[Reland] Relocate shaders to own dir

Consolidate all shader impls under src/shaders/.

(reland of https://skia-review.googlesource.com/c/17927/)

Change-Id: I7918bdc1aafe842ed194412ba95b9ae53a2ec1d7
Reviewed-on: https://skia-review.googlesource.com/18146
Reviewed-by: Florin Malita <fmalita@chromium.org>
Commit-Queue: Florin Malita <fmalita@chromium.org>

1 files changed, 1496 insertions, 0 deletions

diff --git a/src/shaders/SkPerlinNoiseShader.cpp b/src/shaders/SkPerlinNoiseShader.cpp
new file mode 100644
index 0000000000..9d8d030002
--- /dev/null
+++ b/src/shaders/SkPerlinNoiseShader.cpp
@@ -0,0 +1,1496 @@
+/*
+ * Copyright 2013 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#include "SkPerlinNoiseShader.h"
+
+#include "SkArenaAlloc.h"
+#include "SkDither.h"
+#include "SkColorFilter.h"
+#include "SkReadBuffer.h"
+#include "SkWriteBuffer.h"
+#include "SkShader.h"
+#include "SkUnPreMultiply.h"
+#include "SkString.h"
+
+#if SK_SUPPORT_GPU
+#include "GrContext.h"
+#include "GrCoordTransform.h"
+#include "SkGr.h"
+#include "effects/GrConstColorProcessor.h"
+#include "glsl/GrGLSLFragmentProcessor.h"
+#include "glsl/GrGLSLFragmentShaderBuilder.h"
+#include "glsl/GrGLSLProgramDataManager.h"
+#include "glsl/GrGLSLUniformHandler.h"
+#endif
+
+static const int kBlockSize = 256;
+static const int kBlockMask = kBlockSize - 1;
+static const int kPerlinNoise = 4096;
+static const int kRandMaximum = SK_MaxS32; // 2**31 - 1
+
+static uint8_t improved_noise_permutations[] = {
+    151, 160, 137,  91,  90,  15, 131,  13, 201,  95,  96,  53, 194, 233,   7, 225, 140,  36, 103,
+     30,  69, 142,   8,  99,  37, 240,  21,  10,  23, 190,   6, 148, 247, 120, 234,  75,   0,  26,
+    197,  62,  94, 252, 219, 203, 117,  35,  11,  32,  57, 177,  33,  88, 237, 149,  56,  87, 174,
+     20, 125, 136, 171, 168,  68, 175,  74, 165,  71, 134, 139,  48,  27, 166,  77, 146, 158, 231,
+     83, 111, 229, 122,  60, 211, 133, 230, 220, 105,  92,  41,  55,  46, 245,  40, 244, 102, 143,
+     54,  65,  25,  63, 161,   1, 216,  80,  73, 209,  76, 132, 187, 208,  89,  18, 169, 200, 196,
+    135, 130, 116, 188, 159,  86, 164, 100, 109, 198, 173, 186,   3,  64,  52, 217, 226, 250, 124,
+    123,   5, 202,  38, 147, 118, 126, 255,  82,  85, 212, 207, 206,  59, 227,  47,  16,  58,  17,
+    182, 189,  28,  42, 223, 183, 170, 213, 119, 248, 152,   2,  44, 154, 163,  70, 221, 153, 101,
+    155, 167,  43, 172,   9, 129,  22,  39, 253,  19,  98, 108, 110,  79, 113, 224, 232, 178, 185,
+    112, 104, 218, 246,  97, 228, 251,  34, 242, 193, 238, 210, 144,  12, 191, 179, 162, 241,  81,
+     51, 145, 235, 249,  14, 239, 107,  49, 192, 214,  31, 181, 199, 106, 157, 184,  84, 204, 176,
+    115, 121,  50,  45, 127,   4, 150, 254, 138, 236, 205,  93, 222, 114,  67,  29,  24,  72, 243,
+    141, 128, 195,  78,  66, 215,  61, 156, 180,
+    151, 160, 137,  91,  90,  15, 131,  13, 201,  95,  96,  53, 194, 233,   7, 225, 140,  36, 103,
+     30,  69, 142,   8,  99,  37, 240,  21,  10,  23, 190,   6, 148, 247, 120, 234,  75,   0,  26,
+    197,  62,  94, 252, 219, 203, 117,  35,  11,  32,  57, 177,  33,  88, 237, 149,  56,  87, 174,
+     20, 125, 136, 171, 168,  68, 175,  74, 165,  71, 134, 139,  48,  27, 166,  77, 146, 158, 231,
+     83, 111, 229, 122,  60, 211, 133, 230, 220, 105,  92,  41,  55,  46, 245,  40, 244, 102, 143,
+     54,  65,  25,  63, 161,   1, 216,  80,  73, 209,  76, 132, 187, 208,  89,  18, 169, 200, 196,
+    135, 130, 116, 188, 159,  86, 164, 100, 109, 198, 173, 186,   3,  64,  52, 217, 226, 250, 124,
+    123,   5, 202,  38, 147, 118, 126, 255,  82,  85, 212, 207, 206,  59, 227,  47,  16,  58,  17,
+    182, 189,  28,  42, 223, 183, 170, 213, 119, 248, 152,   2,  44, 154, 163,  70, 221, 153, 101,
+    155, 167,  43, 172,   9, 129,  22,  39, 253,  19,  98, 108, 110,  79, 113, 224, 232, 178, 185,
+    112, 104, 218, 246,  97, 228, 251,  34, 242, 193, 238, 210, 144,  12, 191, 179, 162, 241,  81,
+     51, 145, 235, 249,  14, 239, 107,  49, 192, 214,  31, 181, 199, 106, 157, 184,  84, 204, 176,
+    115, 121,  50,  45, 127,   4, 150, 254, 138, 236, 205,  93, 222, 114,  67,  29,  24,  72, 243,
+    141, 128, 195,  78,  66, 215,  61, 156, 180
+};
+
+class SkPerlinNoiseShaderImpl : public SkShaderBase {
+public:
+    struct StitchData;
+    struct PaintingData;
+
+    /**
+     *  About the noise types : the difference between the first 2 is just minor tweaks to the
+     *  algorithm, they're not 2 entirely different noises. The output looks different, but once the
+     *  noise is generated in the [1, -1] range, the output is brought back in the [0, 1] range by
+     *  doing :
+     *  kFractalNoise_Type : noise * 0.5 + 0.5
+     *  kTurbulence_Type   : abs(noise)
+     *  Very little differences between the 2 types, although you can tell the difference visually.
+     *  "Improved" is based on the Improved Perlin Noise algorithm described at
+     *  http://mrl.nyu.edu/~perlin/noise/. It is quite distinct from the other two, and the noise is
+     *  a 2D slice of a 3D noise texture. Minor changes to the Z coordinate will result in minor
+     *  changes to the noise, making it suitable for animated noise.
+     */
+    enum Type {
+        kFractalNoise_Type,
+        kTurbulence_Type,
+        kImprovedNoise_Type,
+        kFirstType = kFractalNoise_Type,
+        kLastType = kImprovedNoise_Type
+    };
+
+    SkPerlinNoiseShaderImpl(SkPerlinNoiseShaderImpl::Type type, SkScalar baseFrequencyX,
+                      SkScalar baseFrequencyY, int numOctaves, SkScalar seed,
+                      const SkISize* tileSize);
+    ~SkPerlinNoiseShaderImpl() override;
+
+
+    class PerlinNoiseShaderContext : public Context {
+    public:
+        PerlinNoiseShaderContext(const SkPerlinNoiseShaderImpl& shader, const ContextRec&);
+        ~PerlinNoiseShaderContext() override;
+
+        void shadeSpan(int x, int y, SkPMColor[], int count) override;
+
+    private:
+        SkPMColor shade(const SkPoint& point, StitchData& stitchData) const;
+        SkScalar calculateTurbulenceValueForPoint(
+                                                  int channel,
+                                                  StitchData& stitchData, const SkPoint& point) const;
+        SkScalar calculateImprovedNoiseValueForPoint(int channel, const SkPoint& point) const;
+        SkScalar noise2D(int channel,
+                         const StitchData& stitchData, const SkPoint& noiseVector) const;
+
+        SkMatrix fMatrix;
+        PaintingData* fPaintingData;
+
+        typedef Context INHERITED;
+    };
+
+#if SK_SUPPORT_GPU
+    sk_sp<GrFragmentProcessor> asFragmentProcessor(const AsFPArgs&) const override;
+#endif
+
+    SK_TO_STRING_OVERRIDE()
+    SK_DECLARE_PUBLIC_FLATTENABLE_DESERIALIZATION_PROCS(SkPerlinNoiseShaderImpl)
+
+protected:
+    void flatten(SkWriteBuffer&) const override;
+    Context* onMakeContext(const ContextRec&, SkArenaAlloc*) const override;
+
+private:
+    const SkPerlinNoiseShaderImpl::Type fType;
+    const SkScalar                  fBaseFrequencyX;
+    const SkScalar                  fBaseFrequencyY;
+    const int                       fNumOctaves;
+    const SkScalar                  fSeed;
+    const SkISize                   fTileSize;
+    const bool                      fStitchTiles;
+
+    friend class ::SkPerlinNoiseShader;
+
+    typedef SkShaderBase INHERITED;
+};
+
+namespace {
+
+// noiseValue is the color component's value (or color)
+// limitValue is the maximum perlin noise array index value allowed
+// newValue is the current noise dimension (either width or height)
+inline int checkNoise(int noiseValue, int limitValue, int newValue) {
+    // If the noise value would bring us out of bounds of the current noise array while we are
+    // stiching noise tiles together, wrap the noise around the current dimension of the noise to
+    // stay within the array bounds in a continuous fashion (so that tiling lines are not visible)
+    if (noiseValue >= limitValue) {
+        noiseValue -= newValue;
+    }
+    return noiseValue;
+}
+
+inline SkScalar smoothCurve(SkScalar t) {
+    return t * t * (3 - 2 * t);
+}
+
+} // end namespace
+
+struct SkPerlinNoiseShaderImpl::StitchData {
+    StitchData()
+      : fWidth(0)
+      , fWrapX(0)
+      , fHeight(0)
+      , fWrapY(0)
+    {}
+
+    bool operator==(const StitchData& other) const {
+        return fWidth == other.fWidth &&
+               fWrapX == other.fWrapX &&
+               fHeight == other.fHeight &&
+               fWrapY == other.fWrapY;
+    }
+
+    int fWidth; // How much to subtract to wrap for stitching.
