核心图形色彩融合

Question

I have a line of text which I want to display behind a CALayer, and when behind, then the text color should appear in a different color in the overlapping area.

The color of the text is black, and the text color should appear as white on the red layer when they overlap (they may both move around, so this needs to be continuously updated).

How may this be accomplished?

Answer 1

This can't be done with any blend mode. You'll need to render the text into the foreground layer in white by hand.

One trick you could try is to keep the white text always visible, but clipped by the layer that moves around using a second layer that also moves, set as the text's mask.