This fixes a bug where partially loaded content is displayed to the user
before it should be, usually before stylesheets have loaded. This commit
supresses reflows until either FirstLoad or RefreshTick, whichever comes
first.
Unfortunately, hit_test and mouse_over did not do reflows if they were
necessary, and so by suppressing the initial spurious reflows, these
methods started to panic without a display list to query. This patch
also transforms these into queries similar to the other existing
queries.
Previously, the flow for ticking animations was:
Compositor -> Constellation -> Layout -> Script
However, this means that the compositor <-> layout messages can thrash, meaning layout thread is very rarely idle.
This means that the script thread (which joins on the layout thread during reflow) was unable to execute and run rAF callbacks.
With this change, the flow is now:
Compositor -> Constellation -> Script (when rAF is active).
Compositor -> Constellation -> Layout (when transitions / animations are active and no rAF is present).
This makes rAF based animation *much* smoother.
Optimize flat display lists
Flat display lists were a 2x regression on the spheres demo. This patch series fixes that.
See the individual commits for more details.
r? @mrobinson
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`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.
script: Fix MouseOver handling
Now we only query for the topmost node, and apply the hover state to all
of the parent elements.
This fixes things like #9705, where the hover state was applied only to
the children.
This also makes us more conformant with other browsers in the case of
taking in account margins and paddings.
For example, prior to this PR, when your mouse was over the inner
element, in the bottom part, `hover` styles didn't apply to the parent.
```html
<style>
div {
padding: 10px;
margin: 10px;
height: 15px;
background: blue;
}
div:hover {
background: red;
}
</style>
<div>
<div></div>
</div>
```
Fixes#9705
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Now we only query for the topmost node, and apply the hover state to all
of the parent elements.
This fixes things like #9705, where the hover state was applied only to
the children.
This also makes us more conformant with other browsers in the case of
taking in account margins and paddings.
For example, prior to this PR, when your mouse was over the inner
element, in the bottom part, `hover` styles didn't apply to the parent.
```html
<style>
div {
padding: 10px;
margin: 10px;
height: 15px;
background: blue;
}
div:hover {
background: red;
}
</style>
<div>
<div></div>
</div>
```
Fixes#9705
Flatten display list structure
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.
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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.
This fixes the border-end calculation for table rows whose borders are
collapsed with rows in different rowgroups. The border collapsing code now
uses an iterator that yields all the rows as a flat sequence, regardless of
how they are grouped in rowgroups. It gets rid of
`TableRowGroupFlow::preliminary_collapsed_borders` which was never correct.
(It was read but never written.)
This may fix#8120 but I'm not 100% certain. (I haven't managed to reproduce
the intermittent failure locally, and my reduced test case still fails but in
a different way.)
This fixes a bug when recalculating border collapsing for an existing table
now. The bug was caused by using `push_or_mutate` which has no effect if there
is already a value at the specified index.
The fix switches incorrect `push_or_mutate` calls to use `push_or_set`
instead. It also renames `push_or_mutate` to `get_mut_or_push` which I think
is a less-confusing name for this method.
PR #9208 added the ability to perform layout before an `<img>` resource is
fully loaded. However, when we are rendering to an image file for testing
purposes, we need to block until the image content is fully loaded (until
issue #9441 is fixed).
Fixes#9550.
compositing: Stop compositing unnecessarily after each animation frame.
Instead, schedule a delayed composite after each frame of an animation.
The previous code would cause jank, because the following sequence
frequently occurred:
1. The page uses `requestAnimationFrame()` to request a frame.
2. The compositor receives the message, schedules a composite,
dispatches the rAF message to the script thread, composites, and goes to
sleep waiting for vblank (frame 1).
3. The script makes a change and sends it through the pipeline.
Eventually it gets painted and is sent to the compositor, but the
compositor is sleeping.
4. The compositor wakes up, sees the new painted content, page flips,
and goes to sleep (frame 2). Repeat from step 1.
The problem is that we have two composition frames, not just one. This
halves Web apps' framerate!
This commit fixes the problem by scheduling the composite in step 2 to
12 ms in the future. We already have this delayed-composition
functionality in the form of the scrolling timer, which I repurposed and
renamed to the "delayed composition timer" for this task. This change
gives the page 12 ms to prepare the frame, which seems to usually be
enough, especially with WebRender.
