Fixes#2499
We rely on CoreText's font discovery to find the best font for a
fallback by using the character set attribute. It appears that for some
codepoints, the character set attribute is not enough to find a font
that supports the codepoint.
In this case, we use CTFontCreateForString to find the font that
CoreText would use. The one subtlety here is we need to ignore the
last resort font, which just has replacement glyphs for all codepoints.
We already had a function to do this for CJK characters (#1637)
thankfully so we can just reuse that!
This also fixes a bug where CTFontCreateForString range param expects
the range length to be utf16 code units, not utf32.
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.
- move wuffs code from src/ to pkg/
- eliminate stray debug logs
- make logs a warning instead of an error
- remove initialization of some structs to zero
There are scenarios where this configuration looks bad. This commit
introduces some heuristics to prevent it. Here are the heuristics:
* Extension is always enabled on alt screen.
* Extension is disabled if a row contains any default bg color. The
thinking is that in this scenario, using the default bg color looks
just fine.
* Extension is disabled if a row is marked as a prompt (using semantic
prompt sequences). The thinking here is that prompts often contain
perfect fit glyphs such as Powerline glyphs and those look bad when
extended.
This introduces some CPU cost to the extension feature but it should be
minimal and respects dirty tracking. This is unfortunate but the feature
makes many terminal scenarios look much better and the performance cost
is minimal so I believe it is worth it.
Further heuristics are likely warranted but this should be a good
starting set.
