typedef struct FT_LibraryRec_  *FT_Library;

A handle to a FreeType library instance. Each ‘library’ is completely independent from the others; it is the ‘root’ of a set of objects like fonts, faces, sizes, etc.

It also embeds a memory manager (see FT_Memory), as well as a scan-line converter object (see FT_Raster).

For multi-threading applications each thread should have its own FT_Library object.

Library objects are normally created by FT_Init_FreeType, and destroyed with FT_Done_FreeType.

  typedef struct FT_FaceRec_*  FT_Face;

A handle to a given typographic face object. A face object models a given typeface, in a given style.

Each face object also owns a single FT_GlyphSlot object, as well as one or more FT_Size objects.

Use FT_New_Face or FT_Open_Face to create a new face object from a given filepathname or a custom input stream.

Use FT_Done_Face to destroy it (along with its slot and sizes).

See FT_FaceRec for the publicly accessible fields of a given face object.

  typedef struct FT_SizeRec_*  FT_Size;

A handle to an object used to model a face scaled to a given character size.

Each FT_Face has an active FT_Size object that is used by functions like FT_Load_Glyph to determine the scaling transformation which is used to load and hint glyphs and metrics.

You can use FT_Set_Char_Size, FT_Set_Pixel_Sizes, FT_Request_Size or even FT_Select_Size to change the content (i.e., the scaling values) of the active FT_Size.

You can use FT_New_Size to create additional size objects for a given FT_Face, but they won't be used by other functions until you activate it through FT_Activate_Size. Only one size can be activated at any given time per face.

See FT_SizeRec for the publicly accessible fields of a given size object.

  typedef struct FT_GlyphSlotRec_*  FT_GlyphSlot;

A handle to a given ‘glyph slot’. A slot is a container where it is possible to load any of the glyphs contained in its parent face.

In other words, each time you call FT_Load_Glyph or FT_Load_Char, the slot's content is erased by the new glyph data, i.e., the glyph's metrics, its image (bitmap or outline), and other control information.

See FT_GlyphSlotRec for the publicly accessible glyph fields.

  typedef struct FT_CharMapRec_*  FT_CharMap;

A handle to a given character map. A charmap is used to translate character codes in a given encoding into glyph indexes for its parent's face. Some font formats may provide several charmaps per font.

Each face object owns zero or more charmaps, but only one of them can be ‘active’ and used by FT_Get_Char_Index or FT_Load_Char.

The list of available charmaps in a face is available through the ‘face->num_charmaps’ and ‘face->charmaps’ fields of FT_FaceRec.

The currently active charmap is available as ‘face->charmap’. You should call FT_Set_Charmap to change it.

When a new face is created (either through FT_New_Face or FT_Open_Face), the library looks for a Unicode charmap within the list and automatically activates it.

See FT_CharMapRec for the publicly accessible fields of a given character map.

  typedef enum  FT_Encoding_
  {
    FT_ENC_TAG( FT_ENCODING_NONE, 0, 0, 0, 0 ),

    FT_ENC_TAG( FT_ENCODING_MS_SYMBOL, 's', 'y', 'm', 'b' ),
    FT_ENC_TAG( FT_ENCODING_UNICODE,   'u', 'n', 'i', 'c' ),

    FT_ENC_TAG( FT_ENCODING_SJIS,    's', 'j', 'i', 's' ),
    FT_ENC_TAG( FT_ENCODING_GB2312,  'g', 'b', ' ', ' ' ),
    FT_ENC_TAG( FT_ENCODING_BIG5,    'b', 'i', 'g', '5' ),
    FT_ENC_TAG( FT_ENCODING_WANSUNG, 'w', 'a', 'n', 's' ),
    FT_ENC_TAG( FT_ENCODING_JOHAB,   'j', 'o', 'h', 'a' ),

    /* for backwards compatibility */
    FT_ENCODING_MS_SJIS    = FT_ENCODING_SJIS,
    FT_ENCODING_MS_GB2312  = FT_ENCODING_GB2312,
    FT_ENCODING_MS_BIG5    = FT_ENCODING_BIG5,
    FT_ENCODING_MS_WANSUNG = FT_ENCODING_WANSUNG,
    FT_ENCODING_MS_JOHAB   = FT_ENCODING_JOHAB,

    FT_ENC_TAG( FT_ENCODING_ADOBE_STANDARD, 'A', 'D', 'O', 'B' ),
    FT_ENC_TAG( FT_ENCODING_ADOBE_EXPERT,   'A', 'D', 'B', 'E' ),
    FT_ENC_TAG( FT_ENCODING_ADOBE_CUSTOM,   'A', 'D', 'B', 'C' ),
    FT_ENC_TAG( FT_ENCODING_ADOBE_LATIN_1,  'l', 'a', 't', '1' ),

    FT_ENC_TAG( FT_ENCODING_OLD_LATIN_2, 'l', 'a', 't', '2' ),

    FT_ENC_TAG( FT_ENCODING_APPLE_ROMAN, 'a', 'r', 'm', 'n' )

  } FT_Encoding;

An enumeration used to specify character sets supported by charmaps. Used in the FT_Select_Charmap API function.

Despite the name, this enumeration lists specific character repertories (i.e., charsets), and not text encoding methods (e.g., UTF-8, UTF-16, etc.).

Other encodings might be defined in the future.

By default, FreeType automatically synthesizes a Unicode charmap for PostScript fonts, using their glyph names dictionaries. However, it also reports the encodings defined explicitly in the font file, for the cases when they are needed, with the Adobe values as well.

FT_ENCODING_NONE is set by the BDF and PCF drivers if the charmap is neither Unicode nor ISO-8859-1 (otherwise it is set to FT_ENCODING_UNICODE). Use FT_Get_BDF_Charset_ID to find out which encoding is really present. If, for example, the ‘cs_registry’ field is ‘KOI8’ and the ‘cs_encoding’ field is ‘R’, the font is encoded in KOI8-R.

FT_ENCODING_NONE is always set (with a single exception) by the winfonts driver. Use FT_Get_WinFNT_Header and examine the ‘charset’ field of the FT_WinFNT_HeaderRec structure to find out which encoding is really present. For example, FT_WinFNT_ID_CP1251 (204) means Windows code page 1251 (for Russian).

