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.
Fixes the problem that width is incorrectly computed in intrinsic
sizing mode when there are blocks that have min-width or max-width
specified.
Actually that is just the fix of a symptom of the larger problem that
Length::to_px() returns 0 when value is auto regardless of available
size.
This fix resolves issue where calculating the min size of a block could
result in incorrect value if width of the block's children was
compensated by margins to fit into container width (which is equal to 0
during min size calculation).
When we determine that a size is definite because it can be resolved now
without performing layout, we also need to account for the box-sizing
property.
This lets us remove a hack from flex layout where box-sizing:border-box
was manually undone at one point in the layout algorithm.
This commit implements following missing steps in table layout:
- Calculate final table height
- Resolve percentage height of cells and rows using final table height
- Distribute avilable height to table rows
If total max columns width (grid_max) is zero then available width
should be divided equally between columns. Previously there was
division by zero: `column.max_width / grid_max`.
Previously, the minimum height of a table row was calculated based
on the automatic height of the cells inner layout. This change makes
computed height of a cell boxes also be considered if it has definite
value.
When deciding on a box type transformation (blockify/inlinify) for a
pseudo element, we have to use the originating element as a reference
rather than the parent.
(The originating element *is* the parent for its pseudo elements.)
If there is a remaining margin-bottom in margin collapsing state
tracker after laying out all boxes in the current BFC, it must be
assigned to the last in-flow child since margin collapsing cannot
occur across a formatting context boundary.
The current issue where margin-bottom may be counted twice due to
"collapse through" margins in the last in-flow child box is addressed
with this fix by excluding such boxes during the search for a box to
assign the remaining margin.
Test case coming with this fix has a layout bug with incorrectly
computed line height.
This fixes a bug that was seen when a combination of the grid having
been floated with `float: left` and a `minmax()` column size were used.
The issue was that a grid track size should be considered intrinsically
sized if both the min and max sizes are intrinsic, not just one of them.
This is a tiny bit messy because:
- The spec says we should expand this to `flex: <flex-grow> 1 0`
- All major engines expand it to `flex: <flex-grow> 1 0%`
Spec bug: https://github.com/w3c/csswg-drafts/issues/5742
This is far from perfect, but let's at least make an attempt at laying
out <svg> when encountering it inside another <svg>.
This makes https://awesomekling.substack.com actually load and render
instead of asserting. :^)
Although the spec doesn't mention it, if a flex item has box-sizing:
border-box, and the specified size suggestion is a definite size, we
have to subtract the borders and padding from the size before using it.
This fixes an issue seen in "This Week in Ladybird #4" where the
screenshots ended up in one long vertical stack instead of paired up
2 by 2.
Per SVG2, any coordinate pairs following a moveto command should be
treated as implicit lineto commands with the same absoluteness as the
moveto command.
This attribute is used to define how the viewBox should be scaled.
Previously the behaviour implemented was that of "xMidYMid meet", now
all of them work (expect none :P).
With this the Discord login backend is now correctly scaled/positioned.
This also brings our SVG code a little closer to the spec! With spec
comments and all :^)
(Minor non-visible update to layout tests)
When sizing a flex container with flex-direction:column under a
max-content height constraint, we were incorrectly truncating the
infinite available height to 0 when collecting flex items into lines.
This caused us to put every flex item in its own flex line, which is the
complete opposite of what we want during max-content intrinsic sizing,
as the layout would grow wide but not tall.
This isn't actually part of CSS-FLEXBOX-1, but all major engines honor
these properties in flex layout, and it's widely used on the web.
There's a bug open against the flexbox spec where fantasai says the
algorithm will be updated in CSS-FLEXBOX-2:
https://github.com/w3c/csswg-drafts/issues/2336
I've added comments to all the places where we adjust calculations for
gaps with "CSS-FLEXBOX-2" so we can find them easily. When that spec
becomes available, we can add proper spec links.
VALUES-4 defines the internal representation of `calc()` as a tree of
calculation nodes. ( https://www.w3.org/TR/css-values-4/#calc-internal )
VALUES-3 lacked any definition here, so we had our own ad-hoc
implementation based around the spec grammar. This commit replaces that
with CalculationNodes representing each possible node in the tree.
There are no intended functional changes, though we do now support
nested calc() which previously did not work. For example:
`width: calc( 42 * calc(3 + 7) );`
I have added an example of this to our test page.
A couple of the layout tests that used `calc()` now return values that
are 0.5px different from before. There's no visual difference, so I
have updated the tests to use the new results.
Now that these are kind of working, lets add a layout test to prevent
future regressions :^)
This test is the same as the previous example (it is copied, though
that seems to have been done for other tests, e.g. Acid 1).
Grid and flex containers have their own rules for abspos items, so we
shouldn't try to be clever and put them in the "current" anonymous
wrapper block. That behavior is primarily for the benefit of block &
inline layout.
When calculating the intrinsic width of a block-level box, we now ignore
the preferred width entirely, and not just when the preferred width
should be treated as auto.
The condition for this was both confused and wrong, as it looked at the
available width around the box, but didn't check for a width constraint
on the box itself.
Just because the available width has an intrinsic sizing constraint
doesn't mean that the box is undergoing intrinsic sizing. It could also
be the box's containing block!
Due to CSSImportRule::has_import_result() being backwards, we never
actually entered imported style sheets when traversing style rules or
media queries.
With this fixed, we no longer need the "collect style sheets" step in
StyleComputer, as normal for_each_effective_style_rule() will now
actually find all the rules. :^)
In situations where we need a width to calculate the intrinsic height of
a flex item, we use the fit-content width as a stand-in. However, we
also need to clamp it to any min-width and max-width properties present.
In `flex-direction: column` layouts, a flex item's intrinsic height may
depend on its width, but the width is calculated *after* the intrinsic
height is required.
Unfortunately, the specification doesn't tell us exactly what to do here
(missing inputs to intrinsic sizing is a common problem) so we take the
solution that flexbox applies in 9.2.3.C and apply it to all intrinsic
height calculations within FlexFormattingContext: if the used width of
an item is not yet known when its intrinsic height is requested, we
substitute the fit-content width instead.
Note that while this is technically ad-hoc, it's basically extrapolating
the spec's suggestion in one specific case and using it in all cases.
