When inline layout emits a whitespace chunk, it previously selected the
surrounding text's font without checking whether that font actually
contains a glyph for the whitespace codepoint. On pages that use
`@font-face` rules sharded by `unicode-range` (e.g. a Roboto webfont
split across one file for Cyrillic letters and another for basic Latin),
the shard covering the letters is picked for an adjacent space even
though the space codepoint lives in a different shard. HarfBuzz then
shapes the space with a font that has no glyph for it and emits
`.notdef`, rendering spaces as tofu boxes.
Check `contains_glyph(space_code_point)` on each candidate in
`font_for_space()` and fall through to
`FontCascadeList::font_for_code_point()` for the whitespace codepoint
when no surrounding font has the glyph.
Fixes whitespace rendering on web.telegram.org/a.
This tightens the implementation of video element sizing to the spec by
implementing two spec concepts:
- The media resource's natural width and height, and
- The video element's natural width and height.
The element's natural dimensions change based on the representation,
which has many inputs, so update checks are triggered from many
locations.
The resize event is fired when the media resource's natural dimensions
change, and the layout is invalidated if the element's natural
dimensions change.
Tests for a few important resize triggers have been added.
This fixes a crash when a track is enabled and then disabled while a
seek is in progress.
The logic in SeekingStateHandler is reworked to keep track of the
tracks that are currently being seeked, and when a track is disabled,
it is no longer counted against the seek completion. Any seek
completion callback that was instated is cleared by calling seek with
a null callback.
It may be worth making a separate function on the data providers to
clear the current seek instead, to avoid the extra work of seeking, but
this scenario is a very rare one unless someone intentionally triggers
it, and the cost is minimal unless the toggles are spammed.
A crash test is included, which both tests for the crash, and would
also time out if the failing VERIFY in on_track_enabled() was avoided
with the previous seeking implementation, due to the originally-enabled
video track's seek callback being clobbered by on_track_enabled()'s
seek.
If we fire the error event synchronously within the on_error callback,
then we'll end up destroying the PlaybackManager inside its own
callback and crash. Instead, queue a task to execute the error steps.
This could happen with or without MSE, but I observed it occurring on
YouTube with MSE when we hit a decoding error, since they immediately
try another source when an error is reported.
We use Harfbuzz to lay out glyphs at their right positions, but we
should not do so for substrings as we were doing for selection/range
rects: their positioning is dependent on their full context to properly
determine kerning and ligatures, for example.
Instead, use the stored glyph positions & widths directly to calculate
the range rect for a partial fragment selection. This makes the
selection rect visually stable - it no longer jitters when expanding the
selection character by character.
Previously we wouldn't respect font-variation-settings for fonts matched
through `font_matching_algorithm` (i.e. any fonts which didn't have an
exact loaded match).
The text track processing model would previously spin forever waiting
for the track URL to change. It would then recursively invoke itself
to handle the new URL, again entering the spin loop. This meant that
tracks could easily cause event loop hangs.
We now have an observer system to be notified when the track state
changes instead. This lets us exit the processing model and move on.
The video was accidentally removed in commit d5ba665f89.
This adds the video back to the LibWeb/Text/data folder, and validates
that the video loads in the test that depends on it loading.