FT_ENCODING_NONE is set if ‘platform_id’ is TT_PLATFORM_MACINTOSH and ‘encoding_id’ is not TT_MAC_ID_ROMAN (otherwise it is set to FT_ENCODING_APPLE_ROMAN).

If ‘platform_id’ is TT_PLATFORM_MACINTOSH, use the function FT_Get_CMap_Language_ID to query the Mac language ID which may be needed to be able to distinguish Apple encoding variants. See

http://www.unicode.org/Public/MAPPINGS/VENDORS/APPLE/README.TXT

to get an idea how to do that. Basically, if the language ID is 0, don't use it, otherwise subtract 1 from the language ID. Then examine ‘encoding_id’. If, for example, ‘encoding_id’ is TT_MAC_ID_ROMAN and the language ID (minus 1) is ‘TT_MAC_LANGID_GREEK’, it is the Greek encoding, not Roman. TT_MAC_ID_ARABIC with ‘TT_MAC_LANGID_FARSI’ means the Farsi variant the Arabic encoding.

  typedef struct  FT_Glyph_Metrics_
  {
    FT_Pos  width;
    FT_Pos  height;

    FT_Pos  horiBearingX;
    FT_Pos  horiBearingY;
    FT_Pos  horiAdvance;

    FT_Pos  vertBearingX;
    FT_Pos  vertBearingY;
    FT_Pos  vertAdvance;

  } FT_Glyph_Metrics;

A structure used to model the metrics of a single glyph. The values are expressed in 26.6 fractional pixel format; if the flag FT_LOAD_NO_SCALE has been used while loading the glyph, values are expressed in font units instead.

If not disabled with FT_LOAD_NO_HINTING, the values represent dimensions of the hinted glyph (in case hinting is applicable).

Stroking a glyph with an outside border does not increase ‘horiAdvance’ or ‘vertAdvance’; you have to manually adjust these values to account for the added width and height.

  typedef struct  FT_Bitmap_Size_
  {
    FT_Short  height;
    FT_Short  width;

    FT_Pos    size;

    FT_Pos    x_ppem;
    FT_Pos    y_ppem;

  } FT_Bitmap_Size;

This structure models the metrics of a bitmap strike (i.e., a set of glyphs for a given point size and resolution) in a bitmap font. It is used for the ‘available_sizes’ field of FT_Face.

Windows FNT: The nominal size given in a FNT font is not reliable. Thus when the driver finds it incorrect, it sets ‘size’ to some calculated values and sets ‘x_ppem’ and ‘y_ppem’ to the pixel width and height given in the font, respectively.

TrueType embedded bitmaps: ‘size’, ‘width’, and ‘height’ values are not contained in the bitmap strike itself. They are computed from the global font parameters.

  typedef struct FT_ModuleRec_*  FT_Module;

A handle to a given FreeType module object. Each module can be a font driver, a renderer, or anything else that provides services to the formers.

  typedef struct FT_DriverRec_*  FT_Driver;

A handle to a given FreeType font driver object. Each font driver is a special module capable of creating faces from font files.

  typedef struct FT_RendererRec_*  FT_Renderer;

A handle to a given FreeType renderer. A renderer is a special module in charge of converting a glyph image to a bitmap, when necessary. Each renderer supports a given glyph image format, and one or more target surface depths.

#ifndef FT_ENC_TAG
#define FT_ENC_TAG( value, a, b, c, d )         \
          value = ( ( (FT_UInt32)(a) << 24 ) |  \
                    ( (FT_UInt32)(b) << 16 ) |  \
                    ( (FT_UInt32)(c) <<  8 ) |  \
                      (FT_UInt32)(d)         )

#endif /* FT_ENC_TAG */

This macro converts four-letter tags into an unsigned long. It is used to define ‘encoding’ identifiers (see FT_Encoding).

Since many 16-bit compilers don't like 32-bit enumerations, you should redefine this macro in case of problems to something like this:

  #define FT_ENC_TAG( value, a, b, c, d )  value                   

to get a simple enumeration without assigning special numbers.

#define ft_encoding_none            FT_ENCODING_NONE
#define ft_encoding_unicode         FT_ENCODING_UNICODE
#define ft_encoding_symbol          FT_ENCODING_MS_SYMBOL
#define ft_encoding_latin_1         FT_ENCODING_ADOBE_LATIN_1
#define ft_encoding_latin_2         FT_ENCODING_OLD_LATIN_2
#define ft_encoding_sjis            FT_ENCODING_SJIS
#define ft_encoding_gb2312          FT_ENCODING_GB2312
#define ft_encoding_big5            FT_ENCODING_BIG5
#define ft_encoding_wansung         FT_ENCODING_WANSUNG
#define ft_encoding_johab           FT_ENCODING_JOHAB

#define ft_encoding_adobe_standard  FT_ENCODING_ADOBE_STANDARD
#define ft_encoding_adobe_expert    FT_ENCODING_ADOBE_EXPERT
#define ft_encoding_adobe_custom    FT_ENCODING_ADOBE_CUSTOM
#define ft_encoding_apple_roman     FT_ENCODING_APPLE_ROMAN

These constants are deprecated; use the corresponding FT_Encoding values instead.

  typedef struct  FT_CharMapRec_
  {
    FT_Face      face;
    FT_Encoding  encoding;
    FT_UShort    platform_id;
    FT_UShort    encoding_id;

  } FT_CharMapRec;

The base charmap structure.

  typedef struct FT_Face_InternalRec_*  FT_Face_Internal;

An opaque handle to an ‘FT_Face_InternalRec’ structure, used to model private data of a given FT_Face object.