+    int fWrapX; // Minimum value to wrap.
+    int fHeight;
+    int fWrapY;
+};
+
+struct SkPerlinNoiseShaderImpl::PaintingData {
+    PaintingData(const SkISize& tileSize, SkScalar seed,
+                 SkScalar baseFrequencyX, SkScalar baseFrequencyY,
+                 const SkMatrix& matrix)
+    {
+        SkVector vec[2] = {
+            { SkScalarInvert(baseFrequencyX),   SkScalarInvert(baseFrequencyY)  },
+            { SkIntToScalar(tileSize.fWidth),   SkIntToScalar(tileSize.fHeight) },
+        };
+        matrix.mapVectors(vec, 2);
+
+        fBaseFrequency.set(SkScalarInvert(vec[0].fX), SkScalarInvert(vec[0].fY));
+        fTileSize.set(SkScalarRoundToInt(vec[1].fX), SkScalarRoundToInt(vec[1].fY));
+        this->init(seed);
+        if (!fTileSize.isEmpty()) {
+            this->stitch();
+        }
+
+#if SK_SUPPORT_GPU
+        fPermutationsBitmap.setInfo(SkImageInfo::MakeA8(kBlockSize, 1));
+        fPermutationsBitmap.setPixels(fLatticeSelector);
+
+        fNoiseBitmap.setInfo(SkImageInfo::MakeN32Premul(kBlockSize, 4));
+        fNoiseBitmap.setPixels(fNoise[0][0]);
+
+        fImprovedPermutationsBitmap.setInfo(SkImageInfo::MakeA8(256, 1));
+        fImprovedPermutationsBitmap.setPixels(improved_noise_permutations);
+
+        fGradientBitmap.setInfo(SkImageInfo::MakeN32Premul(16, 1));
+        static uint8_t gradients[] = { 2, 2, 1, 0,
+                                       0, 2, 1, 0,
+                                       2, 0, 1, 0,
+                                       0, 0, 1, 0,
+                                       2, 1, 2, 0,
+                                       0, 1, 2, 0,
+                                       2, 1, 0, 0,
+                                       0, 1, 0, 0,
+                                       1, 2, 2, 0,
+                                       1, 0, 2, 0,
+                                       1, 2, 0, 0,
+                                       1, 0, 0, 0,
+                                       2, 2, 1, 0,
+                                       1, 0, 2, 0,
+                                       0, 2, 1, 0,
+                                       1, 0, 0, 0 };
+        fGradientBitmap.setPixels(gradients);
+#endif
+    }
+
+    int         fSeed;
+    uint8_t     fLatticeSelector[kBlockSize];
+    uint16_t    fNoise[4][kBlockSize][2];
+    SkPoint     fGradient[4][kBlockSize];
+    SkISize     fTileSize;
+    SkVector    fBaseFrequency;
+    StitchData  fStitchDataInit;
+
+private:
+
+#if SK_SUPPORT_GPU
+    SkBitmap   fPermutationsBitmap;
+    SkBitmap   fNoiseBitmap;
+    SkBitmap   fImprovedPermutationsBitmap;
+    SkBitmap   fGradientBitmap;
+#endif
+
+    inline int random()  {
+        static const int gRandAmplitude = 16807; // 7**5; primitive root of m
+        static const int gRandQ = 127773; // m / a
+        static const int gRandR = 2836; // m % a
+
+        int result = gRandAmplitude * (fSeed % gRandQ) - gRandR * (fSeed / gRandQ);
+        if (result <= 0)
+            result += kRandMaximum;
+        fSeed = result;
+        return result;
+    }
+
+    // Only called once. Could be part of the constructor.
+    void init(SkScalar seed)
+    {
+        static const SkScalar gInvBlockSizef = SkScalarInvert(SkIntToScalar(kBlockSize));
+
+        // According to the SVG spec, we must truncate (not round) the seed value.
+        fSeed = SkScalarTruncToInt(seed);
+        // The seed value clamp to the range [1, kRandMaximum - 1].
+        if (fSeed <= 0) {
+            fSeed = -(fSeed % (kRandMaximum - 1)) + 1;
+        }
+        if (fSeed > kRandMaximum - 1) {
+            fSeed = kRandMaximum - 1;
+        }
+        for (int channel = 0; channel < 4; ++channel) {
+            for (int i = 0; i < kBlockSize; ++i) {
+                fLatticeSelector[i] = i;
+                fNoise[channel][i][0] = (random() % (2 * kBlockSize));
+                fNoise[channel][i][1] = (random() % (2 * kBlockSize));
+            }
+        }
+        for (int i = kBlockSize - 1; i > 0; --i) {
+            int k = fLatticeSelector[i];
+            int j = random() % kBlockSize;
+            SkASSERT(j >= 0);
+            SkASSERT(j < kBlockSize);
+            fLatticeSelector[i] = fLatticeSelector[j];
+            fLatticeSelector[j] = k;
+        }
+
+        // Perform the permutations now
+        {
+            // Copy noise data
+            uint16_t noise[4][kBlockSize][2];
+            for (int i = 0; i < kBlockSize; ++i) {
+                for (int channel = 0; channel < 4; ++channel) {
+                    for (int j = 0; j < 2; ++j) {
+                        noise[channel][i][j] = fNoise[channel][i][j];
+                    }
+                }
+            }
+            // Do permutations on noise data
+            for (int i = 0; i < kBlockSize; ++i) {
+                for (int channel = 0; channel < 4; ++channel) {
+                    for (int j = 0; j < 2; ++j) {
+                        fNoise[channel][i][j] = noise[channel][fLatticeSelector[i]][j];
+                    }
+                }
+            }
+        }
+
+        // Half of the largest possible value for 16 bit unsigned int
+        static const SkScalar gHalfMax16bits = 32767.5f;
+
+        // Compute gradients from permutated noise data
+        for (int channel = 0; channel < 4; ++channel) {
+            for (int i = 0; i < kBlockSize; ++i) {
+                fGradient[channel][i] = SkPoint::Make(
+                    (fNoise[channel][i][0] - kBlockSize) * gInvBlockSizef,
+                    (fNoise[channel][i][1] - kBlockSize) * gInvBlockSizef);
+                fGradient[channel][i].normalize();
+                // Put the normalized gradient back into the noise data
+                fNoise[channel][i][0] = SkScalarRoundToInt(
+                                               (fGradient[channel][i].fX + 1) * gHalfMax16bits);
+                fNoise[channel][i][1] = SkScalarRoundToInt(
+                                               (fGradient[channel][i].fY + 1) * gHalfMax16bits);
+            }
+        }
+    }
+
+    // Only called once. Could be part of the constructor.
+    void stitch() {
+        SkScalar tileWidth  = SkIntToScalar(fTileSize.width());
+        SkScalar tileHeight = SkIntToScalar(fTileSize.height());
+        SkASSERT(tileWidth > 0 && tileHeight > 0);
+        // When stitching tiled turbulence, the frequencies must be adjusted
+        // so that the tile borders will be continuous.
+        if (fBaseFrequency.fX) {
+            SkScalar lowFrequencx =
+                SkScalarFloorToScalar(tileWidth * fBaseFrequency.fX) / tileWidth;
+            SkScalar highFrequencx =
+                SkScalarCeilToScalar(tileWidth * fBaseFrequency.fX) / tileWidth;
+            // BaseFrequency should be non-negative according to the standard.
+            if (fBaseFrequency.fX / lowFrequencx < highFrequencx / fBaseFrequency.fX) {
+                fBaseFrequency.fX = lowFrequencx;
+            } else {
+                fBaseFrequency.fX = highFrequencx;
+            }
+        }
+        if (fBaseFrequency.fY) {
+            SkScalar lowFrequency =
+                SkScalarFloorToScalar(tileHeight * fBaseFrequency.fY) / tileHeight;
+            SkScalar highFrequency =
+                SkScalarCeilToScalar(tileHeight * fBaseFrequency.fY) / tileHeight;
+            if (fBaseFrequency.fY / lowFrequency < highFrequency / fBaseFrequency.fY) {
+                fBaseFrequency.fY = lowFrequency;
+            } else {
+                fBaseFrequency.fY = highFrequency;
+            }
+        }
+        // Set up TurbulenceInitial stitch values.
