From: reed@google.com <reed@google.com@2bbb7eff-a529-9590-31e7-b0007b416f81>
Date: Thu, 23 Jun 2011 15:07:04 +0000 (+0000)
Subject: detect when our quadratic is really linear for 2-point radial, and don't
X-Git-Tag: accepted/tizen/5.0/unified/20181102.025319~18187
X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=8871a84935d3606aad2bb490f2704c388fcfed90;p=platform%2Fupstream%2FlibSkiaSharp.git

detect when our quadratic is really linear for 2-point radial, and don't
divide by zero, but rather just return -c/b



git-svn-id: http://skia.googlecode.com/svn/trunk@1684 2bbb7eff-a529-9590-31e7-b0007b416f81
---

diff --git a/src/effects/SkGradientShader.cpp b/src/effects/SkGradientShader.cpp
index cfe444e..89b9d34 100644
--- a/src/effects/SkGradientShader.cpp
+++ b/src/effects/SkGradientShader.cpp
@@ -1476,6 +1476,9 @@ private:
 #ifdef SK_USE_SLOW_2POINT_RADIAL_GRADIENT
 static inline SkFixed two_point_radial(SkFixed b, SkFixed fx, SkFixed fy, SkFixed sr2d2, SkFixed foura, SkFixed oneOverTwoA, bool posRoot) {
     SkFixed c = SkFixedSquare(fx) + SkFixedSquare(fy) - sr2d2;
+    if (0 == foura) {
+        return SkFixedDiv(-c, b);
+    }
     SkFixed discrim = SkFixedSquare(b) - SkFixedMul(foura, c);
     if (discrim < 0) {
         discrim = -discrim;
@@ -1492,6 +1495,10 @@ static inline SkFixed two_point_radial(SkScalar b, SkScalar fx, SkScalar fy,
                                        SkScalar sr2d2, SkScalar foura,
                                        SkScalar oneOverTwoA, bool posRoot) {
     SkScalar c = SkScalarSquare(fx) + SkScalarSquare(fy) - sr2d2;
+    if (0 == foura) {
+        return SkScalarToFixed(SkScalarDiv(-c, b));
+    }
+
     SkScalar discrim = SkScalarSquare(b) - SkScalarMul(foura, c);
     if (discrim < 0) {
         discrim = -discrim;