This structure might change between releases of FreeType 2 and is not generally available to client applications.

  typedef struct  FT_FaceRec_
  {
    FT_Long           num_faces;
    FT_Long           face_index;

    FT_Long           face_flags;
    FT_Long           style_flags;

    FT_Long           num_glyphs;

    FT_String*        family_name;
    FT_String*        style_name;

    FT_Int            num_fixed_sizes;
    FT_Bitmap_Size*   available_sizes;

    FT_Int            num_charmaps;
    FT_CharMap*       charmaps;

    FT_Generic        generic;

    /*# The following member variables (down to `underline_thickness') */
    /*# are only relevant to scalable outlines; cf. @FT_Bitmap_Size    */
    /*# for bitmap fonts.                                              */
    FT_BBox           bbox;

    FT_UShort         units_per_EM;
    FT_Short          ascender;
    FT_Short          descender;
    FT_Short          height;

    FT_Short          max_advance_width;
    FT_Short          max_advance_height;

    FT_Short          underline_position;
    FT_Short          underline_thickness;

    FT_GlyphSlot      glyph;
    FT_Size           size;
    FT_CharMap        charmap;

    /*@private begin */

    FT_Driver         driver;
    FT_Memory         memory;
    FT_Stream         stream;

    FT_ListRec        sizes_list;

    FT_Generic        autohint;   /* face-specific auto-hinter data */
    void*             extensions; /* unused                         */

    FT_Face_Internal  internal;

    /*@private end */

  } FT_FaceRec;

FreeType root face class structure. A face object models a typeface in a font file.

Fields may be changed after a call to FT_Attach_File or FT_Attach_Stream.

#define FT_FACE_FLAG_SCALABLE          ( 1L <<  0 )
#define FT_FACE_FLAG_FIXED_SIZES       ( 1L <<  1 )
#define FT_FACE_FLAG_FIXED_WIDTH       ( 1L <<  2 )
#define FT_FACE_FLAG_SFNT              ( 1L <<  3 )
#define FT_FACE_FLAG_HORIZONTAL        ( 1L <<  4 )
#define FT_FACE_FLAG_VERTICAL          ( 1L <<  5 )
#define FT_FACE_FLAG_KERNING           ( 1L <<  6 )
#define FT_FACE_FLAG_FAST_GLYPHS       ( 1L <<  7 )
#define FT_FACE_FLAG_MULTIPLE_MASTERS  ( 1L <<  8 )
#define FT_FACE_FLAG_GLYPH_NAMES       ( 1L <<  9 )
#define FT_FACE_FLAG_EXTERNAL_STREAM   ( 1L << 10 )
#define FT_FACE_FLAG_HINTER            ( 1L << 11 )
#define FT_FACE_FLAG_CID_KEYED         ( 1L << 12 )
#define FT_FACE_FLAG_TRICKY            ( 1L << 13 )

A list of bit flags used in the ‘face_flags’ field of the FT_FaceRec structure. They inform client applications of properties of the corresponding face.

#define FT_HAS_HORIZONTAL( face ) \
          ( face->face_flags & FT_FACE_FLAG_HORIZONTAL )

A macro that returns true whenever a face object contains horizontal metrics (this is true for all font formats though).

FT_HAS_VERTICAL can be used to check for vertical metrics.

#define FT_HAS_VERTICAL( face ) \
          ( face->face_flags & FT_FACE_FLAG_VERTICAL )

A macro that returns true whenever a face object contains vertical metrics.

#define FT_HAS_KERNING( face ) \
          ( face->face_flags & FT_FACE_FLAG_KERNING )

A macro that returns true whenever a face object contains kerning data that can be accessed with FT_Get_Kerning.

#define FT_IS_SCALABLE( face ) \
          ( face->face_flags & FT_FACE_FLAG_SCALABLE )

A macro that returns true whenever a face object contains a scalable font face (true for TrueType, Type 1, Type 42, CID, OpenType/CFF, and PFR font formats.

#define FT_IS_SFNT( face ) \
          ( face->face_flags & FT_FACE_FLAG_SFNT )

A macro that returns true whenever a face object contains a font whose format is based on the SFNT storage scheme. This usually means: TrueType fonts, OpenType fonts, as well as SFNT-based embedded bitmap fonts.

If this macro is true, all functions defined in FT_SFNT_NAMES_H and FT_TRUETYPE_TABLES_H are available.

#define FT_IS_FIXED_WIDTH( face ) \
          ( face->face_flags & FT_FACE_FLAG_FIXED_WIDTH )

A macro that returns true whenever a face object contains a font face that contains fixed-width (or ‘monospace’, ‘fixed-pitch’, etc.) glyphs.

#define FT_HAS_FIXED_SIZES( face ) \
          ( face->face_flags & FT_FACE_FLAG_FIXED_SIZES )

A macro that returns true whenever a face object contains some embedded bitmaps. See the ‘available_sizes’ field of the FT_FaceRec structure.

#define FT_HAS_FAST_GLYPHS( face )  0

Deprecated.

#define FT_HAS_GLYPH_NAMES( face ) \
          ( face->face_flags & FT_FACE_FLAG_GLYPH_NAMES )

A macro that returns true whenever a face object contains some glyph names that can be accessed through FT_Get_Glyph_Name.

#define FT_HAS_MULTIPLE_MASTERS( face ) \
          ( face->face_flags & FT_FACE_FLAG_MULTIPLE_MASTERS )

A macro that returns true whenever a face object contains some multiple masters. The functions provided by FT_MULTIPLE_MASTERS_H are then available to choose the exact design you want.

#define FT_IS_CID_KEYED( face ) \
          ( face->face_flags & FT_FACE_FLAG_CID_KEYED )

A macro that returns true whenever a face object contains a CID-keyed font. See the discussion of FT_FACE_FLAG_CID_KEYED for more details.

If this macro is true, all functions defined in FT_CID_H are available.

#define FT_IS_TRICKY( face ) \
          ( face->face_flags & FT_FACE_FLAG_TRICKY )

A macro that returns true whenever a face represents a ‘tricky’ font. See the discussion of FT_FACE_FLAG_TRICKY for more details.

#define FT_STYLE_FLAG_ITALIC  ( 1 << 0 )
#define FT_STYLE_FLAG_BOLD    ( 1 << 1 )

A list of bit-flags used to indicate the style of a given face. These are used in the ‘style_flags’ field of FT_FaceRec.

