Instead of rendering a reference HTML page that wraps an <img> tag
pointing to a PNG, Screenshot tests now load the expected PNG directly
from disk and compare it against the rendered screenshot. This
eliminates the indirection of loading and rendering a second page just
to display a static image.
This also means --rebaseline now works for Screenshot tests, generating
the expected PNG automatically instead of requiring manual screenshot
capture and placement.
Changes:
- Add TestMode::Screenshot with its own collector and runner
- Move PNGs from Screenshot/images/ to Screenshot/expected/ with
normalized names matching input filenames
- Remove all 92 reference HTML wrapper files and the images/
directory
- Remove <link rel="match"> from all 94 Screenshot input HTML
files
- Update add_libweb_test.py Screenshot boilerplate accordingly
- Add Screenshot mode to results viewer image comparison tabs
There's a fairly complicated interaction between an SVG gradient's paint
transformation and the gradient coordinate transformation required to
correctly draw gradient fills. This was especially noticeable when
scaling down an SVG, resulting in broken gradient coordinates and
graphical glitches.
This changes the objectBoundingBox units to immediately map to the
bounding box's coordinate system, so we can unify the gradient paint
transformation logic and make it a lot simpler. We only need to undo the
bounding box offset and apply the paint transformation to fix a lot of
gradient fill bugs.
With the newly supported fuzzy matching in our test-web runner, we can
now define the expected maximum color channel and pixel count errors per
failing test and set a baseline they should not exceed.
The figures I added to these tests all come from my macOS M4 machine.
Most discrepancies seem to come from color calculations being slightly
off.
In commit 1b82cb43c2 I accidentally
removed the paint transformation altogether. The result was that
zoomed-in SVGs, or SVG elements with a transformation applied could have
their gradient coordinates misplaced significantly.
This was also exposed in the `svg-text-effects` test by way of a slight
visual difference. Add a new test that very clearly exposes the fixed
issue by rotating the gradient coordinates by 45 degrees.
