I have 1-bit grayscale, non-interlace PNG icons. The pixels are white or fully transparent.
To be safe, I set my colors
dc.setColor(Graphics.COLOR_WHITE, Graphics.COLOR_TRANSPARENT);
then I render my image:
dc.drawBitmap(...);
the (white) image content is round, and the corners should be transparent.
They overlap other content and end up painting black pixels where they should be transparent.