The style information as provided by FreeType is very basic. More details are beyond the scope and should be done on a higher level (for example, by analyzing various fields of the ‘OS/2’ table in SFNT based fonts).

  typedef struct FT_Size_InternalRec_*  FT_Size_Internal;

An opaque handle to an ‘FT_Size_InternalRec’ structure, used to model private data of a given FT_Size object.

  typedef struct  FT_Size_Metrics_
  {
    FT_UShort  x_ppem;      /* horizontal pixels per EM               */
    FT_UShort  y_ppem;      /* vertical pixels per EM                 */

    FT_Fixed   x_scale;     /* scaling values used to convert font    */
    FT_Fixed   y_scale;     /* units to 26.6 fractional pixels        */

    FT_Pos     ascender;    /* ascender in 26.6 frac. pixels          */
    FT_Pos     descender;   /* descender in 26.6 frac. pixels         */
    FT_Pos     height;      /* text height in 26.6 frac. pixels       */
    FT_Pos     max_advance; /* max horizontal advance, in 26.6 pixels */

  } FT_Size_Metrics;

The size metrics structure gives the metrics of a size object.

The scaling values, if relevant, are determined first during a size changing operation. The remaining fields are then set by the driver. For scalable formats, they are usually set to scaled values of the corresponding fields in FT_FaceRec.

Note that due to glyph hinting, these values might not be exact for certain fonts. Thus they must be treated as unreliable with an error margin of at least one pixel!

Indeed, the only way to get the exact metrics is to render all glyphs. As this would be a definite performance hit, it is up to client applications to perform such computations.

The FT_Size_Metrics structure is valid for bitmap fonts also.

  typedef struct  FT_SizeRec_
  {
    FT_Face           face;      /* parent face object              */
    FT_Generic        generic;   /* generic pointer for client uses */
    FT_Size_Metrics   metrics;   /* size metrics                    */
    FT_Size_Internal  internal;

  } FT_SizeRec;

FreeType root size class structure. A size object models a face object at a given size.

  typedef struct FT_SubGlyphRec_*  FT_SubGlyph;

The subglyph structure is an internal object used to describe subglyphs (for example, in the case of composites).

The subglyph implementation is not part of the high-level API, hence the forward structure declaration.

You can however retrieve subglyph information with FT_Get_SubGlyph_Info.

  typedef struct FT_Slot_InternalRec_*  FT_Slot_Internal;

An opaque handle to an ‘FT_Slot_InternalRec’ structure, used to model private data of a given FT_GlyphSlot object.

  typedef struct  FT_GlyphSlotRec_
  {
    FT_Library        library;
    FT_Face           face;
    FT_GlyphSlot      next;
    FT_UInt           reserved;       /* retained for binary compatibility */
    FT_Generic        generic;

    FT_Glyph_Metrics  metrics;
    FT_Fixed          linearHoriAdvance;
    FT_Fixed          linearVertAdvance;
    FT_Vector         advance;

    FT_Glyph_Format   format;

    FT_Bitmap         bitmap;
    FT_Int            bitmap_left;
    FT_Int            bitmap_top;

    FT_Outline        outline;

    FT_UInt           num_subglyphs;
    FT_SubGlyph       subglyphs;

    void*             control_data;
    long              control_len;

    FT_Pos            lsb_delta;
    FT_Pos            rsb_delta;

    void*             other;

    FT_Slot_Internal  internal;

  } FT_GlyphSlotRec;

FreeType root glyph slot class structure. A glyph slot is a container where individual glyphs can be loaded, be they in outline or bitmap format.

If FT_Load_Glyph is called with default flags (see FT_LOAD_DEFAULT) the glyph image is loaded in the glyph slot in its native format (e.g., an outline glyph for TrueType and Type 1 formats).

This image can later be converted into a bitmap by calling FT_Render_Glyph. This function finds the current renderer for the native image's format, then invokes it.

The renderer is in charge of transforming the native image through the slot's face transformation fields, then converting it into a bitmap that is returned in ‘slot->bitmap’.

Note that ‘slot->bitmap_left’ and ‘slot->bitmap_top’ are also used to specify the position of the bitmap relative to the current pen position (e.g., coordinates (0,0) on the baseline). Of course, ‘slot->format’ is also changed to FT_GLYPH_FORMAT_BITMAP.

Here a small pseudo code fragment which shows how to use ‘lsb_delta’ and ‘rsb_delta’:

  FT_Pos  origin_x       = 0;                                      
  FT_Pos  prev_rsb_delta = 0;                                      
                                                                   
                                                                   
  for all glyphs do                                                
    <compute kern between current and previous glyph and add it to 
     `origin_x'>                                                   
                                                                   
    <load glyph with `FT_Load_Glyph'>                              
                                                                   
    if ( prev_rsb_delta - face->glyph->lsb_delta >= 32 )           
      origin_x -= 64;                                              
    else if ( prev_rsb_delta - face->glyph->lsb_delta < -32 )      
      origin_x += 64;                                              
                                                                   
    prev_rsb_delta = face->glyph->rsb_delta;                       
                                                                   
    <save glyph image, or render glyph, or ...>                    
                                                                   
    origin_x += face->glyph->advance.x;                            
  endfor                                                           

  FT_EXPORT( FT_Error )
  FT_Init_FreeType( FT_Library  *alibrary );

Initialize a new FreeType library object. The set of modules that are registered by this function is determined at build time.

FreeType error code. 0 means success.

In case you want to provide your own memory allocating routines, use FT_New_Library instead, followed by a call to FT_Add_Default_Modules (or a series of calls to FT_Add_Module).

For multi-threading applications each thread should have its own FT_Library object.

  FT_EXPORT( FT_Error )
  FT_Done_FreeType( FT_Library  library );

Destroy a given FreeType library object and all of its children, including resources, drivers, faces, sizes, etc.

FreeType error code. 0 means success.

#define FT_OPEN_MEMORY    0x1
#define FT_OPEN_STREAM    0x2
#define FT_OPEN_PATHNAME  0x4
#define FT_OPEN_DRIVER    0x8
#define FT_OPEN_PARAMS    0x10

#define ft_open_memory    FT_OPEN_MEMORY     /* deprecated */
#define ft_open_stream    FT_OPEN_STREAM     /* deprecated */
#define ft_open_pathname  FT_OPEN_PATHNAME   /* deprecated */
#define ft_open_driver    FT_OPEN_DRIVER     /* deprecated */
#define ft_open_params    FT_OPEN_PARAMS     /* deprecated */

A list of bit-field constants used within the ‘flags’ field of the FT_Open_Args structure.

The ‘FT_OPEN_MEMORY’, ‘FT_OPEN_STREAM’, and ‘FT_OPEN_PATHNAME’ flags are mutually exclusive.

  typedef struct  FT_Parameter_
  {
    FT_ULong    tag;
    FT_Pointer  data;

  } FT_Parameter;

A simple structure used to pass more or less generic parameters to FT_Open_Face.

