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.
This fixes an issue where images with padding and/or border did not have
their size adjusted for `border-box`, thereby becoming larger than
intended by the author.
These are only used during layout, and always within formatting context
code, so we might as well put them in FormattingContext and avoid having
to pass the LayoutState around all the time.
At one point in the past, we had some functions that were called across
different formatting context types, which necessitated making them
static and taking the LayoutState as a parameter.
In all cases, those functions were used to do incorrect hacks, all of
which we've replaced with more correct solutions. :^)
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.
In order to support intrinsic size keywords (such as fit-content), we
need to be able to calculate the intrinsic sizes of any element, not
just those that form their own formatting context.
When a non-FC-root element is passed to calculate_some_intrinsic_size(),
we now create a synthetic BFC to handle sizing of them.
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.
This fixes a plethora of rounding problems on many websites.
In the future, we may want to replace this with fixed-point arithmetic
(bug #18566) for performance (and consistency with other engines),
but in the meantime this makes the web look a bit better. :^)
There's a lot more things that could be converted to doubles, which
would reduce the amount of casting necessary in this patch.
We can do that incrementally, however.
Previously, calling `.right()` on a `Gfx::Rect` would return the last
column's coordinate still inside the rectangle, or `left + width - 1`.
This is called 'endpoint inclusive' and does not make a lot of sense for
`Gfx::Rect<float>` where a rectangle of width 5 at position (0, 0) would
return 4 as its right side. This same problem exists for `.bottom()`.
This changes `Gfx::Rect` to be endpoint exclusive, which gives us the
nice property that `width = right - left` and `height = bottom - top`.
It enables us to treat `Gfx::Rect<int>` and `Gfx::Rect<float>` exactly
the same.
All users of `Gfx::Rect` have been updated accordingly.
There are a couple of things that went into this:
- We now calculate the intrinsic width/height and aspect ratio of <svg>
elements based on the spec algorithm instead of our previous ad-hoc
guesswork solution.
- Replaced elements with automatic size and intrinsic aspect ratio but
no intrinsic dimensions are now sized with the stretch-fit width
formula.
- We take care to assign both used width and used height to <svg>
elements before running their SVG formatting contexts. This ensures
that the inside SVG content is laid out with knowledge of its
viewport geometry.
- We avoid infinite recursion in tentative_height_for_replaced_element()
by using the already-calculated used width instead of calling the
function that calculates the used width (since that may call us right
back again).
If just .to_px() is used the height can end up as the float `inf` or
`nan`. This caused an OOM when loading Polygon as this `inf` would
become a `nan` and propagate to the SVG painting, which then attempts
to draw a path with nan control points, which would make the
Gfx::Painter infinitely split the path till it OOM'd.
Instead of bailing after resolving one violated constraint, we have to
continue down the list of remaining constraints.
We now also call the constraint solver for all replaced elements with
"auto" for both width and height.
Co-authored-by: 0GreenClover0 <clovers02123@gmail.com>
It's not safe to hold on to a pointer to the cache slot across layout
work, since the nested layout may end up causing new entries to get
added to the cache, potentially invalidating a cache slot pointer.
`Length::resolved(Node&)` transforms infinite values to "auto".
Following transformations:
Infinite (Length) -> "auto" -> 0 (px)
cause border-box width to be resolved in zero when it should be inf px.
Removing `Length::resolved(Node&)` makes it work right:
Infinite (Length) -> Infinite (px)
Fixes#18649
This patch does three things:
- Factors out the code that determines whether a box will create a new
formatting context for its children (and which type of context)
- Uses that code to mark all formatting context roots in layout tree
dumps. This makes it much easier to follow along with layout since
you can now see exactly where control is transferred to a new
formatting context.
- Rebaselines all existing layout tests, since the output format has
changed slightly.
When calculating the intrinsic width of a box, we now make its content
width & height indefinite before entering the intrinsic sizing layout.
This ensures that any geometry assigned to the box by its parent
formatting context is ignored.
For intrinsic heights, we only make the content height indefinite.
This is because used content width is a valid (but optional) input
to intrinsic height calculation.
