Ogen Ogen - 16 days ago 8
Android Question

Is it possible to make a drag shadow opaque?

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? (fully solid)

public class MyDragShadowBuilder extends View.DragShadowBuilder {
View view;
int width;
int height;
Bitmap bitmap;
public MyDragShadowBuilder(View v) {
super(v);
view = v;
ImageView b = (ImageView)view;
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
public void onDrawShadow(Canvas canvas) {
Rect source = new Rect(0, 0, InGameActivity.chessSquareHeightWidth, InGameActivity.chessSquareHeightWidth);
canvas.drawBitmap(bitmap, null, source, null);
}

@Override
public void onProvideShadowMetrics(Point shadowSize, Point touchPoint) {
shadowSize.set(InGameActivity.chessSquareHeightWidth, InGameActivity.chessSquareHeightWidth);
touchPoint.set(InGameActivity.chessSquareHeightWidth/2, InGameActivity.chessSquareHeightWidth/2);
}
}


EDIT: Here is my current onTouch code, I'll also provide a background of the app.

OnTouchListener myOnTouchListener = new OnTouchListener() {

@Override
public boolean onTouch(View view, MotionEvent event) {
System.out.println(event.toString());
if (event.getAction() == MotionEvent.ACTION_DOWN) {
ImageView b = (ImageView)view;
int x = Character.getNumericValue(b.getContentDescription().charAt(0));
int y = Character.getNumericValue(b.getContentDescription().charAt(1));
if (!currentBoardState[x][y].isEmpty()) {
((ImageView)view).setImageBitmap(null);
DragShadowBuilder shadowBuilder = new MyDragShadowBuilder(view);
view.startDrag(null, shadowBuilder, view, 0);
}

moveChessPiece;
return true;
}

return false;
}
});


Ok so here's what you need to know. I am developing a chess application. I have an 8x8 GridLayout which I have named
currentBoardState
. So currently I want to be able to drag the piece, which works, but I want the dragged piece to be opaque so the user gets the feeling that he/she is actually MOVING the piece rather than just clicking then clicking on a destination as I previously had it.

Answer

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.

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