Reduce size of LinearBitmapPipeline from 281K to 134K, but keep the same speed.

Speed checked using top25desk SKPS.

Size measured using:
 llvm-nm-3.6  -print-file-name  -print-size -U out/Release/libskia_core.a | awk '{totals[$1] += strtonum("0x" $3)} END { for (i in totals) {print totals[i], i}}' | sort -n | column -t

GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=2100323002

Review-Url: https://codereview.chromium.org/2100323002

src/core/SkBitmapProcShader.h

@@ -56,7 +56,7 @@ private:
     typedef SkShader INHERITED;
 };
 
-enum {kSkBlitterContextSize = 3100};
+enum {kSkBlitterContextSize = 3200};
 
 // Commonly used allocator. It currently is only used to allocate up to 3 objects. The total
 // bytes requested is calculated using one of our large shaders, its context size plus the size of

src/core/SkLinearBitmapPipeline.cpp

@@ -567,62 +567,70 @@ private:
 
 using Blender = SkLinearBitmapPipeline::BlendProcessorInterface;
 
-template <SkColorType colorType, template <SkColorType, SkGammaType, typename> class Sampler>
+template <SkColorType colorType>
-static void choose_specific_sampler(
+static SkLinearBitmapPipeline::PixelAccessorInterface* choose_specific_accessor(
-    Blender* next,
+    const SkPixmap& srcPixmap, SkLinearBitmapPipeline::Accessor* accessor)
-    const SkPixmap& srcPixmap,
-    SkLinearBitmapPipeline::SampleStage* sampleStage)
 {
     if (srcPixmap.info().gammaCloseToSRGB()) {
-        using S = Sampler<colorType, kSRGB_SkGammaType, Blender>;
+        using PA = PixelAccessor<colorType, kSRGB_SkGammaType>;
-        sampleStage->initStage<S>(next, srcPixmap);
+        accessor->init<PA>(srcPixmap);
+        return accessor->get();
     } else {
-        using S = Sampler<colorType, kLinear_SkGammaType, Blender>;
+        using PA = PixelAccessor<colorType, kLinear_SkGammaType>;
-        sampleStage->initStage<S>(next, srcPixmap);
+        accessor->init<PA>(srcPixmap);
+        return accessor->get();
     }
 }
 
-template<template <SkColorType, SkGammaType, typename> class Sampler>
+template<template <typename, typename> class Sampler>
 static SkLinearBitmapPipeline::SampleProcessorInterface* choose_pixel_sampler_base(
     Blender* next,
     const SkPixmap& srcPixmap,
     const SkColor A8TintColor,
-    SkLinearBitmapPipeline::SampleStage* sampleStage)
+    SkLinearBitmapPipeline::SampleStage* sampleStage,
+    SkLinearBitmapPipeline::Accessor* accessor)
 {
     const SkImageInfo& imageInfo = srcPixmap.info();
+
+    SkLinearBitmapPipeline::PixelAccessorInterface* pixelAccessor = nullptr;
     switch (imageInfo.colorType()) {
         case kAlpha_8_SkColorType: {
-                using S = Sampler<kAlpha_8_SkColorType, kLinear_SkGammaType, Blender>;
+                using PA = PixelAccessor<kAlpha_8_SkColorType, kLinear_SkGammaType>;
-                sampleStage->initStage<S>(next, srcPixmap, A8TintColor);
+                accessor->init<PA>(srcPixmap, A8TintColor);
+                pixelAccessor = accessor->get();
             }
             break;
         case kARGB_4444_SkColorType:
-            choose_specific_sampler<kARGB_4444_SkColorType, Sampler>(next, srcPixmap, sampleStage);
+            pixelAccessor = choose_specific_accessor<kARGB_4444_SkColorType>(srcPixmap, accessor);
             break;
         case kRGB_565_SkColorType:
-            choose_specific_sampler<kRGB_565_SkColorType, Sampler>(next, srcPixmap, sampleStage);
+            pixelAccessor = choose_specific_accessor<kRGB_565_SkColorType>(srcPixmap, accessor);
             break;
         case kRGBA_8888_SkColorType:
-            choose_specific_sampler<kRGBA_8888_SkColorType, Sampler>(next, srcPixmap, sampleStage);
+            pixelAccessor = choose_specific_accessor<kRGBA_8888_SkColorType>(srcPixmap, accessor);
             break;
         case kBGRA_8888_SkColorType:
-            choose_specific_sampler<kBGRA_8888_SkColorType, Sampler>(next, srcPixmap, sampleStage);
+            pixelAccessor = choose_specific_accessor<kBGRA_8888_SkColorType>(srcPixmap, accessor);
             break;
         case kIndex_8_SkColorType:
-            choose_specific_sampler<kIndex_8_SkColorType, Sampler>(next, srcPixmap, sampleStage);
+            pixelAccessor = choose_specific_accessor<kIndex_8_SkColorType>(srcPixmap, accessor);
             break;
         case kGray_8_SkColorType:
-            choose_specific_sampler<kGray_8_SkColorType, Sampler>(next, srcPixmap, sampleStage);
+            pixelAccessor = choose_specific_accessor<kGray_8_SkColorType>(srcPixmap, accessor);
             break;
         case kRGBA_F16_SkColorType: {
-                using S = Sampler<kRGBA_F16_SkColorType, kLinear_SkGammaType, Blender>;
+                using PA = PixelAccessor<kRGBA_F16_SkColorType, kLinear_SkGammaType>;
-                sampleStage->initStage<S>(next, srcPixmap);
+                accessor->init<PA>(srcPixmap);
+                pixelAccessor = accessor->get();
             }
             break;
         default:
             SkFAIL("Not implemented. Unsupported src");
             break;
     }
+
+    using S = Sampler<PixelAccessorShim, Blender>;
+    sampleStage->initStage<S>(next, pixelAccessor);
     return sampleStage->get();
 }
 
