LinearGradientContext::shade4_clamp: fix div by 0
getScaleX() may return 0; move division using it after a
SkScalarNearlyZero check and closer to its first use.
Change-Id: Ie209d46dc101213e20e90486651ee17570425bb8
Reviewed-on: https://skia-review.googlesource.com/4643
Reviewed-by: Florin Malita <fmalita@chromium.org>
Commit-Queue: Florin Malita <fmalita@chromium.org>
diff --git a/src/effects/gradients/SkLinearGradient.cpp b/src/effects/gradients/SkLinearGradient.cpp
index ea20595..66accd8 100644
--- a/src/effects/gradients/SkLinearGradient.cpp
+++ b/src/effects/gradients/SkLinearGradient.cpp
@@ -737,7 +737,6 @@
}
}
const float dither[2] = { dither0, dither1 };
- const float invDx = 1 / dx;
if (SkScalarNearlyZero(dx * count)) { // gradient is vertical
const float pinFx = SkTPin(fx, 0.0f, 1.0f);
@@ -750,6 +749,8 @@
return;
}
+ SkASSERT(0.f != dx);
+ const float invDx = 1 / dx;
if (dx > 0) {
if (fApplyAlphaAfterInterp) {
this->shade4_dx_clamp<true, true>(dstC, count, fx, dx, invDx, dither);
diff --git a/tests/GradientTest.cpp b/tests/GradientTest.cpp
index ee776e3..50643f1 100644
--- a/tests/GradientTest.cpp
+++ b/tests/GradientTest.cpp
@@ -279,6 +279,18 @@
surface->getCanvas()->drawPaint(paint);
}
+static void test_vertical(skiatest::Reporter* reporter) {
+ auto surface(SkSurface::MakeRasterN32Premul(200, 200));
+
+ const SkPoint pts[] = {{ 100, 50 }, { 100, 50 }};
+ const SkColor colors[] = { SK_ColorBLACK, SK_ColorWHITE };
+ const SkScalar pos[] = { 0, 1 };
+ SkPaint paint;
+ paint.setShader(SkGradientShader::MakeLinear(pts, colors, pos, 2, SkShader::kClamp_TileMode));
+
+ surface->getCanvas()->drawPaint(paint);
+}
+
// A linear gradient interval can, due to numerical imprecision (likely in the divide)
// finish an interval with the final fx not landing outside of [p0...p1].
// The old code had an assert which this test triggered.
@@ -359,6 +371,7 @@
TestConstantGradient(reporter);
test_big_grad(reporter);
test_nearly_vertical(reporter);
+ test_vertical(reporter);
test_linear_fuzz(reporter);
test_two_point_conical_zero_radius(reporter);
test_clamping_overflow(reporter);