The main change here is that collapsed and `text-transform`'d text is
computed as it's processed by DOM traversal. This single transformed
text is stored in the root of the `InlineFormattingContext`.
This will eventually allow performing linebreaking and shaping of the
entire inline formatting context at once. Allowing for intelligent
processing of linebreaking and also shaping across elements. This
matches more closely what LayoutNG does.
This shouldn't have any (or negligable) behavioral changes, but will
allow us to prevent linebreaking inside of clusters in a followup
change.
Co-authored-by: Rakhi Sharma <atbrakhi@igalia.com>
This change adds support for `white-space-collapse: break-spaces` and
adds initial parsing support for `overflow-wrap` and `word-break`. The
later two properties are not fully supported, only in their interaction
with `break-spaces`. This is a preliminary change preparing to implement
them.
In addition, `break_and_shape` is now forked and added to Layout 2020.
This function is going to change a lot soon and forking is preparation
for this. More code that is only used by Layout 2013 is moved from `gfx`
to that crate.
Co-authored-by: Rakhi Sharma <atbrakhi@igalia.com>
- Better detect situations where emoji is necessary by looking ahead one
character while laying out. This allow processing Unicode presentation
selectors. When detecting emoji, put emoji fonts at the front of
fallback lists for all platforms.
This enables monochrome emoji on Windows. Full-color emoji on Windows
probably needs full support for processing the COLR table and drawing
separate glyph color layers.
- Improve the font fallback list on FreeType platforms. Ideally, Servo
would be able to look through the entire font list to find the best
font for a certain character, but until that time we can make sure the
font list contains the "Noto Sans" fonts which cover most situations.
Fixes#31664.
Fixes#12944.
This allows sharing font templates, fonts, and platform fonts across
layout threads. It's the first step toward storing web fonts in the
layout versus the shared `FontCacheThread`. Now fonts and font groups
have some locking (especially on FreeType), which will probably affect
performance. On the other hand, we measured memory usage and this saves
roughly 40 megabytes of memory when loading servo.org based on data from
the memory profiler.
Signed-off-by: Martin Robinson <mrobinson@igalia.com>
Co-authored-by: Mukilan Thiyagarajan <mukilan@igalia.com>
Bumps Stylo to servo/stylo#37
`white-space` is split into `white-space-collapse` and `text-wrap-mode`:
| white-space | white-space-collapse | text-wrap-mode |
| ----------- | -------------------- | -------------- |
| normal | collapse | wrap |
| nowrap | collapse | nowrap |
| pre-wrap | preserve | wrap |
| pre | preserve | nowrap |
| pre-line | preserve-breaks | wrap |
| - | preserve-breaks | nowrap |
Note this introduces a combination that wasn't previously possible,
but I think the existing logic can handle it well enough.
The old `allow_wrap()` is replaced by checking whether `text-wrap-mode`
is set to `wrap`.
The old `preserve_newlines()` is replaced by checking whether
`white-space-collapse` is *not* set to `collapse`.
The old `preserve_spaces()` is replaced by checking whether
`white-space-collapse` is set to `preserve`.
A `TextRun` is composed of `TextRunSegment`s that are composed of
`GlyphRun`s.
`TextRun::glyph_run_is_preserved_newline` is indexing into the `TextRun`
text, but the `GlyphRun` indexes that it uses are relative to the
`TextRunSegment`
offset. Before the code was using the offset without incorporating the
`TextRunSegment` offset. This led to miscalculation of preserved newline
location while processing text content.
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The logic was to remove any collapsible white space preceded by other
white space. However, this should only happen if the preceding space
is also collapsible.
Also fixing the logic in ContentSizesComputation, which was wrong
but previously it didn't matter.
The old logic was assuming that all whitespace was a break opportunity,
and that no newlines would be preserved.
Note that text shaping considers the advance of a newline to be the same
as a space. This was problematic because if we have a segment with a
preserved space and newline, only the advance of the space should
contrinute to the size of the block container. Therefore, I'm changing
the breaker logic in other to have newline characters in their own
segment.
Then glyph_run_is_whitespace_ending_with_preserved_newline can just be
renamed to glyph_run_is_preserved_newline.
This patch is still not perfect because it doesn't check allow_wrap(),
so `nowrap` is treated like `normal`, and `pre-wrap` like `pre`.
Synthetic small caps is supported by the font subsystem, but this is
disabled in Layout 2020. We can turn this on to bring support to parity
with the old layout system.
In addition to turning on synthetic small-caps this change also improves
the way that they work. Before, synthetic small caps meant that every
character was a small version of capitalized character. After this
change, capital letters are larger than small caps versions of small
letters -- matching other browsers and the common expectation of how
small caps works.
This adds basic support for `text-transform` in a way that is more
complete than legacy layout. There are still many missing elements of
proper `text-transform` support such as:
1. Support for `full-width` and `full-size-kana`
2. Support for grapheme based uppercasing, lowercasing, and
capitalization. These are all done per-code point right now.
3. Support for the language-specific `SpecialCasing.txt` cases for case
mapping such as the ones for Irish and Turkish.
Co-authored-by: Rakhi Sharma <atbrakhi@igalia.com>
This moves white space collapse to right before breaking and shaping
happens, which is more similar to what happens in legacy layout. This is
the first step toward making this procedure more efficient (avoiding
string copies) and also implementing support for `text-transform`.
Co-authored-by: Rakhi Sharma <atbrakhi@igalia.com>
This adds an initial implementation of font fallback, on part with the
one used in legacy layout. There are still issues. For instance, font
matching is done per unicode character rather than based on graphemes or
the shape first approach of Chrome. The idea is that these changes can
be made later.
Shape text during InlineFormattingContext construction rather than doing
it twice during fragment tree construction. This is a step on the way
toward proper font fallback.
This also moves all `TextRun` related code into `text_run.rs` to try to
trim down the size of `inline.rs`.
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