@@ -631,13 +639,60 @@ SkLinearBitmapPipeline::SampleProcessorInterface* choose_pixel_sampler(
     SkFilterQuality filterQuality,
     const SkPixmap& srcPixmap,
     const SkColor A8TintColor,
-    SkLinearBitmapPipeline::SampleStage* sampleStage)
+    SkLinearBitmapPipeline::SampleStage* sampleStage,
-{
+    SkLinearBitmapPipeline::Accessor* accessor) {
+    const SkImageInfo& imageInfo = srcPixmap.info();
+
+    // Special case samplers with fully expanded templates
+    if (imageInfo.gammaCloseToSRGB()) {
+        if (filterQuality == kNone_SkFilterQuality) {
+            switch (imageInfo.colorType()) {
+                case kN32_SkColorType: {
+                    using S =
+                    NearestNeighborSampler<
+                        PixelAccessor<kN32_SkColorType, kSRGB_SkGammaType>, Blender>;
+                    sampleStage->initStage<S>(next, srcPixmap);
+                    return sampleStage->get();
+                }
+                case kIndex_8_SkColorType: {
+                    using S =
+                    NearestNeighborSampler<
+                        PixelAccessor<kIndex_8_SkColorType, kSRGB_SkGammaType>, Blender>;
+                    sampleStage->initStage<S>(next, srcPixmap);
+                    return sampleStage->get();
+                }
+                default:
+                    break;
+            }
+        } else {
+            switch (imageInfo.colorType()) {
+                case kN32_SkColorType: {
+                    using S =
+                    BilerpSampler<
+                        PixelAccessor<kN32_SkColorType, kSRGB_SkGammaType>, Blender>;
+                    sampleStage->initStage<S>(next, srcPixmap);
+                    return sampleStage->get();
+                }
+                case kIndex_8_SkColorType: {
+                    using S =
+                    BilerpSampler<
+                        PixelAccessor<kIndex_8_SkColorType, kSRGB_SkGammaType>, Blender>;
+                    sampleStage->initStage<S>(next, srcPixmap);
+                    return sampleStage->get();
+                }
+                default:
+                    break;
+            }
+        }
+    }
+
+    // General cases.
     if (filterQuality == kNone_SkFilterQuality) {
         return choose_pixel_sampler_base<NearestNeighborSampler>(
-            next, srcPixmap, A8TintColor, sampleStage);
+            next, srcPixmap, A8TintColor, sampleStage, accessor);
     } else {
-        return choose_pixel_sampler_base<BilerpSampler>(next, srcPixmap, A8TintColor, sampleStage);
+        return choose_pixel_sampler_base<BilerpSampler>(
+            next, srcPixmap, A8TintColor, sampleStage, accessor);
     }
 }
 
@@ -742,7 +797,7 @@ SkLinearBitmapPipeline::SkLinearBitmapPipeline(
     // identity matrix, the matrix stage is skipped, and the tilerStage is the first stage.
     auto blenderStage = choose_blender_for_shading(alphaType, postAlpha, &fBlenderStage);
     auto samplerStage = choose_pixel_sampler(
-        blenderStage, filterQuality, srcPixmap, paintColor, &fSampleStage);
+        blenderStage, filterQuality, srcPixmap, paintColor, &fSampleStage, &fAccessor);
     auto tilerStage   = choose_tiler(samplerStage, dimensions, xTile, yTile,
                                      filterQuality, dx, &fTileStage);
     fFirstStage       = choose_matrix(tilerStage, adjustedInverse, &fMatrixStage);

src/core/SkLinearBitmapPipeline.h

@@ -91,16 +91,51 @@ public:
         mutable Space fSpace;
     };
 
+///////////////////////////////////////////////////////////////////////////////////////////////////
+// PolyMemory
+    template <typename Base, size_t kSize>
+    class PolyMemory {
+    public:
+        PolyMemory() : fIsInitialized{false} { }
+        ~PolyMemory() {
+            if (fIsInitialized) {
+                this->get()->~Base();
+            }
+        }
+        template<typename Variant, typename... Args>
+        void init(Args&& ... args) {
+            SkASSERTF(sizeof(Variant) <= sizeof(fSpace),
+                      "Size Variant: %d, Space: %d", sizeof(Variant), sizeof(fSpace));
+
+            new (&fSpace) Variant(std::forward<Args>(args)...);
+            fIsInitialized = true;
+        }
+
+        Base* get() const { return reinterpret_cast<Base*>(&fSpace); }
+        Base* operator->() const { return this->get(); }
+        Base& operator*() const { return *(this->get()); }
+
+    private:
+        struct SK_STRUCT_ALIGN(16) Space {
+            char space[kSize];
+        };
+        mutable Space fSpace;
+        bool          fIsInitialized;
+
+    };
+
     class PointProcessorInterface;
     class SampleProcessorInterface;
     class BlendProcessorInterface;
     class DestinationInterface;
+    class PixelAccessorInterface;
 
