Relocate shaders to own dir

Consolidate all shader impls under src/shaders/.

Change-Id: I450e37541214704c1ad9e379d9d753b7cc62fac3
Reviewed-on: https://skia-review.googlesource.com/17927
Commit-Queue: Florin Malita <fmalita@chromium.org>
Reviewed-by: Herb Derby <herb@google.com>

1 files changed, 303 insertions, 0 deletions

diff --git a/src/shaders/SkShaderBase.h b/src/shaders/SkShaderBase.h
new file mode 100644
index 0000000000..895fc6cf05
--- /dev/null
+++ b/src/shaders/SkShaderBase.h
@@ -0,0 +1,303 @@
+/*
+ * Copyright 2017 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#ifndef SkShaderBase_DEFINED
+#define SkShaderBase_DEFINED
+
+#include "SkFilterQuality.h"
+#include "SkMatrix.h"
+#include "SkShader.h"
+
+class GrContext;
+class GrFragmentProcessor;
+class SkArenaAlloc;
+class SkColorSpace;
+class SkColorSpaceXformer;
+class SkImage;
+struct SkImageInfo;
+class SkPaint;
+class SkRasterPipeline;
+
+class SkShaderBase : public SkShader {
+public:
+    SkShaderBase(const SkMatrix* localMatrix = nullptr);
+
+    ~SkShaderBase() override;
+
+    /**
+     *  Returns true if the shader is guaranteed to produce only a single color.
+     *  Subclasses can override this to allow loop-hoisting optimization.
+     */
+    virtual bool isConstant() const { return false; }
+
+    const SkMatrix& getLocalMatrix() const { return fLocalMatrix; }
+
+    enum Flags {
+        //!< set if all of the colors will be opaque
+        kOpaqueAlpha_Flag = 1 << 0,
+
+        /** set if the spans only vary in X (const in Y).
+            e.g. an Nx1 bitmap that is being tiled in Y, or a linear-gradient
+            that varies from left-to-right. This flag specifies this for
+            shadeSpan().
+         */
+        kConstInY32_Flag = 1 << 1,
+
+        /** hint for the blitter that 4f is the preferred shading mode.
+         */
+        kPrefers4f_Flag  = 1 << 2,
+    };
+
+    /**
+     *  ContextRec acts as a parameter bundle for creating Contexts.
+     */
+    struct ContextRec {
+        enum DstType {
+            kPMColor_DstType, // clients prefer shading into PMColor dest
+            kPM4f_DstType,    // clients prefer shading into PM4f dest
+        };
+
+        ContextRec(const SkPaint& paint, const SkMatrix& matrix, const SkMatrix* localM,
+                   DstType dstType, SkColorSpace* dstColorSpace)
+            : fPaint(&paint)
+            , fMatrix(&matrix)
+            , fLocalMatrix(localM)
+            , fPreferredDstType(dstType)
+            , fDstColorSpace(dstColorSpace) {}
+
+        const SkPaint*  fPaint;            // the current paint associated with the draw
+        const SkMatrix* fMatrix;           // the current matrix in the canvas
+        const SkMatrix* fLocalMatrix;      // optional local matrix
+        const DstType   fPreferredDstType; // the "natural" client dest type
+        SkColorSpace*   fDstColorSpace;    // the color space of the dest surface (if any)
+    };
+
+    class Context : public ::SkNoncopyable {
+    public:
+        Context(const SkShaderBase& shader, const ContextRec&);
+
+        virtual ~Context();
+
+        /**
+         *  Called sometimes before drawing with this shader. Return the type of
+         *  alpha your shader will return. The default implementation returns 0.
+         *  Your subclass should override if it can (even sometimes) report a
+         *  non-zero value, since that will enable various blitters to perform
+         *  faster.
+         */
+        virtual uint32_t getFlags() const { return 0; }
+
+        /**
+         *  Called for each span of the object being drawn. Your subclass should
+         *  set the appropriate colors (with premultiplied alpha) that correspond
+         *  to the specified device coordinates.