Instead of special-casing FlexFormattingContext in the intrinsic sizing
layout helpers, add FormattingContext::automatic_content_width() and let
each context subclass decide what that means.
No behavior change here, just moving this responsibility.
The padding-top and padding-bottom properties are relative to the
*width* of the containing block, not the height.
It's funny how we keep making this same mistake again and again. :^)
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! :^)
Per CSS-SIZING-3, the min-content block size should be equivalent to the
max-content block size for some boxes.
Honoring this gives more correct results, and avoids unnecessary work in
many cases since the cached max-content size can be reused.
Grid containers were incorrectly represented as BlockContainer before.
Furthermore, GridFormattingContext had a bogus inheritance relationship
with BlockFormattingContext.
This patch brings our architecture closer to spec by making grid
containers be plain boxes and making GFC not inherit from BFC.
When laying out abspos boxes, we compute the height twice: before and
after the inside of the box has been laid out.
The first pass allows percentage vertical values inside the box to be
resolved against the box's height. The second pass resolves the final
used value for the height of the box itself.
In cases where the box height depends on the results of inside layout,
we were incorrectly setting the box to having a definite zero height.
This led to incorrect results when sizing an abspos flex container,
since the FFC sizes containers (in row layouts) based on whether the
container has a definite height.
To avoid this problem, this patch adds an enum so we can differentiate
between the two abspos height computation passes. If the first pass
discovers a dependency on the inside layout, we simply bail out of
computing the height, leaving it as indefinite. This allows the FFC
to size its container correctly, and the correct height gets set by
the second pass.
Previously y position of boxes in block formatting context
was calculated by looking at y position of previous in-flow
sibling and adding collapsed margin of "collapse through"
boxes lying between box currently being laid out and it's
previous in-flow sibling.
Here introduced BlockMarginState structure that maintains
array of currently collapsible margins hence we no longer
need to look at previous sibling to calculate y position
of a box.
This fixes a few sizing issues too. The page size is now correct in most
cases! \o/
We get to remove some of the `to_type<>()` shenanigans, though it
reappears in some other places.
Even if block has all children inline there need to be a check
if it creates BFC because otherwise IFC will be looking in
wrong parent BFC to calculate space used by floats.
This will make it easier to support both string types at the same time
while we convert code, and tracking down remaining uses.
One big exception is Value::to_string() in LibJS, where the name is
dictated by the ToString AO.
This change makes calculate_static_position to return content box
for both x and y (at least for the case when children are not inline).
It makes it possible to be consistent about x and y when calculating
box offset inside layout_absolutely_positioned_element.
This can resolve height early in some cases, notably this kind of setup:
position: absolute;
top: 0px;
bottom: 0px;
By resolving height before inside layout, descendants of the abspos
element can resolve automatic and relative vertical lengths against it.
This makes the Discord UI occupy the whole window instead of looking
"shrink-to-fit".
For replaced elements with percentage width or height, we were treating
them as 0 instead of auto when their containing block had an indefinite
corresponding size.
This produced incorrect layouts in various cases, and although I can't
actually find something about this exact scenario in specs, the new
behavior does match other browsers.
As it turns out, we sometimes query the intrinsic height of a box before
having fully resolved and/or constrained its containing block. Because
of this, we may enter intrinsic sizing with different amounts of
available width for the same box.
To accommodate this scenario, we now allow caching of multiple intrinsic
heights, separated by the amount of available width provided as input.
We were using the available space in place of the stretch-fit size.
This was an oversight, and this patch fixes that. It's very possible
that this will uncover broken behavior elsewhere.
This refactors the solve_for_{top, bottom, height, etc} lambdas to use a
common solve_for lambda that takes the length to be solved as an
argument. This way some code duplication is removed.
This patch implements the full "old model" height algorithm from the
CSS Positioned Layout spec. I went with the old model since we don't
yet have the machinery required to implement the new model.
Also, the width calculations already follow the old model, so this
is symmetric with that. Eventually we should of course implement the new
positioned layout model.
Now that intrinsic heights (correctly) depend on the amount of available
width, we can't just cache the first calculated min-content and
max-content heights and reuse it without thinking.
