Add implicit hairline conic rendering to GPU

src/core/SkGeometry.cpp

Index: src/core/SkGeometry.cpp
diff --git a/src/core/SkGeometry.cpp b/src/core/SkGeometry.cpp
index a12f961948c77b6695ce2e250fa66d94e3eef96c..e6049f9f7bd993804d1fc7e8948b936cb02fad6f 100644
--- a/src/core/SkGeometry.cpp
+++ b/src/core/SkGeometry.cpp
@@ -382,20 +382,8 @@ int SkChopQuadAtXExtrema(const SkPoint src[3], SkPoint dst[5])
     return 0;
 }
 
-//  F(t)    = a (1 - t) ^ 2 + 2 b t (1 - t) + c t ^ 2
-//  F'(t)   = 2 (b - a) + 2 (a - 2b + c) t
-//  F''(t)  = 2 (a - 2b + c)
-//
-//  A = 2 (b - a)
-//  B = 2 (a - 2b + c)
-//
-//  Maximum curvature for a quadratic means solving
-//  Fx' Fx'' + Fy' Fy'' = 0
-//
-//  t = - (Ax Bx + Ay By) / (Bx ^ 2 + By ^ 2)
-//
-int SkChopQuadAtMaxCurvature(const SkPoint src[3], SkPoint dst[5])
-{
+float SkGetTQuadAtMaxCurvature(const SkPoint src[3]) {
+
     SkScalar    Ax = src[1].fX - src[0].fX;
     SkScalar    Ay = src[1].fY - src[0].fY;
     SkScalar    Bx = src[0].fX - src[1].fX - src[1].fX + src[2].fX;
@@ -427,7 +415,24 @@ int SkChopQuadAtMaxCurvature(const SkPoint src[3], SkPoint dst[5])
         }
     }
 #endif
+    return t;
+}
 
+//  F(t)    = a (1 - t) ^ 2 + 2 b t (1 - t) + c t ^ 2

[bsalomon, 2013/07/10 15:14:36]

Maybe these comments belong with the new function that does all the work?

+//  F'(t)   = 2 (b - a) + 2 (a - 2b + c) t
+//  F''(t)  = 2 (a - 2b + c)
+//
+//  A = 2 (b - a)
+//  B = 2 (a - 2b + c)
+//
+//  Maximum curvature for a quadratic means solving
+//  Fx' Fx'' + Fy' Fy'' = 0
+//
+//  t = - (Ax Bx + Ay By) / (Bx ^ 2 + By ^ 2)
+//
+int SkChopQuadAtMaxCurvature(const SkPoint src[3], SkPoint dst[5])
+{
+    SkScalar t = SkGetTQuadAtMaxCurvature(src);
     if (t == 0)
     {
         memcpy(dst, src, 3 * sizeof(SkPoint));