Generate Signed Distance Field directly from vector path

Add SkGenerateDistanceFieldFromPath API to generate signed distance field directly from SkPath.

BUG=skia:
GOLD_TRYBOT_URL= https://gold.skia.org/search2?unt=true&query=source_type%3Dgm&master=false&issue=1643143002

Committed: https://skia.googlesource.com/skia/+/4de97a64e8829323a7070b623411d9f9ddb0cd0f
Committed: https://skia.googlesource.com/skia/+/e8f0a7b986f1e5583c9bc162efcdd92fd6430549
Review-Url: https://codereview.chromium.org/1643143002

1 files changed, 35 insertions, 0 deletions

diff --git a/src/gpu/GrDistanceFieldGenFromVector.h b/src/gpu/GrDistanceFieldGenFromVector.h
new file mode 100644
index 0000000000..1d83ee28ff
--- /dev/null
+++ b/src/gpu/GrDistanceFieldGenFromVector.h
@@ -0,0 +1,35 @@
+/*
+ * Copyright 2016 ARM Ltd.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#ifndef GrDistanceFieldGenFromVector_DEFINED
+#define GrDistanceFieldGenFromVector_DEFINED
+
+#include "SkDistanceFieldGen.h"
+#include "SkPath.h"
+#include "SkMatrix.h"
+
+/** Given a vector path, generate the associated distance field.
+
+ *  @param distanceField     The distance field to be generated. Should already be allocated
+ *                           by the client with the padding defined in "SkDistanceFieldGen.h".
+ *  @param path              The path we're using to generate the distance field.
+ *  @param matrix            Transformation matrix for path.
+ *  @param width             Width of the distance field.
+ *  @param height            Height of the distance field.
+ *  @param rowBytes          Size of each row in the distance field, in bytes.
+ */
+bool GrGenerateDistanceFieldFromPath(unsigned char* distanceField,
+                                     const SkPath& path, const SkMatrix& viewMatrix,
+                                     int width, int height, size_t rowBytes);
+
+inline bool IsDistanceFieldSupportedFillType(SkPath::FillType fFillType)
+{
+	return (SkPath::kEvenOdd_FillType == fFillType ||
+            SkPath::kInverseEvenOdd_FillType == fFillType);
+}
+
+#endif