For malformed tables which only have cells with span greater than 1, the
content sizes for row and column aren't initialized to non-zero values.
Avoid undefined behavior in such cases, which sometimes show up on
Wikipedia.
Follow the computing column measures section of the specification, which
gives an algorithm for setting intrinsic percentage widths when spanning
columns are involved.
Change how we store type of columns. It was used where the specification
only distinguishes between percent and everything else, so it makes more
sense to store and use it as a boolean.
Make used widths of the columns a linear combination of two consecutive
sizing-guesses when the assignable table width is less than or equal to
the max-content sizing-guess, as the specification describes.
The specification says we should distribute excess width proportionally
to the width of the cell, not to the preferred increment. Doing the
latter leads to distributing all excess width to just the cells which
demand some increment, even if it's very modest. Moreover, there's code
which partially implements the correct criteria just below the one we
remove here.
Max width shouldn't be tied to min width, commit d33b99d went too far
and made them the same when the table-root had a specified percentage
width.
Fixes#19940.
Follow the specification in making the borders centered on the grid
lines. This avoids visual bugs due to double-rendering of borders on
either side of an edge and paves the way for a full implementation of
the harmonization algorithm for collapsed borders.
Currently, this still lacks complete handling of row and column spans.
Also, the box model for cells still considers the full width of the
internal borders instead of just half, as the specification requires.
Some additional handling of rounding issues will be needed to avoid very
subtle visual bugs.
Despite these limitations, this improves the appearance of all the
tables with collapsed borders I've tried while limiting the amount of
change to something reasonable.
Add a cell border specificity comparator which preserves the winning
border logic according to specification and makes it possible to sort
borders by specificity. This will be important for handling the style of
table cell corners in a way consistent with other browsers.
Computing the table width algorithm bifurcates based on whether
table-root width is auto. We only adjust the used table width based on
cell percentage widths on the auto branch, thus the same check is needed
when we initialize cell widths.
Cell percentage widths are relative to table width, not containing
block width. If the table width is auto, there isn't a normative
specification, only a brief mention that the user agent should try to
meet it.
As a starting point, we increase the width of the table such that it's
sufficient to cover min-width of cells with a percentage width. This
matches the behavior of other browsers, at least for simple cases.
This ensures that min-content contributions from cells with no content
are computed using their calculated values, which are never considered
for min-content before then. The specification diverges from column
measures algorithm, which doesn't use specified width of cells anywhere.
The used width is already a content width, which doesn't include
borders. Border widths should be subtracted from the specified width
instead, since that initially specifies the total width including
borders, for consistent comparison. Also handle table box padding as an
additional fix.
Adding undistributable space right before setting the content width is
incorrect when it's a percentage. Follow the specification and add it to
GRIDMIN and GRIDMAX instead.
The shortcut we put in place didn't resolve percentage widths and
ignored border spacing. We can still return early after we compute the
width per the specifications.
Compute the contributions to a spanning cell width from each cell in the
span. This better handles uneven column widths, since each cell
contribution is proportional with its own width as opposed to the own
width of the first cell in the span.
This better matches the behavior of other browsers and further aligns
with the specification.
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
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.
Add logic to compute {min, max}-height and use min-height when
calculating table height, per specifications.
Fixes some issues with phylogenetic tree visualizations on Wikipedia.
