Do some minor cleanups in display list building
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First, we define computed::CSSPixelLength which contains a CSSFloat, a
pixel value, and then we replace computed::Length with CSSPixelLength.
Therefore, the |ComputedValue| of NoCalcLength, AbsoluteLength,
FontRelativeLength, ViewportPercentageLength, CharacterWidth, and
PhysicalLength is CSSPixelLength.
Besides, we drop NonNegativeAu, and replace computed::NonNegativeLength
with NonNegative<computed::Length>. (i.e. NonNegative<CSSPixelLength>)
These are two different passes during layout, but previously they
shared a state object. While some of the members are the same, many are
different so we separate them out into two separate objects. We also
change the HashMaps of these state objects to use the FnvHashMap.
Instead of only promoting flows with positioned fragments to containing
blocks, also do this for flows which have the transform, perspective or
filter properties set. This is what the spec requires and also fixes
some failing tests. It will allow us to stop creating stacking contexts
for overflow:hidden and overflow:scroll flows.
Fixes#18091.
Add NonNegativeLength, which could be computed to NonNegativeAu. So we
can declare Either<NonNegativeLength, X>, X=Auto, Normal, or Number.
NonNegativeLengthOrAuto is for column-width.
NonNegativeLengthOrNormal is for column-gap.
NonNegativeLengthOrNumber is for -moz-tab-size.
MozReview-Commit-ID: AfU8XpA1um0
The alias is left there temporarilly and will be removed completely in a later commit where
also components/style/gecko/generated/structs_{debug|release}.rs are re-generated (they still
use the old alias).
At least until we support scrollbars properly, this size is going to be the
correct one. I've left a TODO to grab the proper one once we support it.
This allows to trivially test viewport units for now.
MozReview-Commit-ID: JdaZ6WlZ2C6
Signed-off-by: Emilio Cobos Álvarez <emilio@crisal.io>
Collect scroll roots during the collect_stacking_context phase instead
of during display list construction. This will be useful in order to
collect containing block scroll roots as well as to give scroll roots
sequential ids in the future. This change also pulls stacking context
children out of the StackingContext struct itself, which should reduce
very slightly the memory used by the finished display list. This also
simplifies the DisplayListBuilder because it no longer has to maintain
a stack of ScrollRootIds and StackingContextIds and can instead just
rely on the program stack.
This allows us to get rid of a bunch of lifetimes and simplify a lot of code. It
also lets us get rid of that nasty lifetime transmute, which is awesome.
The situation with thread-local contexts is still suboptimal, but we fix that in
subsequent patches.
This creates a sharp distinction between `Arc<Flow>`s, which may be
owned by anyone, and `FlowRef`s, which may only be owned by the
traversal code. By checking the reference count, we ensure that a `Flow`
cannot be pointed to by `Arc`s and `FlowRef`s simultaneously.
This is not a complete fix for #6503, though it is a necessary start
(enforcing the no-aliasing rule of `FlowRef::deref_mut` will require far
more work).
Fixes#14014
This is a step in disassociating scrolling areas from stacking
contexts. Now scroll areas are defined by unique ids, which means that
in the future stacking context will be able to contain more than one.
Simplify the way that stacking contexts are collected. Instead of
passing the StackingContextId down the tree, pass the parent
StackingContext itself. This will allow future patches to get more
information about the parent stacking context (such as location).
Also remove the return value of collect_stacking_contexts, which was
unused.
WebRender.
This happens asynchronously, just as it does in non-WebRender mode.
This functionality is a prerequisite for doing proper display-list-based
hit testing in WebRender, since it moves the scroll offsets into Servo
(and, specifically, into the script thread, enabling iframe event
forwarding) instead of keeping them private to WebRender.
Requires servo/webrender_traits#55 and servo/webrender#277.
Partially addresses #11108.
This is the first part of #10185. More to follow. I have built this locally with both servo and geckolib without errors; let's see if it succeeds on all platforms as well.
`memmove` was showing up high in the profile when concatenating and
shorting display lists. This change drastically reduces the `memmove`
cost in exchange for some minor additional allocation cost.
Instead of producing a tree of stacking contexts, display list
generation now produces a flat list of display items and a tree of
stacking contexts. This will eventually allow display list construction
to produce and modify WebRender vertex buffers directly, removing the
overhead of display list conversion. This change also moves
layerization of the display list to the paint thread, since it isn't
currently useful for WebRender.
To accomplish this, display list generation now takes three passes of
the flow tree:
1. Calculation of absolute positions.
2. Collection of a tree of stacking contexts.
3. Creation of a list of display items.
After collection of display items, they are sorted based upon the index
of their parent stacking contexts and their position in CSS 2.1
Appendeix E stacking order.
This is a big change, but it actually simplifies display list generation.
Use the PrintTree utility to improve the readability of flow tree
dumps. Blocks and fragments are now split over two dump levels, because
otherwise they are impenetrable. Also start printing the restyle damage of
fragments.