     // These values were generated by the assert above in Stage::init{Sink|Stage}.
     using MatrixStage  = Stage<PointProcessorInterface,    160, PointProcessorInterface>;
     using TileStage    = Stage<PointProcessorInterface,    160, SampleProcessorInterface>;
     using SampleStage  = Stage<SampleProcessorInterface,   100, BlendProcessorInterface>;
     using BlenderStage = Stage<BlendProcessorInterface,     40>;
+    using Accessor     = PolyMemory<PixelAccessorInterface, 48>;
 
 private:
     PointProcessorInterface* fFirstStage;
@@ -109,6 +144,7 @@ private:
     SampleStage              fSampleStage;
     BlenderStage             fBlenderStage;
     DestinationInterface*    fLastStage;
+    Accessor                 fAccessor;
 };
 
 ////////////////////////////////////////////////////////////////////////////////////////////////////

src/core/SkLinearBitmapPipeline_core.h

@@ -8,6 +8,7 @@
 #ifndef SkLinearBitmapPipeline_core_DEFINED
 #define SkLinearBitmapPipeline_core_DEFINED
 
+#include <algorithm>
 #include <cmath>
 #include "SkNx.h"
 
@@ -238,4 +239,23 @@ public:
     virtual void SK_VECTORCALL blend4Pixels(Sk4f p0, Sk4f p1, Sk4f p2, Sk4f p3) = 0;
 };
 
+class SkLinearBitmapPipeline::PixelAccessorInterface {
+public:
+    virtual ~PixelAccessorInterface() { }
+    virtual void SK_VECTORCALL getFewPixels(
+        int n, Sk4s xs, Sk4s ys, Sk4f* px0, Sk4f* px1, Sk4f* px2) const = 0;
+
+    virtual void SK_VECTORCALL get4Pixels(
+        Sk4s xs, Sk4s ys, Sk4f* px0, Sk4f* px1, Sk4f* px2, Sk4f* px3) const = 0;
+
+    virtual void get4Pixels(
+        const void* src, int index, Sk4f* px0, Sk4f* px1, Sk4f* px2, Sk4f* px3) const = 0;
+
+    virtual Sk4f getPixelFromRow(const void* row, int index) const = 0;
+
+    virtual Sk4f getPixelAt(int index) const = 0;
+
+    virtual const void* row(int y) const = 0;
+};
+
 #endif // SkLinearBitmapPipeline_core_DEFINED

src/core/SkLinearBitmapPipeline_sample.h

@@ -53,23 +53,23 @@ static Sk4s SK_VECTORCALL bilerp4(Sk4s xs, Sk4s ys, Sk4f px00, Sk4f px10,
 }
 
 ////////////////////////////////////////////////////////////////////////////////////////////////////
-// PixelGetter is the lowest level interface to the source data. There is a PixelGetter for each
+// PixelGetter is the lowest level interface to the source data. There is a PixelConverter for each
 // of the different SkColorTypes.
-template <SkColorType, SkGammaType> class PixelGetter;
+template <SkColorType, SkGammaType> class PixelConverter;
 
 // Alpha handling:
 //   The alpha from the paint (tintColor) is used in the blend part of the pipeline to modulate
 // the entire bitmap. So, the tint color is given an alpha of 1.0 so that the later alpha can
 // modulate this color later.
 template <>
-class PixelGetter<kAlpha_8_SkColorType, kLinear_SkGammaType> {
+class PixelConverter<kAlpha_8_SkColorType, kLinear_SkGammaType> {
 public:
     using Element = uint8_t;
-    PixelGetter(const SkPixmap& srcPixmap, SkColor tintColor)
+    PixelConverter(const SkPixmap& srcPixmap, SkColor tintColor)
         : fTintColor{set_alpha(Sk4f_from_SkColor(tintColor), 1.0f)} { }
 
-    Sk4f getPixelAt(const uint8_t* src) {
+    Sk4f toSk4f(const Element pixel) const {
-        return fTintColor * (*src * (1.0f/255.0f));
+        return fTintColor * (pixel * (1.0f/255.0f));
     }
 
 private:
@@ -77,13 +77,40 @@ private:
 };
 
 template <SkGammaType gammaType>
-class PixelGetter<kRGB_565_SkColorType, gammaType> {
+class PixelConverter<kRGB_565_SkColorType, gammaType> {
 public:
     using Element = uint16_t;
-    PixelGetter(const SkPixmap& srcPixmap) { }
+    PixelConverter(const SkPixmap& srcPixmap) { }
 
-    Sk4f getPixelAt(const uint16_t* src) {
+    Sk4f toSk4f(Element pixel) const {
-        SkPMColor pixel = SkPixel16ToPixel32(*src);
+        SkPMColor pixel32 = SkPixel16ToPixel32(pixel);
+        return gammaType == kSRGB_SkGammaType
+               ? Sk4f_fromS32(pixel32)
+               : Sk4f_fromL32(pixel32);
+    }
+};
+
+template <SkGammaType gammaType>
+class PixelConverter<kARGB_4444_SkColorType, gammaType> {
+public:
+    using Element = uint16_t;
+    PixelConverter(const SkPixmap& srcPixmap) { }
+
+    Sk4f toSk4f(Element pixel) const {
+        SkPMColor pixel32 = SkPixel4444ToPixel32(pixel);
+        return gammaType == kSRGB_SkGammaType
+               ? Sk4f_fromS32(pixel32)
+               : Sk4f_fromL32(pixel32);
+    }
+};
+
+template <SkGammaType gammaType>
+class PixelConverter<kRGBA_8888_SkColorType, gammaType> {
+public:
+    using Element = uint32_t;
+    PixelConverter(const SkPixmap& srcPixmap) { }
+
+    Sk4f toSk4f(Element pixel) const {
         return gammaType == kSRGB_SkGammaType
                ? Sk4f_fromS32(pixel)
                : Sk4f_fromL32(pixel);
@@ -91,51 +118,22 @@ public:
 };
 
