WR now has a concept of font templates and font instances. This
makes the WR font interfaces closer to Cairo and Gecko, and also
makes some future performance optimizations possible.
A font template is the font family, and data backing the font.
A font instance is a reference to a font template and per-instance
options, such as font size, anti-aliasing settings etc.
To update Servo in a minimally invasive way, I added a new font
cache call, that creates a font instance. This means that when
a font is created, and doesn't exist in the cache there are now
two calls to the font cache thread. We could refactor the font
cache to make this work in one call, which we should do in the
future. However, refactoring the font cache is a large chunk of
work by itself. The extra call is only when a font doesn't already
exist in the font context cache, so it should have minimal
performance impact.
This removes paint threads, rust-layers dependency, and changes
optional webrender types to be required.
The use_webrender option has been removed, however I've left
the "-w" command line option in place so that wpt
runner can continue to pass that. Once it's removed from there
we can also remove the -w option.
Once this stage is complete, it should be fine to change the
display list building code to generate webrender display
lists directly and avoid the conversion step.
Replace character indices with UTF-8 byte offsets throughout the code dealing
with text shaping and breaking. This eliminates a lot of complexity when
converting from one to the other, and interoperates better with the rest of
the Rust ecosystem.
This is a no-op, since a "non-glyph" is simply `GlyphEntry(0)`. This is the
same as `GlyphEntry::initial()`, which all the entries are already initialized
to.
Shaper::save_glyph_results incorrectly starts its loop by setting glyph_span
to a length of 1. This means that the `if glyph_span.len() == 0` test in the
inner loop will never succeed.
Instead the glyph span should start out empty, and a glyph should be added only
as the corresponding char is found. For comparison, see the Gecko code this
was ported from:
https://hg.mozilla.org/mozilla-central/file/ab0044bf/gfx/thebes/gfxHarfBuzzShaper.cpp#l1682
WebRender is an experimental GPU accelerated rendering backend for Servo.
The WebRender backend can be specified by running Servo with the -w option (otherwise the default rendering backend will be used).
WebRender has many bugs, and missing features - but it is usable to browse most websites - please report any WebRender specific rendering bugs you encounter!
