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.
This allows us to retain perfect precision for aspect ratios derived
from either the intrinsic sizes of replaced elements, or the
`aspect-ratio` CSS property.
Calculate a "preferred aspect ratio" based on the value of
`aspect-ratio` and the presence of a natural aspect ratio, and use that
in layout.
This is by no means complete or perfect, but we do now apply the given
aspect-ratio to things.
The spec is a bit vague, just saying to calculate sizes for
aspect-ratio'ed boxes the same as you would for replaced elements. My
naive solution here is to find everywhere we were checking for a
ReplacedBox, and then also accept a regular Box with a preferred aspect
ratio. This gets us pretty far. :^)
https://www.w3.org/TR/css-sizing-4/#aspect-ratio-minimum is not at all
implemented.
Having this here instead of in ReplacedBox means we can access it when
figuring out what the "preferred aspect ratio" is.
There's some inconsistency between specs about what this is called, but
they're moving towards referring to this as "natural width/height/
aspect-ratio", so let's copy that terminology.
After finishing layout, iframe layout boxes (FrameBox) get notified
about their new size by LayoutState::commit(). This information is
forwarded to the nested browsing context, where it can be used for
layout of the nested document.
The problem here was that we notified the FrameBox twice. Once when
assigning the used offset to its paintable, and once when assigning its
size. Because the offset was assigned first, we ended up telling the
FrameBox "btw, your size is 0x0". This caused us to throw away all
the layout information we had for the nested document.
We'd then say "actually, your size is 300x200" (or something) but by
then it was already too late, and we had to do a full relayout.
This caused iframes to flicker as every time their containing document
was laid out, we'd nuke the iframe layout and redo it (on a zero timer).
The fix is pleasantly simple: we didn't need to inform the nested
document of its offset in the containing document's layout anyway. Only
its size is relevant. So we can simply remove the first call, which
removes the bogus 0x0 temporary size.
Note that iframes may still flicker if they change size in the
containing document. That's a separate issue that will require more
finesse to solve. However, this fixes a very noticeable common case.
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.
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.
This removes a set of complex reference cycles between DOM, layout tree
and browsing context.
It also makes lifetimes much easier to reason about, as the DOM and
layout trees are now free to keep each other alive.
This patch adds a bunch of Paintable subclasses, each corresponding to
the Layout::Node subclasses that had a paint() override. All painting
logic is moved from layout nodes into their corresponding paintables.
Paintables are now created by asking a Layout::Box to produce one:
static NonnullOwnPtr<Paintable> Layout::Box::create_paintable()
Note that inline nodes still have their painting logic. Since they
are not boxes, and all paintables have a corresponding box, we'll need
to come up with some other solution for them.
BlockContainer paint boxes are the only ones that have line boxes
associated, so let's not waste memory on line boxes in all the other
types of boxes.
This also adds Layout::Box::paint_box() and the more tightly typed
Layout::BlockContainer::paint_box() to get at the paint box from the
corresponding layout box.
The "paintable" state in Layout::Box was actually not safe to access
until after layout had been performed.
As a first step towards making this harder to mess up accidentally,
this patch moves painting information from Layout::Box to a new class:
Painting::Box. Every layout can have a corresponding paint box, and
it holds the final used metrics determined by layout.
The paint box is created and populated by FormattingState::commit().
I've also added DOM::Node::paint_box() as a convenient way to access
the paint box (if available) of a given DOM node.
Going forward, I believe this will allow us to better separate data
that belongs to layout vs painting, and also open up opportunities
for naturally invalidating caches in the paint box (since it's
reconstituted by every layout.)
Using WeakPtr to remember which LineBoxFragment owns which Box was
imposing some annoying constraints on the layout code. Importantly, it
was forcing us to heap-allocate fragments, which makes it much harder to
clone a FormattingState.
This patch replaces the WeakPtr with a coordinate system instead.
Fragments are referred to by their line box index + fragment index
within the line box.
This patch adds a map of Layout::Node to FormattingState::NodeState.
Instead of updating layout nodes incrementally as layout progresses
through the formatting contexts, all updates are now written to the
corresponding NodeState instead.
At the end of layout, FormattingState::commit() is called, which
transfers all the values from the NodeState objects to the Node.
This will soon allow us to perform completely non-destructive layouts
which don't affect the tree.
Note that there are many imperfections here, and still many places
where we assign to the NodeState, but later read directly from the Node
instead. I'm just committing at this stage to make subsequent diffs
easier to understand.
This property represents the CSS content size, so let's reduce ambiguity
by using the spec terminology.
We also bring a bunch of related functions along for the ride.
While IFC flows text into a block container, floating objects are
anchored at the BFC root, not necessarily the local block container.
Because of this, we have to use root-relative coordinates when checking
how much space is available in between left and right floated objects.
This option is already enabled when building Lagom, so let's enable it
for the main build too. We will no longer be surprised by Lagom Clang
CI builds failing while everything compiles locally.
Furthermore, the stronger `-Wsuggest-override` warning is enabled in
this commit, which enforces the use of the `override` keyword in all
classes, not just those which already have some methods marked as
`override`. This works with both GCC and Clang.
This was a hack to percentages within tables relative to the nearest
table-row ancestor instead of the nearest table container.
That didn't actually make sense, so this patch simply removes the hack
in favor of containing_block()->width().
Per spec, the initial containing block (ICB) should have the size of the
viewport. We have only done this for the width until now, since we had
no way to express scrollable overflow.
This patch adds Layout::Box::m_overflow_data, an optional struct that
can hold on to information about a box's overflow. Then we have BFC
set the ICB up with some scrollable overflow instead of sizing it to fit
its content vertically.
This fixes a number of broken layouts where correctness depends on
having the appropriate ICB height.
Apparently it's not only replaced elements that can have intrinsic
sizes, so let's move this concept from ReplacedBox to Box. To avoid
bloating Box, we make the accessors virtual.
Per the spec, only a BlockContainer" can have line boxes, so let's not
clutter up every Layout::Box with line boxes.
This also allows us to establish an invariant that BFC and IFC always
operate on a Layout::BlockContainer.
Note that if BlockContainer has all block-level children, its line boxes
are not used for anything. They are only used in the all inline-level
children scenario.
