This is a fairly large rework of how we handle the sprite font drawing.
Drawing routines are now context-less, provided only a canvas and some
metrics. There is now a separate file per unicode block / PUA area.
Sprites are now drawn on canvases with an extra quarter-cell of padding
on each edge, and automatically cropped when sent to the atlas, this
allows sprites to extend past cell boundaries which makes it possible to
have, for example, diagonal box drawing characters that connect across
cell diagonals instead of being pinched in.
Most of the sprites the code is just directly ported from the old code,
but I've rewritten a handful. Moving forward, I'd like to rewrite more
of these since the way they're currently written isn't ideal.
This rework, in addition to improving the packing efficiency of sprites
on the atlas, and allowing for out-of-cell drawing, will make it a lot
easier to add new sprites in the future, since all it takes now is to
add a single function and an import (if it's a new file).
I reworked the regression/change testing to be more robust as well, it
now covers all sprite glyphs (except non-codepoint ones) and does so at
4 different sizes. Addition/removal of glyphs will no longer create diff
noise in the generated diff image, since the position in the image of
each glyph is now fixed.
More complete coverage of the Symbols For Legacy Computing block,
including characters from Unicode 16.0.
Pixman and the web canvas impl for Canvas have been removed in favor of
z2d for drawing, since it has a nicer API with more powerful methods,
and is in Zig with no specific platform optimizations so should compile
to wasm no problem.