+        fStitchDataInit.fWidth  =
+            SkScalarRoundToInt(tileWidth * fBaseFrequency.fX);
+        fStitchDataInit.fWrapX  = kPerlinNoise + fStitchDataInit.fWidth;
+        fStitchDataInit.fHeight =
+            SkScalarRoundToInt(tileHeight * fBaseFrequency.fY);
+        fStitchDataInit.fWrapY  = kPerlinNoise + fStitchDataInit.fHeight;
+    }
+
+public:
+
+#if SK_SUPPORT_GPU
+    const SkBitmap& getPermutationsBitmap() const { return fPermutationsBitmap; }
+
+    const SkBitmap& getNoiseBitmap() const { return fNoiseBitmap; }
+
+    const SkBitmap& getImprovedPermutationsBitmap() const { return fImprovedPermutationsBitmap; }
+
+    const SkBitmap& getGradientBitmap() const { return fGradientBitmap; }
+#endif
+};
+
+SkPerlinNoiseShaderImpl::SkPerlinNoiseShaderImpl(SkPerlinNoiseShaderImpl::Type type,
+                                         SkScalar baseFrequencyX,
+                                         SkScalar baseFrequencyY,
+                                         int numOctaves,
+                                         SkScalar seed,
+                                         const SkISize* tileSize)
+  : fType(type)
+  , fBaseFrequencyX(baseFrequencyX)
+  , fBaseFrequencyY(baseFrequencyY)
+  , fNumOctaves(numOctaves > 255 ? 255 : numOctaves/*[0,255] octaves allowed*/)
+  , fSeed(seed)
+  , fTileSize(nullptr == tileSize ? SkISize::Make(0, 0) : *tileSize)
+  , fStitchTiles(!fTileSize.isEmpty())
+{
+    SkASSERT(numOctaves >= 0 && numOctaves < 256);
+}
+
+SkPerlinNoiseShaderImpl::~SkPerlinNoiseShaderImpl() {
+}
+
+sk_sp<SkFlattenable> SkPerlinNoiseShaderImpl::CreateProc(SkReadBuffer& buffer) {
+    Type type = (Type)buffer.readInt();
+    SkScalar freqX = buffer.readScalar();
+    SkScalar freqY = buffer.readScalar();
+    int octaves = buffer.readInt();
+    SkScalar seed = buffer.readScalar();
+    SkISize tileSize;
+    tileSize.fWidth = buffer.readInt();
+    tileSize.fHeight = buffer.readInt();
+
+    switch (type) {
+        case kFractalNoise_Type:
+            return SkPerlinNoiseShader::MakeFractalNoise(freqX, freqY, octaves, seed, &tileSize);
+        case kTurbulence_Type:
+            return SkPerlinNoiseShader::MakeTurbulence(freqX, freqY, octaves, seed, &tileSize);
+        case kImprovedNoise_Type:
+            return SkPerlinNoiseShader::MakeImprovedNoise(freqX, freqY, octaves, seed);
+        default:
+            return nullptr;
+    }
+}
+
+void SkPerlinNoiseShaderImpl::flatten(SkWriteBuffer& buffer) const {
+    buffer.writeInt((int) fType);
+    buffer.writeScalar(fBaseFrequencyX);
+    buffer.writeScalar(fBaseFrequencyY);
+    buffer.writeInt(fNumOctaves);
+    buffer.writeScalar(fSeed);
+    buffer.writeInt(fTileSize.fWidth);
+    buffer.writeInt(fTileSize.fHeight);
+}
+
+SkScalar SkPerlinNoiseShaderImpl::PerlinNoiseShaderContext::noise2D(
+        int channel, const StitchData& stitchData, const SkPoint& noiseVector) const {
+    struct Noise {
+        int noisePositionIntegerValue;
+        int nextNoisePositionIntegerValue;
+        SkScalar noisePositionFractionValue;
+        Noise(SkScalar component)
+        {
+            SkScalar position = component + kPerlinNoise;
+            noisePositionIntegerValue = SkScalarFloorToInt(position);
+            noisePositionFractionValue = position - SkIntToScalar(noisePositionIntegerValue);
+            nextNoisePositionIntegerValue = noisePositionIntegerValue + 1;
+        }
+    };
+    Noise noiseX(noiseVector.x());
+    Noise noiseY(noiseVector.y());
+    SkScalar u, v;
+    const SkPerlinNoiseShaderImpl& perlinNoiseShader = static_cast<const SkPerlinNoiseShaderImpl&>(fShader);
+    // If stitching, adjust lattice points accordingly.
+    if (perlinNoiseShader.fStitchTiles) {
+        noiseX.noisePositionIntegerValue =
+            checkNoise(noiseX.noisePositionIntegerValue, stitchData.fWrapX, stitchData.fWidth);
+        noiseY.noisePositionIntegerValue =
+            checkNoise(noiseY.noisePositionIntegerValue, stitchData.fWrapY, stitchData.fHeight);
+        noiseX.nextNoisePositionIntegerValue =
+            checkNoise(noiseX.nextNoisePositionIntegerValue, stitchData.fWrapX, stitchData.fWidth);
+        noiseY.nextNoisePositionIntegerValue =
+            checkNoise(noiseY.nextNoisePositionIntegerValue, stitchData.fWrapY, stitchData.fHeight);
+    }
+    noiseX.noisePositionIntegerValue &= kBlockMask;
+    noiseY.noisePositionIntegerValue &= kBlockMask;
+    noiseX.nextNoisePositionIntegerValue &= kBlockMask;
+    noiseY.nextNoisePositionIntegerValue &= kBlockMask;
+    int i =
+        fPaintingData->fLatticeSelector[noiseX.noisePositionIntegerValue];
+    int j =
+        fPaintingData->fLatticeSelector[noiseX.nextNoisePositionIntegerValue];
+    int b00 = (i + noiseY.noisePositionIntegerValue) & kBlockMask;
+    int b10 = (j + noiseY.noisePositionIntegerValue) & kBlockMask;
+    int b01 = (i + noiseY.nextNoisePositionIntegerValue) & kBlockMask;
+    int b11 = (j + noiseY.nextNoisePositionIntegerValue) & kBlockMask;
+    SkScalar sx = smoothCurve(noiseX.noisePositionFractionValue);
+    SkScalar sy = smoothCurve(noiseY.noisePositionFractionValue);
+
+    if (sx < 0 || sy < 0 || sx > 1 || sy > 1) {
+        return 0;  // Check for pathological inputs.
+    }
+    
+    // This is taken 1:1 from SVG spec: http://www.w3.org/TR/SVG11/filters.html#feTurbulenceElement
+    SkPoint fractionValue = SkPoint::Make(noiseX.noisePositionFractionValue,
+                                          noiseY.noisePositionFractionValue); // Offset (0,0)
+    u = fPaintingData->fGradient[channel][b00].dot(fractionValue);
+    fractionValue.fX -= SK_Scalar1; // Offset (-1,0)
+    v = fPaintingData->fGradient[channel][b10].dot(fractionValue);
+    SkScalar a = SkScalarInterp(u, v, sx);
+    fractionValue.fY -= SK_Scalar1; // Offset (-1,-1)
+    v = fPaintingData->fGradient[channel][b11].dot(fractionValue);
+    fractionValue.fX = noiseX.noisePositionFractionValue; // Offset (0,-1)
+    u = fPaintingData->fGradient[channel][b01].dot(fractionValue);
+    SkScalar b = SkScalarInterp(u, v, sx);
+    return SkScalarInterp(a, b, sy);
+}
+
+SkScalar SkPerlinNoiseShaderImpl::PerlinNoiseShaderContext::calculateTurbulenceValueForPoint(
+        int channel, StitchData& stitchData, const SkPoint& point) const {
+    const SkPerlinNoiseShaderImpl& perlinNoiseShader = static_cast<const SkPerlinNoiseShaderImpl&>(fShader);
+    if (perlinNoiseShader.fStitchTiles) {
+        // Set up TurbulenceInitial stitch values.
+        stitchData = fPaintingData->fStitchDataInit;
+    }
+    SkScalar turbulenceFunctionResult = 0;
+    SkPoint noiseVector(SkPoint::Make(point.x() * fPaintingData->fBaseFrequency.fX,
+                                      point.y() * fPaintingData->fBaseFrequency.fY));
+    SkScalar ratio = SK_Scalar1;
+    for (int octave = 0; octave < perlinNoiseShader.fNumOctaves; ++octave) {
+        SkScalar noise = noise2D(channel, stitchData, noiseVector);
+        SkScalar numer = (perlinNoiseShader.fType == kFractalNoise_Type) ?
+                            noise : SkScalarAbs(noise);
+        turbulenceFunctionResult += numer / ratio;
+        noiseVector.fX *= 2;
+        noiseVector.fY *= 2;
+        ratio *= 2;
+        if (perlinNoiseShader.fStitchTiles) {
+            // Update stitch values
+            stitchData.fWidth  *= 2;
+            stitchData.fWrapX   = stitchData.fWidth + kPerlinNoise;
+            stitchData.fHeight *= 2;
+            stitchData.fWrapY   = stitchData.fHeight + kPerlinNoise;
+        }
+    }
+
+    // The value of turbulenceFunctionResult comes from ((turbulenceFunctionResult) + 1) / 2
+    // by fractalNoise and (turbulenceFunctionResult) by turbulence.
