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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 
     27 #ifdef SK_DEBUG
     28 const char* SkTraceFtrGetError(int);
     29 #define SK_TRACEFTR(ERR, MSG, ...) \
     30     SkDebugf("%s:%lu:1: error: 0x%x '%s' " MSG "\n", __FILE__, __LINE__, ERR, \
     31             SkTraceFtrGetError((int)(ERR)), __VA_ARGS__)
     32 #else
     33 #define SK_TRACEFTR(ERR, ...) do { sk_ignore_unused_variable(ERR); } while (false)
     34 #endif
     35 
     36 
     37 class SkScalerContext_FreeType_Base : public SkScalerContext {
     38 protected:
     39     // See http://freetype.sourceforge.net/freetype2/docs/reference/ft2-bitmap_handling.html#FT_Bitmap_Embolden
     40     // This value was chosen by eyeballing the result in Firefox and trying to match it.
     41     static const FT_Pos kBitmapEmboldenStrength = 1 << 6;
     42 
     43     SkScalerContext_FreeType_Base(sk_sp<SkTypeface> typeface, const SkScalerContextEffects& effects,
     44                                   const SkDescriptor *desc)
     45         : INHERITED(std::move(typeface), effects, desc)
     46     {}
     47 
     48     void generateGlyphImage(FT_Face face, const SkGlyph& glyph, const SkMatrix& bitmapTransform);
     49     void generateGlyphPath(FT_Face face, SkPath* path);
     50 private:
     51     typedef SkScalerContext INHERITED;
     52 };
     53 
     54 class SkTypeface_FreeType : public SkTypeface {
     55 public:
     56     /** For SkFontMgrs to make use of our ability to extract
     57      *  name and style from a stream, using FreeType's API.
     58      */
     59     class Scanner : ::SkNoncopyable {
     60     public:
     61         Scanner();
     62         ~Scanner();
     63         struct AxisDefinition {
     64             SkFourByteTag fTag;
     65             SkFixed fMinimum;
     66             SkFixed fDefault;
     67             SkFixed fMaximum;
     68         };
     69         using AxisDefinitions = SkSTArray<4, AxisDefinition, true>;
     70         bool recognizedFont(SkStreamAsset* stream, int* numFonts) const;
     71         bool scanFont(SkStreamAsset* stream, int ttcIndex,
     72                       SkString* name, SkFontStyle* style, bool* isFixedPitch,
     73                       AxisDefinitions* axes) const;
     74         static void computeAxisValues(
     75             AxisDefinitions axisDefinitions,
     76             const SkFontArguments::VariationPosition position,
     77             SkFixed* axisValues,
     78             const SkString& name);
     79 
     80     private:
     81         FT_Face openFace(SkStreamAsset* stream, int ttcIndex, FT_Stream ftStream) const;
     82         FT_Library fLibrary;
     83         mutable SkMutex fLibraryMutex;
     84     };
     85 
     86 protected:
     87     SkTypeface_FreeType(const SkFontStyle& style, bool isFixedPitch)
     88         : INHERITED(style, isFixedPitch)
     89     {}
     90 
     91     virtual SkScalerContext* onCreateScalerContext(const SkScalerContextEffects&,
     92                                                    const SkDescriptor*) const override;
     93     void onFilterRec(SkScalerContextRec*) const override;
     94     std::unique_ptr<SkAdvancedTypefaceMetrics> onGetAdvancedMetrics() const override;
     95     int onGetUPEM() const override;
     96     bool onGetKerningPairAdjustments(const uint16_t glyphs[], int count,
     97                                      int32_t adjustments[]) const override;
     98     int onCharsToGlyphs(const void* chars, Encoding, uint16_t glyphs[],
     99                         int glyphCount) const override;
    100     int onCountGlyphs() const override;
    101 
    102     LocalizedStrings* onCreateFamilyNameIterator() const override;
    103 
    104     int onGetVariationDesignPosition(SkFontArguments::VariationPosition::Coordinate coordinates[],
    105                                      int coordinateCount) const override;
    106     int onGetTableTags(SkFontTableTag tags[]) const override;
    107     size_t onGetTableData(SkFontTableTag, size_t offset,
    108                           size_t length, void* data) const override;
    109 
    110 private:
    111     typedef SkTypeface INHERITED;
    112 };
    113 
    114 #endif // SKFONTHOST_FREETYPE_COMMON_H_
    115