Android custom XferMode / PorterDuff.Mode

Question

There are some predefined blending modes described here: https://developer.android.com/reference/android/graphics/PorterDuff.Mode.html

Is there a possibility to use some other custom modes? (for drawing various stuff on Canvas)

For example, I really need two more:

• Replace the alpha (it would be written as [Sa, Dc] if I understand right)
• Blend using destination alpha [Sa, Da * Sc + (1 - Da) * Dc] (here I don't really care about the result's alpha)

And it would be OK if it would require OpenGL ES 2+.

There's a [remotely] similar question here: Implementing different PorterDuff modes in android — but the answer seems to require using two bitmaps, and I want to stay free of temporary bitmaps, because they are… not free.

Tearjerker

what about ColorMatrixColorFilter? – Clairclairaudience

ColorFilter can't be used for blending two images, it can only apply a transform to one image, isn't it? – Tearjerker

When saying "blending" what exactly do you mean? – Clairclairaudience

draw image A (a Paint probably) over an existing image B (Canvas), using some function with 2 inputs (pixel from A, pixel from B) to compute the final pixels. – Tearjerker

@Clairclairaudience "blending" means "mixing". He wants to overlay 2 images. – Amorist