Properly size synthesized layers
Layers that are composed of several stacking contexts that need to be
rendered on top of other layered content need synthesized layers.
Previously, these layers were placed into a stacking context that was
the same size as their parent. This patch creates a new type of
PaintLayer which simply holds a display list. The layer is sized to the
bounds of the DisplayList and its children are positioned relative to
the parent stacking context.
This will also be useful in the future, when items outside of
StackingContexts are given their own layer for render order purposes.
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Layers that are composed of several stacking contexts that need to be
rendered on top of other layered content need synthesized layers.
Previously, these layers were placed into a stacking context that was
the same size as their parent. This patch creates a new type of
PaintLayer which simply holds a display list. The layer is sized to the
bounds of the DisplayList and its children are positioned relative to
the parent stacking context.
This will also be useful in the future, when items outside of
StackingContexts are given their own layer for render order purposes.
StackingContexts are added to layers when it is necessary to maintain
their ordering on top of other layered StackingContexts. Instead of
tracking the information about a layer scattered around into different
structs, combine it all into LayerInfo. LayerInfo will be used in the
future to hold layer information for DisplayItems that are layerized
independently of StackingContexts.
Make DisplayList hit testing a method on DisplayList
This will allow us to hit test into DisplayLists that are not directly
contained in StackingContexts, but instead are children of PaintLayers.
It also makes things slightly simpler.
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each iframe.
The old code that attempted to do this during layout wasn't able to work
for multiple reasons: it couldn't know where the iframe was going to be
on the page (because of nested iframes), and at the time it was building
the display list for a fragment it couldn't know where that fragment was
going to be in page coordinates.
This patch rewrites that code so that both the sizes and positions of
iframes are determined by the compositor. Layout layerizes all iframes
and marks the iframe layers with the appropriate pipeline and subpage
IDs so that the compositor can place them correctly. This approach is
similar in spirit to Gecko's `RefLayer` infrastructure. The logic that
determines when it is time to take the screenshot for reftests has been
significantly revamped to deal with this change in delegation of
responsibility.
Additionally, this code removes the infrastructure that sends layout
data back to the layout task to be destroyed, since it is now all
thread-safe and can be destroyed on the script task.
The failing tests now fail because of a pre-existing bug related to
intrinsic heights and borders on inline replaced elements. They happened
to pass before because we never rendered the iframes at all, which meant
they never had a chance to draw the red border the tests expect to not
render!
Closes#7377.
This will allow us to hit test into DisplayLists that are not directly
contained in StackingContexts, but instead are children of PaintLayers.
It also makes things slightly simpler.
A few small bits of refactoring to prepare for more advanced DisplayList layerization
This will be useful when PaintLayers that contain DisplayLists instead
of StackingContexts need to draw themselves. This is a simple
preparatory refactoring and doesn't change any behavior.
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This will be useful when PaintLayers that contain DisplayLists instead
of StackingContexts need to draw themselves. This is a simple
preparatory refactoring and doesn't change any behavior.
Currently pseudo-elements, like the fragments created for ::before and
::after, with layers will have the same LayerId as the body of their
owning fragments. Instead all LayerIds should be unique.
Fixes#2010.
StackingContexts that should be painted on top of StackingContexts that
are already layerized should automatically get their own layer. This
will ensure proper painting order.
Have PaintLayers own StackingContexts instead of the opposite
Previously, StackingContexts might have a PaintLayer. We switch the
ownership, for several reasons:
* We want PaintLayers to potentially contain something other
than a StackingContext soon.
* We want to delay the creation of PaintLayers until the last
minute, so that we can synthesize new layers for sandwiched
content.
This commit also implements the second goal. Instead of creating
PaintLayers during layout itself, wait until we are sorting and
layerizing a completed DisplayList.
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Previously, StackingContexts might have a PaintLayer. We switch the
ownership, for several reasons:
* We want PaintLayers to potentially contain something other
than a StackingContext soon.
* We want to delay the creation of PaintLayers until the last
minute, so that we can synthesize new layers for sandwiched
content.
This commit also implements the second goal. Instead of creating
PaintLayers during layout itself, wait until we are sorting and
layerizing a completed DisplayList.
This patch is in preparation for more dynamic layerization of the
pieces of display lists. It also prevents having to sort the children
by z-index multiple times.
Known issues:
* Display list optimization can sometimes optimize out elements that
should be shown. This affects the Enyo demo.
* The `overflow: scroll` container doesn't clip the inner layer properly
when borders, border radius, etc. are present.
* `overflow-x: scroll` and `overflow-y: scroll` don't work individually;
elements are scrolled all at once.
* Scrolling only works on absolutely-positioned elements.
new styles are set.
Tying transitions to the DOM node avoids quadratic complexity when
updating them.
Finishing transitions instantly when styles are updated makes our
behavior more correct.
This commit introduces the `serde` dependency, which we will use to
serialize messages going between processes in multiprocess Servo.
This also adds a new debugging flag, `-Z print-display-list-json`,
allowing the output of display list serialization to be visualized.
This will be useful for our experiments with alternate rasterizers.
