For Example, I want to change DrawImage in Function that is alpha blend in under source code.
void ExmampleCtrl::Paint(Draw& w)
{
w.DrawImage(0,0,Sample::Image() );→change alpha blend function
};
Image already has alpha channel, so DrawImage will use standard alpha blending. More complex alpha bledning modes are not supported in Draw, because Draw is supposed to be lowest common denominator that allows HW acceleration on all targets.
If you need anything more fancy (like different blend function), you need to perform calculations in memory - which in fact is quite easy, as Image internals are easily accessible.