Prior to this change, if none of the fonts specified in CSS contained a
glyph for a codepoint, we tried only one fallback font. If that font
didn't contain the glyph, we'd give up.
With this change, we try multiple fonts in turn. The font names we try
differ across each platform, and based on the codepoint we're trying to
match. The current implementation is heavily inspired by the analogous
code in Gecko, but I've used to ucd lib to make it more readable,
whereas Gecko matches raw unicode ranges.
This fixes some of the issues reported in #17267, although colour emoji
support is not implemented.
== Notes on changes to WPT metadata ==
=== css/css-text/i18n/css3-text-line-break-opclns-* ===
A bunch of these have started failing on macos when they previously
passed.
These tests check that the browser automatically inserts line breaks
near certain characters that are classified as "opening and closing
punctuation". The idea is that if we have e.g. an opening parenthesis,
it does not make sense for it to appear at the end of a line box; it
should "stick" to the next character and go into the next line box.
Before this change, a lot of these codepoints rendered as a missing
glyph on Mac and Linux. In some cases, that meant that the test was
passing.
After this change, a bunch of these codepoints are now rendering glyphs
on Mac (but not Linux). In some cases, the test should continue to pass
where it previously did when rendering with the missing glyph.
However, it seems this has also exposed a layout bug. The "ref" div in
these tests contains a <br> element, and it seems that this, combined
with these punctuation characters, makes the spacing between glyphs ever
so slightly different to the "test" div. (Speculation: might be
something to do with shaping?)
Therefore I've had to mark a bunch of these tests failing on mac.
=== css/css-text/i18n/css3-text-line-break-baspglwj-* ===
Some of these previously passed on Mac due to a missing glyph. Now that
we're rendering the correct glyph, they are failing.
=== css/css-text/word-break/word-break-normal-bo-000.html ===
The characters now render correctly on Mac, and the test is passing. But
we do not find a suitable fallback font on Linux, so it is still failing
on that platform.
=== css/css-text/word-break/word-break-break-all-007.html ===
This was previously passing on Mac, but only because missing character
glyphs were rendered. Now that a fallback font is able to be found, it
(correctly) fails.
=== mozilla/tests/css/font_fallback_* ===
These are new tests added in this commit. 01 and 02 are marked failing
on Linux because the builders don't have the appropriate fonts installed
(that will be a follow-up).
Fix build errors from rebase
FontTemplateDescriptor can no longer just derive(Hash). We need to
implement it on each component part, because the components now
generally wrap floats, which do not impl Hash because of NaN. However in
this case we know that we won't have a NaN, so it is safe to manually
impl Hash.
This also changes their ToCss impl to use SequenceWriter instead of
checking has_value manually.
SpecifiedValueInfo for those types are also implemented in this patch.
Bug: 1434130
Reviewed-by: emilio
MozReview-Commit-ID: 23h2VWS417H
System font keywords are not a valid value for those properties.
The newly-added #[css(skip)] would be reused by deriving algorithm of
SpecifiedValueInfo to skip them as well.
Bug: 1434130
Reviewed-by: emilio
MozReview-Commit-ID: EmnhkaA9RR5
Most of types just derive it using proc_macro directly. Some of value
types need manual impl.
In my current plan, this new trait will be used in bug 1434130 to expose
values as well.
Bug: 1455576
Reviewed-by: emilio
MozReview-Commit-ID: LI7fy45VkRw
If I had to write that again I would've killed myself :).
This is still not perfect, and the system font code is still quite a mess, but
well, little steps.
Bug: 1455358
Reviewed-by: xidorn
MozReview-Commit-ID: BmrZlCSejo7
These won't "just work", pending changes from bug 1436048 to use a floating
point representation for those.
Bug: 1454883
Reviewed-by: xidorn
MozReview-Commit-ID: Bi5iTdFreMA
This more concrete wrapper type can write a prefix the very first time something
is written to it. This allows removing plenty of useless monomorphisations caused
by the former W/SequenceWriter<W> pair of types.
It makes no sense to pass a custom base size of zero in presence of rem, ex, or
ch units.
Bug: 1431031
Reviewed-by: Manishearth
MozReview-Commit-ID: 7ZZwRzQKREX
style: Move font-feature-settings outside of mako
This is a sub-PR of #19015
r? emilio
---
- [x] `./mach build -d` does not report any errors
- [x] `./mach test-tidy` does not report any errors
- [x] These changes fix#19290
- [x] These changes do not require tests
<!-- Reviewable:start -->
---
This change is [<img src="https://reviewable.io/review_button.svg" height="34" align="absmiddle" alt="Reviewable"/>](https://reviewable.io/reviews/servo/servo/19293)
<!-- Reviewable:end -->
