PorterduffXfermode: Clear a section of a bitmap

Question

The goal is to draw a bitmap and over the top of something, and draw shapes that ERASE the underlying area of the bitmap.

I have a proof of concept to try and underst

Answer 1

As Romain Guy points out here: google stuff you need to write on the Bitmap, not the canvas with the circles you are trying to clear, then set it to the main Canvas in your View. So, do something like:

// Generate bitmap used for background
            bm = BitmapFactory.decodeFile("mnt/sdcard/Pictures/test.jpg");

// Create the paint and set the bitmap
Canvas temp = new Canvas(bm.getHeight(), bm.getWidth, Config.ARGB_8888);

// in onDraw()
temp.drawCircle((w / 8) * (ii * 2 + 1), (h / 8) * (i * 2 + 1), w / 8 * 0.8f, pDraw[i*4 + ii]);

// After loop
canvas.drawBitmap(....);

Hope this helps.