 template <SkGammaType gammaType>
-class PixelGetter<kARGB_4444_SkColorType, gammaType> {
+class PixelConverter<kBGRA_8888_SkColorType, gammaType> {
-public:
-    using Element = uint16_t;
-    PixelGetter(const SkPixmap& srcPixmap) { }
-
-    Sk4f getPixelAt(const uint16_t* src) {
-        SkPMColor pixel = SkPixel4444ToPixel32(*src);
-        return gammaType == kSRGB_SkGammaType
-               ? Sk4f_fromS32(pixel)
-               : Sk4f_fromL32(pixel);
-    }
-};
-
-template <SkGammaType gammaType>
-class PixelGetter<kRGBA_8888_SkColorType, gammaType> {
 public:
     using Element = uint32_t;
-    PixelGetter(const SkPixmap& srcPixmap) { }
+    PixelConverter(const SkPixmap& srcPixmap) { }
 
-    Sk4f getPixelAt(const uint32_t* src) {
+    Sk4f toSk4f(Element pixel) const {
-        return gammaType == kSRGB_SkGammaType
+        return swizzle_rb(
-               ? Sk4f_fromS32(*src)
+                   gammaType == kSRGB_SkGammaType ? Sk4f_fromS32(pixel) : Sk4f_fromL32(pixel));
-               : Sk4f_fromL32(*src);
     }
 };
 
 template <SkGammaType gammaType>
-class PixelGetter<kBGRA_8888_SkColorType, gammaType> {
+class PixelConverter<kIndex_8_SkColorType, gammaType> {
-public:
-    using Element = uint32_t;
-    PixelGetter(const SkPixmap& srcPixmap) { }
-
-    Sk4f getPixelAt(const uint32_t* src) {
-        Sk4f pixel = gammaType == kSRGB_SkGammaType
-                     ? Sk4f_fromS32(*src)
-                     : Sk4f_fromL32(*src);
-        return swizzle_rb(pixel);
-    }
-};
-
-template <SkGammaType gammaType>
-class PixelGetter<kIndex_8_SkColorType, gammaType> {
 public:
     using Element = uint8_t;
-    PixelGetter(const SkPixmap& srcPixmap) {
+    PixelConverter(const SkPixmap& srcPixmap) {
         SkColorTable* skColorTable = srcPixmap.ctable();
         SkASSERT(skColorTable != nullptr);
 
@@ -145,7 +143,7 @@ public:
         }
     }
 
-    PixelGetter(const PixelGetter& strategy) {
+    PixelConverter(const PixelConverter& strategy) {
         fColorTable = (Sk4f*)SkAlign16((intptr_t)fColorTableStorage.get());
         // TODO: figure out the count.
         for (int i = 0; i < 256; i++) {
@@ -153,8 +151,8 @@ public:
         }
     }
 
-    Sk4f getPixelAt(const uint8_t* src) {
+    Sk4f toSk4f(Element index) const {
-        return fColorTable[*src];
+        return fColorTable[index];
     }
 
 private:
@@ -179,44 +177,81 @@ private:
 };
 
 template <SkGammaType gammaType>
-class PixelGetter<kGray_8_SkColorType, gammaType> {
+class PixelConverter<kGray_8_SkColorType, gammaType> {
 public:
     using Element = uint8_t;
-    PixelGetter(const SkPixmap& srcPixmap) { }
+    PixelConverter(const SkPixmap& srcPixmap) { }
 
-    Sk4f getPixelAt(const uint8_t* src) {
+    Sk4f toSk4f(Element pixel) const {
-        float gray = *src * (1.0f/255.0f);
+        float gray = pixel * (1.0f/255.0f);
-        Sk4f pixel = Sk4f{gray, gray, gray, 1.0f};
+        Sk4f result = Sk4f{gray, gray, gray, 1.0f};
         return gammaType == kSRGB_SkGammaType
-               ? srgb_to_linear(pixel)
+               ? srgb_to_linear(result)
-               : pixel;
+               : result;
     }
 };
 
 template <>
-class PixelGetter<kRGBA_F16_SkColorType, kLinear_SkGammaType> {
+class PixelConverter<kRGBA_F16_SkColorType, kLinear_SkGammaType> {
 public:
     using Element = uint64_t;
-    PixelGetter(const SkPixmap& srcPixmap) { }
+    PixelConverter(const SkPixmap& srcPixmap) { }
 
-    Sk4f getPixelAt(const uint64_t* src) {
+    Sk4f toSk4f(const Element pixel) const {
-        return SkHalfToFloat_01(*src);
+        return SkHalfToFloat_01(pixel);
     }
 };
 