The ID and function of parameters are driver-specific. See the various FT_PARAM_TAG_XXX flags for more information.

  typedef struct  FT_Open_Args_
  {
    FT_UInt         flags;
    const FT_Byte*  memory_base;
    FT_Long         memory_size;
    FT_String*      pathname;
    FT_Stream       stream;
    FT_Module       driver;
    FT_Int          num_params;
    FT_Parameter*   params;

  } FT_Open_Args;

A structure used to indicate how to open a new font file or stream. A pointer to such a structure can be used as a parameter for the functions FT_Open_Face and FT_Attach_Stream.

The stream type is determined by the contents of ‘flags’ which are tested in the following order by FT_Open_Face:

If the ‘FT_OPEN_MEMORY’ bit is set, assume that this is a memory file of ‘memory_size’ bytes, located at ‘memory_address’. The data are are not copied, and the client is responsible for releasing and destroying them after the corresponding call to FT_Done_Face.

Otherwise, if the ‘FT_OPEN_STREAM’ bit is set, assume that a custom input stream ‘stream’ is used.

Otherwise, if the ‘FT_OPEN_PATHNAME’ bit is set, assume that this is a normal file and use ‘pathname’ to open it.

If the ‘FT_OPEN_DRIVER’ bit is set, FT_Open_Face only tries to open the file with the driver whose handler is in ‘driver’.

If the ‘FT_OPEN_PARAMS’ bit is set, the parameters given by ‘num_params’ and ‘params’ is used. They are ignored otherwise.

Ideally, both the ‘pathname’ and ‘params’ fields should be tagged as ‘const’; this is missing for API backwards compatibility. In other words, applications should treat them as read-only.

  FT_EXPORT( FT_Error )
  FT_New_Face( FT_Library   library,
               const char*  filepathname,
               FT_Long      face_index,
               FT_Face     *aface );

This function calls FT_Open_Face to open a font by its pathname.

FreeType error code. 0 means success.

  FT_EXPORT( FT_Error )
  FT_New_Memory_Face( FT_Library      library,
                      const FT_Byte*  file_base,
                      FT_Long         file_size,
                      FT_Long         face_index,
                      FT_Face        *aface );

This function calls FT_Open_Face to open a font which has been loaded into memory.

FreeType error code. 0 means success.

You must not deallocate the memory before calling FT_Done_Face.

  FT_EXPORT( FT_Error )
  FT_Open_Face( FT_Library           library,
                const FT_Open_Args*  args,
                FT_Long              face_index,
                FT_Face             *aface );

Create a face object from a given resource described by FT_Open_Args.

FreeType error code. 0 means success.

Unlike FreeType 1.x, this function automatically creates a glyph slot for the face object which can be accessed directly through ‘face->glyph’.

FT_Open_Face can be used to quickly check whether the font format of a given font resource is supported by FreeType. If the ‘face_index’ field is negative, the function's return value is 0 if the font format is recognized, or non-zero otherwise; the function returns a more or less empty face handle in ‘*aface’ (if ‘aface’ isn't NULL). The only useful field in this special case is ‘face->num_faces’ which gives the number of faces within the font file. After examination, the returned FT_Face structure should be deallocated with a call to FT_Done_Face.

Each new face object created with this function also owns a default FT_Size object, accessible as ‘face->size’.

One FT_Library instance can have multiple face objects, this is, FT_Open_Face and its siblings can be called multiple times using the same ‘library’ argument.

See the discussion of reference counters in the description of FT_Reference_Face.

  FT_EXPORT( FT_Error )
  FT_Attach_File( FT_Face      face,
                  const char*  filepathname );

This function calls FT_Attach_Stream to attach a file.

FreeType error code. 0 means success.

  FT_EXPORT( FT_Error )
  FT_Attach_Stream( FT_Face        face,
                    FT_Open_Args*  parameters );

‘Attach’ data to a face object. Normally, this is used to read additional information for the face object. For example, you can attach an AFM file that comes with a Type 1 font to get the kerning values and other metrics.

FreeType error code. 0 means success.

The meaning of the ‘attach’ (i.e., what really happens when the new file is read) is not fixed by FreeType itself. It really depends on the font format (and thus the font driver).

Client applications are expected to know what they are doing when invoking this function. Most drivers simply do not implement file attachments.

  FT_EXPORT( FT_Error )
  FT_Reference_Face( FT_Face  face );

A counter gets initialized to 1 at the time an FT_Face structure is created. This function increments the counter. FT_Done_Face then only destroys a face if the counter is 1, otherwise it simply decrements the counter.

This function helps in managing life-cycles of structures which reference FT_Face objects.

FreeType error code. 0 means success.

2.4.2

  FT_EXPORT( FT_Error )
  FT_Done_Face( FT_Face  face );

Discard a given face object, as well as all of its child slots and sizes.

FreeType error code. 0 means success.

See the discussion of reference counters in the description of FT_Reference_Face.

  FT_EXPORT( FT_Error )
  FT_Select_Size( FT_Face  face,
                  FT_Int   strike_index );

Select a bitmap strike.

FreeType error code. 0 means success.

  typedef enum  FT_Size_Request_Type_
  {
    FT_SIZE_REQUEST_TYPE_NOMINAL,
    FT_SIZE_REQUEST_TYPE_REAL_DIM,
    FT_SIZE_REQUEST_TYPE_BBOX,
    FT_SIZE_REQUEST_TYPE_CELL,
    FT_SIZE_REQUEST_TYPE_SCALES,

    FT_SIZE_REQUEST_TYPE_MAX

  } FT_Size_Request_Type;

An enumeration type that lists the supported size request types.

The above descriptions only apply to scalable formats. For bitmap formats, the behaviour is up to the driver.

See the note section of FT_Size_Metrics if you wonder how size requesting relates to scaling values.

  typedef struct  FT_Size_RequestRec_
  {
    FT_Size_Request_Type  type;
    FT_Long               width;
    FT_Long               height;
    FT_UInt               horiResolution;
    FT_UInt               vertResolution;

  } FT_Size_RequestRec;

A structure used to model a size request.

