Improvements to gradients.
This is a collection of commits improving the rendering of linear and radial gradients by making them conform more closely to the spec.
All commits are are independent and should work without the others.
These commits address the following issues:
* a956e3fd52resolves#3908 but contains also some other necessary changes to `convert_gradient_stops`. The updated function has a few more copys but should be more correct. Maybe @pcwalton wants to comment since he has originally written the code.
* b230be8aaf partially solves #16638. (Partially because `border-image-outset` is not implemented. This is an older issue for border gradients: #15894.
To quickly catch regressions and see changes to gradients I have created [a set of twelve manual testcases](https://pyfisch.org/stuff/testcases-gradients.html) and placed them in a single file. Attached are two files. One shows how the gradients were rendered before the PR the other one with the changes applied.


r? @emilio
and maybe also @jdm?
---
- [X] `./mach build -d` does not report any errors
- [X] `./mach test-tidy` does not report any errors
<!-- Reviewable:start -->
---
This change is [<img src="https://reviewable.io/review_button.svg" height="34" align="absmiddle" alt="Reviewable"/>](https://reviewable.io/reviews/servo/servo/16666)
<!-- Reviewable:end -->
Just use WebRender's ClipId directly. This will allow us to create and
use ReferenceFrames in the future, if we need to do that. It will also
make it easier to have Servo responsible for creating the root
scrolling area, which will allow removing some old hacks in the future.
Instead of passing down a complex clipping region to each item, used
shared clipping to handle overflow:hidden and CSS clips. In addition to
being more efficient, this should also fix quite a few issues related
to absolutely positioned elements.
One existing reftest is slightly modified to avoid tickling a quirk
with the way that WebRender rasterizes masks. We are working out how to
best express these combined masks with the API or need to. The change
does not affect the original subject of the reftest.
Fixes#13109.
Fixes#10151.
Fixes#7575.
Fixes#8074.
Fixes#8780.
This includes the new border code path for simple (solid) borders.
This gives much higher quality border rendering, including proper
support for elliptical border segments.
The quality on https://github.com/servo/servo is noticeably improved.
- Tidy and optimize the batching code.
- Support tiling / repeat for linear and radial gradients.
- Fix some edge cases of subpixel text AA.
- Add clip mask support to border shaders.
- Optimization to text run creation on CPU.
- Handle more box-shadow clipping cases.
- Fix a panic that could occur when window size is 0.
- Clip / scroll API improvements.
This is the first step toward removing inherited clips in favor of
scroll roots for handling overflow and CSS clipping. This will allow us
to more easily handle elements that should not be clipped. While we are
still using inherited clips here, we now properly clip some types of
content that wasn't clipped before.
Correct viewport test references
These references were using an incorrect value for the expected
container width. Now that WebRender is no longer clipping to stacking
context boundaries the rendered width is correct (100% of viewport
width = 240px).
Add gradient border support.
webrender add gradient border support in https://github.com/servo/webrender/pull/953. This pr add support in servo.
---
<!-- Thank you for contributing to Servo! Please replace each `[ ]` by `[X]` when the step is complete, and replace `__` with appropriate data: -->
- [X] `./mach build -d` does not report any errors
- [X] `./mach test-tidy` does not report any errors
<!-- Either: -->
- [X] These changes do not require tests because it should be covered by wpt
<!-- Pull requests that do not address these steps are welcome, but they will require additional verification as part of the review process. -->
<!-- Reviewable:start -->
---
This change is [<img src="https://reviewable.io/review_button.svg" height="34" align="absmiddle" alt="Reviewable"/>](https://reviewable.io/reviews/servo/servo/15905)
<!-- Reviewable:end -->
Now that WebRender can handle splitting scrolling layers on its own, we
don't need to do any work to split up scroll roots. This should also
make it possible to handle overflow:scroll and containing block scroll
roots in the future.
I have a follow up PR for Servo that uses the new border-image
APIs, but I'll land that separately, so that we don't delay
landing the WR update itself.