+    if (perlinNoiseShader.fType == kFractalNoise_Type) {
+        turbulenceFunctionResult = SkScalarHalf(turbulenceFunctionResult + 1);
+    }
+
+    if (channel == 3) { // Scale alpha by paint value
+        turbulenceFunctionResult *= SkIntToScalar(getPaintAlpha()) / 255;
+    }
+
+    // Clamp result
+    return SkScalarPin(turbulenceFunctionResult, 0, SK_Scalar1);
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+// Improved Perlin Noise based on Java implementation found at http://mrl.nyu.edu/~perlin/noise/
+static SkScalar fade(SkScalar t) {
+    return t * t * t * (t * (t * 6 - 15) + 10);
+}
+
+static SkScalar lerp(SkScalar t, SkScalar a, SkScalar b) {
+    return a + t * (b - a);
+}
+
+static SkScalar grad(int hash, SkScalar x, SkScalar y, SkScalar z) {
+    int h = hash & 15;
+    SkScalar u = h < 8 ? x : y;
+    SkScalar v = h < 4 ? y : h == 12 || h == 14 ? x : z;
+    return ((h & 1) == 0 ? u : -u) + ((h & 2) == 0 ? v : -v);
+}
+
+SkScalar SkPerlinNoiseShaderImpl::PerlinNoiseShaderContext::calculateImprovedNoiseValueForPoint(
+        int channel, const SkPoint& point) const {
+    const SkPerlinNoiseShaderImpl& perlinNoiseShader = static_cast<const SkPerlinNoiseShaderImpl&>(fShader);
+    SkScalar x = point.fX * perlinNoiseShader.fBaseFrequencyX;
+    SkScalar y = point.fY * perlinNoiseShader.fBaseFrequencyY;
+    // z offset between different channels, chosen arbitrarily
+    static const SkScalar CHANNEL_DELTA = 1000.0f;
+    SkScalar z = channel * CHANNEL_DELTA + perlinNoiseShader.fSeed;
+    SkScalar result = 0;
+    SkScalar ratio = SK_Scalar1;
+    for (int i = 0; i < perlinNoiseShader.fNumOctaves; i++) {
+        int X = SkScalarFloorToInt(x) & 255;
+        int Y = SkScalarFloorToInt(y) & 255;
+        int Z = SkScalarFloorToInt(z) & 255;
+        SkScalar px = x - SkScalarFloorToScalar(x);
+        SkScalar py = y - SkScalarFloorToScalar(y);
+        SkScalar pz = z - SkScalarFloorToScalar(z);
+        SkScalar u = fade(px);
+        SkScalar v = fade(py);
+        SkScalar w = fade(pz);
+        uint8_t* permutations = improved_noise_permutations;
+        int A  = permutations[X] + Y;
+        int AA = permutations[A] + Z;
+        int AB = permutations[A + 1] + Z;
+        int B  = permutations[X + 1] + Y;
+        int BA = permutations[B] + Z;
+        int BB = permutations[B + 1] + Z;
+        result += lerp(w, lerp(v, lerp(u, grad(permutations[AA    ], px    , py    , pz    ),
+                                          grad(permutations[BA    ], px - 1, py    , pz    )),
+                                  lerp(u, grad(permutations[AB    ], px    , py - 1, pz    ),
+                                          grad(permutations[BB    ], px - 1, py - 1, pz    ))),
+                          lerp(v, lerp(u, grad(permutations[AA + 1], px    , py    , pz - 1),
+                                          grad(permutations[BA + 1], px - 1, py    , pz - 1)),
+                                  lerp(u, grad(permutations[AB + 1], px    , py - 1, pz - 1),
+                                          grad(permutations[BB + 1], px - 1, py - 1, pz - 1)))) /
+                   ratio;
+        x *= 2;
+        y *= 2;
+        ratio *= 2;
+    }
+    result = SkScalarClampMax((result + 1.0f) / 2.0f, 1.0f);
+    return result;
+}
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+SkPMColor SkPerlinNoiseShaderImpl::PerlinNoiseShaderContext::shade(
+        const SkPoint& point, StitchData& stitchData) const {
+    const SkPerlinNoiseShaderImpl& perlinNoiseShader = static_cast<const SkPerlinNoiseShaderImpl&>(fShader);
+    SkPoint newPoint;
+    fMatrix.mapPoints(&newPoint, &point, 1);
+    newPoint.fX = SkScalarRoundToScalar(newPoint.fX);
+    newPoint.fY = SkScalarRoundToScalar(newPoint.fY);
+
+    U8CPU rgba[4];
+    for (int channel = 3; channel >= 0; --channel) {
+        SkScalar value;
+        if (perlinNoiseShader.fType == kImprovedNoise_Type) {
+            value = calculateImprovedNoiseValueForPoint(channel, newPoint);
+        }
+        else {
+            value = calculateTurbulenceValueForPoint(channel, stitchData, newPoint);
+        }
+        rgba[channel] = SkScalarFloorToInt(255 * value);
+    }
+    return SkPreMultiplyARGB(rgba[3], rgba[0], rgba[1], rgba[2]);
+}
+
+SkShaderBase::Context* SkPerlinNoiseShaderImpl::onMakeContext(const ContextRec& rec,
+                                                           SkArenaAlloc* alloc) const {
+    return alloc->make<PerlinNoiseShaderContext>(*this, rec);
+}
+
+SkPerlinNoiseShaderImpl::PerlinNoiseShaderContext::PerlinNoiseShaderContext(
+        const SkPerlinNoiseShaderImpl& shader, const ContextRec& rec)
+    : INHERITED(shader, rec)
+{
+    SkMatrix newMatrix = *rec.fMatrix;
+    newMatrix.preConcat(shader.getLocalMatrix());
+    if (rec.fLocalMatrix) {
+        newMatrix.preConcat(*rec.fLocalMatrix);
+    }
+    // This (1,1) translation is due to WebKit's 1 based coordinates for the noise
+    // (as opposed to 0 based, usually). The same adjustment is in the setData() function.
+    fMatrix.setTranslate(-newMatrix.getTranslateX() + SK_Scalar1, -newMatrix.getTranslateY() + SK_Scalar1);
+    fPaintingData = new PaintingData(shader.fTileSize, shader.fSeed, shader.fBaseFrequencyX,
+                                     shader.fBaseFrequencyY, newMatrix);
+}
+
+SkPerlinNoiseShaderImpl::PerlinNoiseShaderContext::~PerlinNoiseShaderContext() { delete fPaintingData; }
+
+void SkPerlinNoiseShaderImpl::PerlinNoiseShaderContext::shadeSpan(
+        int x, int y, SkPMColor result[], int count) {
+    SkPoint point = SkPoint::Make(SkIntToScalar(x), SkIntToScalar(y));
+    StitchData stitchData;
+    for (int i = 0; i < count; ++i) {
+        result[i] = shade(point, stitchData);
+        point.fX += SK_Scalar1;
+    }
+}
+
+/////////////////////////////////////////////////////////////////////
+
+#if SK_SUPPORT_GPU
+
+class GrGLPerlinNoise : public GrGLSLFragmentProcessor {
+public:
+    void emitCode(EmitArgs&) override;
+
+    static inline void GenKey(const GrProcessor&, const GrShaderCaps&, GrProcessorKeyBuilder* b);
+
+protected:
+    void onSetData(const GrGLSLProgramDataManager&, const GrFragmentProcessor&) override;
+
+private:
+    GrGLSLProgramDataManager::UniformHandle fStitchDataUni;
+    GrGLSLProgramDataManager::UniformHandle fBaseFrequencyUni;
+
+    typedef GrGLSLFragmentProcessor INHERITED;
+};
+
+/////////////////////////////////////////////////////////////////////
+
+class GrPerlinNoise2Effect : public GrFragmentProcessor {
+public:
+    static sk_sp<GrFragmentProcessor> Make(GrResourceProvider* resourceProvider,
+                                           SkPerlinNoiseShaderImpl::Type type,
+                                           int numOctaves, bool stitchTiles,
+                                           SkPerlinNoiseShaderImpl::PaintingData* paintingData,
+                                           sk_sp<GrTextureProxy> permutationsProxy,
+                                           sk_sp<GrTextureProxy> noiseProxy,
+                                           const SkMatrix& matrix) {
+        return sk_sp<GrFragmentProcessor>(
+            new GrPerlinNoise2Effect(resourceProvider, type, numOctaves, stitchTiles, paintingData,
+                                     std::move(permutationsProxy), std::move(noiseProxy), matrix));
+    }
+
+    ~GrPerlinNoise2Effect() override { delete fPaintingData; }
+
+    const char* name() const override { return "PerlinNoise"; }
+
+    const SkPerlinNoiseShaderImpl::StitchData& stitchData() const { return fPaintingData->fStitchDataInit; }
+
+    SkPerlinNoiseShaderImpl::Type type() const { return fType; }
+    bool stitchTiles() const { return fStitchTiles; }
+    const SkVector& baseFrequency() const { return fPaintingData->fBaseFrequency; }
+    int numOctaves() const { return fNumOctaves; }
+    const SkMatrix& matrix() const { return fCoordTransform.getMatrix(); }
+
+private:
+    GrGLSLFragmentProcessor* onCreateGLSLInstance() const override {
+        return new GrGLPerlinNoise;
+    }
+
+    virtual void onGetGLSLProcessorKey(const GrShaderCaps& caps,
+                                       GrProcessorKeyBuilder* b) const override {
+        GrGLPerlinNoise::GenKey(*this, caps, b);
+    }
+
+    bool onIsEqual(const GrFragmentProcessor& sBase) const override {
+        const GrPerlinNoise2Effect& s = sBase.cast<GrPerlinNoise2Effect>();
+        return fType == s.fType &&
+               fPaintingData->fBaseFrequency == s.fPaintingData->fBaseFrequency &&
+               fNumOctaves == s.fNumOctaves &&
+               fStitchTiles == s.fStitchTiles &&
+               fPaintingData->fStitchDataInit == s.fPaintingData->fStitchDataInit;
+    }
+
+    GrPerlinNoise2Effect(GrResourceProvider* resourceProvider,
+                         SkPerlinNoiseShaderImpl::Type type, int numOctaves, bool stitchTiles,
+                         SkPerlinNoiseShaderImpl::PaintingData* paintingData,
+                         sk_sp<GrTextureProxy> permutationsProxy,
+                         sk_sp<GrTextureProxy> noiseProxy,
+                         const SkMatrix& matrix)
+            : INHERITED(kNone_OptimizationFlags)
+            , fType(type)
+            , fNumOctaves(numOctaves)
+            , fStitchTiles(stitchTiles)
+            , fPermutationsSampler(resourceProvider, std::move(permutationsProxy))
+            , fNoiseSampler(resourceProvider, std::move(noiseProxy))
+            , fPaintingData(paintingData) {
+        this->initClassID<GrPerlinNoise2Effect>();
+        this->addTextureSampler(&fPermutationsSampler);
+        this->addTextureSampler(&fNoiseSampler);
+        fCoordTransform.reset(matrix);
+        this->addCoordTransform(&fCoordTransform);
+    }
+
+    GR_DECLARE_FRAGMENT_PROCESSOR_TEST;
+
+    SkPerlinNoiseShaderImpl::Type           fType;
+    GrCoordTransform                    fCoordTransform;
+    int                                 fNumOctaves;
+    bool                                fStitchTiles;
+    TextureSampler                      fPermutationsSampler;
+    TextureSampler                      fNoiseSampler;
+    SkPerlinNoiseShaderImpl::PaintingData*  fPaintingData;
+
+    typedef GrFragmentProcessor INHERITED;
+};
+
+/////////////////////////////////////////////////////////////////////
+GR_DEFINE_FRAGMENT_PROCESSOR_TEST(GrPerlinNoise2Effect);
+
+#if GR_TEST_UTILS
+sk_sp<GrFragmentProcessor> GrPerlinNoise2Effect::TestCreate(GrProcessorTestData* d) {
+    int      numOctaves = d->fRandom->nextRangeU(2, 10);
+    bool     stitchTiles = d->fRandom->nextBool();
+    SkScalar seed = SkIntToScalar(d->fRandom->nextU());
+    SkISize  tileSize = SkISize::Make(d->fRandom->nextRangeU(4, 4096),
+                                      d->fRandom->nextRangeU(4, 4096));
+    SkScalar baseFrequencyX = d->fRandom->nextRangeScalar(0.01f,
+                                                          0.99f);
+    SkScalar baseFrequencyY = d->fRandom->nextRangeScalar(0.01f,
+                                                          0.99f);
+
+    sk_sp<SkShader> shader(d->fRandom->nextBool() ?
