The algorithm for starting a transition requires us to examine the
before-change and after-change values of the property, without taking
any current animations into account.
This makes the way we've implemented the CSS `revert` keyword a lot less
expensive.
Until now, we were making a deep copy of all property values at the
start of each cascade origin. (Those are the values that `revert` would
bring us back to if encountered.)
With this patch, the revert property set becomes a shallow copy, and we
only clone the property set if the cascade ends up writing something.
This knocks a 5% profile item down to 1.3% on https://tailwindcss.com
Not every value in a StyleProperties will be non-null by the time we
perform `revert`, so let's make a specialized function for reverting a
property instead of using the path that requires the value to be
non-null.
We were saving to source declarations for *every* property, even though
we only ever looked it up for animation-name.
This patch gets rid of the per-property source pointer and we now keep
a single pointer to the animation-name source only.
This shrinks StyleProperties from 6512 bytes to 4368 bytes per instance.
These control the state of CSS counters.
Parsing code for `reversed(counter-name)` is implemented, but disabled
for now until we are able to resolve values for those.
- Compare only the animated properties
- Clone only the hash map containing animated properties, instead of
the entire StyleProperties.
Reduces `KeyframeEffect::update_style_properties()` from 10% to 3% in
GitHub profiles.
Instead of wrapping every entry in Optional, use the null state of the
style pointer for the same purpose.
This shrinks StyleProperties by 1752 bytes per instance.
Instead of a gigantic array with space for every possible CSS property
being animated at the same time.
This shrinks StyleProperties by 3480 bytes per instance.
Patch up existing style properties instead of using the regular style
invalidation path, which requires rule matching for each element in the
invalidated subtree.
- !important properties: this change introduces a flag used to skip the
update of animated properties overridden by !important.
- inherited animated properties: for now, these are invalidated by
traversing animated element's subtree to propagate the update.
- StyleProperties has a separate array for animated properties that
allows the removal animated properties after animation has ended,
without requiring full style invalidation.
This patch makes a few changes to the way we calculate line-height:
- `line-height: normal` is now resolved using metrics from the used
font (specifically, round(A + D + lineGap)).
- `line-height: calc(...)` is now resolved at style compute time.
- `line-height` values are now absolutized at style compute time.
As a consequence of the above, we no longer need to walk the DOM
ancestor chain looking for line-heights during style computation.
Instead, values are inherited, resolved and absolutized locally.
This is not only much faster, but also makes our line-height metrics
match those of other engines like Gecko and Blink.
According to the CSS font matching algorithm specification, it is
supposed to be executed for each glyph instead of each text run, as is
currently done. This change partially implements this by having the
font matching algorithm produce a list of fonts against which each
glyph will be tested to find its suitable font.
Now, it becomes possible to have per-glyph fallback fonts: if the
needed glyph is not present in a font, we can check the subsequent
fonts in the list.
Now, the 'object-position' property gets properly parsed and is
provided to the rest of the ecosystem.
In the parser we use the same parsing as for the background-position,
which is not entirely correct but almost a <position>.
The postitioning enum values are used by the position CSS property.
Unfortunately, the prior naming clashes with the CSS Values-4 type
named position, which will be implemented in a later commit.
This makes multiple levels of quote actually use different quotation
marks, instead of always the first available pair of them.
Each Layout::Node remembers what the quote-nesting level was before its
content was evaluated, so that we can re-use this number in
`apply_style()`. This is a bit hacky, since we end up converting the
`content` value into a string twice.
`StyleProperties::content()` now takes an initial quote-nesting level,
and returns the final level after that content.
This one is a bit fun because it can be `add(<integer>)` or `auto-add`,
but children have to inherit the computed value not the specified one.
We also have to compute it before computing the font-size, because of
`font-size: math` which will be implemented later.
...along with `outline-color`, `outline-style`, and `outline-width`.
This re-uses the existing border-painting code, which seems to work well
enough!
This replaces the previous code for drawing focus-outlines, with generic
outline painting for any elements that want it. Focus outlines are now
instead supported by this code in Default.css:
```css
:focus-visible {
outline: auto;
}
```
This is a universal value like `initial` and `inherit` and works by
reverting the current value to whatever we had at the start of the
current cascade origin.
The implementation is somewhat inefficient as we make a copy of all
current values at the start of each origin. I'm sure we can come up with
a way to make this faster eventually.
The CSS box-shadow property takes 2-4 properties that are `<length>`s,
those being:
- offset-x
- offset-y
- blur-radius
- spread-radius
Previously these were resolved directly to concrete Lengths at parse
time, but now they will be parsed as LengthStyleValues and/or
CalculatedStyleValues and be stored that way until styles are later
resolved.