Instead, we have to cache three pairs:
- min-content & max-content height with definite available width
- min-content & max-content height with min-content available width
- min-content & max-content height with max-content available width
There might be some more elegant way of solving this, but basically this
makes the cache work correctly when someone's containing block is being
sized under a width constraint.
After speaking with fantasai at CSSWG about this, it turns out I had
misunderstood intrinsic heights. I originally believed all intrinsic
sizes had to be computed with no influence from the surrounding context.
As it turns out, intrinsic heights *are* influenced by the available
width, since it's needed to determine where lines break.
The APIs for calculating min-content and max-content heights now take
the available width as inputs. This instantly improves layout in many
cases where we'd previously make things way too wide.
When an absolutely positioned box has auto insets on both sides of an
axis, it's placed according to the "static position rectangle". This is,
roughly, the rectangle a box would occupy if it were position:static
instead of position:absolute or position:fixed.
This patch implements a rough, but still significantly better,
estimation of such static positions. It gets pretty hairy in the case
where an abspos box has a parent whose children are inline.
This is a big and messy change, and here's the gist:
- AvaliableSpace is now 2x AvailableSize (width and height)
- Layout algorithms are redesigned around the idea of available space
- When doing layout across nested formatting contexts, the parent
context tells the child context how much space is available for the
child's root box in both axes.
- "Available space" replaces "containing block width" in most places.
- The width and height in a box's UsedValues are considered to be
definite after they're assigned to. Marking something as having
definite size is no longer a separate step,
This probably introduces various regressions, but the big win here is
that our layout system now works with available space, just like the
specs are written. Fixing issues will be much easier going forward,
since you don't need to do nearly as much conversion from "spec logic"
to "LibWeb logic" as you previously did.
If a flex item is itself a flex container, we were previously lying when
asked if the item created a BFC. It creates an FFC, so stop lying about
this in FormattingContext::creates_block_formatting_context().
Instead of formatting contexts flailing around to figure out from the
"inside" how much space is available on the "outside", we should
provide the amount of available space in both axes as an input to run().
This basically means that when something creates a nested formatting
context, the parent context is responsible for telling the nested context
how much space is available for layout. This information is provided
immediately when invoking run().
Note that this commit doesn't pass accurate values in all cases yet.
This first step just makes it build, and passes available values in some
cases where getting them was trivial.
This patch changes the *computed* representation of the following CSS
properties to use CSS::Size:
- width, min-width, max-width
- height, min-height, max-height
A few things had to change in order for things to keep working,
but I tried to keep the diff to a minimum.
The main trouble was that `min-width` and `max-width` can't actually be
`auto`, but they *can* be `none`. We previously treated `auto` as a
valid value (and it behaved mostly like `none`).
This function should return the automatic height of the formatting
context's root box.
Until now, we've been relying on some magical handshakes between parent
and child context, when negotiating the height of child context root
boxes. This is a step towards something more reasonable.
This remained undetected for a long time as HeaderCheck is disabled by
default. This commit makes the following file compile again:
// file: compile_me.cpp
#include <LibWeb/CSS/GridTrackSize.h>
// That's it, this was enough to cause a compilation error.
When calculating the automatic height of a BFC root, we stretch it to
contain the bottommost margin edge of floating boxes.
Before this change, we assumed that floating boxes had coordinates
relative to the BFC root, when they're actually relative to the floating
box's containing block. This may or may not be the BFC root, so we have
to use margin_box_in_ancestor_coordinate_space() to apply offsets from
all boxes in the containing block chain (up to the BFC root).
Before this change, block-level boxes were laid out vertically by
placing them after the nearest previous BlockContainer sibling. This
only worked if the preceding block-level box happened to be a
BlockContainer.
This fixes an issue where the screenshot on netsurf-browser.org was not
being laid out properly (it was `img { display: block }` which creates
a block-level ImageBox, and ImageBox is not a BlockContainer but a
ReplacedBox, so the following block-level box was skipping over the
ImageBox and being placed next to whatever was before the ImageBox..)