+        SkPerlinNoiseShader::MakeFractalNoise(baseFrequencyX, baseFrequencyY, numOctaves, seed,
+                                               stitchTiles ? &tileSize : nullptr) :
+        SkPerlinNoiseShader::MakeTurbulence(baseFrequencyX, baseFrequencyY, numOctaves, seed,
+                                             stitchTiles ? &tileSize : nullptr));
+
+    GrTest::TestAsFPArgs asFPArgs(d);
+    return as_SB(shader)->asFragmentProcessor(asFPArgs.args());
+}
+#endif
+
+void GrGLPerlinNoise::emitCode(EmitArgs& args) {
+    const GrPerlinNoise2Effect& pne = args.fFp.cast<GrPerlinNoise2Effect>();
+
+    GrGLSLFragmentBuilder* fragBuilder = args.fFragBuilder;
+    GrGLSLUniformHandler* uniformHandler = args.fUniformHandler;
+    SkString vCoords = fragBuilder->ensureCoords2D(args.fTransformedCoords[0]);
+
+    fBaseFrequencyUni = uniformHandler->addUniform(kFragment_GrShaderFlag,
+                                                   kVec2f_GrSLType, kDefault_GrSLPrecision,
+                                                   "baseFrequency");
+    const char* baseFrequencyUni = uniformHandler->getUniformCStr(fBaseFrequencyUni);
+
+    const char* stitchDataUni = nullptr;
+    if (pne.stitchTiles()) {
+        fStitchDataUni = uniformHandler->addUniform(kFragment_GrShaderFlag,
+                                                    kVec2f_GrSLType, kDefault_GrSLPrecision,
+                                                    "stitchData");
+        stitchDataUni = uniformHandler->getUniformCStr(fStitchDataUni);
+    }
+
+    // There are 4 lines, so the center of each line is 1/8, 3/8, 5/8 and 7/8
+    const char* chanCoordR  = "0.125";
+    const char* chanCoordG  = "0.375";
+    const char* chanCoordB  = "0.625";
+    const char* chanCoordA  = "0.875";
+    const char* chanCoord   = "chanCoord";
+    const char* stitchData  = "stitchData";
+    const char* ratio       = "ratio";
+    const char* noiseVec    = "noiseVec";
+    const char* noiseSmooth = "noiseSmooth";
+    const char* floorVal    = "floorVal";
+    const char* fractVal    = "fractVal";
+    const char* uv          = "uv";
+    const char* ab          = "ab";
+    const char* latticeIdx  = "latticeIdx";
+    const char* bcoords     = "bcoords";
+    const char* lattice     = "lattice";
+    const char* inc8bit     = "0.00390625";  // 1.0 / 256.0
+    // This is the math to convert the two 16bit integer packed into rgba 8 bit input into a
+    // [-1,1] vector and perform a dot product between that vector and the provided vector.
+    const char* dotLattice  = "dot(((%s.ga + %s.rb * vec2(%s)) * vec2(2.0) - vec2(1.0)), %s);";
+
+    // Add noise function
+    static const GrShaderVar gPerlinNoiseArgs[] =  {
+        GrShaderVar(chanCoord, kFloat_GrSLType),
+        GrShaderVar(noiseVec, kVec2f_GrSLType)
+    };
+
+    static const GrShaderVar gPerlinNoiseStitchArgs[] =  {
+        GrShaderVar(chanCoord, kFloat_GrSLType),
+        GrShaderVar(noiseVec, kVec2f_GrSLType),
+        GrShaderVar(stitchData, kVec2f_GrSLType)
+    };
+
+    SkString noiseCode;
+
+    noiseCode.appendf("\tvec4 %s;\n", floorVal);
+    noiseCode.appendf("\t%s.xy = floor(%s);\n", floorVal, noiseVec);
+    noiseCode.appendf("\t%s.zw = %s.xy + vec2(1.0);\n", floorVal, floorVal);
+    noiseCode.appendf("\tvec2 %s = fract(%s);\n", fractVal, noiseVec);
+
+    // smooth curve : t * t * (3 - 2 * t)
+    noiseCode.appendf("\n\tvec2 %s = %s * %s * (vec2(3.0) - vec2(2.0) * %s);",
+        noiseSmooth, fractVal, fractVal, fractVal);
+
+    // Adjust frequencies if we're stitching tiles
+    if (pne.stitchTiles()) {
+        noiseCode.appendf("\n\tif(%s.x >= %s.x) { %s.x -= %s.x; }",
+            floorVal, stitchData, floorVal, stitchData);
+        noiseCode.appendf("\n\tif(%s.y >= %s.y) { %s.y -= %s.y; }",
+            floorVal, stitchData, floorVal, stitchData);
+        noiseCode.appendf("\n\tif(%s.z >= %s.x) { %s.z -= %s.x; }",
+            floorVal, stitchData, floorVal, stitchData);
+        noiseCode.appendf("\n\tif(%s.w >= %s.y) { %s.w -= %s.y; }",
+            floorVal, stitchData, floorVal, stitchData);
+    }
+
+    // Get texture coordinates and normalize
+    noiseCode.appendf("\n\t%s = fract(floor(mod(%s, 256.0)) / vec4(256.0));\n",
+        floorVal, floorVal);
+
+    // Get permutation for x
+    {
+        SkString xCoords("");
+        xCoords.appendf("vec2(%s.x, 0.5)", floorVal);
+
+        noiseCode.appendf("\n\tvec2 %s;\n\t%s.x = ", latticeIdx, latticeIdx);
+        fragBuilder->appendTextureLookup(&noiseCode, args.fTexSamplers[0], xCoords.c_str(),
+                                         kVec2f_GrSLType);
+        noiseCode.append(".r;");
+    }
+
+    // Get permutation for x + 1
+    {
+        SkString xCoords("");
+        xCoords.appendf("vec2(%s.z, 0.5)", floorVal);
+
+        noiseCode.appendf("\n\t%s.y = ", latticeIdx);
+        fragBuilder->appendTextureLookup(&noiseCode, args.fTexSamplers[0], xCoords.c_str(),
+                                         kVec2f_GrSLType);
+        noiseCode.append(".r;");
+    }
+
+#if defined(SK_BUILD_FOR_ANDROID)
+    // Android rounding for Tegra devices, like, for example: Xoom (Tegra 2), Nexus 7 (Tegra 3).
+    // The issue is that colors aren't accurate enough on Tegra devices. For example, if an 8 bit
+    // value of 124 (or 0.486275 here) is entered, we can get a texture value of 123.513725
+    // (or 0.484368 here). The following rounding operation prevents these precision issues from
+    // affecting the result of the noise by making sure that we only have multiples of 1/255.
+    // (Note that 1/255 is about 0.003921569, which is the value used here).
+    noiseCode.appendf("\n\t%s = floor(%s * vec2(255.0) + vec2(0.5)) * vec2(0.003921569);",
+                      latticeIdx, latticeIdx);
+#endif
+
+    // Get (x,y) coordinates with the permutated x
+    noiseCode.appendf("\n\tvec4 %s = fract(%s.xyxy + %s.yyww);", bcoords, latticeIdx, floorVal);
+
+    noiseCode.appendf("\n\n\tvec2 %s;", uv);
+    // Compute u, at offset (0,0)
+    {
+        SkString latticeCoords("");
+        latticeCoords.appendf("vec2(%s.x, %s)", bcoords, chanCoord);
+        noiseCode.appendf("\n\tvec4 %s = ", lattice);
+        fragBuilder->appendTextureLookup(&noiseCode, args.fTexSamplers[1], latticeCoords.c_str(),
+                                         kVec2f_GrSLType);
+        noiseCode.appendf(".bgra;\n\t%s.x = ", uv);
+        noiseCode.appendf(dotLattice, lattice, lattice, inc8bit, fractVal);
+    }
+
+    noiseCode.appendf("\n\t%s.x -= 1.0;", fractVal);
+    // Compute v, at offset (-1,0)
+    {
+        SkString latticeCoords("");
+        latticeCoords.appendf("vec2(%s.y, %s)", bcoords, chanCoord);
+        noiseCode.append("\n\tlattice = ");
+        fragBuilder->appendTextureLookup(&noiseCode, args.fTexSamplers[1], latticeCoords.c_str(),
+                                         kVec2f_GrSLType);
+        noiseCode.appendf(".bgra;\n\t%s.y = ", uv);
+        noiseCode.appendf(dotLattice, lattice, lattice, inc8bit, fractVal);
+    }
+
+    // Compute 'a' as a linear interpolation of 'u' and 'v'
+    noiseCode.appendf("\n\tvec2 %s;", ab);
+    noiseCode.appendf("\n\t%s.x = mix(%s.x, %s.y, %s.x);", ab, uv, uv, noiseSmooth);
+
+    noiseCode.appendf("\n\t%s.y -= 1.0;", fractVal);
+    // Compute v, at offset (-1,-1)
+    {
+        SkString latticeCoords("");
+        latticeCoords.appendf("vec2(%s.w, %s)", bcoords, chanCoord);
+        noiseCode.append("\n\tlattice = ");
+        fragBuilder->appendTextureLookup(&noiseCode, args.fTexSamplers[1], latticeCoords.c_str(),
+                                         kVec2f_GrSLType);
+        noiseCode.appendf(".bgra;\n\t%s.y = ", uv);
+        noiseCode.appendf(dotLattice, lattice, lattice, inc8bit, fractVal);
+    }
+
+    noiseCode.appendf("\n\t%s.x += 1.0;", fractVal);
+    // Compute u, at offset (0,-1)
+    {
+        SkString latticeCoords("");
+        latticeCoords.appendf("vec2(%s.z, %s)", bcoords, chanCoord);
+        noiseCode.append("\n\tlattice = ");
+        fragBuilder->appendTextureLookup(&noiseCode, args.fTexSamplers[1], latticeCoords.c_str(),
+                                         kVec2f_GrSLType);
+        noiseCode.appendf(".bgra;\n\t%s.x = ", uv);
+        noiseCode.appendf(dotLattice, lattice, lattice, inc8bit, fractVal);
+    }
+
+    // Compute 'b' as a linear interpolation of 'u' and 'v'
+    noiseCode.appendf("\n\t%s.y = mix(%s.x, %s.y, %s.x);", ab, uv, uv, noiseSmooth);
+    // Compute the noise as a linear interpolation of 'a' and 'b'
+    noiseCode.appendf("\n\treturn mix(%s.x, %s.y, %s.y);\n", ab, ab, noiseSmooth);
+
+    SkString noiseFuncName;
+    if (pne.stitchTiles()) {
+        fragBuilder->emitFunction(kFloat_GrSLType,
+                                  "perlinnoise", SK_ARRAY_COUNT(gPerlinNoiseStitchArgs),
+                                  gPerlinNoiseStitchArgs, noiseCode.c_str(), &noiseFuncName);
+    } else {
+        fragBuilder->emitFunction(kFloat_GrSLType,
+                                  "perlinnoise", SK_ARRAY_COUNT(gPerlinNoiseArgs),
+                                  gPerlinNoiseArgs, noiseCode.c_str(), &noiseFuncName);
+    }
+
+    // There are rounding errors if the floor operation is not performed here
+    fragBuilder->codeAppendf("\n\t\tvec2 %s = floor(%s.xy) * %s;",
+                             noiseVec, vCoords.c_str(), baseFrequencyUni);
+
+    // Clear the color accumulator
+    fragBuilder->codeAppendf("\n\t\t%s = vec4(0.0);", args.fOutputColor);
+
+    if (pne.stitchTiles()) {
+        // Set up TurbulenceInitial stitch values.
