拖放图像可见性

Question

我试图将一张图片拖放到另一张图片上。到目前为止，我得到阴影工作，当用户拖动图像时，它做了一些事情。我想要做的是在拖动图像时使图像可见，因为只显示阴影。

尝试使用此how to drag and drop a image onto a image但无法理解。我想我的剪辑数据有误。

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    tools:context="com.example.imagedrop.MainActivity" >

    <ImageView
        android:id="@+id/view"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:src="@drawable/ic_launcher" 
        android:contentDescription="@string/v"/>

    <ImageView
        android:id="@+id/target"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_below="@+id/view"
        android:layout_centerHorizontal="true"
        android:layout_marginTop="118dp"
        android:src="@drawable/ic_launcher"
        android:contentDescription="@string/v" />

</RelativeLayout>

Java

    public class MainActivity extends Activity {    

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

    //get image
        findViewById(R.id.view).setOnLongClickListener(longListen);
        findViewById(R.id.target).setOnDragListener(dropListener);
    }


    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.main, menu);
        return true;
    }

    OnLongClickListener longListen = new OnLongClickListener() {

        @Override

        public boolean onLongClick(View v) {


            //dragshadow created
            DragShadow dragShadow = new DragShadow(v);

            // clip data
            ClipData data = ClipData.newPlainText("", "");


            v.startDrag(data, dragShadow, v, 0);
            return false;
        }
    };


    OnDragListener dropListener = new OnDragListener()  {

        public boolean onDrag(View v, DragEvent event) 
        {
            int dragEvent = event.getAction();                              

            switch (dragEvent) {
            case DragEvent.ACTION_DRAG_STARTED:
                Log.i("Drag Event", "Started");
                break;

            case DragEvent.ACTION_DRAG_ENTERED:

                Log.i("Drag Event", "Entered");
                break;

            case DragEvent.ACTION_DRAG_EXITED:
                Log.i("Drag Event", "Exited");
                break;

            case DragEvent.ACTION_DROP:             
                //sends to new activity             
                break;
            }
            return true;
        }

    };      



    private class DragShadow extends View.DragShadowBuilder {
        //greybox drawable made
        ColorDrawable greyBox;


        public DragShadow(View view) {
            super(view);
            greyBox = new ColorDrawable(Color.LTGRAY); 
        }

        @Override
        public void onDrawShadow(Canvas canvas) {

            greyBox.draw(canvas);
        }

        @Override
        public void onProvideShadowMetrics(Point shadowSize,
                Point shadowTouchPoint) {

            View v = getView();

            int height = (int) v.getHeight() / 2;
            int width = (int) v.getWidth() / 2;


            greyBox.setBounds(0, 0, width, height);

            shadowSize.set(width, height);

            shadowTouchPoint.set((int) width / 2, (int) height / 2);

        }

    }       


    }

Answer 1

我使用此库DraggablePanel实现了相同的行为。

祝你好运。