We now compute the used height of height:auto by measuring from the top
content edge (y=0) to the bottom of the bottommost line box within the
block container.
This fixes an issue where we'd fail to account for the topmost line box
being taller than any of its fragments (which can happen if the
line-height is greater than the height of all fragments on the line.)
This patch breaks FormattingContext::layout_inside() into two functions,
one that creates an independent formatting context (if needed), and
another that calls the former and then performs the inside layout within
the appropriate context.
The main goal here was to make layout_inside() return the independent
formatting context if one was created. This will allow us to defer
certain operations in child contexts until the parent context has
finished formatting the child root box.
Apparently it's not only replaced elements that can have intrinsic
sizes, so let's move this concept from ReplacedBox to Box. To avoid
bloating Box, we make the accessors virtual.
Per the spec, only a BlockContainer" can have line boxes, so let's not
clutter up every Layout::Box with line boxes.
This also allows us to establish an invariant that BFC and IFC always
operate on a Layout::BlockContainer.
Note that if BlockContainer has all block-level children, its line boxes
are not used for anything. They are only used in the all inline-level
children scenario.
Some boxes cannot have children (most commonly replaced elements),
and so there is nothing meaningful inside them to layout.
We now use the can_have_children() flag to quickly skip over such boxes
instead of creating a formatting context and other pointless busywork.
Until now, we've internally thought of the CSS "display" property as a
single-value property. In practice, "display" is a much more complex
property that comes in a number of configurations.
The most interesting one is the two-part format that describes the
outside and inside behavior of a box. Switching our own internal
representation towards this model will allow for much cleaner
abstractions around layout and the various formatting contexts.
Note that we don't *parse* two-part "display" yet, this is only about
changing the internal representation of the property.
Spec: https://drafts.csswg.org/css-display
Instead of trying to layout SVG boxes as if they are regular CSS boxes,
let's invent an "SVG formatting context" and let it manage SVG boxes.
To facilitate this, Layout::SVGBox no longer inherits from ReplacedBox,
and is instead a simple, "inline-block" style BlockBox.
Previously, the method for computing the height of absolutely positioned
replaced elements only invoked the method for non-replaced elements.
That method is now implemented fully enough that it sometimes computed a
height of 0 for replaced elements. This implements section 10.6.5 rule 1
of the CSS spec to avoid that behavior.
Height computation algorithm is actually
different for absolutely positioned boxes
and block formatting contexts (where it doesn't include floats)
Fixes#6408
SPDX License Identifiers are a more compact / standardized
way of representing file license information.
See: https://spdx.dev/resources/use/#identifiers
This was done with the `ambr` search and replace tool.
ambr --no-parent-ignore --key-from-file --rep-from-file key.txt rep.txt *
This commit fixes algorithm for computing auto height (CSS 2.2 10.6.7)
by including floating boxes into computation and implements one of the cases
for computing the height of absolutely positioned, non-replaced elements (10.6.4 rule 3)
Section 10.6.4 rule 5 of the CSS height property spec outlines a method
to compute the height of an absolutely positioned block when the 'top'
and 'bottom' CSS properties are specified.
(...and ASSERT_NOT_REACHED => VERIFY_NOT_REACHED)
Since all of these checks are done in release builds as well,
let's rename them to VERIFY to prevent confusion, as everyone is
used to assertions being compiled out in release.
We can introduce a new ASSERT macro that is specifically for debug
checks, but I'm doing this wholesale conversion first since we've
accumulated thousands of these already, and it's not immediately
obvious which ones are suitable for ASSERT.
