The root element font metrics were getting queried again and again
during style computation. Before this change we would do some work to
recalculate them each time.
This patch simply caches them in a StyleComputer member. Since style
updates always start with the root element, we know that it'll be
up-to-date by the time we look at any other element.
Before this change, we were spending ~5% of CPU time on Google Groups
in root_element_font_metrics().
This necessitated returning `nullptr` instead of just `{}` in a lot of
places. Also, some temporary hackiness in `parse_css_value()`: That
returns a special `ParseError` type already, so we now have a
`FIXME_TRY()` macro which logs the error and then returns a generic
`ParseError::InternalError` value. Eventually this macro will go away,
once I figure out how to deal with this more nicely.
In particular, we now blockify layout internal boxes (e.g table parts)
by turning them into `block flow`. This fixes a crash when viewing
our GitHub repo :^)
The Display class already supported all specific values, and now they
will be parsed too. The display property now has a special type
DisplayStyleValue.
Rather than passing an increasingly-unwieldy number of font parameters
individually to every function that resolves lengths, let's wrap them
up.
This is frustratingly close to being `Gfx::FontPixelMetrics`, but bitmap
fonts cause issues: We choose the closest font to what the CSS
requests, but that might have a wildly different size than what the
page expects, so we have to fudge the numbers.
No behaviour changes.
When deciding on a box type transformation (blockify/inlinify) for a
pseudo element, we have to use the originating element as a reference
rather than the parent.
(The originating element *is* the parent for its pseudo elements.)
This fixes multi-layer backgrounds with background positions. This
is a little awkard, so maybe it would be better to refactor the
parsing code to make these lists directly, but right now this is
the simplest fix.
This parses the new background-position-x/y longhands and properly
hooks up them up. This requires converting PositionStyleValue to
just contain two EdgeStyleValues so that it can be easily expanded
into the longhands.
Due to CSSImportRule::has_import_result() being backwards, we never
actually entered imported style sheets when traversing style rules or
media queries.
With this fixed, we no longer need the "collect style sheets" step in
StyleComputer, as normal for_each_effective_style_rule() will now
actually find all the rules. :^)
We don't support all parts of the font formats we assume as "supported"
in the CSS parser. For example, if an open type font has a CFF table, we
reject loading it. This meant that until now, when such an
unsupported-supported font url was first in the list of urls, we
couldn't load it at all, even when we would support a later url.
To resolve that, try loading all font urls one after each other, in case
we are not able to load the higher priority one.
This also resolves a FIXME related to spec compliant url prioritization.
Our CSS parser already filters and prioritizes font src urls in
compliance with the spec. However, we still had to resort to brittle
file extension matching, because some websites don't set the `format`
and if the first url in a src list happened to be one we don't support,
the font could not be loaded at all. This now is unnecessary because we
can try and discard the urls instead.
It is not sufficient to just invalidate layout when a new font has
loaded, because while it was loading we might have chosen a fallback
font-family value instead.
Invalidate style instead.
Before this patch, we would build full computed style for these pseudo
elements, for every DOM element, even if no ::before/::after selector
actually matched.
This was a colossal waste of time, and we can also just not do that.
Instead, just abort pseudo element style resolution early if no relevant
selectors matched. :^)
