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      1 /*
      2  * Copyright 2006-2012 The Android Open Source Project
      3  * Copyright 2012 Mozilla Foundation
      4  *
      5  * Use of this source code is governed by a BSD-style license that can be
      6  * found in the LICENSE file.
      7  */
      8 
      9 #ifndef SKFONTHOST_FREETYPE_COMMON_H_
     10 #define SKFONTHOST_FREETYPE_COMMON_H_
     11 
     12 #include "SkGlyph.h"
     13 #include "SkMutex.h"
     14 #include "SkScalerContext.h"
     15 #include "SkTypeface.h"
     16 #include "SkTypes.h"
     17 
     18 #include "SkFontMgr.h"
     19 
     20 // These are forward declared to avoid pimpl but also hide the FreeType implementation.
     21 typedef struct FT_LibraryRec_* FT_Library;
     22 typedef struct FT_FaceRec_* FT_Face;
     23 typedef struct FT_StreamRec_* FT_Stream;
     24 typedef signed long FT_Pos;
     25 
     26 class SkScalerContext_FreeType_Base : public SkScalerContext {
     27 protected:
     28     // See http://freetype.sourceforge.net/freetype2/docs/reference/ft2-bitmap_handling.html#FT_Bitmap_Embolden
     29     // This value was chosen by eyeballing the result in Firefox and trying to match it.
     30     static const FT_Pos kBitmapEmboldenStrength = 1 << 6;
     31 
     32     SkScalerContext_FreeType_Base(sk_sp<SkTypeface> typeface, const SkScalerContextEffects& effects,
     33                                   const SkDescriptor *desc)
     34         : INHERITED(std::move(typeface), effects, desc)
     35     {}
     36 
     37     void generateGlyphImage(FT_Face face, const SkGlyph& glyph, const SkMatrix& bitmapTransform);
     38     void generateGlyphPath(FT_Face face, SkPath* path);
     39 private:
     40     typedef SkScalerContext INHERITED;
     41 };
     42 
     43 class SkTypeface_FreeType : public SkTypeface {
     44 public:
     45     /** For SkFontMgrs to make use of our ability to extract
     46      *  name and style from a stream, using FreeType's API.
     47      */
     48     class Scanner : ::SkNoncopyable {
     49     public:
     50         Scanner();
     51         ~Scanner();
     52         struct AxisDefinition {
     53             SkFourByteTag fTag;
     54             SkFixed fMinimum;
     55             SkFixed fDefault;
     56             SkFixed fMaximum;
     57         };
     58         using AxisDefinitions = SkSTArray<4, AxisDefinition, true>;
     59         bool recognizedFont(SkStreamAsset* stream, int* numFonts) const;
     60         bool scanFont(SkStreamAsset* stream, int ttcIndex,
     61                       SkString* name, SkFontStyle* style, bool* isFixedPitch,
     62                       AxisDefinitions* axes) const;
     63         static void computeAxisValues(
     64             AxisDefinitions axisDefinitions,
     65             const SkFontArguments::VariationPosition position,
     66             SkFixed* axisValues,
     67             const SkString& name);
     68 
     69     private:
     70         FT_Face openFace(SkStreamAsset* stream, int ttcIndex, FT_Stream ftStream) const;
     71         FT_Library fLibrary;
     72         mutable SkMutex fLibraryMutex;
     73     };
     74 
     75 protected:
     76     SkTypeface_FreeType(const SkFontStyle& style, bool isFixedPitch)
     77         : INHERITED(style, isFixedPitch)
     78     {}
     79 
     80     virtual SkScalerContext* onCreateScalerContext(const SkScalerContextEffects&,
     81                                                    const SkDescriptor*) const override;
     82     void onFilterRec(SkScalerContextRec*) const override;
     83     std::unique_ptr<SkAdvancedTypefaceMetrics> onGetAdvancedMetrics() const override;
     84     int onGetUPEM() const override;
     85     bool onGetKerningPairAdjustments(const uint16_t glyphs[], int count,
     86                                      int32_t adjustments[]) const override;
     87     int onCharsToGlyphs(const void* chars, Encoding, uint16_t glyphs[],
     88                         int glyphCount) const override;
     89     int onCountGlyphs() const override;
     90 
     91     LocalizedStrings* onCreateFamilyNameIterator() const override;
     92 
     93     int onGetVariationDesignPosition(SkFontArguments::VariationPosition::Coordinate coordinates[],
     94                                      int coordinateCount) const override;
     95     int onGetTableTags(SkFontTableTag tags[]) const override;
     96     size_t onGetTableData(SkFontTableTag, size_t offset,
     97                           size_t length, void* data) const override;
     98 
     99 private:
    100     typedef SkTypeface INHERITED;
    101 };
    102 
    103 #endif // SKFONTHOST_FREETYPE_COMMON_H_
    104