Do some minor cleanups in display list building
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These are two different passes during layout, but previously they
shared a state object. While some of the members are the same, many are
different so we separate them out into two separate objects. We also
change the HashMaps of these state objects to use the FnvHashMap.
layout: Stop call normal block size assignment for flex container
No need to call the `assign_block_size_block_base()` method of normal block in flex.rs since it is implemented for CSS2.
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Instead of only promoting flows with positioned fragments to containing
blocks, also do this for flows which have the transform, perspective or
filter properties set. This is what the spec requires and also fixes
some failing tests. It will allow us to stop creating stacking contexts
for overflow:hidden and overflow:scroll flows.
Fixes#18091.
This is a better approach than relying on
contains_positioned_fragments, because in the future other properties
will create absolute containing blocks.
In order to properly handle CSS clipping, we need to keep track of what
the different kinds of clips that we have. On one hand, clipping due to
overflow rules should respect the containing block hierarchy, while CSS
clipping should respect the flow tree hierarchy. In order to represent
the complexity of items that are scrolled via one clip/scroll frame and
clipped by another we keep track of that status with a
ClipAndScrollInfo.
The alias is left there temporarilly and will be removed completely in a later commit where
also components/style/gecko/generated/structs_{debug|release}.rs are re-generated (they still
use the old alias).
Just use WebRender's ClipId directly. This will allow us to create and
use ReferenceFrames in the future, if we need to do that. It will also
make it easier to have Servo responsible for creating the root
scrolling area, which will allow removing some old hacks in the future.
Instead of passing down a complex clipping region to each item, used
shared clipping to handle overflow:hidden and CSS clips. In addition to
being more efficient, this should also fix quite a few issues related
to absolutely positioned elements.
One existing reftest is slightly modified to avoid tickling a quirk
with the way that WebRender rasterizes masks. We are working out how to
best express these combined masks with the API or need to. The change
does not affect the original subject of the reftest.
Fixes#13109.
Fixes#10151.
Fixes#7575.
Fixes#8074.
Fixes#8780.
Only create scroll roots for overflow regions when the overflow region
is actually larger than the container size. This prevents creating
scrolling roots for elements that do not have overflow scroll as a
side-effect of the way their height and width is defined. For example,
tables should never respect overflow:scroll since their height and
width should always be large enough to prevent overflow. This also
decreases the size and complexity of the display list in many other
circumstances.
As part of this change, transformed overflow calculation is moved from
display list construction to layout. This should mean that overflow is
handled more accurately earlier.
Fixes#14574.
Collect scroll roots during the collect_stacking_context phase instead
of during display list construction. This will be useful in order to
collect containing block scroll roots as well as to give scroll roots
sequential ids in the future. This change also pulls stacking context
children out of the StackingContext struct itself, which should reduce
very slightly the memory used by the finished display list. This also
simplifies the DisplayListBuilder because it no longer has to maintain
a stack of ScrollRootIds and StackingContextIds and can instead just
rely on the program stack.
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
Reimplement scrolling to fragments
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This reimplemntation of the feature uses ScrollRootIds to scroll
particular scrollable areas of the page.
Fixes#13736.
Fixes#10753.
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Remove unnecessary Flow::column_sizes methods
One of these methods is never called. The other is used only on TableFlow and doesn't need to be implemented for all Flow types.
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Set the flag of the fragment of children in a flex container according
to the direction of the container. The mark is done on the fragment
because flex item enstablish a stacking context when its z-index is
non-zero ,despite its `position' property.
This creates a sharp distinction between `Arc<Flow>`s, which may be
owned by anyone, and `FlowRef`s, which may only be owned by the
traversal code. By checking the reference count, we ensure that a `Flow`
cannot be pointed to by `Arc`s and `FlowRef`s simultaneously.
This is not a complete fix for #6503, though it is a necessary start
(enforcing the no-aliasing rule of `FlowRef::deref_mut` will require far
more work).
Fixes#14014
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.
Layers were a feature of the legacy drawing path. If we re-add them at
some point, it probably makes more sense to make them a product of
display list inspection.
This change also remove a bunch of dead painting code.
This removes paint threads, rust-layers dependency, and changes
optional webrender types to be required.
The use_webrender option has been removed, however I've left
the "-w" command line option in place so that wpt
runner can continue to pass that. Once it's removed from there
we can also remove the -w option.
Once this stage is complete, it should be fine to change the
display list building code to generate webrender display
lists directly and avoid the conversion step.
border box positions and transforms into account.
Clipping region computation now follows a simple process: (1) in the
parent's coordinate system, parents store appropriate clipping regions
into children; (2) each child moves its clipping region to its own
coordinate system if necessary.
Because clipping region computation is now based on stacking-relative
border box positions and the `transform_rect` method, it can handle
`position: relative` offsets and more types of transforms, such as
scaling.
Improves etsy.com.
Closes#13753.
