Android : Retrieve memory of Bitmap/Drawable

I need the raw bitmap memory of an Android drawable (the app icon). By raw bitmap I mean the memory representation of the image. (I need it for reading in a c++ Qt app, to convert that image to Qt formats).

So far I can't find a way to get the memory either of a Drawable Bitmap or Canvas. One way would be geting each pixel's colors but I foresee this uneficient/slow.

Is that possible? Any hint?