+         */
+        virtual void shadeSpan(int x, int y, SkPMColor[], int count) = 0;
+
+        virtual void shadeSpan4f(int x, int y, SkPM4f[], int count);
+
+        struct BlitState;
+        typedef void (*BlitBW)(BlitState*,
+                               int x, int y, const SkPixmap&, int count);
+        typedef void (*BlitAA)(BlitState*,
+                               int x, int y, const SkPixmap&, int count, const SkAlpha[]);
+
+        struct BlitState {
+            // inputs
+            Context*    fCtx;
+            SkBlendMode fMode;
+
+            // outputs
+            enum { N = 2 };
+            void*       fStorage[N];
+            BlitBW      fBlitBW;
+            BlitAA      fBlitAA;
+        };
+
+        // Returns true if one or more of the blitprocs are set in the BlitState
+        bool chooseBlitProcs(const SkImageInfo& info, BlitState* state) {
+            state->fBlitBW = nullptr;
+            state->fBlitAA = nullptr;
+            if (this->onChooseBlitProcs(info, state)) {
+                SkASSERT(state->fBlitBW || state->fBlitAA);
+                return true;
+            }
+            return false;
+        }
+
+        /**
+         * The const void* ctx is only const because all the implementations are const.
+         * This can be changed to non-const if a new shade proc needs to change the ctx.
+         */
+        typedef void (*ShadeProc)(const void* ctx, int x, int y, SkPMColor[], int count);
+        virtual ShadeProc asAShadeProc(void** ctx);
+
+        /**
+         *  Similar to shadeSpan, but only returns the alpha-channel for a span.
+         *  The default implementation calls shadeSpan() and then extracts the alpha
+         *  values from the returned colors.
+         */
+        virtual void shadeSpanAlpha(int x, int y, uint8_t alpha[], int count);
+
+        // Notification from blitter::blitMask in case we need to see the non-alpha channels
+        virtual void set3DMask(const SkMask*) {}
+
+    protected:
+        // Reference to shader, so we don't have to dupe information.
+        const SkShaderBase& fShader;
+
+        enum MatrixClass {
+            kLinear_MatrixClass,            // no perspective
+            kFixedStepInX_MatrixClass,      // fast perspective, need to call fixedStepInX() each
+                                            // scanline
+            kPerspective_MatrixClass        // slow perspective, need to mappoints each pixel
+        };
+        static MatrixClass ComputeMatrixClass(const SkMatrix&);
+
+        uint8_t         getPaintAlpha() const { return fPaintAlpha; }
+        const SkMatrix& getTotalInverse() const { return fTotalInverse; }
+        MatrixClass     getInverseClass() const { return (MatrixClass)fTotalInverseClass; }
+        const SkMatrix& getCTM() const { return fCTM; }
+
+        virtual bool onChooseBlitProcs(const SkImageInfo&, BlitState*) { return false; }
+
+    private:
+        SkMatrix    fCTM;
+        SkMatrix    fTotalInverse;
+        uint8_t     fPaintAlpha;
+        uint8_t     fTotalInverseClass;
+
+        typedef SkNoncopyable INHERITED;
+    };
+
+    /**
+     * Make a context using the memory provided by the arena.
+     *
+     * @return pointer to context or nullptr if can't be created
+     */
+    Context* makeContext(const ContextRec&, SkArenaAlloc*) const;
+
+#if SK_SUPPORT_GPU
+    struct AsFPArgs {
+        AsFPArgs() {}
+        AsFPArgs(GrContext* context,
+                 const SkMatrix* viewMatrix,
+                 const SkMatrix* localMatrix,
+                 SkFilterQuality filterQuality,
+                 SkColorSpace* dstColorSpace)
+            : fContext(context)
+            , fViewMatrix(viewMatrix)
+            , fLocalMatrix(localMatrix)
+            , fFilterQuality(filterQuality)
+            , fDstColorSpace(dstColorSpace) {}
+
+        GrContext*                    fContext;
+        const SkMatrix*               fViewMatrix;
+        const SkMatrix*               fLocalMatrix;
+        SkFilterQuality               fFilterQuality;
+        SkColorSpace*                 fDstColorSpace;
+    };
+
+    /**
+     *  Returns a GrFragmentProcessor that implements the shader for the GPU backend. NULL is
+     *  returned if there is no GPU implementation.
