Is it possible to make a drag shadow opaque?

Question

As question states. here is my dragshadowbuilder for reference. As you know, the shadow that is created when you drag is translucent. Is there anyway to make it opaque? (ful

Answer 1

I think the proper way to achieve this is:

/* Create the shadow from a view */
View.DragShadowBuilder shadowBuilder = new View.DragShadowBuilder(view);
/* Access the view created and set the alpha of it to 1 (totally opaque)*/
shadowBuilder.getView().setAlpha(1);
/* Start dragging the object */
view.startDrag(data, shadowBuilder, view, 0);

EDIT It doesn't seem to work on 4.4 and beyond :(

Answer 2

Its not possible to achieve that. This is how startDragAndDrop is creating the surface to drag on:

final SurfaceControl surfaceControl = new SurfaceControl.Builder(session)
            .setName("drag surface")
            .setParent(root.getSurfaceControl())
            .setBufferSize(shadowSize.x, shadowSize.y)
            .setFormat(PixelFormat.TRANSLUCENT)
            .setCallsite("View.startDragAndDrop")
            .build();

As you can see, the format is set to PixelFormat.TRANSLUCENT, and no option to change that

Answer 3

As @Ernir says, there no API get DragShadow. But we know the drag location and drag view so we can draw it ourselves.

I write a simple and function limited demo you can download it here.

It implement a custom ViewGroup named DragContainer, Use it to wrap your original root view in your layout xml.

<info.dourok.android.demo.DragContainer xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/root"
    android:layout_width="match_parent"
    android:layout_height="match_parent" >

    <!-- original root view -->
    <RelativeLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent">
         <!-- ... -->
    </RelativeLayout>

</info.dourok.android.demo.DragContainer>

call DragContainer#startDragChild to start drag like that(the demo have more detail):

in Activity:

protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        mDragContainer = (DragContainer) findViewById(R.id.root);
        View drag = mDragContainer.findViewById(R.id.drag);
        View drop = mDragContainer.findViewById(R.id.drop);
        drag.setTag(IMAGEVIEW_TAG);
        drag.setOnLongClickListener(new View.OnLongClickListener() {
            public boolean onLongClick(View v) {
                ClipData.Item item = new ClipData.Item((CharSequence) v
                        .getTag());
                ClipData dragData = new ClipData((CharSequence) v.getTag(),
                        new String[] { ClipDescription.MIMETYPE_TEXT_PLAIN },
                        item);
                return mDragContainer.startDragChild(v, dragData, // the data to
                                                                    // be
                                                                    // dragged
                        null, // no need to use local data
                        0 // flags (not currently used, set to 0)
                        );

            }
        });


    }

You also can extend DragContainer to draw custom drag shadow, This is a example for your requirement.

public class MyDragContainer extends DragContainer {
    public MyDragContainer(Context context, AttributeSet attrs) {
        this(context, attrs, 0);
    }

    public MyDragContainer(Context context) {
        super(context, null);
    }

    public MyDragContainer(Context context, AttributeSet attrs, int defStyle) {
        super(context, attrs, defStyle);
    }

    int width;
    int height;
    Bitmap bitmap;

    @Override
    protected void onSetDragTarget(View v) {
        ImageView b = (ImageView) v;
        int x = Character.getNumericValue(b.getContentDescription().charAt(0));
        int y = Character.getNumericValue(b.getContentDescription().charAt(1));
        bitmap = InGameActivity.currentBoardState[x][y].getPicture();
        width = bitmap.getWidth();
        height = bitmap.getHeight();
    }

    @Override
    protected void drawDragShadow(Canvas canvas) {
        Rect source = new Rect(0, 0, InGameActivity.chessSquareHeightWidth, InGameActivity.chessSquareHeightWidth);

        int w =  InGameActivity.chessSquareHeightWidth;
        int h = InGameActivity.chessSquareHeightWidth;

        canvas.translate(getDragX() - w / 2, getDragY() - h / 2);

        canvas.drawBitmap(bitmap, null, source, null);
    }
}

I hope it will help.

Answer 4

No, it is unfortunately not possible as far as I can tell.

The shadow Bitmap is drawn on a surface that you can't reach. The only solution is to implement Drag & Drop like it was done pre API 11. It is actually not as hard as you might think.

Some links to get you started:

Link 1

Link 2 *updated

Answer 5

Dont know if someone is aware of it or not, We can achieve the same using flag DRAG_FLAG_OPAQUE, So the correspondind startDrag method will look like as below:

    View.DragShadowBuilder dragShadowBuilder = new View.DragShadowBuilder(view);
    view.startDrag(clipData, dragShadowBuilder, view, DRAG_FLAG_OPAQUE);