Check if CGContextBeginTransparencyLayer can avoid the 2-step rendering

[AliSoftware]

See Quartz 2D PG: Transparency Layers

Using CGContextBeginTransparencyLayer/CGContextEndTransparencyLayer may be a solution to avoid doing a 2-step rendering (first tinting, then do the final rendering), by using layers instead of generating a first UIImage then using it to generate the second, final image.

This is only a hypothesis and some stuff to experiment — maybe that won't do it, but it's worth testing and digging a bit to check if that may be interesting.