commit 5bf5fd5566cf109cde73651cdb7c71b6219cc417 parent eb5d60087707d1acaf663a8ea2bbf14602e88d2f Author: Glenn Watson <git@chillybin.org> Date: Fri, 28 Nov 2025 01:45:04 +0000 Bug 2001524 - Disable ShouldSnapToGrid in more cases. r=tnikkel Move snapping of reference frame origins to WR, where we can remove the (potentially fractional) external scroll offset reliably. The old non-WR render paths need to keep snapping enabled here. Mark one animated transform test fuzzy on windows, which appears to be caused by a separate bug in the animation / snapping code, to be fixed as a follow up. Differential Revision: https://phabricator.services.mozilla.com/D273529 Diffstat:
6 files changed, 38 insertions(+), 1 deletion(-)
diff --git a/gfx/wr/webrender/src/spatial_node.rs b/gfx/wr/webrender/src/spatial_node.rs @@ -446,8 +446,34 @@ impl SpatialNode { ReferenceFrameKind::Transform { .. } => source_transform, }; + // Previously, the origin of a stacking context transform was snapped + // in Gecko. However, this causes jittering issues during scrolling in + // some cases when fractional scrolling is enabled. The origin used in + // Gecko doesn't have the external scroll offset from the content process + // removed, so if that content-side scroll amount is fractional, it can + // cause inconsistent snapping during scene building. Instead, we need + // to apply the device-pixel snap _after_ the external scroll offset + // has been removed. To further complicate matters, we _don't_ want to + // snap this if this spatial node has a snapping transform, as we rely + // on the fractional intermediate nodes in order to arrive at a correct + // final snapping result. If we don't have a snapping offset, we've + // reached a spatial node where snapping will no longer apply (e.g. a + // complex transform) and then we need to snap the device pixel position + // of that transform. + let parent_origin = match self.snapping_transform { + Some(..) => { + info.origin_in_parent_reference_frame + } + None => { + snap_offset( + info.origin_in_parent_reference_frame, + state.coordinate_system_relative_scale_offset.scale, + ) + } + }; + let resolved_transform = - LayoutFastTransform::with_vector(info.origin_in_parent_reference_frame) + LayoutFastTransform::with_vector(parent_origin) .pre_transform(&source_transform); // The transformation for this viewport in world coordinates is the transformation for diff --git a/gfx/wr/wrench/reftests/filters/blend-clipped.png b/gfx/wr/wrench/reftests/filters/blend-clipped.png Binary files differ. diff --git a/gfx/wr/wrench/reftests/tiles/tile-cache-raster-root.png b/gfx/wr/wrench/reftests/tiles/tile-cache-raster-root.png Binary files differ. diff --git a/layout/base/nsLayoutUtils.cpp b/layout/base/nsLayoutUtils.cpp @@ -1925,6 +1925,11 @@ void nsLayoutUtils::PostTranslate(Matrix4x4& aTransform, const nsPoint& aOrigin, } bool nsLayoutUtils::ShouldSnapToGrid(const nsIFrame* aFrame) { + // TODO: Remove this function when this pref is being removed. + if (StaticPrefs::layout_disable_pixel_alignment()) { + return aFrame && aFrame->IsSVGOuterSVGAnonChildFrame(); + } + return !aFrame || !aFrame->HasAnyStateBits(NS_FRAME_SVG_LAYOUT) || aFrame->IsSVGOuterSVGAnonChildFrame(); } diff --git a/testing/web-platform/meta/css/css-transforms/individual-transform/animation/individual-transform-combine.html.ini b/testing/web-platform/meta/css/css-transforms/individual-transform/animation/individual-transform-combine.html.ini @@ -0,0 +1,3 @@ +[individual-transform-combine.html] + fuzzy: + if (os == "win") and not swgl: maxDifference=255-255;totalPixels=596-596 diff --git a/testing/web-platform/meta/css/css-transforms/transform-input-009.html.ini b/testing/web-platform/meta/css/css-transforms/transform-input-009.html.ini @@ -0,0 +1,3 @@ +[transform-input-009.html] + fuzzy: + if useDrawSnapshot: maxDifference=0-52;totalPixels=0-115
