shadowBuilder = new View.DragShadowBuilder(view);
                this.setVisibility(View.INVISIBLE);
                view.startDrag(data, shadowBuilder, view, 0);
                return true;
        }
        return false;
    }

    @Override
    public boolean onDrag(View view, DragEvent event)
    {
        final View viewToDrag = (View) event.getLocalState();
        switch (event.getAction()) {
            case DragEvent.ACTION_DRAG_STARTED:
                Log.d(TAG,"ACTION_DRAG_STARTED");
                break;
            case DragEvent.ACTION_DRAG_ENTERED:
                Log.d(TAG,"ACTION_DRAG_ENTERED");
                break;
            case DragEvent.ACTION_DRAG_EXITED:
                Log.d(TAG,"ACTION_DRAG_EXITED");
                break;
            case DragEvent.ACTION_DROP:
                Log.d(TAG,"ACTION_DROP");
                break;
            case DragEvent.ACTION_DRAG_ENDED:
                Log.d(TAG,"ACTION_DRAG_ENDED");
                view.post(new Runnable() {
                    public void run() {
                        viewToDrag.setVisibility(View.VISIBLE);
                    }
                });
                break;
            default:
                Log.d(TAG,"default");
                break;
        }
        return true;
    }
}

Answer 1

指向解决方案的指针。

我扩展了 View 类。使用以下代码成功将对象拖动到正确的坐标。

@Override
public boolean onTouchEvent(MotionEvent event)
{
    float oldX, oldY, newX, newY, originalX, originalY;

    switch (event.getAction())
    {
        case MotionEvent.ACTION_DOWN:
            oldX = event.getX();
            oldY = event.getY();
            originalX = oldX;
            originalY = oldY;
            break;
        case MotionEvent.ACTION_MOVE:
            newX = event.getX();
            newY = event.getY();
            updatePositions(oldX, oldY, newX, newY);
            oldX = newX;
            oldY = newY;
            invalidate();
            break;
        case MotionEvent.ACTION_UP:
            newX = event.getX();
            newY = event.getY();

           //  USE ANY OF THE FOLLOWING
           //  updatePositions(oldX, oldY, newX, newY);
           //  updatePositions(originalX, originalY, newX, newY);


            oldX = newX;
            oldY = newY;
    }
}

private void updatePositions(float pt1, float pt2, float pt3, float pt4) {

  // code to change the position of the position

}

制作6个变量类变量，并使用Toast显示位置。希望这能提示解决方案：）

如何确定要拖动的视图的起始位置

1 个答案: