Add implicit hairline conic rendering to GPU

include/core/SkGeometry.h

 
 /*
  * Copyright 2006 The Android Open Source Project
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 
 #ifndef SkGeometry_DEFINED
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 /** Given 3 points on a quadratic bezier, chop it into 1, 2 beziers such that
     the resulting beziers are monotonic in Y. This is called by the scan converter.
     Depending on what is returned, dst[] is treated as follows
     0   dst[0..2] is the original quad
     1   dst[0..2] and dst[2..4] are the two new quads
 */
 int SkChopQuadAtYExtrema(const SkPoint src[3], SkPoint dst[5]);
 int SkChopQuadAtXExtrema(const SkPoint src[3], SkPoint dst[5]);
 
+/** Given 3 points on a quadratic bezier, if the point of maximum
+    curvature exists on the segment, returns the t value for this
+    point along the curve. Otherwise it will return a value of 0.
+*/
+float SkFindQuadMaxCurvature(const SkPoint src[3]);
+
 /** Given 3 points on a quadratic bezier, divide it into 2 quadratics
     if the point of maximum curvature exists on the quad segment.
     Depending on what is returned, dst[] is treated as follows
     1   dst[0..2] is the original quad
     2   dst[0..2] and dst[2..4] are the two new quads
     If dst == null, it is ignored and only the count is returned.
 */
 int SkChopQuadAtMaxCurvature(const SkPoint src[3], SkPoint dst[5]);
 
 /** Given 3 points on a quadratic bezier, use degree elevation to
@@ skipping 207 matching lines @@
 private:
     enum {
         kQuadCount = 8, // should handle most conics
         kPointCount = 1 + 2 * kQuadCount,
     };
     SkAutoSTMalloc<kPointCount, SkPoint> fStorage;
     int fQuadCount; // #quads for current usage
 };
 
 #endif