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+/*
+ * Copyright 2013 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#ifndef SkPerlinNoiseShader_DEFINED
+#define SkPerlinNoiseShader_DEFINED
+
+#include "include/core/SkShader.h"
+
+/** \class SkPerlinNoiseShader
+
+ SkPerlinNoiseShader creates an image using the Perlin turbulence function.
+
+ It can produce tileable noise if asked to stitch tiles and provided a tile size.
+ In order to fill a large area with repeating noise, set the stitchTiles flag to
+ true, and render exactly a single tile of noise. Without this flag, the result
+ will contain visible seams between tiles.
+
+ The algorithm used is described here :
+ http://www.w3.org/TR/SVG/filters.html#feTurbulenceElement
+*/
+class SK_API SkPerlinNoiseShader {
+public:
+ /**
+ * This will construct Perlin noise of the given type (Fractal Noise or Turbulence).
+ *
+ * Both base frequencies (X and Y) have a usual range of (0..1) and must be non-negative.
+ *
+ * The number of octaves provided should be fairly small, with a limit of 255 enforced.
+ * Each octave doubles the frequency, so 10 octaves would produce noise from
+ * baseFrequency * 1, * 2, * 4, ..., * 512, which quickly yields insignificantly small
+ * periods and resembles regular unstructured noise rather than Perlin noise.
+ *
+ * If tileSize isn't NULL or an empty size, the tileSize parameter will be used to modify
+ * the frequencies so that the noise will be tileable for the given tile size. If tileSize
+ * is NULL or an empty size, the frequencies will be used as is without modification.
+ */
+ static sk_sp<SkShader> MakeFractalNoise(SkScalar baseFrequencyX, SkScalar baseFrequencyY,
+ int numOctaves, SkScalar seed,
+ const SkISize* tileSize = nullptr);
+ static sk_sp<SkShader> MakeTurbulence(SkScalar baseFrequencyX, SkScalar baseFrequencyY,
+ int numOctaves, SkScalar seed,
+ const SkISize* tileSize = nullptr);
+
+ static void RegisterFlattenables();
+
+private:
+ SkPerlinNoiseShader() = delete;
+};
+
+#endif