Note that simply removing the scheduled composite after rAF is not the
correct solution. If this is done, then pages that call rAF and don't
modify the page won't receive future rAFs, since the compositor will be
sleeping and won't be notified of vblank.
Fixes a bunch of jank in browser.html. The remaining jank seems to be a
problem with browser.html itself.
r? @glennw
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Instead, schedule a delayed composite after each frame of an animation.
The previous code would cause jank, because the following sequence
frequently occurred:
1. The page uses `requestAnimationFrame()` to request a frame.
2. The compositor receives the message, schedules a composite,
dispatches the rAF message to the script thread, composites, and goes to
sleep waiting for vblank (frame 1).
3. The script makes a change and sends it through the pipeline.
Eventually it gets painted and is sent to the compositor, but the
compositor is sleeping.
4. The compositor wakes up, sees the new painted content, page flips,
and goes to sleep (frame 2). Repeat from step 1.
The problem is that we have two composition frames, not just one. This
halves Web apps' framerate!
This commit fixes the problem by scheduling the composite in step 2 to
12 ms in the future. We already have this delayed-composition
functionality in the form of the scrolling timer, which I repurposed and
renamed to the "delayed composition timer" for this task. This change
gives the page 12 ms to prepare the frame, which seems to usually be
enough, especially with WebRender.
Note that simply removing the scheduled composite after rAF is not the
correct solution. If this is done, then pages that call rAF and don't
modify the page won't receive future rAFs, since the compositor will be
sleeping and won't be notified of vblank.
Fixes a bunch of jank in browser.html. The remaining jank seems to be a
problem with browser.html itself.
Remove parallel display list construction
Parallel display list construction hasn't been shown to give any
performance gains. It is also incompatible with the current flat display
list implementation. Once flat display lists have landed, we can explore
possible benefits of parallel construction once again.
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Dirty elements whose selectors are affected by sibling changes
This fixes incremental layout of nodes that match pseudo-class selectors such as :first-child, :nth-child, :last-child, :first-of-type, etc. Fixes#8191 and other intermittent layout bugs.
This code is based on the following flags from Gecko:
https://hg.mozilla.org/mozilla-central/file/e1cf617a1f28/dom/base/nsINode.h#l134
Depends on servo/rust-selectors#71. r? @SimonSapin
There are a couple of TODO items in this commit, but I'd appreciate feedback on the general approach before I finish it up. (Also, if someone who knows more than I do could give some advice about atomic orderings...)
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Parallel display list construction hasn't been shown to give any
performance gains. It is also incompatible with the current flat display
list implementation. Once flat display lists have landed, we can explore
possible benefits of parallel construction once again.
Add WebRender integration to Servo.
WebRender is an experimental GPU accelerated rendering backend for Servo.
The WebRender backend can be specified by running Servo with the -w option (otherwise the default rendering backend will be used).
WebRender has many bugs, and missing features - but it is usable to browse most websites - please report any WebRender specific rendering bugs you encounter!
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Ensure when calculating font metrics that the total line height matches requested line height.
This fixes rounding accuracy issues that could result in layout producing results off by a small number of Au.
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WebRender is an experimental GPU accelerated rendering backend for Servo.
The WebRender backend can be specified by running Servo with the -w option (otherwise the default rendering backend will be used).
WebRender has many bugs, and missing features - but it is usable to browse most websites - please report any WebRender specific rendering bugs you encounter!
This is unfortunate, but making that useful would require parameterizing
`SharedLayoutContext` and `LayoutContext` depending on the
`SelectorImpl` (which is a **huge** work right now).
Probably the easier way to do it, and probably the one that keeps the
layout code more legible, and since there won't be multiple
implementations at the same compilation unit, would be "defining" a
default implementation for layout via feature flags.
That should allow us to remove the components/style/servo.rs file.
This commit refactors the style crate to be completely independent of
the actual implementation and pseudo-elements supported.
This also adds a gecko backend which introduces parsing for the
anonymous box pseudo-elements[1], although there's still no way of
querying them.
https://mxr.mozilla.org/mozilla-central/source/layout/style/nsCSSAnonBoxList.h
