There was no need to set an available height constraint when doing early
height calculation for inline-flex boxes. It created a situation where
the flex containers could wrongly get zero height early, and then
resolve percentages against zero instead of the real intrinsic size.
Fixes#23942
If box is sized as replaced it still could be anything, not only SVG.
This fixes crashing on https://www.shopify.com/ that was caused by a
missing paintable for a box that has a layout node. This occurred
because the box was not laid out in dimension_box_on_line().
When iterating inline level chunks for a piece of text like " hello ",
we will get three separate items from InlineLevelIterator:
- Text " "
- Text "hello"
- Text " "
If the first item also had some leading margin (e.g margin-left: 10px)
we would lose that information when deciding that the whitespace is
collapsible.
This patch fixes the issue by accumulating the amount of leading margin
present in any collapsed whitespace items, and then adding them to the
next non-whitespace item in IFC.
It's a wee bit hackish, but so is the rest of the leading/trailing
margin mechanism.
This makes the header menu on https://www.gimp.org/ look proper. :^)
Until now, we had implemented flex container sizing by awkwardly doing
exactly what the spec said (basically having FFC size the container)
despite that not really making sense in the big picture. (Parent
formatting contexts should be responsible for sizing and placing their
children)
This patch moves us away from the Flexbox spec text a little bit, by
removing the logic for sizing the flex container in FFC, and instead
making sure that all formatting contexts can set both width and height
of flex container children.
This required changes in BFC and IFC, but it's actually quite simple!
Width was already not a problem, and it turns out height isn't either,
since the automatic height of a flex container is max-content.
With this in mind, we can simply determine the height of flex containers
before transferring control to FFC, and everything flows nicely.
With this change, we can remove all the virtuals and FFC logic for
negotiating container size with the parent formatting context.
We also don't need the "available space for flex container" stuff
anymore either, so that's gone as well.
There are some minor diffs in layout test results from this, but the
new results actually match other browsers more closely, so that's fine.
This should make flex layout, and indeed layout in general, easier to
understand, since this was the main weird special case outside of
BFC/IFC where a formatting context delegates work to its parent instead
of the other way around. :^)
Similar to calculate_inner_width(), let's make the caller responsible
for handling "auto" instead of returning the input height as is when
when it cannot be resolved.
Initially, this function was made to return CSS::Length because some of
its callers were expecting it to ignore "auto" width on input and
return it as is. Instead, let's just forbid using "auto" for input
width and always return CSSPixels.
Sizing already worked correctly, but before this change, we were too
aggressive with inserting line breaks when negative margins would
still an atomic inline to fit on the line.
Previously, we determined the positions of glyphs for each text run at
the time of painting, which constituted a significant portion of the
painting process according to profiles. However, since we already go
through each glyph to figure out the width of each fragment during
layout, we can simultaneously gather data about the position of each
glyph in the layout phase and utilize this information in the painting
phase.
I had to update expectations for a couple of reference tests. These
updates are due to the fact that we now measure glyph positions during
layout using a 1x font, and then linearly scale each glyph's position
to device pixels during painting. This approach should be acceptable,
considering we measure a fragment's width and height with an unscaled
font during layout.
Check the width of the next token after white space to decide line
breaks. The next width can also be the total width of multiple tokens.
This better follows the CSS Text specification and matches behavior of
other browsers.
Fixes#20388.
If an inline-block has a percentage height that relies on the auto
height of the containing block, it should always resolve to the
automatic height of the box, regardless of the percentage value. This
change may seem confusing, but it aligns with the behavior of other
engines.
When the containing block has an indefinite width, any descendants with
a percentage size should resolve that against 0, not infinity.
Fixes an assertion failure when loading https://www.gnu.org/
The part in FFC where we ask the parent formatting context to size the
flex container midway through layout is really weird, but let's at least
be consistently weird for BFC and IFC. Since IFC always works within its
parent BFC, it can simply forward these requests to the BFC.
This fixes an issue where inline-flex containers incorrectly had main
axis margins subtracted from their content size.
When resolving a percentage min-width or min-height size against a
containing block currently under a min-content constraint, we should act
as if the containing block has zero size in that axis.
This is technically "undefined behavior" per CSS 2.2, but it seems
sensible to mirror the behavior of max-height in the same situation.
It also appears to match how other engines behave.
Fixes#19242
The margin from the containing blocks shouldn't be included in the
amount by which we increment x after a float was places. That coordinate
should be relative to the containing block.
Fixes the comments layout on https://lobste.rs.
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.
If a box has a negative margin-left, it may have a negative effective
offset within its parent BFC root coordinate system.
We can account for this when calculating the amount of left-side float
intrusion by flooring the X offset at 0.
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. :^)
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).
While inline content between floating elements was broken correctly,
text justification was still using the original amount of available
space (without accounting for floats) when justifying fragments.
This code now works in terms of *intrusion* by left and right side
floats into a given box whose insides we're trying to layout.
Previously, it worked in terms of space occupied by floats in the root
box of the BFC they participated in. That created a bunch of edge cases
since the code asking about the information wasn't operating in root
coordinate space, but in the coordinate space of some arbitrarily nested
block descendant of the root.
This finally allows horizontal margins in the containing block chain to
affect floats and nested content correctly, and it also allows us to
remove a bogus workaround in InlineFormattingContext.
When there are floats present inside an IFC, we must coordinate with
the parent BFC to calculate the automatic width of the IFC's block box.
This is because the IFC is not directly aware of floats. Only the BFC
knows enough about them to account for them in automatic sizing.
Log a FIXME on the debug log, along with a layout tree dump of the box
that we didn't expect to see. This will be annoying (until fixed),
but far less so than crashing the browser.
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.
