It turns out that it's problematic to embed ThreadLocalStyleContext within
LayoutContext, because parameterizing the former on TElement (which we do
in the next patch) infects all the traversal stuff with the trait parameters,
which we don't really want.
In general, it probably makes sense to use separate scoped TLS types for
the separate DOM and Flow tree passes, so we can add a different ScopedTLS
type for the Flow pass if we ever need it.
We also reorder the |scope| and |shared| parameters in parallel.rs, because
it aligns more with the order in style/parallel.rs. I did this when I was
adding a TLS parameter to all these functions, which I realized we don't need
for now.
This allows us to get rid of a bunch of lifetimes and simplify a lot of code. It
also lets us get rid of that nasty lifetime transmute, which is awesome.
The situation with thread-local contexts is still suboptimal, but we fix that in
subsequent patches.
The primary idea of this patch is to ditch the rigid enum of Previous/Current
styles, and replace it with a series of indicators for the various types of
work that needs to be performed (expanding snapshots, rematching, recascading,
and damage processing). This loses us a little bit of sanity checking (since
the up-to-date-ness of our style is no longer baked into the type system), but
gives us a lot more flexibility that we'll need going forward (especially when
we separate matching from cascading). We also eliminate get_styling_mode in
favor of a method on the traversal.
This patch does a few other things as ridealongs:
* Temporarily eliminates the handling for transfering ownership of styles to the
frame. We'll need this again at some point, but for now it's causing too much
complexity for a half-implemented feature.
* Ditches TRestyleDamage, which is no longer necessary post-crate-merge, and is
a constant source of compilation failures from either needing to be imported
or being unnecessarily imported (which varies between gecko and servo).
* Expands Snapshots for the traversal root, which was missing before.
* Fixes up the skip_root stuff to avoid visiting the skipped root.
* Unifies parallel traversal and avoids spawning for a single work item.
* Adds an explicit pre_traverse step do any pre-processing and determine whether
we need to traverse at all.
MozReview-Commit-ID: IKhLAkAigXE
I realized that I fixed this issue incorrectly when the test failed before. Our design
document specifies that restyle hints must be expanded by the parent before traversing
children, so that we can properly apply LaterSiblings restyle hints. This includes
parents that do not themselves need processing (StylingMode::Traverse).
So we need to preprocess children even in the case where we don't restyle the parent.
On the flip side, we do in fact know whether a child needs processing before enqueuing
it, so we can skip the conservative visit I added before.
MozReview-Commit-ID: AEiRzdsN0h5
The style system never actually does anything with the document. This allows us
to remove a bunch of stubbing on the Gecko side and streamline some things on
the Servo side in future patches.
Don't promote all scrollable regions to stacking contexts
<!-- Please describe your changes on the following line: -->
Don't promote all scrollable regions to stacking contexts
Instead annotate all flows with their owning ScrollRoots. When
processing the display list items into a flattened display list, we add
PushScrollRoot and PopScrollRoot to signal when scrolling regions start
and end. It is possible for content from different scrolling regions to
intersect and when they do, the stack of scrolling regions is
duplicated. When these duplicated scrolling regions stacks reach
WebRender, it will scroll them in tandem.
The PushScrollRoot and PopScrollRoot items are currently represented as
StackingContexts in WebRender, but eventually these will be replaced
with special WebRender display items.
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- [x] `./mach test-tidy` does not report any errors
- [x] These changes fix#13529 and #13298. (github issue number if applicable).
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- [ ] These changes do not require tests because _____
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Instead annotate all flows with their owning ScrollRoots. When
processing the display list items into a flattened display list, we add
PushScrollRoot and PopScrollRoot to signal when scrolling regions start
and end. It is possible for content from different scrolling regions to
intersect and when they do, the stack of scrolling regions is
duplicated. When these duplicated scrolling regions stacks reach
WebRender, it will scroll them in tandem.
The PushScrollRoot and PopScrollRoot items are currently represented as
StackingContexts in WebRender, but eventually these will be replaced
with special WebRender display items.
Fixes#13529.
Fixed#13298.
We also make sure that an element never has an ElementData with ElementDataStyles::Uninitialized,
and eagerly call prepare_for_styling whenever an ElementData is instantiated.
MozReview-Commit-ID: 9YP6eSmdMt0
Track overflow:scroll stacking contexts with ScrollRootId instead of StackingContextId
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- [x] `./mach build -d` does not report any errors
- [x] `./mach test-tidy` does not report any errors
- [ ] These changes fix #__ (github issue number if applicable).
<!-- Either: -->
- [ ] There are tests for these changes OR
- [x] These changes do not require tests because this PR should not change behavior.
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This is a step in disassociating scrolling areas from stacking
contexts. Now scroll areas are defined by unique ids, which means that
in the future stacking context will be able to contain more than one.
Instead of maintaining a dummy restyle damage field for text nodes, we can just
perform the necessary parent inheritance and is_changed adjustments on the fly
in ThreadSafeLayoutNode, simplifying the requirements on the style system.
MozReview-Commit-ID: DCqiCRLsLUF
A couple of changes here:
* Remove the option to unset with the dirty bit setters.
* Add an explicit API for setting text node style.
* Hoist has_changed handling into the restyle damage setter and text node style setter.
* Make set_style take a non-Option.
The style candidate cache had regressed a few times (see #12534), and my
intuition is that being able to disable all style sharing with a single rule in
the page is really unfortunate.
This commit redesigns the style sharing cache in order to be a optimistic cache,
but then reject candidates if they match different sibling-affecting selectors
in the page, for example.
So far the numbers have improved, but not so much as I'd wanted (~10%/20% of
non-incremental restyling time in general). The current implementation is really
dumb though (we recompute and re-match a lot of stuff), so we should be able to
optimise it quite a bit.
I have different ideas for improving it (that may or may not work), apart of the
low-hanging fruit like don't re-matching candidates all the time but I have to
measure the real impact.
Also, I need to verify it against try.
