flows and static positions of hypothetical boxes.
Before this change, Servo used one code path that computed the position
of flows with `position: static` or `position: relative` and another
separate code path that computed the position of flows with `position:
absolute` or `position: fixed`. The latter code attempted to duplicate
the former code to determine the static position of hypothetical boxes,
but this was both fragile and incorrect in the case of hypothetical
boxes nested inside floats. In fact, it's impossible to determine the
static position of an absolute flow relative to its containing block at
inline-size assignment time, because that static position could depend
on a float that cannot be placed until block-size assignment!
This patch changes block layout to use the same code path for static
positioning of regular flows and static positioning of absolute flows
where applicable. This both simplifies the code and improves its
efficiency, since it allows the `hypothetical_position` field and
`static_block_offsets` data structure to be removed. Moreover, it
improves correctness in the above case (which the new reftest checks).
This allows the sidebar in Facebook Timeline to be positioned properly.
text layout, and unify the inline layout paths for pre- and
normally-formatted text.
This fixes a lot of "jumpiness" and removes the `new_line_pos` stuff.
Closes#2260.
§ 12.3-12.5.
Only simple alphabetic and numeric counter styles are supported. (This
is most of them though.)
Although this PR adds a sequential pass to layout, I verified that on
pages that contain a reasonable number of ordered lists (Reddit
`/r/rust`), the time spent in generated content resolution is dwarfed by
the time spent in the parallelizable parts of layout. So I don't expect
this to negatively affect our parallelism expect perhaps in pathological
cases.
...and vice-versa. This is not a complete fix for all mixed-direction layout
cases, but it fixes enough problems to make some simple test cases pass, like
tha attached reftest.
There are FIXME comments for many of the remaining issues. In particular,
this does not yet handle RTL layout of fixed/absolute elements.
Only simple alphabetic and numeric counter styles are supported. (This
is most of them though.)
Although this PR adds a sequential pass to layout, I verified that on
pages that contain a reasonable number of ordered lists (Reddit
`/r/rust`), the time spent in generated content resolution is dwarfed by
the time spent in the parallelizable parts of layout. So I don't expect
this to negatively affect our parallelism expect perhaps in pathological
cases.
Moved from #4544, because Critic.
Fixes#4544.
§ 12.3-12.5.
Only simple alphabetic and numeric counter styles are supported. (This
is most of them though.)
Although this PR adds a sequential pass to layout, I verified that on
pages that contain a reasonable number of ordered lists (Reddit
`/r/rust`), the time spent in generated content resolution is dwarfed by
the time spent in the parallelizable parts of layout. So I don't expect
this to negatively affect our parallelism expect perhaps in pathological
cases.
CSS-TEXT-3 § 7.3.
`text-justify: distribute` is not supported.
The behavior of `text-justify: none` does not seem to match what Firefox
and Chrome do, but it seems to match the spec.
Closes#213.
through display list building.
The old `flow_origin` concept was ill-defined (sometimes the border box
plus the flow origin, sometimes including horizontal margins and
sometimes not, sometimes including relative position and sometimes not),
leading to brittleness and test failures. This commit reworks the logic
to always pass border box origins in during display list building.
This commit removes the "merge-fragments" pass from inline reflow,
instead merging "on the fly". This ended up being simpler, as well as
more fine grained. Additionally, this patch makes the line breaker no
longer clone every fragment (!)
This functionality will be used in the implementation of
`text-overflow`.
This property is used by approximately 55% of page loads.
To implement the line breaking behavior, the "breaking strategy" has
been cleaned up and abstracted. This should allow us to easily support
other similar properties in the future, such as `text-overflow` and
`word-break`.
I had to use a somewhat unconventional method of computing text
indentation (propagating from blocks down to inlines) because of the way
containing blocks are handled in Servo.
(As a side note, neither Gecko nor WebKit correctly handles percentages
in `text-align`, at least incrementally -- i.e. when the percentages are
relative to the viewport and the viewport is resized.)
This adds the infrastructure necessary to support stacking contexts that
are not containing blocks for absolutely-positioned elements. Our
infrastructure did not support that before. This minor revamp actually
ended up simplifying the logic around display list building and
stacking-relative position computation for absolutely-positioned flows,
which was nice.
