I'm having the same problem. A Paint object treats Color.TRANSPARENT as 'paint transparently' - i.e. don't paint anything. What you and I want is something that 'paints transparency' - ie. replace whatever color is there with transparency.
I don't see anything in Canvas or Paint that lets you control this behavior. Pretty silly, since it ought to be easy to implement. Maybe they could just define a Color.TRANSPARENCY that has this behavior. But that would be kludgey. You'd have to set aside a particular ARGB value (0xffffffff?) with that meaning, and wouldn't be able to use it as a normal ARGB value. There is the Canvas.drawColor(color, PorterDuff.Mode). That lets you control the way the color is combined with the Canvas. But drawColor is the only function that seems to support this kind of control. So, I guess if all you wanted to erase was a rectangle, you could set a clipping rectangle and erase just that. In fact, I think I'm going to try that (I am just drawing rectangles). The other thing I was going to try was similar to your 'replace black with transparency' idea. I think you can do that by running a getPixel loop across the whole bitmap, and then replacing any black pixels with transparent pixels (0 should do the trick). Sounds awfully inefficient, but nothing better seems to be provided. If somebody out there knows of a 'right' way to just get a Paint object to erase to transparency, please speak up before I commit the above atrocity. -- You received this message because you are subscribed to the Google Groups "Android Developers" group. To post to this group, send email to [email protected] To unsubscribe from this group, send email to [email protected] For more options, visit this group at http://groups.google.com/group/android-developers?hl=en
