libcore/FreetypeGlyphsProvider.h

   1 // FreetypeGlyphsProvider.h:  Freetype glyphs manager
   2 //
   3 //   Copyright (C) 2005, 2006, 2007, 2008, 2009, 2010, 2011, 2012
   4 //   Free Software Foundation, Inc
   5 //
   6 // This program is free software; you can redistribute it and/or modify
   7 // it under the terms of the GNU General Public License as published by
   8 // the Free Software Foundation; either version 3 of the License, or
   9 // (at your option) any later version.
  10 //
  11 // This program is distributed in the hope that it will be useful,
  12 // but WITHOUT ANY WARRANTY; without even the implied warranty of
  13 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14 // GNU General Public License for more details.
  15 //
  16 // You should have received a copy of the GNU General Public License
  17 // along with this program; if not, write to the Free Software
  18 // Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
  19
  20 #ifndef GNASH_FREETYPE_H
  21 #define GNASH_FREETYPE_H
  22
  23 #include <string>
  24 #include <memory> // for unique_ptr
  25 #include <mutex>
  26 #include <cstdint>
  27
  28 #ifdef USE_FREETYPE
  29 # include <ft2build.h>
  30 # include FT_FREETYPE_H
  31 # include FT_GLYPH_H
  32 #endif
  33
  34 // Forward declarations
  35 namespace gnash {
  36     namespace SWF {
  37         class ShapeRecord;
  38     }
  39 }
  40
  41
  42 namespace gnash {
  43
  44 /// Truetype font rasterizer/converter based on freetype library
  45 //
  46 /// Instances of this class provide rasterized or vectorial glyphs
  47 /// for a given truetype font face.
  48 ///
  49 /// The rasterized glyphs have a max size of 96 (TODO: make parametrizable)
  50 /// but I think the actual size could change between glyphs (see the 'box'
  51 /// parameter of getRenderedGlyph() method).
  52 ///
  53 /// Vectorial glyphs are instances of a SWF::ShapeRecord, same class
  54 /// resulting from parsing of embedded fonts.
  55 ///
  56 class FreetypeGlyphsProvider
  57 {
  58
  59 public:
  60
  61     /// Named constructor for a face-bound rasterizer.
  62     //
  63     /// @param name
  64     ///    Name of the font to get glyphs info from
  65     ///
  66     /// @param bold
  67     ///    Whether to use a bold version of the font
  68     ///
  69     /// @param italic
  70     ///    Whether to use an italic version of the font
  71     ///
  72     /// @return a rasterizer bound to the given font name,
  73     ///         or a NULL unique_ptr if the given truetype font
  74     ///         could not be found.
  75     ///
  76     static std::unique_ptr<FreetypeGlyphsProvider> createFace(
  77             const std::string& name, bool bold, bool italic);
  78
  79     /// Destructor
  80     //
  81     /// Release face resources
  82     ///
  83     ~FreetypeGlyphsProvider();
  84
  85
  86     /// \brief
  87     /// Return the given DisplayObject glyph as a shape DisplayObject definition
  88     /// in unitsPerEM() coordinates.
  89     //
  90     ///
  91     /// TODO: allow using a custom EM square ?
  92     ///
  93     /// @param code
  94     ///     Character code.
  95     ///
  96     /// @param advance
  97     ///    Output parameter... units to advance horizontally from this
  98     ///     glyph to the next, in unitsPerEM() units.
  99     ///
 100     /// @return A DefineShapeTag in unitsPerEM() coordinates,
 101     ///         or a NULL pointer if the given DisplayObject code
 102     ///         doesn't exist in this font.
 103     ///
 104     std::unique_ptr<SWF::ShapeRecord> getGlyph(std::uint16_t code,
 105             float& advance);
 106
 107     /// Return the font's ascender in terms of its EM own square.
 108     float ascent() const;
 109
 110     /// Return the font's descender in terms of its own EM square.
 111     float descent() const;
 112
 113     /// Return the number of units of glyphs EM
 114     //
 115     /// This is currently hard-coded to 1024, but could in future depend
 116     /// on actual font file being used.
 117     ///
 118     unsigned short unitsPerEM() const;
 119
 120 private:
 121
 122     /// Use the named constructor to create an instance
 123     //
 124     /// throw a GnashException on error (unkonwn font name or similar).
 125     ///
 126     FreetypeGlyphsProvider(const std::string& fontname, bool bold, bool italic);
 127
 128 #ifdef USE_FREETYPE
 129
 130     /// Scale factor to make the freetype glyph metrix match our unitsPerEM()
 131     /// coordinate space. Not all font faces have am EM square of unitsPerEM(), so we
 132     /// use this value to scale both coordinates and advance values
 133     /// The value is computed by the costructor, as soon as a face is initialized.
 134     float scale;
 135
 136     /// Get filename containing given font
 137     //
 138     /// @param name
 139     ///    Font name
 140     ///
 141     /// @param bold
 142     ///    Want bold version
 143     ///
 144     /// @param italic
 145     ///    Want italic version
 146     ///
 147     /// @param filename
 148     ///    Where to return the filename to
 149     ///
 150     /// @return true if the font was found, false otherwise.
 151     ///    Actually, this function should return a default
 152     ///    filename in any case, so false should only be
 153     ///    returned if not even a default font was found.
 154     ///
 155     bool getFontFilename(const std::string& name, bool bold, bool italic,
 156             std::string& filename);
 157
 158     /// Initialize the FreeType library if not done so yet
 159     static void init();
 160
 161     static void close();
 162
 163     /// Mutex protecting FreeType library (for initialization basically)
 164     static std::mutex    m_lib_mutex;
 165
 166     /// FreeType library
 167     static FT_Library    m_lib;
 168
 169     FT_Face    _face;
 170
 171 #endif // USE_FREETYPE
 172
 173 };
 174
 175 } // namespace gnash
 176
 177
 178 #endif    // GNASH_FREETYPE_H