If ‘width’ is zero, then the horizontal scaling value is set equal to the vertical scaling value, and vice versa.

  typedef struct FT_Size_RequestRec_  *FT_Size_Request;

A handle to a size request structure.

  FT_EXPORT( FT_Error )
  FT_Request_Size( FT_Face          face,
                   FT_Size_Request  req );

Resize the scale of the active FT_Size object in a face.

FreeType error code. 0 means success.

Although drivers may select the bitmap strike matching the request, you should not rely on this if you intend to select a particular bitmap strike. Use FT_Select_Size instead in that case.

  FT_EXPORT( FT_Error )
  FT_Set_Char_Size( FT_Face     face,
                    FT_F26Dot6  char_width,
                    FT_F26Dot6  char_height,
                    FT_UInt     horz_resolution,
                    FT_UInt     vert_resolution );

This function calls FT_Request_Size to request the nominal size (in points).

FreeType error code. 0 means success.

If either the character width or height is zero, it is set equal to the other value.

If either the horizontal or vertical resolution is zero, it is set equal to the other value.

A character width or height smaller than 1pt is set to 1pt; if both resolution values are zero, they are set to 72dpi.

Don't use this function if you are using the FreeType cache API.

  FT_EXPORT( FT_Error )
  FT_Set_Pixel_Sizes( FT_Face  face,
                      FT_UInt  pixel_width,
                      FT_UInt  pixel_height );

This function calls FT_Request_Size to request the nominal size (in pixels).

FreeType error code. 0 means success.

  FT_EXPORT( FT_Error )
  FT_Load_Glyph( FT_Face   face,
                 FT_UInt   glyph_index,
                 FT_Int32  load_flags );

A function used to load a single glyph into the glyph slot of a face object.

FreeType error code. 0 means success.

The loaded glyph may be transformed. See FT_Set_Transform for the details.

For subsetted CID-keyed fonts, ‘FT_Err_Invalid_Argument’ is returned for invalid CID values (this is, for CID values which don't have a corresponding glyph in the font). See the discussion of the FT_FACE_FLAG_CID_KEYED flag for more details.

  FT_EXPORT( FT_Error )
  FT_Load_Char( FT_Face   face,
                FT_ULong  char_code,
                FT_Int32  load_flags );

A function used to load a single glyph into the glyph slot of a face object, according to its character code.

FreeType error code. 0 means success.

This function simply calls FT_Get_Char_Index and FT_Load_Glyph.

#define FT_LOAD_DEFAULT                      0x0
#define FT_LOAD_NO_SCALE                     ( 1L << 0 )
#define FT_LOAD_NO_HINTING                   ( 1L << 1 )
#define FT_LOAD_RENDER                       ( 1L << 2 )
#define FT_LOAD_NO_BITMAP                    ( 1L << 3 )
#define FT_LOAD_VERTICAL_LAYOUT              ( 1L << 4 )
#define FT_LOAD_FORCE_AUTOHINT               ( 1L << 5 )
#define FT_LOAD_CROP_BITMAP                  ( 1L << 6 )
#define FT_LOAD_PEDANTIC                     ( 1L << 7 )
#define FT_LOAD_IGNORE_GLOBAL_ADVANCE_WIDTH  ( 1L << 9 )
#define FT_LOAD_NO_RECURSE                   ( 1L << 10 )
#define FT_LOAD_IGNORE_TRANSFORM             ( 1L << 11 )
#define FT_LOAD_MONOCHROME                   ( 1L << 12 )
#define FT_LOAD_LINEAR_DESIGN                ( 1L << 13 )
#define FT_LOAD_NO_AUTOHINT                  ( 1L << 15 )

A list of bit-field constants used with FT_Load_Glyph to indicate what kind of operations to perform during glyph loading.

By default, hinting is enabled and the font's native hinter (see FT_FACE_FLAG_HINTER) is preferred over the auto-hinter. You can disable hinting by setting FT_LOAD_NO_HINTING or change the precedence by setting FT_LOAD_FORCE_AUTOHINT. You can also set FT_LOAD_NO_AUTOHINT in case you don't want the auto-hinter to be used at all.

See the description of FT_FACE_FLAG_TRICKY for a special exception (affecting only a handful of Asian fonts).

Besides deciding which hinter to use, you can also decide which hinting algorithm to use. See FT_LOAD_TARGET_XXX for details.

Note that the auto-hinter needs a valid Unicode cmap (either a native one or synthesized by FreeType) for producing correct results. If a font provides an incorrect mapping (for example, assigning the character code U+005A, LATIN CAPITAL LETTER Z, to a glyph depicting a mathematical integral sign), the auto-hinter might produce useless results.

#define FT_LOAD_TARGET_( x )   ( (FT_Int32)( (x) & 15 ) << 16 )

#define FT_LOAD_TARGET_NORMAL  FT_LOAD_TARGET_( FT_RENDER_MODE_NORMAL )
#define FT_LOAD_TARGET_LIGHT   FT_LOAD_TARGET_( FT_RENDER_MODE_LIGHT  )
#define FT_LOAD_TARGET_MONO    FT_LOAD_TARGET_( FT_RENDER_MODE_MONO   )
#define FT_LOAD_TARGET_LCD     FT_LOAD_TARGET_( FT_RENDER_MODE_LCD    )
#define FT_LOAD_TARGET_LCD_V   FT_LOAD_TARGET_( FT_RENDER_MODE_LCD_V  )

A list of values that are used to select a specific hinting algorithm to use by the hinter. You should OR one of these values to your ‘load_flags’ when calling FT_Load_Glyph.

Note that font's native hinters may ignore the hinting algorithm you have specified (e.g., the TrueType bytecode interpreter). You can set FT_LOAD_FORCE_AUTOHINT to ensure that the auto-hinter is used.

Also note that FT_LOAD_TARGET_LIGHT is an exception, in that it always implies FT_LOAD_FORCE_AUTOHINT.

You should use only one of the FT_LOAD_TARGET_XXX values in your ‘load_flags’. They can't be ORed.

If FT_LOAD_RENDER is also set, the glyph is rendered in the corresponding mode (i.e., the mode which matches the used algorithm best). An exeption is FT_LOAD_TARGET_MONO since it implies FT_LOAD_MONOCHROME.