+        fragBuilder->codeAppendf("\n\t\tvec2 %s = %s;", stitchData, stitchDataUni);
+    }
+
+    fragBuilder->codeAppendf("\n\t\tfloat %s = 1.0;", ratio);
+
+    // Loop over all octaves
+    fragBuilder->codeAppendf("for (int octave = 0; octave < %d; ++octave) {", pne.numOctaves());
+
+    fragBuilder->codeAppendf("\n\t\t\t%s += ", args.fOutputColor);
+    if (pne.type() != SkPerlinNoiseShaderImpl::kFractalNoise_Type) {
+        fragBuilder->codeAppend("abs(");
+    }
+    if (pne.stitchTiles()) {
+        fragBuilder->codeAppendf(
+            "vec4(\n\t\t\t\t%s(%s, %s, %s),\n\t\t\t\t%s(%s, %s, %s),"
+                 "\n\t\t\t\t%s(%s, %s, %s),\n\t\t\t\t%s(%s, %s, %s))",
+            noiseFuncName.c_str(), chanCoordR, noiseVec, stitchData,
+            noiseFuncName.c_str(), chanCoordG, noiseVec, stitchData,
+            noiseFuncName.c_str(), chanCoordB, noiseVec, stitchData,
+            noiseFuncName.c_str(), chanCoordA, noiseVec, stitchData);
+    } else {
+        fragBuilder->codeAppendf(
+            "vec4(\n\t\t\t\t%s(%s, %s),\n\t\t\t\t%s(%s, %s),"
+                 "\n\t\t\t\t%s(%s, %s),\n\t\t\t\t%s(%s, %s))",
+            noiseFuncName.c_str(), chanCoordR, noiseVec,
+            noiseFuncName.c_str(), chanCoordG, noiseVec,
+            noiseFuncName.c_str(), chanCoordB, noiseVec,
+            noiseFuncName.c_str(), chanCoordA, noiseVec);
+    }
+    if (pne.type() != SkPerlinNoiseShaderImpl::kFractalNoise_Type) {
+        fragBuilder->codeAppendf(")"); // end of "abs("
+    }
+    fragBuilder->codeAppendf(" * %s;", ratio);
+
+    fragBuilder->codeAppendf("\n\t\t\t%s *= vec2(2.0);", noiseVec);
+    fragBuilder->codeAppendf("\n\t\t\t%s *= 0.5;", ratio);
+
+    if (pne.stitchTiles()) {
+        fragBuilder->codeAppendf("\n\t\t\t%s *= vec2(2.0);", stitchData);
+    }
+    fragBuilder->codeAppend("\n\t\t}"); // end of the for loop on octaves
+
+    if (pne.type() == SkPerlinNoiseShaderImpl::kFractalNoise_Type) {
+        // The value of turbulenceFunctionResult comes from ((turbulenceFunctionResult) + 1) / 2
+        // by fractalNoise and (turbulenceFunctionResult) by turbulence.
+        fragBuilder->codeAppendf("\n\t\t%s = %s * vec4(0.5) + vec4(0.5);",
+                               args.fOutputColor,args.fOutputColor);
+    }
+
+    // Clamp values
+    fragBuilder->codeAppendf("\n\t\t%s = clamp(%s, 0.0, 1.0);", args.fOutputColor, args.fOutputColor);
+
+    // Pre-multiply the result
+    fragBuilder->codeAppendf("\n\t\t%s = vec4(%s.rgb * %s.aaa, %s.a);\n",
+                             args.fOutputColor, args.fOutputColor,
+                             args.fOutputColor, args.fOutputColor);
+}
+
+void GrGLPerlinNoise::GenKey(const GrProcessor& processor, const GrShaderCaps&,
+                             GrProcessorKeyBuilder* b) {
+    const GrPerlinNoise2Effect& turbulence = processor.cast<GrPerlinNoise2Effect>();
+
+    uint32_t key = turbulence.numOctaves();
+
+    key = key << 3; // Make room for next 3 bits
+
+    switch (turbulence.type()) {
+        case SkPerlinNoiseShaderImpl::kFractalNoise_Type:
+            key |= 0x1;
+            break;
+        case SkPerlinNoiseShaderImpl::kTurbulence_Type:
+            key |= 0x2;
+            break;
+        default:
+            // leave key at 0
+            break;
+    }
+
+    if (turbulence.stitchTiles()) {
+        key |= 0x4; // Flip the 3rd bit if tile stitching is on
+    }
+
+    b->add32(key);
+}
+
+void GrGLPerlinNoise::onSetData(const GrGLSLProgramDataManager& pdman,
+                                const GrFragmentProcessor& processor) {
+    INHERITED::onSetData(pdman, processor);
+
+    const GrPerlinNoise2Effect& turbulence = processor.cast<GrPerlinNoise2Effect>();
+
+    const SkVector& baseFrequency = turbulence.baseFrequency();
+    pdman.set2f(fBaseFrequencyUni, baseFrequency.fX, baseFrequency.fY);
+
+    if (turbulence.stitchTiles()) {
+        const SkPerlinNoiseShaderImpl::StitchData& stitchData = turbulence.stitchData();
+        pdman.set2f(fStitchDataUni, SkIntToScalar(stitchData.fWidth),
+                                   SkIntToScalar(stitchData.fHeight));
+    }
+}
+
+/////////////////////////////////////////////////////////////////////
+
+class GrGLImprovedPerlinNoise : public GrGLSLFragmentProcessor {
+public:
+    void emitCode(EmitArgs&) override;
+
+    static inline void GenKey(const GrProcessor&, const GrShaderCaps&, GrProcessorKeyBuilder*);
+
+protected:
+    void onSetData(const GrGLSLProgramDataManager&, const GrFragmentProcessor&) override;
+
+private:
+    GrGLSLProgramDataManager::UniformHandle fZUni;
+    GrGLSLProgramDataManager::UniformHandle fOctavesUni;
+    GrGLSLProgramDataManager::UniformHandle fBaseFrequencyUni;
+
+    typedef GrGLSLFragmentProcessor INHERITED;
+};
+
+/////////////////////////////////////////////////////////////////////
+
+class GrImprovedPerlinNoiseEffect : public GrFragmentProcessor {
+public:
+    static sk_sp<GrFragmentProcessor> Make(GrResourceProvider* resourceProvider,
+                                           int octaves, SkScalar z,
+                                           SkPerlinNoiseShaderImpl::PaintingData* paintingData,
+                                           sk_sp<GrTextureProxy> permutationsProxy,
+                                           sk_sp<GrTextureProxy> gradientProxy,
+                                           const SkMatrix& matrix) {
+        return sk_sp<GrFragmentProcessor>(
+            new GrImprovedPerlinNoiseEffect(resourceProvider, octaves, z, paintingData,
+                                            std::move(permutationsProxy),
+                                            std::move(gradientProxy), matrix));
+    }
+
+    ~GrImprovedPerlinNoiseEffect() override { delete fPaintingData; }
+
+    const char* name() const override { return "ImprovedPerlinNoise"; }
+
+    const SkVector& baseFrequency() const { return fPaintingData->fBaseFrequency; }
+    SkScalar z() const { return fZ; }
+    int octaves() const { return fOctaves; }
+    const SkMatrix& matrix() const { return fCoordTransform.getMatrix(); }
+
+private:
+    GrGLSLFragmentProcessor* onCreateGLSLInstance() const override {
+        return new GrGLImprovedPerlinNoise;
+    }
+
+    void onGetGLSLProcessorKey(const GrShaderCaps& caps, GrProcessorKeyBuilder* b) const override {
+        GrGLImprovedPerlinNoise::GenKey(*this, caps, b);
+    }
+
+    bool onIsEqual(const GrFragmentProcessor& sBase) const override {
+        const GrImprovedPerlinNoiseEffect& s = sBase.cast<GrImprovedPerlinNoiseEffect>();
+        return fZ == fZ &&
+               fPaintingData->fBaseFrequency == s.fPaintingData->fBaseFrequency;
+    }
+
+    GrImprovedPerlinNoiseEffect(GrResourceProvider* resourceProvider,
+                                int octaves, SkScalar z,
+                                SkPerlinNoiseShaderImpl::PaintingData* paintingData,
+                                sk_sp<GrTextureProxy> permutationsProxy,
+                                sk_sp<GrTextureProxy> gradientProxy,
+                                const SkMatrix& matrix)
+            : INHERITED(kNone_OptimizationFlags)
+            , fOctaves(octaves)
+            , fZ(z)
+            , fPermutationsSampler(resourceProvider, std::move(permutationsProxy))
+            , fGradientSampler(resourceProvider, std::move(gradientProxy))
+            , fPaintingData(paintingData) {
+        this->initClassID<GrImprovedPerlinNoiseEffect>();
+        this->addTextureSampler(&fPermutationsSampler);
+        this->addTextureSampler(&fGradientSampler);
+        fCoordTransform.reset(matrix);
+        this->addCoordTransform(&fCoordTransform);
+    }
+
+    GR_DECLARE_FRAGMENT_PROCESSOR_TEST;
+
+    GrCoordTransform                    fCoordTransform;
+    int                                 fOctaves;
+    SkScalar                            fZ;
+    TextureSampler                      fPermutationsSampler;
+    TextureSampler                      fGradientSampler;
+    SkPerlinNoiseShaderImpl::PaintingData*  fPaintingData;
+
+    typedef GrFragmentProcessor INHERITED;
+};
+
+/////////////////////////////////////////////////////////////////////
