Herb Sutter from the ISO C++ group, reached out to the Cairo folks:
We are actively looking at the potential standardization of a basic 2D drawing library for ISO C++, and would like to base it on (or outright adopt, possibly as a binding) solid prior art in the form of an existing library.
we are focused on current Cairo as a starting point, even though it's not C++ -- we believe Cairo itself it is very well written C (already in an OO style, already const-correct, etc.).
Congratulations to the Cairo guys for designing such a pleasant to use 2D API.
But this would not be a Saturday blog post without pointing out that Cairo's C-based API is easier and simpler to use than many of those C++ libraries out there. The more sophisticated the use of the C++ language to get some performance benefit, the more unpleasant the API is to use.
The incredibly powerful Antigrain sports an insanely fast software renderer and also a quite hostile template-based API.
We got to compare Antigrain and Cairo back when we worked on Moonlight. Cairo was the clear winner.
We built Moonlight in C++ for all the wrong reasons ("better performance", "memory usage") and was a decision we came to regret. Not only were the reasons wrong, it is not clear we got any performance benefit and it is clear that we did worse with memory usage.
But that is a story for another time.