After a little sleep, I see now that using ROP_SRCMONOEXPAND_COPY was not my brightest suggestion. It uses a monochrome bitmap as a mask to draw the foreground color--kind of a stamp. Not at all what you want.
It seems to me that you want to draw the the source image as if it were fully transparent at its white pixels. I think the easiest way to do that is to create such an image from the source. Perhaps something like this (totally untested) will work:
int OPAQUE_WHITE = 0xffffffff;
int TRANSPARENT_WHITE = 0x00ffffff;
int w = src.getWidth();
int h = src.getHeight();
int [] pixels = new int[w * h];
src.getARGB(pixels, 0, w, 0, 0, w, h);
for (int i = 0; i < pixels.length; ++i) {
if (pixels[i] == OPAQUE_WHITE) pixels[i] = TRANSPARENT_WHITE;
}
Bitmap src2 = new Bitmap(Bitmap.ROWWISE_16BIT_COLOR, w, h);
src2.createAlpha(Bitmap.ALPHA_BITDEPTH_MONO);
src2.setARGB(pixels, 0, w, 0, 0, w, h);
Then simply use drawBitmap with src2 into/over dest. If I got the logic right, the white areas of src2 ought to not draw.
I don't know if creating a new image from src is going to cause a big performance hit. Perhaps you can cache src2 if the same src image is reused.
Solved? click "Accept as solution". Helpful? give kudos by clicking on the star.
