Browsers such as Chrome and Firefox apply an arbitrary scale to the
current font size if `normal` is used for `line-height`. Firefox uses
1.2 while Chrome uses 1.15. Let's go with the latter for now, it's
relatively easy to change if we ever want to go back on that decision.
This also requires updating the expectations for a lot of layout tests.
The upside of this is that it's a bit easier to compare our layout
results to other browsers', especially Chrome.
Whenever we introduce a block element in a container that at that point
has only had inline children, we create an anonymous wrapper for all the
inline elements so we can keep the invariant that each container
contains either inline or non-inline children. For some reason, we
ignore all the out-of-flow nodes since they are layed out separately and
it was thought that this shouldn't matter.
However, if we are dealing with inline blocks and floating blocks, the
order of the inline contents _including_ out-of-flow nodes becomes very
important: floating blocks need to take the order of nodes into account
when positioning themselves.
Fix this by simply hoisting the out-of-flow nodes into the anonymous
wrapper as well.
Fixes the order of blocks in #4212. The gap is still not present.
This is a part of refactoring towards making the paintable tree
independent of the layout tree. Now, instead of transferring text
fragments from the layout tree to the paintable tree during the layout
commit phase, we allocate separate PaintableFragments that contain only
the information necessary for painting. Doing this also allows us to
get rid LineBoxes, as they are used only during layout.
This patch makes a few changes to the way we calculate line-height:
- `line-height: normal` is now resolved using metrics from the used
font (specifically, round(A + D + lineGap)).
- `line-height: calc(...)` is now resolved at style compute time.
- `line-height` values are now absolutized at style compute time.
As a consequence of the above, we no longer need to walk the DOM
ancestor chain looking for line-heights during style computation.
Instead, values are inherited, resolved and absolutized locally.
This is not only much faster, but also makes our line-height metrics
match those of other engines like Gecko and Blink.
Out-of-flow boxes (floating and absolutely-positioned elements) were
previously collected and put in the anonymous block wrapper as well, but
this actually made hit testing not able to find them, since they were
breaking expectations about tree structure that hit testing relies on.
After this change, we simply let out-of-flow boxes stay in their
original parent, preserving the author's intended box tree structure.
This patch just adds the new root paintable and updates the tests
expectations. The next patch will move painting logic from the layout
viewport to the paint viewport.
The path for floating, replaced elements must not fall through to the
path taken for floating, non-replaced elements. The former works like
inline replaced elements, while the latter uses a completely different
algorithm which doesn't account for intrinsic ratio. Falling through
overrides the correct value computed by the former.
Fixes#19061.
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.
