Masked bitmap on canvas with transparent activity

问题

I implemented custom ShowCase for activity

I am trying to draw on canvas mask: http://i.stack.imgur.com/u23kQ.png

Following this code:

mCanvas.drawColor(Color.TRANSPARENT, PorterDuff.Mode.CLEAR);

    // draw solid background
    mCanvas.drawColor(mMaskColour);

    // Prepare eraser Paint if needed
    if (mEraser == null) {
        mEraser = new Paint();
        mEraser.setColor(0xFFFFFFFF);
        mEraser.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.CLEAR));
        mEraser.setFlags(Paint.ANTI_ALIAS_FLAG);
    }

    // draw (erase) shape
   // mShape.draw(mCanvas, mEraser, mXPosition, mYPosition, mShapePadding);

    mCanvas.drawBitmap(cBitmap,mXPosition,mYPosition,mEraser);

    // Draw background
    canvas.drawBitmap(mBitmap, 0, 0, null);

But it appears like this:

http://i.stack.imgur.com/MhcOt.png

回答1:

I solve this

 Paint paint = new Paint(Paint.ANTI_ALIAS_FLAG);
        paint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.DST_IN));
        mCanvas.drawBitmap(cBitmap,mXPosition,mYPosition,paint);
       // mShape.draw(canvas, mEraser, mXPosition, mYPosition, mShapePadding);
        // Draw the bitmap on our views  canvas.
        canvas.drawBitmap(mBitmap, 0, 0, null);

来源：https://stackoverflow.com/questions/33914555/masked-bitmap-on-canvas-with-transparent-activity