Implement support for rendering color emoji on Windows

src/ports/SkScalerContext_win_dw.h

 /*
  * Copyright 2014 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef SkScalarContext_win_dw_DEFINED
 #define SkScalarContext_win_dw_DEFINED
 
 #include "SkScalar.h"
 #include "SkScalerContext.h"
 #include "SkTypeface_win_dw.h"
 #include "SkTypes.h"
 
 #include <dwrite.h>
+#if SK_HAS_DWRITE_2_H
+#include <dwrite_2.h>
+#endif
 
 class SkGlyph;
 class SkDescriptor;
 
 class SkScalerContext_DW : public SkScalerContext {
 public:
     SkScalerContext_DW(DWriteFontTypeface*, const SkScalerContextEffects&, const SkDescriptor*);
     virtual ~SkScalerContext_DW();
 
 protected:
     unsigned generateGlyphCount() override;
     uint16_t generateCharToGlyph(SkUnichar uni) override;
     void generateAdvance(SkGlyph* glyph) override;
     void generateMetrics(SkGlyph* glyph) override;
     void generateImage(const SkGlyph& glyph) override;
     void generatePath(const SkGlyph& glyph, SkPath* path) override;
     void generateFontMetrics(SkPaint::FontMetrics*) override;
 
 private:
     const void* drawDWMask(const SkGlyph& glyph,
                            DWRITE_RENDERING_MODE renderingMode,
                            DWRITE_TEXTURE_TYPE textureType);
 
     HRESULT getBoundingBox(SkGlyph* glyph,
                            DWRITE_RENDERING_MODE renderingMode,
                            DWRITE_TEXTURE_TYPE textureType,
                            RECT* bbox);
 
+    bool isColorGlyph(const SkGlyph& glyph);
+
+#if SK_HAS_DWRITE_2_H
+    bool getColorGlyphRun(const SkGlyph& glyph, IDWriteColorGlyphRunEnumerator** colorGlyph);
+
+    void generateColorGlyphImage(const SkGlyph& glyph);
+#endif
+
     SkTDArray<uint8_t> fBits;
     /** The total matrix without the text height scale. */
     SkMatrix fSkXform;
     /** The total matrix without the text height scale. */
     DWRITE_MATRIX fXform;
     /** The non-rotational part of total matrix without the text height scale.
      *  This is used to find the magnitude of gdi compatible advances.
      */
     DWRITE_MATRIX fGsA;
     /** The inverse of the rotational part of the total matrix.
      *  This is used to find the direction of gdi compatible advances.
      */
     SkMatrix fG_inv;
     /** The text size to render with. */
     SkScalar fTextSizeRender;
     /** The text size to measure with. */
     SkScalar fTextSizeMeasure;
     SkAutoTUnref<DWriteFontTypeface> fTypeface;
     int fGlyphCount;
     DWRITE_RENDERING_MODE fRenderingMode;
     DWRITE_TEXTURE_TYPE fTextureType;
     DWRITE_MEASURING_MODE fMeasuringMode;
+#if SK_HAS_DWRITE_2_H
+    SkTScopedComPtr<IDWriteFactory2> fFactory2;
+    bool fIsColorFont;
+#endif
 };
 
 #endif