+class PixelAccessorShim {
+public:
+    explicit PixelAccessorShim(SkLinearBitmapPipeline::PixelAccessorInterface* accessor)
+        : fPixelAccessor(accessor) { }
+
+    void SK_VECTORCALL getFewPixels(
+        int n, Sk4s xs, Sk4s ys, Sk4f* px0, Sk4f* px1, Sk4f* px2) const {
+        fPixelAccessor->getFewPixels(n, xs, ys, px0, px1, px2);
+    }
+
+    void SK_VECTORCALL get4Pixels(
+        Sk4s xs, Sk4s ys, Sk4f* px0, Sk4f* px1, Sk4f* px2, Sk4f* px3) const {
+        fPixelAccessor->get4Pixels(xs, ys, px0, px1, px2, px3);
+    }
+
+    void get4Pixels(
+        const void* src, int index, Sk4f* px0, Sk4f* px1, Sk4f* px2, Sk4f* px3) const {
+        fPixelAccessor->get4Pixels(src, index, px0, px1, px2, px3);
+    };
+
+    Sk4f getPixelFromRow(const void* row, int index) const {
+        return fPixelAccessor->getPixelFromRow(row, index);
+    }
+
+    Sk4f getPixelAt(int index) const {
+        return fPixelAccessor->getPixelAt(index);
+    }
+
+    const void* row(int y) const {
+        return fPixelAccessor->row(y);
+    }
+
+private:
+    SkLinearBitmapPipeline::PixelAccessorInterface* const fPixelAccessor;
+};
+
 ////////////////////////////////////////////////////////////////////////////////////////////////////
 // PixelAccessor handles all the same plumbing for all the PixelGetters.
 template <SkColorType colorType, SkGammaType gammaType>
-class PixelAccessor {
+class PixelAccessor final : public SkLinearBitmapPipeline::PixelAccessorInterface {
-    using Element = typename PixelGetter<colorType, gammaType>::Element;
+    using Element = typename PixelConverter<colorType, gammaType>::Element;
 public:
     template <typename... Args>
     PixelAccessor(const SkPixmap& srcPixmap, Args&&... args)
         : fSrc{static_cast<const Element*>(srcPixmap.addr())}
         , fWidth{srcPixmap.rowBytesAsPixels()}
-        , fGetter{srcPixmap, std::move<Args>(args)...} { }
+        , fConverter{srcPixmap, std::move<Args>(args)...} { }
 
-    void SK_VECTORCALL getFewPixels(int n, Sk4s xs, Sk4s ys, Sk4f* px0, Sk4f* px1, Sk4f* px2) {
+    void SK_VECTORCALL getFewPixels (
+        int n, Sk4s xs, Sk4s ys, Sk4f* px0, Sk4f* px1, Sk4f* px2) const override {
         Sk4i XIs = SkNx_cast<int, SkScalar>(xs);
         Sk4i YIs = SkNx_cast<int, SkScalar>(ys);
         Sk4i bufferLoc = YIs * fWidth + XIs;
@@ -232,7 +267,8 @@ public:
         }
     }
 
-    void SK_VECTORCALL get4Pixels(Sk4s xs, Sk4s ys, Sk4f* px0, Sk4f* px1, Sk4f* px2, Sk4f* px3) {
+    void SK_VECTORCALL get4Pixels(
+        Sk4s xs, Sk4s ys, Sk4f* px0, Sk4f* px1, Sk4f* px2, Sk4f* px3) const override {
         Sk4i XIs = SkNx_cast<int, SkScalar>(xs);
         Sk4i YIs = SkNx_cast<int, SkScalar>(ys);
         Sk4i bufferLoc = YIs * fWidth + XIs;
@@ -242,28 +278,29 @@ public:
         *px3 = this->getPixelAt(bufferLoc[3]);
     }
 
-    void get4Pixels(const void* src, int index, Sk4f* px0, Sk4f* px1, Sk4f* px2, Sk4f* px3) {
+    void get4Pixels(
+        const void* src, int index, Sk4f* px0, Sk4f* px1, Sk4f* px2, Sk4f* px3) const override {
         *px0 = this->getPixelFromRow(src, index + 0);
         *px1 = this->getPixelFromRow(src, index + 1);
         *px2 = this->getPixelFromRow(src, index + 2);
         *px3 = this->getPixelFromRow(src, index + 3);
     }
 
-    Sk4f getPixelFromRow(const void* row, int index) {
+    Sk4f getPixelFromRow(const void* row, int index) const override {
         const Element* src = static_cast<const Element*>(row);
-        return fGetter.getPixelAt(src + index);
+        return fConverter.toSk4f(src[index]);
     }
 
-    Sk4f getPixelAt(int index) {
+    Sk4f getPixelAt(int index) const override {
         return this->getPixelFromRow(fSrc, index);
     }
 
-    const void* row(int y) const { return fSrc + y * fWidth[0]; }
+    const void* row(int y) const override { return fSrc + y * fWidth; }
 
 private:
     const Element* const                 fSrc;
-    const Sk4i                           fWidth;
+    const int                            fWidth;
-    PixelGetter<colorType, gammaType> fGetter;
+    PixelConverter<colorType, gammaType> fConverter;
 };
 
 // We're moving through source space at a rate of 1 source pixel per 1 dst pixel.
@@ -308,21 +345,21 @@ static void src_strategy_blend(Span span, Next* next, Strategy* strategy) {
 }
 
