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fix(painting): build the ring without a path-ops difference #3

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Merged
rehmatsg merged 1 commit into from
Sep 2, 2026
Merged

fix(painting): build the ring without a path-ops difference #3

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31 changes: 25 additions & 6 deletions lib/src/painting/ring_geometry.dart
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Original file line number Diff line number Diff line change
Expand Up @@ -394,9 +394,29 @@ class BeamRingGeometry {
);

/// The border ring: [outer] minus [inner].
late final Path ring = rect.isEmpty
? Path()
: Path.combine(PathOperation.difference, outer, inner);
late final Path ring = rect.isEmpty ? Path() : _subtract(outer, inner);

// Subtracts the nested [hole] from [shell].
//
// `Path.combine(PathOperation.difference, ...)` is unreliable on Flutter web
// (CanvasKit): it silently returns the first operand, so the ring collapses
// back into the filled shape and every ring-confined layer washes across the
// whole child. For the built-in shapes both contours are simple and nested,
// so the even-odd fill of the two in one path describes the same region
// without a path-ops pass, and renders identically on every backend.
//
// A custom [contour] can be self-intersecting (a star is), where even-odd
// and non-zero disagree and the shortcut would punch a hole of its own — so
// those keep the path-ops route.
Path _subtract(Path shell, Path hole) {
if (contour != null) {
return Path.combine(PathOperation.difference, shell, hole);
}
return Path()
..fillType = PathFillType.evenOdd
..addPath(shell, Offset.zero)
..addPath(hole, Offset.zero);
}

Path _shapePath(Rect r, BorderRadius cornerRadii) {
// A rect with no area (or an inverted one, from deflating past the
Expand Down Expand Up @@ -433,9 +453,8 @@ class BeamRingGeometry {
/// The halo a comet bloom fills: the shape grown by [reach], minus the
/// content box, so the glow hugs the border and spills outward instead of
/// washing across the child.
Path halo(double reach) => rect.isEmpty
? Path()
: Path.combine(PathOperation.difference, grown(reach), inner);
Path halo(double reach) =>
rect.isEmpty ? Path() : _subtract(grown(reach), inner);

/// [outer] grown outward by [reach], in the shape's own family.
Path grown(double reach) => contour != null
Expand Down
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