We fail these two WPT tests: http://wpt.live/css/css-transforms/scale/svg-scale-013.html http://wpt.live/css/css-transforms/scale/svg-scale-014.html The failure looks like a rounding / antialiasing issue, arguably not really a bug. The test has a rect with fractional size and fractional position, which gets scaled down, and the test is expecting the math to work out precisely correctly for that rect to cover up a red area. We're off by a very small amount, whether due to pixel-snapping or rounding error. We should fix the tests to avoid triggering this rounding error (i.e. avoid depending on precise pixel snapping implementation details), probably by adjusting the scales to not involve fractional pixels. (Or alternately: by making the rect slightly larger so that it's got a bit of wiggle room for rounding error.)
Bug 1838089 Comment 0 Edit History
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We fail these two WPT tests: https://wpt.fyi/results/css/css-transforms/scale/svg-scale-013.html https://wpt.fyi/results/css/css-transforms/scale/svg-scale-014.html Direct links to tests: http://wpt.live/css/css-transforms/scale/svg-scale-013.html http://wpt.live/css/css-transforms/scale/svg-scale-014.html The failure looks like a rounding / antialiasing issue, arguably not really a bug. The test has a rect with fractional size and fractional position, which gets scaled down, and the test is expecting the math to work out precisely correctly for that rect to cover up a red area. We're off by a very small amount, whether due to pixel-snapping or rounding error. We should fix the tests to avoid triggering this rounding error (i.e. avoid depending on precise pixel snapping implementation details), probably by adjusting the scales to not involve fractional pixels. (Or alternately: by making the rect slightly larger so that it's got a bit of wiggle room for rounding error.)