 // NearestNeighborSampler - use nearest neighbor filtering to create runs of destination pixels.
-template<SkColorType colorType, SkGammaType gammaType, typename Next>
+template<typename Accessor, typename Next>
 class NearestNeighborSampler : public SkLinearBitmapPipeline::SampleProcessorInterface {
 public:
     template<typename... Args>
     NearestNeighborSampler(SkLinearBitmapPipeline::BlendProcessorInterface* next, Args&& ... args)
-    : fNext{next}, fStrategy{std::forward<Args>(args)...} { }
+    : fNext{next}, fAccessor{std::forward<Args>(args)...} { }
 
     NearestNeighborSampler(SkLinearBitmapPipeline::BlendProcessorInterface* next,
     const NearestNeighborSampler& sampler)
-    : fNext{next}, fStrategy{sampler.fStrategy} { }
+    : fNext{next}, fAccessor{sampler.fAccessor} { }
 
     void SK_VECTORCALL pointListFew(int n, Sk4s xs, Sk4s ys) override {
         SkASSERT(0 < n && n < 4);
         Sk4f px0, px1, px2;
-        fStrategy.getFewPixels(n, xs, ys, &px0, &px1, &px2);
+        fAccessor.getFewPixels(n, xs, ys, &px0, &px1, &px2);
         if (n >= 1) fNext->blendPixel(px0);
         if (n >= 2) fNext->blendPixel(px1);
         if (n >= 3) fNext->blendPixel(px2);
@@ -330,7 +367,7 @@ public:
 
     void SK_VECTORCALL pointList4(Sk4s xs, Sk4s ys) override {
         Sk4f px0, px1, px2, px3;
-        fStrategy.get4Pixels(xs, ys, &px0, &px1, &px2, &px3);
+        fAccessor.get4Pixels(xs, ys, &px0, &px1, &px2, &px3);
         fNext->blend4Pixels(px0, px1, px2, px3);
     }
 
@@ -344,7 +381,7 @@ public:
         if (absLength < (count - 1)) {
             this->spanSlowRate(span);
         } else if (absLength == (count - 1)) {
-            src_strategy_blend(span, fNext, &fStrategy);
+            src_strategy_blend(span, fNext, &fAccessor);
         } else {
             this->spanFastRate(span);
         }
@@ -378,19 +415,19 @@ private:
         SkScalar dx = length / (count - 1);
         SkFixed fdx = SkScalarToFixed(dx);
 
-        const void* row = fStrategy.row((int)std::floor(Y(start)));
+        const void* row = fAccessor.row((int)std::floor(Y(start)));
         Next* next = fNext;
 
         int ix = SkFixedFloorToInt(fx);
         int prevIX = ix;
-        Sk4f fpixel = fStrategy.getPixelFromRow(row, ix);
+        Sk4f fpixel = fAccessor.getPixelFromRow(row, ix);
 
         // When dx is less than one, each pixel is used more than once. Using the fixed point fx
         // allows the code to quickly check that the same pixel is being used. The code uses this
         // same pixel check to do the sRGB and normalization only once.
         auto getNextPixel = [&]() {
             if (ix != prevIX) {
-                fpixel = fStrategy.getPixelFromRow(row, ix);
+                fpixel = fAccessor.getPixelFromRow(row, ix);
                 prevIX = ix;
             }
             fx += fdx;
@@ -415,7 +452,7 @@ private:
     // We're moving through source space at a rate of 1 source pixel per 1 dst pixel.
     // We'll never re-use pixels, but we can at least load contiguous pixels.
     void spanUnitRate(Span span) {
-        src_strategy_blend(span, fNext, &fStrategy);
+        src_strategy_blend(span, fNext, &fAccessor);
     }
 
     // We're moving through source space faster than dst (zoomed out),
@@ -425,21 +462,21 @@ private:
     }
 
     Next* const fNext;
-    PixelAccessor<colorType, gammaType> fStrategy;
+    Accessor    fAccessor;
 };
 
 // -- BilerpSampler --------------------------------------------------------------------------------
 // BilerpSampler - use a bilerp filter to create runs of destination pixels.
-template<SkColorType colorType, SkGammaType gammaType, typename Next>
+template<typename Accessor, typename Next>
 class BilerpSampler : public SkLinearBitmapPipeline::SampleProcessorInterface {
 public:
     template<typename... Args>
     BilerpSampler(SkLinearBitmapPipeline::BlendProcessorInterface* next, Args&& ... args)
-        : fNext{next}, fStrategy{std::forward<Args>(args)...} { }
+        : fNext{next}, fAccessor{std::forward<Args>(args)...} { }
 
     BilerpSampler(SkLinearBitmapPipeline::BlendProcessorInterface* next,
                    const BilerpSampler& sampler)
-        : fNext{next}, fStrategy{sampler.fStrategy} { }
+        : fNext{next}, fAccessor{sampler.fAccessor} { }
 
     Sk4f bilerpNonEdgePixel(SkScalar x, SkScalar y) {
         Sk4f px00, px10, px01, px11;
@@ -449,7 +486,7 @@ public:
         Sk4f ys = Sk4f{y} - 0.5f;
         Sk4f sampleXs = xs + Sk4f{0.0f, 1.0f, 0.0f, 1.0f};
         Sk4f sampleYs = ys + Sk4f{0.0f, 0.0f, 1.0f, 1.0f};
-        fStrategy.get4Pixels(sampleXs, sampleYs, &px00, &px10, &px01, &px11);
+        fAccessor.get4Pixels(sampleXs, sampleYs, &px00, &px10, &px01, &px11);
         return bilerp4(xs, ys, px00, px10, px01, px11);
     }
 
