make SkColorShader private, use public factory

include/core/SkColorShader.h

-/*
- * Copyright 2007 The Android Open Source Project
- *
- * Use of this source code is governed by a BSD-style license that can be
- * found in the LICENSE file.
- */
-
-#ifndef SkColorShader_DEFINED
-#define SkColorShader_DEFINED
-
-#include "SkShader.h"
-
-/** \class SkColorShader
-    A Shader that represents a single color. In general, this effect can be
-    accomplished by just using the color field on the paint, but if an
-    actual shader object is needed, this provides that feature.
-*/
-class SK_API SkColorShader : public SkShader {
-public:
-    /** Create a ColorShader that ignores the color in the paint, and uses the
-        specified color. Note: like all shaders, at draw time the paint's alpha
-        will be respected, and is applied to the specified color.
-    */
-    explicit SkColorShader(SkColor c);
-
-    virtual bool isOpaque() const SK_OVERRIDE;
-
-    virtual size_t contextSize() const SK_OVERRIDE {
-        return sizeof(ColorShaderContext);
-    }
-
-    class ColorShaderContext : public SkShader::Context {
-    public:
-        ColorShaderContext(const SkColorShader& shader, const ContextRec&);
-
-        virtual uint32_t getFlags() const SK_OVERRIDE;
-        virtual uint8_t getSpan16Alpha() const SK_OVERRIDE;
-        virtual void shadeSpan(int x, int y, SkPMColor span[], int count) SK_OVERRIDE;
-        virtual void shadeSpan16(int x, int y, uint16_t span[], int count) SK_OVERRIDE;
-        virtual void shadeSpanAlpha(int x, int y, uint8_t alpha[], int count) SK_OVERRIDE;
-
-    private:
-        SkPMColor   fPMColor;
-        uint32_t    fFlags;
-        uint16_t    fColor16;
-
-        typedef SkShader::Context INHERITED;
-    };
-
-    // we return false for this, use asAGradient
-    virtual BitmapType asABitmap(SkBitmap* outTexture,
-                                 SkMatrix* outMatrix,
-                                 TileMode xy[2]) const SK_OVERRIDE;
-
-    virtual GradientType asAGradient(GradientInfo* info) const SK_OVERRIDE;
-
-    virtual bool asFragmentProcessor(GrContext*, const SkPaint&, const SkMatrix*, GrColor*,
-                                     GrFragmentProcessor**) const SK_OVERRIDE;
-
-    SK_TO_STRING_OVERRIDE()
-    SK_DECLARE_PUBLIC_FLATTENABLE_DESERIALIZATION_PROCS(SkColorShader)
-
-protected:
-    SkColorShader(SkReadBuffer&);
-    virtual void flatten(SkWriteBuffer&) const SK_OVERRIDE;
-    virtual Context* onCreateContext(const ContextRec&, void* storage) const SK_OVERRIDE;
-    virtual bool onAsLuminanceColor(SkColor* lum) const SK_OVERRIDE {
-        *lum = fColor;
-        return true;
-    }
-
-private:
-    SkColor fColor;
-
-    typedef SkShader INHERITED;
-};
-
-#endif