+GR_DEFINE_FRAGMENT_PROCESSOR_TEST(GrImprovedPerlinNoiseEffect);
+
+#if GR_TEST_UTILS
+sk_sp<GrFragmentProcessor> GrImprovedPerlinNoiseEffect::TestCreate(GrProcessorTestData* d) {
+    SkScalar baseFrequencyX = d->fRandom->nextRangeScalar(0.01f,
+                                                          0.99f);
+    SkScalar baseFrequencyY = d->fRandom->nextRangeScalar(0.01f,
+                                                          0.99f);
+    int numOctaves = d->fRandom->nextRangeU(2, 10);
+    SkScalar z = SkIntToScalar(d->fRandom->nextU());
+
+    sk_sp<SkShader> shader(SkPerlinNoiseShader::MakeImprovedNoise(baseFrequencyX,
+                                                                   baseFrequencyY,
+                                                                   numOctaves,
+                                                                   z));
+
+    GrTest::TestAsFPArgs asFPArgs(d);
+    return as_SB(shader)->asFragmentProcessor(asFPArgs.args());
+}
+#endif
+
+void GrGLImprovedPerlinNoise::emitCode(EmitArgs& args) {
+    GrGLSLFragmentBuilder* fragBuilder = args.fFragBuilder;
+    GrGLSLUniformHandler* uniformHandler = args.fUniformHandler;
+    SkString vCoords = fragBuilder->ensureCoords2D(args.fTransformedCoords[0]);
+
+    fBaseFrequencyUni = uniformHandler->addUniform(kFragment_GrShaderFlag,
+                                                   kVec2f_GrSLType, kDefault_GrSLPrecision,
+                                                   "baseFrequency");
+    const char* baseFrequencyUni = uniformHandler->getUniformCStr(fBaseFrequencyUni);
+
+    fOctavesUni = uniformHandler->addUniform(kFragment_GrShaderFlag,
+                                             kFloat_GrSLType, kDefault_GrSLPrecision,
+                                             "octaves");
+    const char* octavesUni = uniformHandler->getUniformCStr(fOctavesUni);
+
+    fZUni = uniformHandler->addUniform(kFragment_GrShaderFlag,
+                                       kFloat_GrSLType, kDefault_GrSLPrecision,
+                                       "z");
+    const char* zUni = uniformHandler->getUniformCStr(fZUni);
+
+    // fade function
+    static const GrShaderVar fadeArgs[] =  {
+        GrShaderVar("t", kVec3f_GrSLType)
+    };
+    SkString fadeFuncName;
+    fragBuilder->emitFunction(kVec3f_GrSLType, "fade", SK_ARRAY_COUNT(fadeArgs),
+                              fadeArgs,
+                              "return t * t * t * (t * (t * 6.0 - 15.0) + 10.0);",
+                              &fadeFuncName);
+
+    // perm function
+    static const GrShaderVar permArgs[] =  {
+        GrShaderVar("x", kFloat_GrSLType)
+    };
+    SkString permFuncName;
+    SkString permCode("return ");
+    // FIXME even though I'm creating these textures with kRepeat_TileMode, they're clamped. Not
+    // sure why. Using fract() (here and the next texture lookup) as a workaround.
+    fragBuilder->appendTextureLookup(&permCode, args.fTexSamplers[0], "vec2(fract(x / 256.0), 0.0)",
+                                     kVec2f_GrSLType);
+    permCode.append(".r * 255.0;");
+    fragBuilder->emitFunction(kFloat_GrSLType, "perm", SK_ARRAY_COUNT(permArgs), permArgs,
+                              permCode.c_str(), &permFuncName);
+
+    // grad function
+    static const GrShaderVar gradArgs[] =  {
+        GrShaderVar("x", kFloat_GrSLType),
+        GrShaderVar("p", kVec3f_GrSLType)
+    };
+    SkString gradFuncName;
+    SkString gradCode("return dot(");
+    fragBuilder->appendTextureLookup(&gradCode, args.fTexSamplers[1], "vec2(fract(x / 16.0), 0.0)",
+                                     kVec2f_GrSLType);
+    gradCode.append(".rgb * 255.0 - vec3(1.0), p);");
+    fragBuilder->emitFunction(kFloat_GrSLType, "grad", SK_ARRAY_COUNT(gradArgs), gradArgs,
+                              gradCode.c_str(), &gradFuncName);
+
+    // lerp function
+    static const GrShaderVar lerpArgs[] =  {
+        GrShaderVar("a", kFloat_GrSLType),
+        GrShaderVar("b", kFloat_GrSLType),
+        GrShaderVar("w", kFloat_GrSLType)
+    };
+    SkString lerpFuncName;
+    fragBuilder->emitFunction(kFloat_GrSLType, "lerp", SK_ARRAY_COUNT(lerpArgs), lerpArgs,
+                              "return a + w * (b - a);", &lerpFuncName);
+
+    // noise function
+    static const GrShaderVar noiseArgs[] =  {
+        GrShaderVar("p", kVec3f_GrSLType),
+    };
+    SkString noiseFuncName;
+    SkString noiseCode;
+    noiseCode.append("vec3 P = mod(floor(p), 256.0);");
+    noiseCode.append("p -= floor(p);");
+    noiseCode.appendf("vec3 f = %s(p);", fadeFuncName.c_str());
+    noiseCode.appendf("float A = %s(P.x) + P.y;", permFuncName.c_str());
+    noiseCode.appendf("float AA = %s(A) + P.z;", permFuncName.c_str());
+    noiseCode.appendf("float AB = %s(A + 1.0) + P.z;", permFuncName.c_str());
+    noiseCode.appendf("float B =  %s(P.x + 1.0) + P.y;", permFuncName.c_str());
+    noiseCode.appendf("float BA = %s(B) + P.z;", permFuncName.c_str());
+    noiseCode.appendf("float BB = %s(B + 1.0) + P.z;", permFuncName.c_str());
+    noiseCode.appendf("float result = %s(", lerpFuncName.c_str());
+    noiseCode.appendf("%s(%s(%s(%s(AA), p),", lerpFuncName.c_str(), lerpFuncName.c_str(),
+                      gradFuncName.c_str(), permFuncName.c_str());
+    noiseCode.appendf("%s(%s(BA), p + vec3(-1.0, 0.0, 0.0)), f.x),", gradFuncName.c_str(),
+                      permFuncName.c_str());
+    noiseCode.appendf("%s(%s(%s(AB), p + vec3(0.0, -1.0, 0.0)),", lerpFuncName.c_str(),
+                      gradFuncName.c_str(), permFuncName.c_str());
+    noiseCode.appendf("%s(%s(BB), p + vec3(-1.0, -1.0, 0.0)), f.x), f.y),",
+                      gradFuncName.c_str(), permFuncName.c_str());
+    noiseCode.appendf("%s(%s(%s(%s(AA + 1.0), p + vec3(0.0, 0.0, -1.0)),",
+                      lerpFuncName.c_str(), lerpFuncName.c_str(), gradFuncName.c_str(),
+                      permFuncName.c_str());
+    noiseCode.appendf("%s(%s(BA + 1.0), p + vec3(-1.0, 0.0, -1.0)), f.x),",
+                      gradFuncName.c_str(), permFuncName.c_str());
+    noiseCode.appendf("%s(%s(%s(AB + 1.0), p + vec3(0.0, -1.0, -1.0)),",
+                      lerpFuncName.c_str(), gradFuncName.c_str(), permFuncName.c_str());
+    noiseCode.appendf("%s(%s(BB + 1.0), p + vec3(-1.0, -1.0, -1.0)), f.x), f.y), f.z);",
+                      gradFuncName.c_str(), permFuncName.c_str());
+    noiseCode.append("return result;");
+    fragBuilder->emitFunction(kFloat_GrSLType, "noise", SK_ARRAY_COUNT(noiseArgs), noiseArgs,
+                              noiseCode.c_str(), &noiseFuncName);
+
+    // noiseOctaves function
+    static const GrShaderVar noiseOctavesArgs[] =  {
+        GrShaderVar("p", kVec3f_GrSLType),
+        GrShaderVar("octaves", kFloat_GrSLType),
+    };
+    SkString noiseOctavesFuncName;
+    SkString noiseOctavesCode;
+    noiseOctavesCode.append("float result = 0.0;");
+    noiseOctavesCode.append("float ratio = 1.0;");
+    noiseOctavesCode.append("for (float i = 0.0; i < octaves; i++) {");
+    noiseOctavesCode.appendf("result += %s(p) / ratio;", noiseFuncName.c_str());
+    noiseOctavesCode.append("p *= 2.0;");
+    noiseOctavesCode.append("ratio *= 2.0;");
+    noiseOctavesCode.append("}");
+    noiseOctavesCode.append("return (result + 1.0) / 2.0;");
+    fragBuilder->emitFunction(kFloat_GrSLType, "noiseOctaves", SK_ARRAY_COUNT(noiseOctavesArgs),
+                              noiseOctavesArgs, noiseOctavesCode.c_str(), &noiseOctavesFuncName);
+
+    fragBuilder->codeAppendf("vec2 coords = %s * %s;", vCoords.c_str(), baseFrequencyUni);
+    fragBuilder->codeAppendf("float r = %s(vec3(coords, %s), %s);", noiseOctavesFuncName.c_str(),
+                             zUni, octavesUni);
+    fragBuilder->codeAppendf("float g = %s(vec3(coords, %s + 0000.0), %s);",
+                             noiseOctavesFuncName.c_str(), zUni, octavesUni);
+    fragBuilder->codeAppendf("float b = %s(vec3(coords, %s + 0000.0), %s);",
+                             noiseOctavesFuncName.c_str(), zUni, octavesUni);
+    fragBuilder->codeAppendf("float a = %s(vec3(coords, %s + 0000.0), %s);",
