Using fixed-point saturated arithmetics for CSSPixels allows to avoid
accumulating floating-point errors.
This implementation is not complete yet: currently saturated
arithmetics implemented only for addition. But it is enough to not
regress any of layout tests we have :)
See https://github.com/SerenityOS/serenity/issues/18566
This change implements following paragraph from placement algorithm in
the spec:
"If the largest column span among all the items without a definite
column position is larger than the width of the implicit grid, add
columns to the end of the implicit grid to accommodate that column
span."
There were places in the grid implementation code with copies of this
text, but those were completely unrelated to the code where they were
being pasted so I removed them.
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.
Instead of hard-coding a check for "calc", we now call out to
parse_dynamic_value() which allows use of other functions like min(),
max(), clamp(), etc.
Adds a second pass to resolve percentage paddings and margins of grid
items after track sizes are known. If resolving percentage paddings
or margins affects tracks sizes then second pass to re-resolve track
sizes might also be needed but I cannot come up with an example to
reproduce that so we can leave it to improve in the future :)
This fixes the issue when functions that distribute base_size
or growth_limit to tracks only considered *affected* spanned tracks
while calculating left extra that is available for distribution while
indeed it should be just *all* spanned track by specific item that
extra space size.
This fixes the issue that currently we use "auto" as initial value for
grid-template-column and grid-template-rows although spec says it
should be "none". This makes a lot of difference for these properties
because currently we represent "auto" as a list with one auto-sized
track which means initial value for grid-template-column defines one
"explicit" track while it should define none of them.
This change makes grid-auto-columns/rows be applied to the correct
tracks when initial values is used for grid-template-column/rows.
This changes grid items position storage type from unsigned to signed
integer so it can represent negative offsets and also updates placement
for grid items with specified column to correctly handle negative
offsets.
Use contains_percentage() that works for calc() values instead of
is_percentage().
This fixes issue when tracks with calc() that has percentages where
considered as "fixed" tracks with resolvable size which led to
incorrectly resolved infinite final track sizes.
This is a hack to emulate the behavior of other engines that use
fixed-point math. By rounding to 3 decimals, we retain a fair amount of
detail, while still allowing overshooting 100% without breaking lines.
This is both gross and slow, but it fixes real sites. Notably, the
popular Bootstrap library uses overshooting percentages in their
12-column grid system.
This hack can be removed when CSSPixels is made a fixed-point type.
Instead of just measuring the layout viewport, we now measure overflow
in every box that is a scroll container.
This has the side effect of no longer creating paintables for layout
boxes that didn't participate in layout. (For example, empty/anonymous
boxes that were ignored by flex itemization.)
Such boxes are now marked as "(not painted)" in the layout tree dumps,
as they have no paintable to dump geometry from.
From spec https://drafts.csswg.org/css-grid/#grid-items:
"Each in-flow child of a grid container becomes a grid item, and each
child text sequence is wrapped in an anonymous block container grid
item."
Fixes the problem that text sequences inside grid containers are
ignored and not displayed.
Fixes the bug that currently we always consider tracks with percentage
size as ones with "fixed" length even when available size is not
definite. With this change tracks with percentage size when available
size is not definite will be considered as "intrinsic" sized.
Introduces incomplete parsing of grid shorthand property. Only
<grid-template> part of syntax is supported for now but it is enough
to significantly improve rendering of websites that use this shorthand
to define grid :)
This fixes a plethora of rounding problems on many websites.
In the future, we may want to replace this with fixed-point arithmetic
(bug #18566) for performance (and consistency with other engines),
but in the meantime this makes the web look a bit better. :^)
There's a lot more things that could be converted to doubles, which
would reduce the amount of casting necessary in this patch.
We can do that incrementally, however.
Implements more parts of sizing algorithm for tracks with spanning
items to archive parity with implementation for sizing of tracks
with non-spanning items.
Adds support for grid items with fixed size paddings. Supporting
percentage paddings will probably require to do second pass of tracks
layout: second pass is needed to recalculate tracks sizes when final
items sizes are known when percentage paddings are already resolved.
This change addresses the incorrect assumption that the available width
inside a grid item is equal to the width of the track it belongs to.
For instance, if a grid item has a width of 200px, the available width
inside that item is also 200px regardless of its column(s) base size.
To solve this issue, it was necessary to move the final resolution of
grid items to occur immediately after the final column track sizes are
determined. By doing so, it becomes possible to obtain correct
available width inside grid items while resolving the row track sizes.
This change makes grid items be responsible for their borders instead
of grid tracks which can not have borders itself.
There are changes in layout tests but those are improvements :)
item_incurred_increase should be reset before every next distirbution
because otherwise it will accumulate increases from previous
distributions which is not supposed to happen.
When a width/height constraint is applied to GFC it should set its own
width/height to the sum of track sizes according to the spec.
Changes in layout tests are improvement over what we had before.
Previously, the width and height of grid items were set to match the
size of the grid area they belonged to. With this change, if a grid
item has preferred width or height specified to not "auto" value it
will be resolved using grid area as containing block and used instead.
1. Stop using -1 to indicate infinity value of growth limit. Just use
INFINITY for that.
2. More complete implementation of "Expand Flexible Tracks" step.
3. Return AvailableSize from get_free_space: spec says that this
function can return indefinite size and it is ok.
