Absolutes with static insets need to be laid out at their ancestor
containing blocks, but their position is dependent on their parent's
layout. The static layout position is passed up the tree during hoisting
and ancestors each add their own offset to the position until it is
relative to the containing block that contains the absolute.
This is currently done with a closure and a fairly tricky "tree rank"
numbering system that needs to be threaded through the entire layout.
This change replaces that system.
Every time a child is laid out we create a positioning context to hold
any absolute children (this can be optimized away at a later time). At
each of these moments, we call a method to aggregate offsets to the
static insets of hoisted absolutes. This makes the logic easier to
follow and will also allow implementing this behavior for inline-blocks,
which was impossible with the old system.
Typically, block-level contents are stacked vertically, so this was just
taking the maximum size among all contents. However, floats can be
stacked horizontally, so we need to sum their sizes.
Implement BlockLevelBox::inline_content_sizes for floats
This improves #29874, but `BlockContainer::inline_content_sizes` will still need more changes in order to correctly handle sequences of floats.
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Don't pass float stacking containers up to parent stacking contexts
Don't pass up float stacking containers to parent stacking contexts
Instead of passing up stacking containers created by floated content,
keep them in their original parent stacking containers. This is in in
line with specification text for stacking containers:
> To paint a stacking container, given a box root and a canvas canvas:
>
> 1. Paint a stacking context given root and canvas, treating root as
> if it created a new stacking context, but omitting any positioned
> descendants or descendants that actually create a stacking context
> (letting the parent stacking context paint them, instead).
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Instead of passing up stacking containers created by floated content,
keep them in their original parent stacking containers. This is in in
line with specification text for stacking containers:
> To paint a stacking container, given a box root and a canvas canvas:
>
> 1. Paint a stacking context given root and canvas, treating root as
> if it created a new stacking context, but omitting any positioned
> descendants or descendants that actually create a stacking context
> (letting the parent stacking context paint them, instead).
Fix some rustdoc comments which won't process properly unless they start
with three '/' characters. In addition, improve the name of a function
and add some missing documentation.
Layout 2020: Properly handle negative margins in floats
If a float has negative block margins, it should be pushed upward, but shouldn't affect the positioning of any floats that came before it. It should lower the ceiling though when it still has some non-negative block contribution. In order to implement this behavior, we should only place the float considering its non-negative block length contribution. If the float is pushed up completely past it's "natural" position, it should be placed like a float with zero block size.
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If a float has negative block margins, it should be pushed upward, but
shouldn't affect the positioning of any floats that came before it. It
should lower the ceiling though when it still has some non-negative
block contribution. In order to implement this behavior, we should only
place the float considering its non-negative block length contribution. If
the float is pushed up completely past it's "natural" position, it
should be placed like a float with zero block size.
Fix infinite loop in flexbox algorithm
Only apply step 5c of "resolve flexible lengths" if sum of scaled flexible shrink factors > 0
Probably fixes#29852 (but speculative as I can't get mach to run).
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According to https://drafts.csswg.org/css2/#collapsing-margins, bottom
margins should only collapse with the last child if `height` is `auto`.
Also, the note mentions `min-height: 0`, but the normative text doesn't
have such requirement, so I'm dropping it, matching WebKit.
The previous logic is moved into the case of collapsing the top and
bottom margins of the same element, since this can happen either with
`height: auto` or `height: 0`, and requires `min-height: 0`.
Layout 2020: Move all Fragment code to the `fragment_tree` directory
This is a simple code organization change with no behavior change with the idea of making Layout 2020 easier to understand by new folks to the project. The idea is that we will have a cleaner separation between the different parts of layout ie one directory for the fragment tree and one (currently multiple) directory for the box tree.
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This is a simple code organization change with no behavior change with
the idea of making Layout 2020 easier to understand by new folks to the
project. The idea is that we will have a cleaner separation between the
different parts of layout ie one directory for the fragment tree and one
(currently multiple) directory for the box tree.
Lay out floats and handle clearance in layout 2020, but don't flow text around them yet
This is a crude rebase of #27539
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layout_2020: Implement automatic minimum size of flex items
Implement the algorithm described in
https://drafts.csswg.org/css-flexbox/#min-size-auto.
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Instead of hoisting floated fragments to be siblings of the fragment
created by their containing block formatting context, keep them in
"normal" fragment tree position and adjust their positioning to be
relative to the containing block. This means that float fragments follow
the existing invariants of the fragment tree and properly handle hit
testing, painting order, and relative positioning.
The tradeoff here is more complexity tracking the containing block
offsets from the block formatting context (including handling collapsed
margins), but less complexity dealing with hoisting / shared ownership
in addition to the correctness benefits.
Some tests are failing now because this change revealed some additional
shortcomings with clearing block formatting context content size past
the end of their contained floats. This will be fixed in a followup
change.
Co-authored-by: Oriol Brufau <obrufau@igalia.com>
This commit puts floats behind the `layout.floats.enabled` pref, because of the
following issues and unimplemented features:
* Inline formatting contexts don't take floats into account, so text doesn't
flow around the floats yet.
* Non-floated block formatting contexts don't take floats into account, so BFCs
can overlap floats.
* Block formatting contexts that contain floats don't expand vertically to
contain all the floats. That is, floats can stick out the bottom of BFCs,
contra spec.