@@ -486,7 +523,7 @@ public:
         Sk4f px00, px10, px01, px11;
         Sk4f xs = Sk4f{sampleXs[0]};
         Sk4f ys = Sk4f{sampleYs[0]};
-        fStrategy.get4Pixels(sampleXs, sampleYs, &px00, &px10, &px01, &px11);
+        fAccessor.get4Pixels(sampleXs, sampleYs, &px00, &px10, &px01, &px11);
         Sk4f pixel = bilerp4(xs, ys, px00, px10, px01, px11);
         fNext->blendPixel(pixel);
     }
@@ -505,7 +542,7 @@ public:
         } else if (absLength == (count - 1)) {
             if (std::fmod(span.startX() - 0.5f, 1.0f) == 0.0f) {
                 if (std::fmod(span.startY() - 0.5f, 1.0f) == 0.0f) {
-                    src_strategy_blend(span, fNext, &fStrategy);
+                    src_strategy_blend(span, fNext, &fAccessor);
                 } else {
                     this->spanUnitRateAlignedX(span, y);
                 }
@@ -526,8 +563,8 @@ private:
         SkScalar filterY0 = 1.0f - filterY1;
         int iy1 = SkScalarFloorToInt(y1);
         int ix = SkScalarFloorToInt(span.startX());
-        Sk4f pixelY0 = fStrategy.getPixelFromRow(fStrategy.row(iy0), ix);
+        Sk4f pixelY0 = fAccessor.getPixelFromRow(fAccessor.row(iy0), ix);
-        Sk4f pixelY1 = fStrategy.getPixelFromRow(fStrategy.row(iy1), ix);
+        Sk4f pixelY1 = fAccessor.getPixelFromRow(fAccessor.row(iy1), ix);
         Sk4f filterPixel = pixelY0 * filterY0 + pixelY1 * filterY1;
         int count = span.count();
         while (count >= 4) {
@@ -566,18 +603,18 @@ private:
         SkScalar yFloor = std::floor(ry0);
         Sk4f y1 = Sk4f{ry0 - yFloor};
         Sk4f y0 = Sk4f{1.0f} - y1;
-        const void* const row0 = fStrategy.row(SkScalarFloorToInt(ry0));
+        const void* const row0 = fAccessor.row(SkScalarFloorToInt(ry0));
-        const void* const row1 = fStrategy.row(SkScalarFloorToInt(ry1));
+        const void* const row1 = fAccessor.row(SkScalarFloorToInt(ry1));
-        Sk4f fpixel00 = y0 * fStrategy.getPixelFromRow(row0, ix);
+        Sk4f fpixel00 = y0 * fAccessor.getPixelFromRow(row0, ix);
-        Sk4f fpixel01 = y1 * fStrategy.getPixelFromRow(row1, ix);
+        Sk4f fpixel01 = y1 * fAccessor.getPixelFromRow(row1, ix);
-        Sk4f fpixel10 = y0 * fStrategy.getPixelFromRow(row0, ix + 1);
+        Sk4f fpixel10 = y0 * fAccessor.getPixelFromRow(row0, ix + 1);
-        Sk4f fpixel11 = y1 * fStrategy.getPixelFromRow(row1, ix + 1);
+        Sk4f fpixel11 = y1 * fAccessor.getPixelFromRow(row1, ix + 1);
         auto getNextPixel = [&]() {
             if (ix != ioldx) {
                 fpixel00 = fpixel10;
                 fpixel01 = fpixel11;
-                fpixel10 = y0 * fStrategy.getPixelFromRow(row0, ix + 1);
+                fpixel10 = y0 * fAccessor.getPixelFromRow(row0, ix + 1);
-                fpixel11 = y1 * fStrategy.getPixelFromRow(row1, ix + 1);
+                fpixel11 = y1 * fAccessor.getPixelFromRow(row1, ix + 1);
                 ioldx = ix;
                 x = x + xAdjust;
             }
@@ -618,25 +655,25 @@ private:
         SkScalar filterY1 = y0 - iy0;
         SkScalar filterY0 = 1.0f - filterY1;
         int iy1 = SkScalarFloorToInt(y1);
-        const void* rowY0 = fStrategy.row(iy0);
+        const void* rowY0 = fAccessor.row(iy0);
-        const void* rowY1 = fStrategy.row(iy1);
+        const void* rowY1 = fAccessor.row(iy1);
         SkScalar x0 = span.startX() - 0.5f;
         int ix0 = SkScalarFloorToInt(x0);
         SkScalar filterX1 = x0 - ix0;
         SkScalar filterX0 = 1.0f - filterX1;
 
         auto getPixelY0 = [&]() {
-            Sk4f px = fStrategy.getPixelFromRow(rowY0, ix0);
+            Sk4f px = fAccessor.getPixelFromRow(rowY0, ix0);
             return px * filterY0;
         };
 
         auto getPixelY1 = [&]() {
-            Sk4f px = fStrategy.getPixelFromRow(rowY1, ix0);
+            Sk4f px = fAccessor.getPixelFromRow(rowY1, ix0);
             return px * filterY1;
         };
 
         auto get4PixelsY0 = [&](int ix, Sk4f* px0, Sk4f* px1, Sk4f* px2, Sk4f* px3) {
-            fStrategy.get4Pixels(rowY0, ix, px0, px1, px2, px3);
+            fAccessor.get4Pixels(rowY0, ix, px0, px1, px2, px3);
             *px0 = *px0 * filterY0;
             *px1 = *px1 * filterY0;
             *px2 = *px2 * filterY0;
@@ -644,7 +681,7 @@ private:
         };
 
