Although DistinctNumeric, which is supposed to abstract the underlying
type, was used to represent CSSPixels, we have a whole bunch of places
in the layout code that assume CSSPixels::value() returns a
floating-point type. This assumption makes it difficult to replace the
underlying type in CSSPixels with a non-floating type.
To make it easier to transition CSSPixels to fixed-point math, one step
we can take is to prevent access to the underlying type using value()
and instead use explicit conversions with the to_float(), to_double(),
and to_int() methods.
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.
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.
