Add specialized rgba8888 unit sampler.

src/core/SkLinearBitmapPipeline.cpp

Index: src/core/SkLinearBitmapPipeline.cpp
diff --git a/src/core/SkLinearBitmapPipeline.cpp b/src/core/SkLinearBitmapPipeline.cpp
index 3410ec1727f54c417e7623209a35ed552f4f419e..dc2ee513ca259b00ac577190c4b1c38f51744fbf 100644
--- a/src/core/SkLinearBitmapPipeline.cpp
+++ b/src/core/SkLinearBitmapPipeline.cpp
@@ -62,7 +62,14 @@ public:
     virtual void bilerpSpan(Span span, SkScalar y) = 0;
 };
 
-class SkLinearBitmapPipeline::PixelPlacerInterface {
+class SkLinearBitmapPipeline::DestinationInterface {
+public:
+    virtual ~DestinationInterface() { }
+    virtual void setDestination(void* dst, int count) = 0;
+};
+
+class SkLinearBitmapPipeline::PixelPlacerInterface
+    : public SkLinearBitmapPipeline::DestinationInterface {
 public:
     virtual ~PixelPlacerInterface() { }
     // Count is normally not needed, but in these early stages of development it is useful to
@@ -397,7 +404,6 @@ static SkLinearBitmapPipeline::PointProcessorInterface* choose_tiler(
     return tileStage->get();
 }
 
-
 ////////////////////////////////////////////////////////////////////////////////////////////////////
 // Source Sampling Stage
 template <typename SourceStrategy, typename Next>
@@ -476,6 +482,78 @@ private:
     GeneralSampler<SourceStrategy, Next> fSampler;
 };
 
+// RGBA8888UnitRepeatSrc - A sampler that takes advantage of the fact the the src and destination
+// are the same format and do not need in transformations in pixel space. Therefore, there is no
+// need to convert them to HiFi pixel format.
+class RGBA8888UnitRepeat final : public SkLinearBitmapPipeline::SampleProcessorInterface,
+                                 public SkLinearBitmapPipeline::DestinationInterface {
+public:
+    RGBA8888UnitRepeat(const uint32_t* src, int32_t width)
+        : fSrc{src}, fWidth{width} { }
+
+    void VECTORCALL pointListFew(int n, Sk4s xs, Sk4s ys) override {
+        SkASSERT(fDest + n <= fEnd);
+        // At this point xs and ys should be >= 0, so trunc is the same as floor.
+        Sk4i iXs = SkNx_cast<int>(xs);
+        Sk4i iYs = SkNx_cast<int>(ys);
+
+        if (n >= 1) *fDest++ = *this->pixelAddress(iXs[0], iYs[0]);
+        if (n >= 2) *fDest++ = *this->pixelAddress(iXs[1], iYs[1]);
+        if (n >= 3) *fDest++ = *this->pixelAddress(iXs[2], iYs[2]);
+    }
+
+    void VECTORCALL pointList4(Sk4s xs, Sk4s ys) override {
+        SkASSERT(fDest + 4 <= fEnd);
+        Sk4i iXs = SkNx_cast<int>(xs);
+        Sk4i iYs = SkNx_cast<int>(ys);
+        *fDest++ = *this->pixelAddress(iXs[0], iYs[0]);
+        *fDest++ = *this->pixelAddress(iXs[1], iYs[1]);
+        *fDest++ = *this->pixelAddress(iXs[2], iYs[2]);
+        *fDest++ = *this->pixelAddress(iXs[3], iYs[3]);
+    }
+
+    void pointSpan(Span span) override {
+        SkASSERT(fDest + span.count() <= fEnd);
+        int32_t x = (int32_t)span.startX();
+        int32_t y = (int32_t)span.startY();
+        const uint32_t* src = this->pixelAddress(x, y);
+        memmove(fDest, src, span.count() * sizeof(uint32_t));
+        fDest += span.count();
+    }
+
+    void repeatSpan(Span span, int32_t repeatCount) override {
+        SkASSERT(fDest + span.count() * repeatCount <= fEnd);
+
+        int32_t x = (int32_t)span.startX();
+        int32_t y = (int32_t)span.startY();
+        const uint32_t* src = this->pixelAddress(x, y);
+        uint32_t* dest = fDest;
+        while (repeatCount --> 0) {
+            memmove(dest, src, span.count() * sizeof(uint32_t));
+            dest += span.count();
+        }
+        fDest = dest;
+    }
+
+    void VECTORCALL bilerpEdge(Sk4s xs, Sk4s ys) override { SkFAIL("Not Implemented"); }
+
+    void bilerpSpan(Span span, SkScalar y) override { SkFAIL("Not Implemented"); }
+
+    void setDestination(void* dst, int count) override  {
+        fDest = static_cast<uint32_t*>(dst);
+        fEnd = fDest + count;
+    }
+
+private:
+    const uint32_t* pixelAddress(int32_t x, int32_t y) {
+        return &fSrc[fWidth * y + x];

[f(malita), 2016/04/08 12:58:12]

Do we need to worry about row padding here or rowbytes never comes into play?

[herb_g, 2016/04/08 13:48:59]

I talked with MikeR about this. RowBytes must always be a multiple of pixel
size, so just storing the with in pixels is all you need.

+    }
+    const uint32_t* const fSrc;
+    const int32_t         fWidth;
+    uint32_t*             fDest;
+    uint32_t*             fEnd;
+};
+
 using Placer = SkLinearBitmapPipeline::PixelPlacerInterface;
 
 template<template <typename, typename> class Sampler>
@@ -531,6 +609,7 @@ template <SkAlphaType alphaType>
 class PlaceFPPixel final : public SkLinearBitmapPipeline::PixelPlacerInterface {
 public:
     PlaceFPPixel(float postAlpha) : fPostAlpha{postAlpha} { }
+
     void VECTORCALL placePixel(Sk4f pixel) override {
         SkASSERT(fDst + 1 <= fEnd );
         PlacePixel(fDst, pixel, 0);
@@ -626,11 +705,14 @@ SkLinearBitmapPipeline::SkLinearBitmapPipeline(
     auto tilerStage     = choose_tiler(samplerStage,
                                        dimensions, xTile, yTile, filterQuality, dx, &fTiler);
     fFirstStage         = choose_matrix(tilerStage, adjustedInverse, &fMatrixStage);
+    fLastStage          = placementStage;
+
 }
 
 void SkLinearBitmapPipeline::shadeSpan4f(int x, int y, SkPM4f* dst, int count) {
     SkASSERT(count > 0);
-    fPixelStage->setDestination(dst, count);
+    fLastStage->setDestination(dst, count);
+
     // The count and length arguments start out in a precise relation in order to keep the
     // math correct through the different stages. Count is the number of pixel to produce.
     // Since the code samples at pixel centers, length is the distance from the center of the