         auto get4PixelsY1 = [&](int ix, Sk4f* px0, Sk4f* px1, Sk4f* px2, Sk4f* px3) {
-            fStrategy.get4Pixels(rowY1, ix, px0, px1, px2, px3);
+            fAccessor.get4Pixels(rowY1, ix, px0, px1, px2, px3);
             *px0 = *px0 * filterY1;
             *px1 = *px1 * filterY1;
             *px2 = *px2 * filterY1;
@@ -678,8 +715,8 @@ private:
                 count -= 4;
             }
             while (count > 0) {
-                Sk4f pixelY0 = fStrategy.getPixelFromRow(rowY0, ix0);
+                Sk4f pixelY0 = fAccessor.getPixelFromRow(rowY0, ix0);
-                Sk4f pixelY1 = fStrategy.getPixelFromRow(rowY1, ix0);
+                Sk4f pixelY1 = fAccessor.getPixelFromRow(rowY1, ix0);
 
                 fNext->blendPixel(lerp(pixelY0, pixelY1));
                 ix0 += 1;
@@ -706,8 +743,8 @@ private:
                 count -= 4;
             }
             while (count > 0) {
-                Sk4f pixelY0 = fStrategy.getPixelFromRow(rowY0, ix0);
+                Sk4f pixelY0 = fAccessor.getPixelFromRow(rowY0, ix0);
-                Sk4f pixelY1 = fStrategy.getPixelFromRow(rowY1, ix0);
+                Sk4f pixelY1 = fAccessor.getPixelFromRow(rowY1, ix0);
 
                 fNext->blendPixel(lerp(pixelY0, pixelY1));
                 ix0 -= 1;
@@ -724,8 +761,8 @@ private:
         SkScalar filterY0 = 1.0f - filterY1;
         int iy1 = SkScalarFloorToInt(y1);
         int ix = SkScalarFloorToInt(span.startX());
-        const void* rowY0 = fStrategy.row(iy0);
+        const void* rowY0 = fAccessor.row(iy0);
-        const void* rowY1 = fStrategy.row(iy1);
+        const void* rowY1 = fAccessor.row(iy1);
         auto lerp = [&](Sk4f* pixelY0, Sk4f* pixelY1) {
             return *pixelY0 * filterY0 + *pixelY1 * filterY1;
         };
@@ -734,17 +771,17 @@ private:
             int count = span.count();
             while (count >= 4) {
                 Sk4f px00, px10, px20, px30;
-                fStrategy.get4Pixels(rowY0, ix, &px00, &px10, &px20, &px30);
+                fAccessor.get4Pixels(rowY0, ix, &px00, &px10, &px20, &px30);
                 Sk4f px01, px11, px21, px31;
-                fStrategy.get4Pixels(rowY1, ix, &px01, &px11, &px21, &px31);
+                fAccessor.get4Pixels(rowY1, ix, &px01, &px11, &px21, &px31);
                 fNext->blend4Pixels(
                     lerp(&px00, &px01), lerp(&px10, &px11), lerp(&px20, &px21), lerp(&px30, &px31));
                 ix += 4;
                 count -= 4;
             }
             while (count > 0) {
-                Sk4f pixelY0 = fStrategy.getPixelFromRow(rowY0, ix);
+                Sk4f pixelY0 = fAccessor.getPixelFromRow(rowY0, ix);
-                Sk4f pixelY1 = fStrategy.getPixelFromRow(rowY1, ix);
+                Sk4f pixelY1 = fAccessor.getPixelFromRow(rowY1, ix);
 
                 fNext->blendPixel(lerp(&pixelY0, &pixelY1));
                 ix += 1;
@@ -754,17 +791,17 @@ private:
             int count = span.count();
             while (count >= 4) {
                 Sk4f px00, px10, px20, px30;
-                fStrategy.get4Pixels(rowY0, ix - 3, &px30, &px20, &px10, &px00);
+                fAccessor.get4Pixels(rowY0, ix - 3, &px30, &px20, &px10, &px00);
                 Sk4f px01, px11, px21, px31;
-                fStrategy.get4Pixels(rowY1, ix - 3, &px31, &px21, &px11, &px01);
+                fAccessor.get4Pixels(rowY1, ix - 3, &px31, &px21, &px11, &px01);
                 fNext->blend4Pixels(
                     lerp(&px00, &px01), lerp(&px10, &px11), lerp(&px20, &px21), lerp(&px30, &px31));
                 ix -= 4;
                 count -= 4;
             }
             while (count > 0) {
-                Sk4f pixelY0 = fStrategy.getPixelFromRow(rowY0, ix);
+                Sk4f pixelY0 = fAccessor.getPixelFromRow(rowY0, ix);
-                Sk4f pixelY1 = fStrategy.getPixelFromRow(rowY1, ix);
+                Sk4f pixelY1 = fAccessor.getPixelFromRow(rowY1, ix);
 
                 fNext->blendPixel(lerp(&pixelY0, &pixelY1));
                 ix -= 1;
@@ -802,7 +839,7 @@ private:
     }
 
     Next* const fNext;
-    PixelAccessor<colorType, gammaType> fStrategy;
+    Accessor    fAccessor;
 };
 
 }  // namespace