You can use a hinting algorithm that doesn't correspond to the same rendering mode. As an example, it is possible to use the ‘light’ hinting algorithm and have the results rendered in horizontal LCD pixel mode, with code like

  FT_Load_Glyph( face, glyph_index,
                 load_flags | FT_LOAD_TARGET_LIGHT );

  FT_Render_Glyph( face->glyph, FT_RENDER_MODE_LCD );

#define FT_LOAD_TARGET_MODE( x )  ( (FT_Render_Mode)( ( (x) >> 16 ) & 15 ) )

Return the FT_Render_Mode corresponding to a given FT_LOAD_TARGET_XXX value.

  FT_EXPORT( void )
  FT_Set_Transform( FT_Face     face,
                    FT_Matrix*  matrix,
                    FT_Vector*  delta );

A function used to set the transformation that is applied to glyph images when they are loaded into a glyph slot through FT_Load_Glyph.

The transformation is only applied to scalable image formats after the glyph has been loaded. It means that hinting is unaltered by the transformation and is performed on the character size given in the last call to FT_Set_Char_Size or FT_Set_Pixel_Sizes.

Note that this also transforms the ‘face.glyph.advance’ field, but not the values in ‘face.glyph.metrics’.

  typedef enum  FT_Render_Mode_
  {
    FT_RENDER_MODE_NORMAL = 0,
    FT_RENDER_MODE_LIGHT,
    FT_RENDER_MODE_MONO,
    FT_RENDER_MODE_LCD,
    FT_RENDER_MODE_LCD_V,

    FT_RENDER_MODE_MAX

  } FT_Render_Mode;

An enumeration type that lists the render modes supported by FreeType 2. Each mode corresponds to a specific type of scanline conversion performed on the outline.

For bitmap fonts and embedded bitmaps the ‘bitmap->pixel_mode’ field in the FT_GlyphSlotRec structure gives the format of the returned bitmap.

All modes except FT_RENDER_MODE_MONO use 256 levels of opacity.

The LCD-optimized glyph bitmaps produced by FT_Render_Glyph can be filtered to reduce color-fringes by using FT_Library_SetLcdFilter (not active in the default builds). It is up to the caller to either call FT_Library_SetLcdFilter (if available) or do the filtering itself.

The selected render mode only affects vector glyphs of a font. Embedded bitmaps often have a different pixel mode like FT_PIXEL_MODE_MONO. You can use FT_Bitmap_Convert to transform them into 8-bit pixmaps.

#define ft_render_mode_normal  FT_RENDER_MODE_NORMAL
#define ft_render_mode_mono    FT_RENDER_MODE_MONO

These constants are deprecated. Use the corresponding FT_Render_Mode values instead.

  FT_EXPORT( FT_Error )
  FT_Render_Glyph( FT_GlyphSlot    slot,
                   FT_Render_Mode  render_mode );

Convert a given glyph image to a bitmap. It does so by inspecting the glyph image format, finding the relevant renderer, and invoking it.

FreeType error code. 0 means success.

  typedef enum  FT_Kerning_Mode_
  {
    FT_KERNING_DEFAULT  = 0,
    FT_KERNING_UNFITTED,
    FT_KERNING_UNSCALED

  } FT_Kerning_Mode;

An enumeration used to specify which kerning values to return in FT_Get_Kerning.

#define ft_kerning_default   FT_KERNING_DEFAULT

This constant is deprecated. Please use FT_KERNING_DEFAULT instead.

#define ft_kerning_unfitted  FT_KERNING_UNFITTED

This constant is deprecated. Please use FT_KERNING_UNFITTED instead.

#define ft_kerning_unscaled  FT_KERNING_UNSCALED

This constant is deprecated. Please use FT_KERNING_UNSCALED instead.

  FT_EXPORT( FT_Error )
  FT_Get_Kerning( FT_Face     face,
                  FT_UInt     left_glyph,
                  FT_UInt     right_glyph,
                  FT_UInt     kern_mode,
                  FT_Vector  *akerning );

Return the kerning vector between two glyphs of a same face.

FreeType error code. 0 means success.

Only horizontal layouts (left-to-right & right-to-left) are supported by this method. Other layouts, or more sophisticated kernings, are out of the scope of this API function -- they can be implemented through format-specific interfaces.

  FT_EXPORT( FT_Error )
  FT_Get_Track_Kerning( FT_Face    face,
                        FT_Fixed   point_size,
                        FT_Int     degree,
                        FT_Fixed*  akerning );

Return the track kerning for a given face object at a given size.

FreeType error code. 0 means success.

Currently, only the Type 1 font driver supports track kerning, using data from AFM files (if attached with FT_Attach_File or FT_Attach_Stream).

Only very few AFM files come with track kerning data; please refer to the Adobe's AFM specification for more details.

  FT_EXPORT( FT_Error )
  FT_Get_Glyph_Name( FT_Face     face,
                     FT_UInt     glyph_index,
                     FT_Pointer  buffer,
                     FT_UInt     buffer_max );

Retrieve the ASCII name of a given glyph in a face. This only works for those faces where FT_HAS_GLYPH_NAMES(face) returns 1.

FreeType error code. 0 means success.

An error is returned if the face doesn't provide glyph names or if the glyph index is invalid. In all cases of failure, the first byte of ‘buffer’ is set to 0 to indicate an empty name.

The glyph name is truncated to fit within the buffer if it is too long. The returned string is always zero-terminated.

Be aware that FreeType reorders glyph indices internally so that glyph index 0 always corresponds to the ‘missing glyph’ (called ‘.notdef’).

This function is not compiled within the library if the config macro ‘FT_CONFIG_OPTION_NO_GLYPH_NAMES’ is defined in ‘include/freetype/config/ftoptions.h’.

  FT_EXPORT( const char* )
  FT_Get_Postscript_Name( FT_Face  face );

Retrieve the ASCII PostScript name of a given face, if available. This only works with PostScript and TrueType fonts.

A pointer to the face's PostScript name. NULL if unavailable.

The returned pointer is owned by the face and is destroyed with it.

  FT_EXPORT( FT_Error )
  FT_Select_Charmap( FT_Face      face,
                     FT_Encoding  encoding );

Select a given charmap by its encoding tag (as listed in ‘freetype.h’).

FreeType error code. 0 means success.

