Backends

Currently, Skia and Quartz-2D are supported. Historically, the Artist library was the 2D vector graphics component for the Elements Library, implemented using the Cairo 2D graphics library as the sole backend. After many years waiting for Cairo to support path effects, needed for modern GUI applications, it is apparent that Cairo development has gone stale with the latest entry stating “cairo 1.16 (2017?)”. See Cairo Roadmap. It is probably forthcoming that Cairo support in the Elements library will be dropped and will not be ported to the Artist library (Although there is an initial port if someone is interested).

Before Cairo, the precursor of the Artist library used NanoVG. It was then that the basic design principles took shape. Like Artist, the NanoVG API is modeled after HTML5 canvas API. NanoVG was dropped early on due to lack of support from its author, poor text rendering quality and inferior rendering quality (in general) compared to my gold standard: Quartz-2D. Currently, the NanoVG project is not actively maintained.

It was a good decision to isolate the NanoVG backend with a clean-cut C++ canvas API. NanoVG had a C interface to begin with, so it was a necessary step. But isolating it in a well-defined API also meant that it could be replaced any time. If, on the other hand, I hard-coded application code to use NanoVG directly, I would have been locked to that specific library. Abstraction is the key. Libraries come and go. The king of the hill now, may be superseded by another “better” library in the future. Case in point: Cairo.

There is also a half-baked Direct-2D port on windows, currently shelved. It is working, except for the text layout part which has its own text-layout engine. Direct-2D is such a pain to work with compared to other graphics libraries and for lack of time, for now, it is indefinitely shelved (Again, I welcome it if anyone wants to continue where I stopped).

A few graphics libraries have splendid support for text-layout. Some don’t, in particular, Skia. For Skia, I am using the Harfbuzz library for text-layout.