Sticky positioning is implemented by modifying the algorithm for
assigning and refreshing scroll frames. Now, elements with
"position: sticky" are assigned their own scroll frame, and their
position is refreshed independently from regular scroll boxes.
Refreshing the scroll offsets for sticky boxes does not require display
list invalidation.
A separate hash map is used for the scroll frames of sticky boxes. This
is necessary because a single paintable box can have two scroll frames
if it 1) has "position: sticky" and 2) contains scrollable overflow.
Overflow clipping is currently implemented as:
1. Create clip frame for each box with hidden overflow
2. Calculate clip rect for each clip frame by intersecting padding boxes
of all boxes with hidden overflow in containing block chain
3. Assign enclosing clip frame (closest clip frame in containing block
chain) to each PaintableBox
4. Apply clip rect of enclosing clip frame in Paintable::before_paint()
It breaks when any CSS transform other than simple translation is lying
between box with hidden overflow and a clipped box, because clip
rectangle will be applied when transform has already changed.
The fix is implemented by relying on the following rule:
"For elements whose layout is governed by the CSS box model, any value
other than none for the transform also causes the element to establish
a containing block for all descendants."
It means everything nested into a stacking context with CSS transform
can't escape its clip, so it's safe to apply its clip for all children.
For bitmap fonts, we will often not have an exact match for requested
sizes. Return the closest match instead of a nullptr.
LibWeb is currently the only user of this API. If it needs to be
configurable in the future to only allow exact matches, we can add a
parameter or another method at that time.
When both insets in a given axis are auto, we should use the static
position for absolutely positioned elements.
By doing this correctly, we exposed a bunch of other small bugs which
had to be fixed to compensate for new test failures. Those fixes are
included here as well:
- Don't apply margins twice.
- Compute the static position containing block chain correctly.
This makes https://brave.com/ look much better. :^)
A bunch of this is leftover from pre porting over to new AK::String.
For example, for functions which previously took a ByteString const&
now accepting a StringView.
This makes them cheap to move around, since we can store them in a
NonnullOwnPtr instead of memcopying 2584(!) bytes.
Drastically reduces the chance of stack overflow while building the
layout tree for deeply nested DOMs (since tree building was putting
these things on the stack).
This change also exposed a completely unnecessary ComputedValues deep
copy in block layout.
- We now propagate changes in font and line-height to anonymous wrappers
when doing a partial style update after invalidation.
- We no longer (incorrectly) propagate style from table wrapper boxes
to the table root, since inheritance works in the other direction.
Fixes#22395
Before this change, we would only cache and reuse Gfx::ScaledFont
instances for downloaded CSS fonts.
By moving it into Gfx::VectorFont, we get caching for all vector fonts,
including local system TTFs etc.
This avoids a *lot* of style invalidations in LibWeb, since we now vend
the same Gfx::Font pointer for the same font when used repeatedly.
This commit un-deprecates DeprecatedString, and repurposes it as a byte
string.
As the null state has already been removed, there are no other
particularly hairy blockers in repurposing this type as a byte string
(what it _really_ is).
This commit is auto-generated:
$ xs=$(ack -l \bDeprecatedString\b\|deprecated_string AK Userland \
Meta Ports Ladybird Tests Kernel)
$ perl -pie 's/\bDeprecatedString\b/ByteString/g;
s/deprecated_string/byte_string/g' $xs
$ clang-format --style=file -i \
$(git diff --name-only | grep \.cpp\|\.h)
$ gn format $(git ls-files '*.gn' '*.gni')
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.
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.
ImageStyleValue has a visit_edges() method, although it is not a
GC-allocated object. This is necessary because it owns a GC-allocated
ImageRequest that we want to visit, instead of using JS::Handle, to
avoid leaks. In the future, we might want to make StyleValue be
GC-allocated.
For now, this change adds missing visit_edges() calls for objects that
own ImageStyleValue.
This fixes an issue where the value would be out of sync with reality
in anonymous wrapper block boxes, since we forgot to compute m_visible
after assigning the computed values to them.
Fixes#21106
This effectively makes it per-Document, but we hang it off of
StyleComputer since that's what it's used for.
The purpose of this is to prevent downloaded fonts from escaping the
context that loaded them. There's probably a more elegant solution where
we still share caching of system fonts, but let's start here.
On style update, we have to preserve the invariant established when we
built the layout tree - some properties are applied to the table wrapper
and the table box values are reset to their initial values.
This also ensures that the containing block of a table box is always a
table wrapper, which isn't the case if we set absolute position on the
box instead of the wrapper.
Fixes#19452.
Solves conflict in layout tree "type system" when elements <label> (or
<button>) can't have `display: table` because Box can't be
Layout::Label (or Layout::ButtonBox) and Layout::TableBox at the same
time.
Ignore anonymous block boxes when resolving percentage weights that
would refer to them, per the CSS 2 visual formatting model
specification. This fixes the case when we create an anonymous block
between an image which uses a percentage height relative to a parent
which specifies a definite height.
Fixes#19052.
Before this change, LayoutState essentially had a Vector<UsedValues*>
resized to the exact number of layout nodes in the current document.
When a nested layout is performed (to calculate the intrinsic size of
something), we make a new LayoutState with its own Vector. If an entry
is missing in a nested LayoutState, we check the parent chain all the
way up to the root.
Because each nested LayoutState had to allocate a new Vector with space
for all layout nodes, this could get really nasty on very large pages
(such as the ECMA262 specification).
This patch replaces the Vector with a HashMap. There's now a small cost
to lookups, but what we get in return is the ability to handle huge
layout trees without spending eternity in page faults.
For example, it's possible to access Node::computed_values() on a node
that neither has style nor a parent with style. This ultimately results
in a null pointer dereference when we return parent()->computed_values()
as a fallback. This can be a little tricky to track down due to these
functions being inlined, so add an explicit verification.
The name "initial containing block" was wrong for this, as it doesn't
correspond to the HTML element, and that's specifically what it's
supposed to do! :^)
The goal here is to allow Cell::initialize to return a ThrowCompletion,
to handle OOM for example. Cell.h will then need to include Completion.h
which must include Value.h. This currently can't happen because Value.h
includes BigInt.h, which in turn includes Cell.h. So we would have an
include cycle.
This removes BigInt.h from Value.h, as it is forward-declarable (it is
only referred to with a reference or pointer). Then the Value overload
for Cell::Visitor::visit is moved to Cell.h, and missing BigInt.h
includes as peppered as needed.
Introduce `TableWrapper` type so table wrappers could be
distinguished from block containers and override width
calculation for table wrappers (CSS 2.2 spec, section 17.5.2)
inside BFCs in the way that their width should be equal to
width of table box they wrap.
This simplifies the ownership model between DOM/layout/paint nodes
immensely by deferring to the garbage collector for figuring out what's
live and what's not.
According to table fixup algorithm:
https://www.w3.org/TR/css-tables-3/#fixup-algorithm
around every table-root should be generated anonymous
box wrapper.
Also this patch implements important part of CSS 2.2
spec that is currently not present in CSS Tables 3
spec draft: https://www.w3.org/TR/CSS22/tables.html#model
that portion of computed properties should be moved
from table-root to table wrapper box. Without having
this part implemented height of absolutely positioned
table with `height: auto` won't be computed correctly.
