How to draw on bitmap using another bitmap as mask?

Question

I want to draw on a bitmap using another bitmap as mask. The mask is a black bitmap with a transparent object in it. I want this transparent part to be filled with an arbitrary color and added to my original image. How can this be done?

+

+ blue color =

Lundt

do you have any choice/possibility to change the masks? e.g. using white object on transparent background? then you could use some kind of multiply between mask and blue color – Imhoff

in either case, this guide could help you to do what you'd like kevindion.com/2011/01/android-bitmap-blending-color-channels – Imhoff

Yes, I believe I could change the masks. The link provided is great! Thanks! – Lundt

Answer 1

I had to change the masks as described by @Christian. Then, the wanted result could easily be produced:

canvas.drawRect(rect, paint);
paint.setXfermode(new PorterDuffXfermode(Mode.DST_IN));
canvas.drawBitmap(mask, 0.0f, 0.0f, paint);

Lundt

Answer 2

If you're setting this to an ImageView, a quick way is to set the background to the gradient drawable, and a blue 'T' with a transparent background as the ImageView's source. Not fancy, but fast and simple!

Lepley