83e939bcb7
- Added default implementation of onMakeContext to support use in android. Searches for uses: "public SkShader" package:^chromium$ -file:^src/third_party/skia package:^aosp.* "public SkShader" -file:external/skia -file:.*third_party/skia package:^android$ "public SkShader" -file:external/skia -file:.*third_party/skia ... shows that no subclass overrides onCreateContext. TBR=reed@google.com TBR=mtklein@google.com Change-Id: I8bd5f57a79534574e344b165d31dccee41c31767 Reviewed-on: https://skia-review.googlesource.com/8140 Commit-Queue: Herb Derby <herb@google.com> Reviewed-by: Herb Derby <herb@google.com>
115 lines
4.5 KiB
C++
115 lines
4.5 KiB
C++
/*
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* Copyright 2013 Google Inc.
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*
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* Use of this source code is governed by a BSD-style license that can be
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* found in the LICENSE file.
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*/
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#ifndef SkPerlinNoiseShader_DEFINED
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#define SkPerlinNoiseShader_DEFINED
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#include "SkShader.h"
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/** \class SkPerlinNoiseShader
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SkPerlinNoiseShader creates an image using the Perlin turbulence function.
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It can produce tileable noise if asked to stitch tiles and provided a tile size.
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In order to fill a large area with repeating noise, set the stitchTiles flag to
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true, and render exactly a single tile of noise. Without this flag, the result
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will contain visible seams between tiles.
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The algorithm used is described here :
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http://www.w3.org/TR/SVG/filters.html#feTurbulenceElement
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*/
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class SK_API SkPerlinNoiseShader : public SkShader {
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public:
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struct StitchData;
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struct PaintingData;
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/**
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* About the noise types : the difference between the 2 is just minor tweaks to the algorithm,
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* they're not 2 entirely different noises. The output looks different, but once the noise is
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* generated in the [1, -1] range, the output is brought back in the [0, 1] range by doing :
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* kFractalNoise_Type : noise * 0.5 + 0.5
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* kTurbulence_Type : abs(noise)
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* Very little differences between the 2 types, although you can tell the difference visually.
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*/
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enum Type {
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kFractalNoise_Type,
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kTurbulence_Type,
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kFirstType = kFractalNoise_Type,
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kLastType = kTurbulence_Type
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};
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/**
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* This will construct Perlin noise of the given type (Fractal Noise or Turbulence).
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*
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* Both base frequencies (X and Y) have a usual range of (0..1).
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*
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* The number of octaves provided should be fairly small, although no limit is enforced.
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* Each octave doubles the frequency, so 10 octaves would produce noise from
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* baseFrequency * 1, * 2, * 4, ..., * 512, which quickly yields insignificantly small
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* periods and resembles regular unstructured noise rather than Perlin noise.
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*
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* If tileSize isn't NULL or an empty size, the tileSize parameter will be used to modify
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* the frequencies so that the noise will be tileable for the given tile size. If tileSize
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* is NULL or an empty size, the frequencies will be used as is without modification.
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*/
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static sk_sp<SkShader> MakeFractalNoise(SkScalar baseFrequencyX, SkScalar baseFrequencyY,
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int numOctaves, SkScalar seed,
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const SkISize* tileSize = nullptr);
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static sk_sp<SkShader> MakeTurbulence(SkScalar baseFrequencyX, SkScalar baseFrequencyY,
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int numOctaves, SkScalar seed,
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const SkISize* tileSize = nullptr);
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class PerlinNoiseShaderContext : public SkShader::Context {
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public:
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PerlinNoiseShaderContext(const SkPerlinNoiseShader& shader, const ContextRec&);
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virtual ~PerlinNoiseShaderContext();
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void shadeSpan(int x, int y, SkPMColor[], int count) override;
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private:
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SkPMColor shade(const SkPoint& point, StitchData& stitchData) const;
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SkScalar calculateTurbulenceValueForPoint(
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int channel,
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StitchData& stitchData, const SkPoint& point) const;
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SkScalar noise2D(int channel,
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const StitchData& stitchData, const SkPoint& noiseVector) const;
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SkMatrix fMatrix;
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PaintingData* fPaintingData;
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typedef SkShader::Context INHERITED;
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};
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#if SK_SUPPORT_GPU
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sk_sp<GrFragmentProcessor> asFragmentProcessor(const AsFPArgs&) const override;
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#endif
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SK_TO_STRING_OVERRIDE()
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SK_DECLARE_PUBLIC_FLATTENABLE_DESERIALIZATION_PROCS(SkPerlinNoiseShader)
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protected:
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void flatten(SkWriteBuffer&) const override;
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Context* onMakeContext(const ContextRec&, SkArenaAlloc* storage) const override;
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private:
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SkPerlinNoiseShader(SkPerlinNoiseShader::Type type, SkScalar baseFrequencyX,
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SkScalar baseFrequencyY, int numOctaves, SkScalar seed,
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const SkISize* tileSize);
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virtual ~SkPerlinNoiseShader();
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const SkPerlinNoiseShader::Type fType;
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const SkScalar fBaseFrequencyX;
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const SkScalar fBaseFrequencyY;
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const int fNumOctaves;
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const SkScalar fSeed;
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const SkISize fTileSize;
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const bool fStitchTiles;
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typedef SkShader INHERITED;
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};
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#endif
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