Apparently, it was in skia m68 but gone in m80, and the SkiaSharp people decided to reimplement it in c# mono/SkiaSharp#1198 .

In our case, we just need to fish the deleted code out and bundle it ourself.

Mostly so that skiasharp examples can be rewritten in skia-python in a easy way.

Found this when asking github copilot to port my skia-python opengl examples from sdl2 to gtk. On the way it offers to add more sophisticated skia drawing code to illustrate. I thought, why not? And it gave me python code which assumes equivalent code to skiasharp exists. Interesting.

Skia Sharp has a larger user base and seems to suffer from similar problems as here: while it offers some of the latest like runtime effect filters, it is also carrying a lot of old APIs, new emulations of old APIs from m68.