+                             noiseOctavesFuncName.c_str(), zUni, octavesUni);
+    fragBuilder->codeAppendf("%s = vec4(r, g, b, a);", args.fOutputColor);
+
+    // Clamp values
+    fragBuilder->codeAppendf("%s = clamp(%s, 0.0, 1.0);", args.fOutputColor, args.fOutputColor);
+
+    // Pre-multiply the result
+    fragBuilder->codeAppendf("\n\t\t%s = vec4(%s.rgb * %s.aaa, %s.a);\n",
+                             args.fOutputColor, args.fOutputColor,
+                             args.fOutputColor, args.fOutputColor);
+}
+
+void GrGLImprovedPerlinNoise::GenKey(const GrProcessor& processor, const GrShaderCaps&,
+                                     GrProcessorKeyBuilder* b) {
+}
+
+void GrGLImprovedPerlinNoise::onSetData(const GrGLSLProgramDataManager& pdman,
+                                        const GrFragmentProcessor& processor) {
+    INHERITED::onSetData(pdman, processor);
+
+    const GrImprovedPerlinNoiseEffect& noise = processor.cast<GrImprovedPerlinNoiseEffect>();
+
+    const SkVector& baseFrequency = noise.baseFrequency();
+    pdman.set2f(fBaseFrequencyUni, baseFrequency.fX, baseFrequency.fY);
+
+    pdman.set1f(fOctavesUni, SkIntToScalar(noise.octaves()));
+
+    pdman.set1f(fZUni, noise.z());
+}
+
+/////////////////////////////////////////////////////////////////////
+sk_sp<GrFragmentProcessor> SkPerlinNoiseShaderImpl::asFragmentProcessor(const AsFPArgs& args) const {
+    SkASSERT(args.fContext);
+
+    SkMatrix localMatrix = this->getLocalMatrix();
+    if (args.fLocalMatrix) {
+        localMatrix.preConcat(*args.fLocalMatrix);
+    }
+
+    SkMatrix matrix = *args.fViewMatrix;
+    matrix.preConcat(localMatrix);
+
+    // Either we don't stitch tiles, either we have a valid tile size
+    SkASSERT(!fStitchTiles || !fTileSize.isEmpty());
+
+    SkPerlinNoiseShaderImpl::PaintingData* paintingData =
+            new PaintingData(fTileSize, fSeed, fBaseFrequencyX, fBaseFrequencyY, matrix);
+
+    SkMatrix m = *args.fViewMatrix;
+    m.setTranslateX(-localMatrix.getTranslateX() + SK_Scalar1);
+    m.setTranslateY(-localMatrix.getTranslateY() + SK_Scalar1);
+
+    if (fType == kImprovedNoise_Type) {
+        GrSamplerParams textureParams(SkShader::TileMode::kRepeat_TileMode,
+                                      GrSamplerParams::FilterMode::kNone_FilterMode);
+        sk_sp<GrTextureProxy> permutationsTexture(
+            GrRefCachedBitmapTextureProxy(args.fContext,
+                                          paintingData->getImprovedPermutationsBitmap(),
+                                          textureParams, nullptr));
+        sk_sp<GrTextureProxy> gradientTexture(
+            GrRefCachedBitmapTextureProxy(args.fContext,
+                                          paintingData->getGradientBitmap(),
+                                          textureParams, nullptr));
+        return GrImprovedPerlinNoiseEffect::Make(args.fContext->resourceProvider(),
+                                                 fNumOctaves, fSeed, paintingData,
+                                                 std::move(permutationsTexture),
+                                                 std::move(gradientTexture), m);
+    }
+
+    if (0 == fNumOctaves) {
+        if (kFractalNoise_Type == fType) {
+            // Extract the incoming alpha and emit rgba = (a/4, a/4, a/4, a/2)
+            // TODO: Either treat the output of this shader as sRGB or allow client to specify a
+            // color space of the noise. Either way, this case (and the GLSL) need to convert to
+            // the destination.
+            sk_sp<GrFragmentProcessor> inner(
+                GrConstColorProcessor::Make(GrColor4f::FromGrColor(0x80404040),
+                                            GrConstColorProcessor::kModulateRGBA_InputMode));
+            return GrFragmentProcessor::MulOutputByInputAlpha(std::move(inner));
+        }
+        // Emit zero.
+        return GrConstColorProcessor::Make(GrColor4f::TransparentBlack(),
+                                           GrConstColorProcessor::kIgnore_InputMode);
+    }
+
+    sk_sp<GrTextureProxy> permutationsProxy = GrMakeCachedBitmapProxy(
+                                                         args.fContext->resourceProvider(),
+                                                         paintingData->getPermutationsBitmap());
+    sk_sp<GrTextureProxy> noiseProxy = GrMakeCachedBitmapProxy(args.fContext->resourceProvider(),
+                                                               paintingData->getNoiseBitmap());
+
+    if (permutationsProxy && noiseProxy) {
+        sk_sp<GrFragmentProcessor> inner(
+            GrPerlinNoise2Effect::Make(args.fContext->resourceProvider(),
+                                       fType,
+                                       fNumOctaves,
+                                       fStitchTiles,
+                                       paintingData,
+                                       std::move(permutationsProxy),
+                                       std::move(noiseProxy),
+                                       m));
+        return GrFragmentProcessor::MulOutputByInputAlpha(std::move(inner));
+    }
+    delete paintingData;
+    return nullptr;
+}
+
+#endif
+
+#ifndef SK_IGNORE_TO_STRING
+void SkPerlinNoiseShaderImpl::toString(SkString* str) const {
+    str->append("SkPerlinNoiseShaderImpl: (");
+
+    str->append("type: ");
+    switch (fType) {
+        case kFractalNoise_Type:
+            str->append("\"fractal noise\"");
+            break;
+        case kTurbulence_Type:
+            str->append("\"turbulence\"");
+            break;
+        default:
+            str->append("\"unknown\"");
+            break;
+    }
+    str->append(" base frequency: (");
+    str->appendScalar(fBaseFrequencyX);
+    str->append(", ");
+    str->appendScalar(fBaseFrequencyY);
+    str->append(") number of octaves: ");
+    str->appendS32(fNumOctaves);
+    str->append(" seed: ");
+    str->appendScalar(fSeed);
+    str->append(" stitch tiles: ");
+    str->append(fStitchTiles ? "true " : "false ");
+
+    this->INHERITED::toString(str);
+
+    str->append(")");
+}
+#endif
+
+///////////////////////////////////////////////////////////////////////////////////////////////////
+
+sk_sp<SkShader> SkPerlinNoiseShader::MakeFractalNoise(SkScalar baseFrequencyX,
+                                                      SkScalar baseFrequencyY,
+                                                      int numOctaves, SkScalar seed,
+                                                      const SkISize* tileSize) {
+    return sk_sp<SkShader>(new SkPerlinNoiseShaderImpl(SkPerlinNoiseShaderImpl::kFractalNoise_Type,
+                                                 baseFrequencyX, baseFrequencyY, numOctaves, seed,
+                                                 tileSize));
+}
+
+sk_sp<SkShader> SkPerlinNoiseShader::MakeTurbulence(SkScalar baseFrequencyX,
+                                                    SkScalar baseFrequencyY,
+                                                    int numOctaves, SkScalar seed,
+                                                    const SkISize* tileSize) {
+    return sk_sp<SkShader>(new SkPerlinNoiseShaderImpl(SkPerlinNoiseShaderImpl::kTurbulence_Type,
+                                                 baseFrequencyX, baseFrequencyY, numOctaves, seed,
+                                                 tileSize));
+}
+
+sk_sp<SkShader> SkPerlinNoiseShader::MakeImprovedNoise(SkScalar baseFrequencyX,
+                                                       SkScalar baseFrequencyY,
+                                                       int numOctaves, SkScalar z) {
+    return sk_sp<SkShader>(new SkPerlinNoiseShaderImpl(SkPerlinNoiseShaderImpl::kImprovedNoise_Type,
+                                                 baseFrequencyX, baseFrequencyY, numOctaves, z,
+                                                 nullptr));
+}
+
+SK_DEFINE_FLATTENABLE_REGISTRAR_GROUP_START(SkPerlinNoiseShader)
+    SK_DEFINE_FLATTENABLE_REGISTRAR_ENTRY(SkPerlinNoiseShaderImpl)
+SK_DEFINE_FLATTENABLE_REGISTRAR_GROUP_END