+     *
+     *  The GPU device does not call SkShader::createContext(), instead we pass the view matrix,
+     *  local matrix, and filter quality directly.
+     *
+     *  The GrContext may be used by the to create textures that are required by the returned
+     *  processor.
+     *
+     *  The returned GrFragmentProcessor should expect an unpremultiplied input color and
+     *  produce a premultiplied output.
+     */
+    virtual sk_sp<GrFragmentProcessor> asFragmentProcessor(const AsFPArgs&) const;
+#endif
+
+    /**
+     *  If the shader can represent its "average" luminance in a single color, return true and
+     *  if color is not NULL, return that color. If it cannot, return false and ignore the color
+     *  parameter.
+     *
+     *  Note: if this returns true, the returned color will always be opaque, as only the RGB
+     *  components are used to compute luminance.
+     */
+    bool asLuminanceColor(SkColor*) const;
+
+    /**
+     *  Returns a shader transformed into a new color space via the |xformer|.
+     */
+    sk_sp<SkShader> makeColorSpace(SkColorSpaceXformer* xformer) const {
+        return this->onMakeColorSpace(xformer);
+    }
+
+    virtual bool isRasterPipelineOnly() const { return false; }
+
+    bool appendStages(SkRasterPipeline*, SkColorSpace* dstCS, SkArenaAlloc*,
+                      const SkMatrix& ctm, const SkPaint&, const SkMatrix* localM=nullptr) const;
+
+    bool computeTotalInverse(const SkMatrix& ctm,
+                             const SkMatrix* outerLocalMatrix,
+                             SkMatrix* totalInverse) const;
+
+#ifdef SK_SUPPORT_LEGACY_SHADER_ISABITMAP
+    virtual bool onIsABitmap(SkBitmap*, SkMatrix*, TileMode[2]) const {
+        return false;
+    }
+#endif
+
+    virtual SkImage* onIsAImage(SkMatrix*, TileMode[2]) const {
+        return nullptr;
+    }
+
+    SK_TO_STRING_VIRT()
+
+    SK_DEFINE_FLATTENABLE_TYPE(SkShaderBase)
+    SK_DECLARE_FLATTENABLE_REGISTRAR_GROUP()
+
+protected:
+    void flatten(SkWriteBuffer&) const override;
+
+    /**
+     * Specialize creating a SkShader context using the supplied allocator.
+     * @return pointer to context owned by the arena allocator.
+     */
+    virtual Context* onMakeContext(const ContextRec&, SkArenaAlloc*) const {
+        return nullptr;
+    }
+
+    virtual bool onAsLuminanceColor(SkColor*) const {
+        return false;
+    }
+
+    virtual sk_sp<SkShader> onMakeColorSpace(SkColorSpaceXformer*) const {
+        return sk_ref_sp(const_cast<SkShaderBase*>(this));
+    }
+
+    virtual bool onAppendStages(SkRasterPipeline*, SkColorSpace* dstCS, SkArenaAlloc*,
+                                const SkMatrix&, const SkPaint&, const SkMatrix* localM) const;
+
+private:
+    // This is essentially const, but not officially so it can be modified in constructors.
+    SkMatrix fLocalMatrix;
+
+    typedef SkShader INHERITED;
+};
+
+inline SkShaderBase* as_SB(SkShader* shader) {
+    return static_cast<SkShaderBase*>(shader);
+}
+
+inline const SkShaderBase* as_SB(const SkShader* shader) {
+    return static_cast<const SkShaderBase*>(shader);
+}
+
+inline const SkShaderBase* as_SB(const sk_sp<SkShader>& shader) {
+    return static_cast<SkShaderBase*>(shader.get());
+}
+
+#endif // SkShaderBase_DEFINED