This reverts commit a73cd88f0c.
Emitting SaveLayer for each paintable made rasterization a lot slower
on every website because now Skia has to allocate enormous amounts of
temporary surfaces. Let's revert it for now and figure how to implement
it with less aggressive SaveLayer usage.
When decoding data into bitmaps, we end up with different alpha types
(premultiplied vs. unpremultiplied color data). Unfortunately, Skia only
seems to handle premultiplied color data well when scaling bitmaps with
an alpha channel. This might be due to Skia historically only supporting
premultiplied color blending, with unpremultiplied support having been
added more recently.
When using Skia to blend bitmaps, we need the color data to be
premultiplied. ImmutableBitmap gains a new method to enforce the alpha
type to be used, which is now used by SharedResourceRequest and
CanvasRenderingContext2D to enforce the right alpha type.
Our LibWeb tests actually had a couple of screenshot tests that exposed
the graphical glitches caused by Skia; see the big smiley faces in the
CSS backgrounds tests for example. The failing tests are now updated to
accommodate the new behavior.
Chromium and Firefox both seem to apply the same behavior; e.g. they
actively decode PNGs (which are unpremultiplied in nature) to a
premultiplied bitmap.
Fixes#3691.
With this change, instead of recording a display list item for each
instance of a repeated background, a new DrawRepeatedImmutableBitmap
type is used. This allows the painter to use optimized repeated image
painting and, when the GPU backend is used, avoid re-uploading the image
texture for each repetition.
Some screenshot tests are affected, but there are no visible
regressions.
https://null.com/games/chainstaff works a lof faster with this change.
Skia painter is visibly faster than LibGfx painter and has more complete
CSS transforms support. With this change:
- On Linux, it will try to use Vulkan-backend with fallback to
CPU-backend
- On macOS it will try to use Metal-backend with fallback to
CPU-backend
- headless-browser always runs with CPU-backend in layout mode
This change will make it easier to disable screenshot comparison tests
on a specific platform or have per-platform expectations.
Additionally, it's nice to be able to tell if a ref-test uses a
screenshot as an expectation by looking at the test path.
