在android中拖动时如何逐渐减小弹出窗口的大小？

Question

我需要创建一个演示，其中会出现一个弹出窗口，当用户拖动该弹出窗口时，它的大小会逐渐减小。大小取决于用户拖动时所覆盖的距离。该功能类似于 PAPER 应用程序（FACEBOOK）。 我可以通过以下代码拖动弹出窗口。但是代码无法减小弹出窗口的大小，同时拖动它会减小弹出窗口释放时的大小。

public class MainActivity extends Activity implements OnTouchListener,
        OnDragListener {
    private static final String LOGCAT = null;
    private LayoutParams layoutParams;

    ImageView img;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        img = (ImageView) findViewById(R.id.textView1);
        img.setOnTouchListener(this);
        findViewById(R.id.pinkLayout).setOnDragListener(this);
        findViewById(R.id.yellowLayout).setOnDragListener(this);
    }

    public boolean onTouch(View view, MotionEvent motionEvent) {
        if (motionEvent.getAction() == MotionEvent.ACTION_DOWN) {
            layoutParams = (LayoutParams) img.getLayoutParams();
            DragShadowBuilder shadowBuilder = new View.DragShadowBuilder(view);
            view.startDrag(null, shadowBuilder, view, 0);
            view.setVisibility(View.INVISIBLE);
            return true;
        } else {
            return false;
        }
    }

    public boolean onDrag(View layoutview, DragEvent dragevent) {
        int action = dragevent.getAction();
        switch (action) {

        case DragEvent.ACTION_DRAG_LOCATION:

            Toast.makeText(getApplicationContext(), "" + dragevent.getX(),
                    Toast.LENGTH_SHORT).show();

            layoutParams.height = (int) dragevent.getX();
            layoutParams.width = (int) dragevent.getX();

            img.setLayoutParams(layoutParams);

            break;

        case DragEvent.ACTION_DRAG_STARTED:

            System.out.println("Action drag started");

            /*
             * Log.d(LOGCAT, "Drag event started");
             * 
             * System.out.println("Drag event started");
             */

            break;
        case DragEvent.ACTION_DRAG_ENTERED:
            System.out.println("Action drag entered");
            /*
             * System.out.println("Drag event entered into " +
             * layoutview.toString()); Log.d(LOGCAT, "Drag event entered into "
             * + layoutview.toString());
             */
            break;
        case DragEvent.ACTION_DRAG_EXITED:
            System.out.println("Action drag exited");
            /*
             * System.out.println("Drag event exited from " +
             * layoutview.toString());
             * 
             * Log.d(LOGCAT, "Drag event exited from " + layoutview.toString());
             */
            break;
        case DragEvent.ACTION_DROP:
            System.out.println("Action drag drop");
            // Log.d(LOGCAT, "Dropped");
            View view = (View) dragevent.getLocalState();
            ViewGroup owner = (ViewGroup) view.getParent();
            owner.removeView(view);
            LinearLayout container = (LinearLayout) layoutview;
            container.addView(view);
            view.setVisibility(View.VISIBLE);
            break;
        case DragEvent.ACTION_DRAG_ENDED:

            System.out.println("Action drag ended");

            /* Log.d(LOGCAT, "Drag ended"); */
            break;
        default:
            break;
        }
        return true;
    }
}

谁能告诉我应该如何处理我的存在代码来实现上述功能。谢谢

Answer 1

为了让我的回答 100% 准确，我需要了解更多关于您的应用程序工作的详细信息。根据您所写的内容，我假设“弹出窗口”会在您的手指下移动，并且您希望在移动它时调整它的大小。

解决方案非常简单。要做到这一点，您必须做两件事：

1. 创建一个虚拟阴影构建器类，这样当您移动视图时它不会显示任何阴影（更改阴影大小很棘手，但据我了解，您根本不需要阴影......）。你可以这样做：

   public class DummyShadowBuilder extends View.DragShadowBuilder {
   
       @Override
       public void onDrawShadow(Canvas canvas) {
       }
   
       @Override
       public void onProvideShadowMetrics(Point shadowSize, Point touchPoint) {
       }
   }
   

   并将其用作您的阴影构建器进行拖动：

   DummyShadowBuilder shadowBuilder = new DummyShadowBuilder();
   view.startDrag(null, shadowBuilder, view, 0);
   

2. 控制内部拖拽视图的大小和位置

   case DragEvent.ACTION_DRAG_LOCATION
   

   使用旧代码的示例：

   public boolean onDrag(View layoutview, DragEvent dragevent) {
       int action = dragevent.getAction();
       switch (action) {
           case DragEvent.ACTION_DRAG_LOCATION:
               //CONTROL POSITION AND SIZE OF DRAGGED VIEW
   
               //EXAMPLE USING YOUR OLD CODE (previously in ACTION_DRAG_ENDED):
               int x = (int) dragevent.getX();
               int y = (int) dragevent.getY();
   
               layoutParams.height = x;
               layoutParams.width = x;
   
               img.setLayoutParams(layoutParams);
   
               View view = (View) dragevent.getLocalState();
               ViewGroup owner = (ViewGroup) view.getParent();
               owner.removeView(view);
               LinearLayout container = (LinearLayout) layoutview;
               container.addView(view);
               view.setVisibility(View.VISIBLE);
   
               break;
           case DragEvent.ACTION_DRAG_STARTED:
               break;
           case DragEvent.ACTION_DRAG_ENTERED:
               break;
           case DragEvent.ACTION_DRAG_EXITED:
               break;
           case DragEvent.ACTION_DROP:
               break;
           case DragEvent.ACTION_DRAG_ENDED:
               break;
           default:
               break;
           }
       return true;
   }