Simplified linear pipeline.

src/core/SkLinearBitmapPipeline.h

+/*
+ * Copyright 2016 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#ifndef SkLinearBitmapPipeline_DEFINED
+#define SkLinearBitmapPipeline_DEFINED
+
+#include <algorithm>
+#include <cmath>
+#include <limits>
+#include <cstdio>
+#include "SkColor.h"
+#include "SkImageInfo.h"
+#include "SkMatrix.h"
+#include "SkShader.h"
+#include "SkSize.h"
+#include "SkNx.h"
+
+class PointProcessorInterface {
+public:
+    virtual ~PointProcessorInterface() { }
+    virtual void pointListFew(int n, Sk4f x, Sk4f y) = 0;
+    virtual void pointList4(Sk4f Xs, Sk4f Ys) = 0;
+};
+
+class PixelPlacerInterface {
+public:
+    virtual ~PixelPlacerInterface() { }
+    virtual void setDestination(SkPM4f* dst) = 0;
+    virtual void placePixel(Sk4f pixel0) = 0;
+    virtual void place4Pixels(Sk4f p0, Sk4f p1, Sk4f p2, Sk4f p3) = 0;
+};
+
+template<typename Base, size_t kSize = 80>

[mtklein, 2016/02/16 21:13:10]

Seems clearer without a default.

[herb_g, 2016/02/16 22:04:25]

Done.

+class PolymorphicUnion {
+public:
+    PolymorphicUnion() {}
+
+    ~PolymorphicUnion() { get()->~Base(); }
+
+    template<typename Variant, typename... Args>
+    void Initialize(Args&&... args) {
+        SkASSERTF(sizeof(Variant) <= sizeof(fSpace),
+                  "Size Variant: %d, Space: %d", sizeof(Variant), sizeof(fSpace));
+        #if defined(_MSC_VER) && _MSC_VER < 1900
+        #define alignof __alignof
+        #endif
+        SkASSERT(alignof(Variant) <= alignof(Space));
+        new(&fSpace) Variant(std::forward<Args>(args)...);
+    };
+
+    Base* get() const { return reinterpret_cast<Base*>(&fSpace); }
+    Base* operator->() const { return get(); }
+    Base& operator*() const { return *get(); }
+
+private:
+    using Space = typename std::aligned_union<kSize, Base, Sk4f>::type;
+    mutable Space fSpace;
+};
+
+using MatrixStage = PolymorphicUnion<PointProcessorInterface, 112>;

[mtklein, 2016/02/16 21:13:10]

Move inside SKLinearBitmapPipeline?

[herb_g, 2016/02/16 22:04:25]

Done.

+using TileStage   = PolymorphicUnion<PointProcessorInterface, 96>;
+using SampleStage = PolymorphicUnion<PointProcessorInterface>;
+using PixelStage  = PolymorphicUnion<PixelPlacerInterface>;
+
+class SkLinearBitmapPipeline {
+public:
+    SkLinearBitmapPipeline(
+        const SkMatrix& inverse,
+        SkShader::TileMode xTile, SkShader::TileMode yTile,
+        const SkImageInfo& srcImageInfo,
+        const void* srcImageData);
+
+    void shadeSpan4f(int x, int y, SkPM4f* dst, int count);
+
+private:
+    PointProcessorInterface* fFirstStage;
+    MatrixStage fMatrixStage;
+    TileStage   fTileXOrBothStage;
+    TileStage   fTileYStage;
+    SampleStage fSampleStage;
+    PixelStage  fPixelStage;
+};
+
+#endif  // SkLinearBitmapPipeline_DEFINED