Fixed layout flow tree JSON serialization
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The second argument for the `emit_struct()` is the number of fields, if given `0`, the output JSON will always be empty.
This is used in `./mach run -d -Z trace-layout https://servo.org`, which will dump the layout flow tree into a `layout_trace.json` file for debugging.
This also unblocks https://github.com/servo/servo/issues/12675
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layout: Clear non-inherited properties on anonymous block
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This is one of my pull requests that imlement basic flexible box layout.
This pull request adds a `modify_style_for_anonymous_flow()` function to use initial values for non-inherited properties and parent values for inherited properties as the flow style. It also set border and outline to zero and set the display property from the parameter. This function may also be reused to modify style of anonymous table object in the future.
Part of code comes from `cascade_anonymous()` from @SimonSapin .
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Add a modify_style_for_anonymous_flow() function to use initial values
for non-inherited properties and parent values for inherited properties
as the block style. It also set border and outline to zero and set the
display property from the parameter.
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.
speculation code.
The old code tried to do the speculation as a single bottom-up pass
after intrinsic inline-size calculation, which was unable to handle
cases like this:
<div>
<div style="float: left">Foo</div>
</div>
<div>
<div style="overflow: hidden">Bar</div>
</div>
No single bottom-up pass could possibly handle this case, because the
inline-size of the float flowing out of the "Foo" block could never make
it down to the "Bar" block, where it is needed for speculation.
On the pages I tried, this regresses layout performance by 1%-2%.
I first noticed this breaking some pages, like the Google SERPs, several
months ago.
`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.
absolutely-positioned flows separately when storing overflow.
This code dates back to the time when absolutely positioned flows were
ignored by all of their ancestors up to the containing block. This
hasn't been true for at least a year.
Closes#9306.
Closes#9309.
Is a partial fix for #9308.
There wasn't a good way to split this up, unfortunately.
With this change, the only remaining usage of the Servo-specific structures is
in layout_task, where the root node is received from the script task. \o/
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.
