This adds the infrastructure necessary to support stacking contexts that
are not containing blocks for absolutely-positioned elements. Our
infrastructure did not support that before. This minor revamp actually
ended up simplifying the logic around display list building and
stacking-relative position computation for absolutely-positioned flows,
which was nice.
This patch is a first stab at implementing border-radius. It looks fine as long as
the border isn't an ellipse (that might not even parse yet), and the border-widths
around a border-radius are the same.
Here's a cool screenshot!
r? @pcwalton @SimonSapin
first-class.
This implements the scheme described here:
https://groups.google.com/forum/#!topic/mozilla.dev.servo/sZVPSfPVfkg
This commit changes Servo to generate one display list per stacking
context instead of one display list per layer. This is purely a
refactoring; there are no functional changes. Performance is essentially
the same as before. However, there should be numerous future benefits
that this is intended to allow for:
* It makes the code simpler to understand because the "new layer needed"
vs. "no new layer needed" code paths are more consolidated.
* It makes it easy to support CSS properties that did not fit into our
previous flat display list model (without unconditionally layerizing
them):
o `opacity` should be easy to support because the stacking context
provides the higher-level grouping of display items to which opacity
is to be applied.
o `transform` can be easily supported because the stacking context
provides a place to stash the transformation matrix. This has the side
benefit of nicely separating the transformation matrix from the
clipping regions.
* The `flatten` logic is now O(1) instead of O(n) and now only needs to
be invoked for pseudo-stacking contexts (right now: just floats),
instead of for every stacking context.
* Layers are now a proper tree instead of a flat list as far as layout
is concerned, bringing us closer to a production-quality
compositing/layers framework.
* This commit opens the door to incremental display list construction at
the level of stacking contexts.
Future performance improvements could come from optimizing allocation of
display list items, and, of course, incremental display list
construction.
I'm sad to say that this improved performance significantly. A lot of
this win is due to the Rust compiler not being smart about not zeroing
objects out if it doesn't need to.
One part (of 8!) of css font family disambiguation is that font families should
be matched case-insensitively.
This patch implements that. Once it lands, a bug needs to be filed to do lowercasing
properly (as a string, instead of char-by-char -- it's a unicode thing).
r? @gw
During debugging, I found it useful to hook all task creation in a
central location, and util::task was the perfect place for it.
r? @pcwalton (or maybe someone else, I'm kinda sending you a bunch of
reviews today because I don't know who better to give them to)
We've discussed this some and I think there's consensus to do it as a
pragmatic decision for now. CPU painting is more stable, especially with
buggy drivers, and faster (because we aren't caching the necessary
OpenGL objects yet and possibly for other reasons), so it provides a
better "out of the box" experience for newcomers to Servo who don't know
to pass the `-c` option. This patch continues to reftest both Skia and
Skia-GL out of a desire to keep options open. Skia-GL remains a
first-class citizen.
r? @metajack
We've discussed this some and I think there's consensus to do it as a
pragmatic decision for now. CPU painting is more stable, especially with
buggy drivers, and faster (because we aren't caching the necessary
OpenGL objects yet and possibly for other reasons), so it provides a
better "out of the box" experience for newcomers to Servo who don't know
to pass the `-c` option. This patch continues to reftest both Skia and
Skia-GL out of a desire to keep options open. Skia-GL remains a
first-class citizen.
This is a grab bag of performance improvements that significantly improve style recalculation, layout, and painting on a few static pages.
Let me know if you'd like me to split this PR up.
r? @glennw
construction to avoid cloning and moving flows so much.
Besides amounting to a 5%-10% win on a page with a lot of text, this
simplifies and refactors the text layout code.