This includes a WR update that improves pixel snapping. Specifically,
the non-transform shader now snaps to device pixels in world space,
rather than local space.
This makes 31 new tests pass, and adds 4 new failures.
Of the new failures:
- The three background size tests appear to be an OSMesa accuracy
issue. Near the bottom of the image, a small number of pixels
are different from the reference by a value of 1.0 / 255.0. I've
confirmed on 3 real GPUs and also on llvmpipe that the tests
match on those devices. This would be a good case for fuzzy test
support in WPT.
- The other failing test appears to have unreasonable accuracy
requirements as it also fails on Gecko and Chromium in the same
way that the test now fails on WR.
switch to using webrender_traits::ImageData
update use of webrender_traits::StackingContext in layout
use webrender_traits::channel::msg_channel in webgl ipc
fix use of resource_override_path in components/servo/lib
Instead annotate all flows with their owning ScrollRoots. When
processing the display list items into a flattened display list, we add
PushScrollRoot and PopScrollRoot to signal when scrolling regions start
and end. It is possible for content from different scrolling regions to
intersect and when they do, the stack of scrolling regions is
duplicated. When these duplicated scrolling regions stacks reach
WebRender, it will scroll them in tandem.
The PushScrollRoot and PopScrollRoot items are currently represented as
StackingContexts in WebRender, but eventually these will be replaced
with special WebRender display items.
Fixes#13529.
Fixed#13298.
This is a step in disassociating scrolling areas from stacking
contexts. Now scroll areas are defined by unique ids, which means that
in the future stacking context will be able to contain more than one.
Prefer auto-generation for some keyword props
<!-- Please describe your changes on the following line: -->
---
<!-- Thank you for contributing to Servo! Please replace each `[ ]` by `[X]` when the step is complete, and replace `__` with appropriate data: -->
- [x] `./mach build-geckolib` does not report any errors
<!-- Either: -->
- [x] These changes do not require tests because it's a refactor
<!-- Pull requests that do not address these steps are welcome, but they will require additional verification as part of the review process. -->
r? @Manishearth or @emilio
<!-- Reviewable:start -->
---
This change is [<img src="https://reviewable.io/review_button.svg" height="34" align="absmiddle" alt="Reviewable"/>](https://reviewable.io/reviews/servo/servo/13902)
<!-- Reviewable:end -->
Layers were a feature of the legacy drawing path. If we re-add them at
some point, it probably makes more sense to make them a product of
display list inspection.
This change also remove a bunch of dead painting code.
Remove the concept of nested stacking contexts from display list builder
<!-- Please describe your changes on the following line: -->
---
<!-- Thank you for contributing to Servo! Please replace each `[ ]` by `[X]` when the step is complete, and replace `__` with appropriate data: -->
- [x] `./mach build -d` does not report any errors
- [x] `./mach test-tidy` does not report any errors
- [ ] These changes fix #__ (github issue number if applicable).
<!-- Either: -->
- [ ] There are tests for these changes OR
- [x] These changes do not require tests because they should not change behavior.
<!-- Pull requests that do not address these steps are welcome, but they will require additional verification as part of the review process. -->
With the removal of the legacy rendering path, we don't need to worry
about nested stacking contexts. This change just pushes the
complication to the WebRender conversion step, but a later change will
remove the concept from WebRender as well.
This also helps to prepare for the introduction of ids for particular
scrolling regions, an integral part of multiple ScrollLayers per block.
<!-- Reviewable:start -->
---
This change is [<img src="https://reviewable.io/review_button.svg" height="34" align="absmiddle" alt="Reviewable"/>](https://reviewable.io/reviews/servo/servo/13820)
<!-- Reviewable:end -->
With the removal of the legacy rendering path, we don't need to worry
about nested stacking contexts. This change just pushes the
complication to the WebRender conversion step, but a later change will
remove the concept from WebRender as well.
This also helps to prepare for the introduction of ids for particular
scrolling regions, an integral part of multiple ScrollLayers per block.