Computing the pseudo element of a CSS::Selector was very hot when
mousing around on GitHub in Browser. A profile had it at ~10%.
After these changes, it's totally gone from the profile. :^)
Instead of calling quick_sort() every time a StackingContext child
is added to a parent, we now do a single pass of sorting work after the
full StackingContext tree has been built.
Before this change, the quick_sort() was ~13.5% of the profile while
hovering links on GitHub in the Browser. After the change, it's down to
~0.6%. Pretty good! :^)
For seletors whose subject is unversal (i.e selectors that end in "*")
we were not serializing the asterisk. Instead "foo bar *" came out as
"foo bar foo". This patch fixes that by correctly serializing the last
simple selector if it's universal.
Simplify automatic cross sizing of items in flex-direction:column by
using the fit-content width directly.
There's obviously a lot more nuance to this, but for now this makes
flex items with both width:auto and height:auto actually get some height
in column flex layouts.
I'm a little confused about intrinsic heights *really* work, and I'm
struggling to extract that information from the spec. In the meantime,
let's ensure that min-content is always smaller than (or equal to)
max-content so that other math works as expected.
Previously, each NodeState in a FormattingState was shared with the
parent FormattingState, but the HashMap of NodeState had to be copied
when making FormattingState copies.
This patch makes copying instant by keeping a pointer to the parent
FormattingState instead. When fetching immutable state via get(), we may
now return a reference to a NodeState owned by a parent FormattingState.
get_mutable() will copy any NodeState found in the ancestor chain before
making a brand new one.
The flexbox specification barely even handwaves about automatically
sized items, but there's actually a lot of work to do in order for them
to get the correct size.
This patch is messy, but does make significant progress on supporting
flex items with indefinite width and/or height.
There's a fair amount of nested layout going on here, but do note that
we'll be hitting the intrinsic sizes cache whenever possible.
FormattingContext can now calculate the intrinsic sizes (min-content and
max-content in both axes) for a given Layout::Box.
This is a rather expensive operation, as it necessitates performing two
throwaway layouts of the subtree rooted at the box. Fortunately, we can
cache the results of these calculations, as intrinsic sizes don't change
based on other context around the box. They are intrinsic after all. :^)
This wasn't worth the headache of trying to make SVG boxes work together
with BFC right now. Let's just make it a block container once again, and
have its corresponding SVGPaintable inherit from PaintableWithLines.
We'll have to revisit this as SVG support improves.
Although something has a definite size, we may still have to "resolve"
it, since FFC is quite liberal in what it considers to be definite.
Let's put that logic in a set of helper functions.
1. Make this decision *after* we've inserted the layout node into the
layout tree. Otherwise, we can't reach its containing block!
2. Per css-sizing-3, consider auto-sized blocks whose sizes resolve
solely against other definite sizes as definite themselves.
In particular, (2) makes us consider width:auto block children of a
definite-size containing block as having definite size. This becomes
very important in flex layout.
If there's some non-block-level box (like an SVG element of some kind)
between to blocks, just skip over the non-block for purposes of margin
collapsing. This is basically a hack, and something we'll need to
improve as part of our general SVG support.
For single-line flex containers, center the only flex line along the
cross axis. Alignment of multi-line flex containers are left as a FIXME.
This patch also moves out the assignment of final metrics to the
FormattingState from align_all_flex_lines() to a separate function.
- Avoid performing inside layout on definite-size flex items (since
their computed size can be used as-is.)
- Use FormattingState::clone() to generate a throwaway layout instead of
mutating the tree in-place.
- Update spec link & comments based on current CSSWG draft. The latest
version is quite a bit clearer on how this should work.
Instead of doing internal child layout incrementally as we go, save it
for the end of flex layout. The code will become simpler if we can focus
on simply computing the dimensions of each flex item while we're doing
the main FFC algorithm.
We don't need to perform inside layout here. The only information we
need in this step is whether an anonymous block container has nothing
but empty-or-whitespace text children.
This information is already accurate after the initial layout tree
construction. Performing a layout does not change the answer. It does
however have many other side effects, so let's defer those.
This implements at least some of the specification. inter-character is
not yet handled. However as our current algorithm only considers
whitespace as word breaks, inter-word could technically be considered to
be handled. :^)
All the justification-related code is now in
InlineFormattingContext::apply_justification_to_fragments and is
performed after all the line boxes have been added.
Text justification now only happens on the last line if the excess space
including whitespace is below a certain threshold. 10% seemed reasonable
since it prevents the "over-justification" of text. Note that fragments
in line boxes before the last one are always justified.
When doing viewbox transforms, elliptical always had large arc and
sweep flag set to false. Preserve these flags so they can be set
correctly when applying viewbox transformations.
The absolute rect of a paintable is somewhat expensive to compute. This
is because all coordinates are relative to the nearest containing block,
so we have to traverse the containing block chain and apply each offset
to get the final rect.
Paintables will never move between containing blocks, nor will their
absolute rect change. If anything changes, we'll simpl make a new
paintable and replace the old one.
Take advantage of this by caching the containing block and absolute rect
after first access.
Previously this queried the root layout-node's font, which was both
wrong and could crash if the layout wasn't ready yet. Now, it's just
wrong. But at least all the font-related wrongness is grouped together
in StyleComputer. :^)
Everything related to hit testing is better off using the painting tree.
The thing being mousemoved over is a paintable, so let's hand that out
directly instead of the corresponding layout node.
Input events have nothing to do with layout, so let's not send them to
layout nodes.
The job of Paintable starts to become clear. It represents a paintable
item that can be rendered into the viewport, which means it can also
be targeted by the mouse cursor.