Clear PositioningContext for speculative layouts
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Developed in collaboration with @mrobinson
`try_layout` is used for laying out absolutely positioned descendants multiple times when min/max-{width, height} properties are set. When the same PositioningContext instance is used between successive attempts without clearing the accumulated descendants, we will generate multiple fragments which reference the same box, which then will lead to a double borrow error when layout is performed in parallel.
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layout_2020: Only count for content size for height of non-replaced inline elements
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Accorinding to https://drafts.csswg.org/css2/#inline-non-replaced, The vertical padding, border and margin of an inline, non-replaced box start at the top and bottom of the content area, and has nothing to do with the line-height. But only the line-height is used when calculating the height of the line box.
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`try_layout` is used for laying out absolutely positioned
descendants multiple times when min/max-{width, height}
properties are set. When the same PositioningContext instance
is used between successive attempts without clearing the accumulated
descendants, we will generate multiple fragments which reference
the same box, which then will lead to a double borrow error
when layout is performed in parallel.
Signed-off-by: Mukilan Thiyagarajan <me@mukilan.in>
layout_2020: Specify the used cross size when replaced item is stretched
According to spec, if the flex item has [align-self: stretch](https://drafts.csswg.org/css-flexbox/#propdef-align-self), redo layout for its contents, treating this used size as its definite cross size so that percentage-sized children can be resolved.
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- [x] These changes fix#29788 (GitHub issue number if applicable)
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inline elements
Accorinding to https://drafts.csswg.org/css2/#inline-non-replaced, The
vertical padding, border and margin of an inline, non-replaced box
start at the top and bottom of the content area, and has nothing to do
with the line-height. But only the line-height is used when
calculating the height of the line box.
If the flex item has align-self: stretch, redo layout for its
contents, reating this used size as its definite cross size so that
percentage-sized children can be resolved.
This moves more members to the CompositorDisplayListInfo struct, which
now holds all miscellaneous, non-WebRender data when sending display
lists. It also documents what each things sent with a display list does.
Add a compositor-side scroll tree
This will allow the compositor to properly chain scrolling requests up
when a node has reached the extent of the scroll area. In addition, it
removes the use of the deprecated WebRender `scroll()` API. This fixes
scrolling on servo.org.
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- [x] These changes:
- Fix#29402.
- Fix#27996.
- Fix#27624.
- Fix#24028.
- Fix#23918.
- Fix#21165.
- [x] There are tests for these changes
layout_2020: fix target main size not get clamped in flexbox
When Resolving flexible lengths, the clamp result of item's target main size is not actually saved when it should.
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Backport several style changes from Gecko
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This will allow the compositor to properly chain scrolling requests up
when a node has reached the extent of the scroll area. This fixes
scrolling on servo.org.
Start the transition to workspace dependencies
This will ultimately make it simpler to update crate dependencies and reduce duplication when specifying requirements. Generally, this change does not touch dependencies that are only used by a single crate. We could consider moving them to workspace dependencies in the future.
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This will ultimately make it simpler to update crate dependencies and
reduce duplicate when specifying requirements. Generally, this change
does not touch dependencies that are only used by a single crate. We
could consider moving them to workspace dependencies in the future.
This change refactors how layout is done in Layout 2020 in preparation
for a compositor-side scroll tree:
1. Now the SpatialId and ClipId of each fragment is stored separately.
This will allow storing a scroll node id instead of only the handle
to the WebRender spatial node.
2. Separate out stacking context tree construction and display list
building. This change will make it possible to eventually build the
stacking context tree without the full display list if we find that
necessary. For instance, this might be useful to cache containing
block boundaries.
3. Add a `DisplayList` struct that stores both the WebRender display
list builder and the compositor info. This exposes the API to the
layout thread for display list building.
In addition, this change adds a lot of missing documentation. This
should not change behavior.
More cleanup of the layout DOM wrappers
This PR includes two commits which continue to clean up the layout DOM wrappers.
- in the first the unused `DangerousThreadSafeLayoutNode` trait is removed
- in the second DOM-related code is combined into one source file in Layout 2020 and some traits are combined and removed.
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- [x] These changes fix#29688
- [x] These changes fix#29722
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layout 2020: Implement justify-content in flexbox
Align the items along the main-axis per justify-content.
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Better implement getComputedStyle() for positioned insets
The specification dictates quite quite idiosyncratic return values when
querying insets of positioned elements via `getComputedStyle()`. These
depend on whether or not the element's size was overconstrained. This
change adds a better implementation of that in preparation for returning
proper values for `position: sticky`.
There are two changes here:
- The containing block used in `FragmentTree::find` is properly computed using the `ContainingBlockManager` data structure. This data structure is now updated during traversal through the fragment tree in `Fragment::find`.
- We now take into account whether or not a absolute elements are overconstrained when calculating their resolved insets. For absolutely positioned elements, this happens during absolute positioning. For relatively positioned elements, we can determine this when a `BoxFragment` is constructed.
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The specification dictates quite quite idiosyncratic return values when
querying insets of positioned elements via getComputedStyle(). These
depend on whether or not the elements size was overconstrained. This
change adds a better implementation of that in preparation for returning
proper values for position: sticky.
There are duplicate sets of Layout DOM wrappers: one for Layout 2013 and
one for Layout 2020. As part of cleaning up and simplifying the
wrappers, this change parameterizes them on the specific layout data
they contain. This allows them to be shared again. In addition, various
small cleanups are included.
Fixes#29691.