This function returns an error if no charmap in the face corresponds to the encoding queried here.

Because many fonts contain more than a single cmap for Unicode encoding, this function has some special code to select the one which covers Unicode best (‘best’ in the sense that a UCS-4 cmap is preferred to a UCS-2 cmap). It is thus preferable to FT_Set_Charmap in this case.

  FT_EXPORT( FT_Error )
  FT_Set_Charmap( FT_Face     face,
                  FT_CharMap  charmap );

Select a given charmap for character code to glyph index mapping.

FreeType error code. 0 means success.

This function returns an error if the charmap is not part of the face (i.e., if it is not listed in the ‘face->charmaps’ table).

It also fails if a type 14 charmap is selected.

  FT_EXPORT( FT_Int )
  FT_Get_Charmap_Index( FT_CharMap  charmap );

Retrieve index of a given charmap.

The index into the array of character maps within the face to which ‘charmap’ belongs. If an error occurs, -1 is returned.

  FT_EXPORT( FT_UInt )
  FT_Get_Char_Index( FT_Face   face,
                     FT_ULong  charcode );

Return the glyph index of a given character code. This function uses a charmap object to do the mapping.

The glyph index. 0 means ‘undefined character code’.

If you use FreeType to manipulate the contents of font files directly, be aware that the glyph index returned by this function doesn't always correspond to the internal indices used within the file. This is done to ensure that value 0 always corresponds to the ‘missing glyph’. If the first glyph is not named ‘.notdef’, then for Type 1 and Type 42 fonts, ‘.notdef’ will be moved into the glyph ID 0 position, and whatever was there will be moved to the position ‘.notdef’ had. For Type 1 fonts, if there is no ‘.notdef’ glyph at all, then one will be created at index 0 and whatever was there will be moved to the last index -- Type 42 fonts are considered invalid under this condition.

  FT_EXPORT( FT_ULong )
  FT_Get_First_Char( FT_Face   face,
                     FT_UInt  *agindex );

This function is used to return the first character code in the current charmap of a given face. It also returns the corresponding glyph index.

The charmap's first character code.

You should use this function with FT_Get_Next_Char to be able to parse all character codes available in a given charmap. The code should look like this:

  FT_ULong  charcode;                                              
  FT_UInt   gindex;                                                
                                                                   
                                                                   
  charcode = FT_Get_First_Char( face, &gindex );                   
  while ( gindex != 0 )                                            
  {                                                                
    ... do something with (charcode,gindex) pair ...               
                                                                   
    charcode = FT_Get_Next_Char( face, charcode, &gindex );        
  }                                                                

Note that ‘*agindex’ is set to 0 if the charmap is empty. The result itself can be 0 in two cases: if the charmap is empty or if the value 0 is the first valid character code.

  FT_EXPORT( FT_ULong )
  FT_Get_Next_Char( FT_Face    face,
                    FT_ULong   char_code,
                    FT_UInt   *agindex );

This function is used to return the next character code in the current charmap of a given face following the value ‘char_code’, as well as the corresponding glyph index.

The charmap's next character code.

You should use this function with FT_Get_First_Char to walk over all character codes available in a given charmap. See the note for this function for a simple code example.

Note that ‘*agindex’ is set to 0 when there are no more codes in the charmap.

  FT_EXPORT( FT_UInt )
  FT_Get_Name_Index( FT_Face     face,
                     FT_String*  glyph_name );

Return the glyph index of a given glyph name. This function uses driver specific objects to do the translation.

The glyph index. 0 means ‘undefined character code’.

#define FT_SUBGLYPH_FLAG_ARGS_ARE_WORDS          1
#define FT_SUBGLYPH_FLAG_ARGS_ARE_XY_VALUES      2
#define FT_SUBGLYPH_FLAG_ROUND_XY_TO_GRID        4
#define FT_SUBGLYPH_FLAG_SCALE                   8
#define FT_SUBGLYPH_FLAG_XY_SCALE             0x40
#define FT_SUBGLYPH_FLAG_2X2                  0x80
#define FT_SUBGLYPH_FLAG_USE_MY_METRICS      0x200

A list of constants used to describe subglyphs. Please refer to the TrueType specification for the meaning of the various flags.

  FT_EXPORT( FT_Error )
  FT_Get_SubGlyph_Info( FT_GlyphSlot  glyph,
                        FT_UInt       sub_index,
                        FT_Int       *p_index,
                        FT_UInt      *p_flags,
                        FT_Int       *p_arg1,
                        FT_Int       *p_arg2,
                        FT_Matrix    *p_transform );

Retrieve a description of a given subglyph. Only use it if ‘glyph->format’ is FT_GLYPH_FORMAT_COMPOSITE; an error is returned otherwise.

FreeType error code. 0 means success.

The values of ‘*p_arg1’, ‘*p_arg2’, and ‘*p_transform’ must be interpreted depending on the flags returned in ‘*p_flags’. See the TrueType specification for details.

#define FT_FSTYPE_INSTALLABLE_EMBEDDING         0x0000
#define FT_FSTYPE_RESTRICTED_LICENSE_EMBEDDING  0x0002
#define FT_FSTYPE_PREVIEW_AND_PRINT_EMBEDDING   0x0004
#define FT_FSTYPE_EDITABLE_EMBEDDING            0x0008
#define FT_FSTYPE_NO_SUBSETTING                 0x0100
#define FT_FSTYPE_BITMAP_EMBEDDING_ONLY         0x0200

A list of bit flags used in the ‘fsType’ field of the OS/2 table in a TrueType or OpenType font and the ‘FSType’ entry in a PostScript font. These bit flags are returned by FT_Get_FSType_Flags; they inform client applications of embedding and subsetting restrictions associated with a font.

See http://www.adobe.com/devnet/acrobat/pdfs/FontPolicies.pdf for more details.

While the fsType flags can indicate that a font may be embedded, a license with the font vendor may be separately required to use the font in this way.

  FT_EXPORT( FT_UShort )
  FT_Get_FSType_Flags( FT_Face  face );

Return the fsType flags for a font.

The fsType flags, FT_FSTYPE_XXX.

Use this function rather than directly reading the ‘fs_type’ field in the PS_FontInfoRec structure which is only guaranteed to return the correct results for Type 1 fonts.

2.3.8