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.
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.
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.
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.
an IPC channel instead.
Because this used a boxed trait object to invoke messages across a
process boundary, and boxed trait objects are not supported across IPC,
we spawn a helper thread inside the compositor to perform the marshaling
for us.
Now that NativeDisplay can be shared between the compositor and the
paint task, we can move the LayerBuffer cache to the compositor. This
allows surfaces to be potentially reused between different paint tasks
and will eventually allow OpenGL contexts to be preserved between
instances of GL rasterization.
The basic idea is it's safe to output an image for reftest by testing:
- That the compositor doesn't have any animations active.
- That the compositor is not waiting on any outstanding paint messages to arrive.
- That the script tasks are "idle" and therefore won't cause reflow.
- This currently means page loaded, onload fired, reftest-wait not active, first reflow triggered.
- It could easily be expanded to handle pending timers etc.
- That the "epoch" that the layout tasks have last laid out after script went idle, is reflected by the compositor in all visible layers for that pipeline.
