Similar tests should be added throughout the codebase for any function
that's supposed to gracefully handle OOM conditions. This one was added
because grow previously had a use-after-free bug under OOM, which this
would have caught.
Reordered to form a more logical sequence of steps, cleaned up and
clarified comments, fixed invalid `appendAssumeCapacity` call which
erroneously passed `alloc`, so this compiles again.
Grow needs to allocate and might fail midway. It tries to handle this
using "undo" pattern, and restoring old state on error. But this is
exactly what steps into UAF, as, on error, both errdefer and defer are
run, and the old data is freed.
Instead, use a more robust "reservation" pattern, where we first
fallibly resrve all the resources we need, without applying any changes,
and than do the actual change once we are sure that cannot fail.
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.
Forgot to change these instances when I renamed rgb(a) to bgr(a), which
was breaking test builds. Also went ahead and fixed some code that was
assuming rgba was actually rgba order and added a note to another part.
Also changes color atlas to always use an sRGB internal format so that
the texture reads automatically linearize the colors.
Renames the misleading `rgba` atlas format to `bgra`, since both
FreeType and CoreText are set up to draw color glyphs in bgra.
This switches our wasm build to use "shared" memory. Shared memory can
be shared across multiple web workers, which is something we'll want to
support for our multi-threaded behaviors later.
Shared memory has a number of different restrictions so this updates
zig-js to support it as well as updates some of our functions that need
to be aware of it.
We don't need the Atlas API for wasm at all, but its a good way to test
things work incrementally and its a pretty cool thing to have as a wasm
library really.
