Update threshold for degenerate gradients
Bug: chromium:905607
Change-Id: I17aff1bffeb5bf3673568f57107b7014d46eb986
Reviewed-on: https://skia-review.googlesource.com/c/171521
Reviewed-by: Brian Salomon <bsalomon@google.com>
Reviewed-by: Florin Malita <fmalita@chromium.org>
Commit-Queue: Michael Ludwig <michaelludwig@google.com>
diff --git a/src/shaders/gradients/SkGradientShader.cpp b/src/shaders/gradients/SkGradientShader.cpp
index 4726f09..2a9bfdd 100644
--- a/src/shaders/gradients/SkGradientShader.cpp
+++ b/src/shaders/gradients/SkGradientShader.cpp
@@ -557,6 +557,10 @@
return avg;
}
+// The default SkScalarNearlyZero threshold of .0024 is too big and causes regressions for svg
+// gradients defined in the wild.
+static constexpr SkScalar kDegenerateThreshold = SK_Scalar1 / (1 << 15);
+
// Except for special circumstances of clamped gradients, every gradient shape--when degenerate--
// can be mapped to the same fallbacks. The specific shape factories must account for special
// clamped conditions separately, this will always return the last color for clamped gradients.
@@ -686,7 +690,7 @@
return nullptr;
}
- if (SkScalarNearlyZero((pts[1] - pts[0]).length())) {
+ if (SkScalarNearlyZero((pts[1] - pts[0]).length(), kDegenerateThreshold)) {
// Degenerate gradient, the only tricky complication is when in clamp mode, the limit of
// the gradient approaches two half planes of solid color (first and last). However, they
// are divided by the line perpendicular to the start and end point, which becomes undefined
@@ -733,7 +737,7 @@
return nullptr;
}
- if (SkScalarNearlyZero(radius)) {
+ if (SkScalarNearlyZero(radius, kDegenerateThreshold)) {
// Degenerate gradient optimization, and no special logic needed for clamped radial gradient
return make_degenerate_gradient(colors, pos, colorCount, std::move(colorSpace), mode);
}
@@ -778,15 +782,15 @@
if (!valid_grad(colors, pos, colorCount, mode)) {
return nullptr;
}
- if (SkScalarNearlyZero((start - end).length())) {
+ if (SkScalarNearlyZero((start - end).length(), kDegenerateThreshold)) {
// If the center positions are the same, then the gradient is the radial variant of a 2 pt
// conical gradient, an actual radial gradient (startRadius == 0), or it is fully degenerate
// (startRadius == endRadius).
- if (SkScalarNearlyEqual(startRadius, endRadius)) {
+ if (SkScalarNearlyEqual(startRadius, endRadius, kDegenerateThreshold)) {
// Degenerate case, where the interpolation region area approaches zero. The proper
// behavior depends on the tile mode, which is consistent with the default degenerate
// gradient behavior, except when mode = clamp and the radii > 0.
- if (mode == SkShader::TileMode::kClamp_TileMode && endRadius > SK_ScalarNearlyZero) {
+ if (mode == SkShader::TileMode::kClamp_TileMode && endRadius > kDegenerateThreshold) {
// The interpolation region becomes an infinitely thin ring at the radius, so the
// final gradient will be the first color repeated from p=0 to 1, and then a hard
// stop switching to the last color at p=1.
@@ -799,7 +803,7 @@
return make_degenerate_gradient(
colors, pos, colorCount, std::move(colorSpace), mode);
}
- } else if (SkScalarNearlyZero(startRadius)) {
+ } else if (SkScalarNearlyZero(startRadius, kDegenerateThreshold)) {
// We can treat this gradient as radial, which is faster. If we got here, we know
// that endRadius is not equal to 0, so this produces a meaningful gradient
return MakeRadial(start, endRadius, colors, std::move(colorSpace), pos, colorCount,
@@ -859,10 +863,10 @@
return nullptr;
}
- if (SkScalarNearlyEqual(startAngle, endAngle)) {
+ if (SkScalarNearlyEqual(startAngle, endAngle, kDegenerateThreshold)) {
// Degenerate gradient, which should follow default degenerate behavior unless it is
// clamped and the angle is greater than 0.
- if (mode == SkShader::kClamp_TileMode && endAngle > SK_ScalarNearlyZero) {
+ if (mode == SkShader::kClamp_TileMode && endAngle > kDegenerateThreshold) {
// In this case, the first color is repeated from 0 to the angle, then a hardstop
// switches to the last color (all other colors are compressed to the infinitely thin
// interpolation region).