# FreeType-2.1.8 API Reference

# Base Interface

## Synopsis

| FT_Library |  | FT_HAS_FIXED_SIZES |  | FT_Set_Char_Size
| FT_Face |  | FT_HAS_FAST_GLYPHS |  | FT_Set_Pixel_Sizes
| FT_Size |  | FT_HAS_GLYPH_NAMES |  | FT_Load_Glyph
| FT_GlyphSlot |  | FT_HAS_MULTIPLE_MASTERS |  | FT_Load_Char
| FT_CharMap |  | FT_STYLE_FLAG_XXX |  | FT_LOAD_XXX
| FT_Encoding |  | FT_Size_Internal |  | FT_Set_Transform
| FT_Glyph_Metrics |  | FT_Size_Metrics |  | FT_Render_Mode
| FT_Bitmap_Size |  | FT_SizeRec |  | ft_render_mode_xxx
| FT_Module |  | FT_SubGlyph |  | FT_Render_Glyph
| FT_Driver |  | FT_Slot_Internal |  | FT_Kerning_Mode
| FT_Renderer |  | FT_GlyphSlotRec |  | ft_kerning_default
| FT_ENC_TAG |  | FT_Init_FreeType |  | ft_kerning_unfitted
| ft_encoding_xxx |  | FT_Library_Version |  | ft_kerning_unscaled
| FT_CharMapRec |  | FT_Done_FreeType |  | FT_Get_Kerning
| FT_Face_Internal |  | FT_OPEN_XXX |  | FT_Get_Glyph_Name
| FT_FaceRec |  | FT_Parameter |  | FT_Get_Postscript_Name
| FT_FACE_FLAG_XXX |  | FT_Open_Args |  | FT_Select_Charmap
| FT_HAS_HORIZONTAL |  | FT_New_Face |  | FT_Set_Charmap
| FT_HAS_VERTICAL |  | FT_New_Memory_Face |  | FT_Get_Char_Index
| FT_HAS_KERNING |  | FT_Open_Face |  | FT_Get_First_Char
| FT_IS_SCALABLE |  | FT_Attach_File |  | FT_Get_Next_Char
| FT_IS_SFNT |  | FT_Attach_Stream |  | FT_Get_Name_Index
| FT_IS_FIXED_WIDTH |  | FT_Done_Face |  |

This section describes the public high-level API of FreeType 2.

#### FT_Library

      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).

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

#### FT_Face

      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.

note
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).

also
The FT_FaceRec details the publicly accessible fields of a given face object.

#### FT_Size

      typedef struct FT_SizeRec_*  FT_Size;

A handle to a given size object. Such an object models the data that depends on the current resolution and _character size_ in a given FT_Face.

note
Each face object owns one or more sizes. There is however a single active size for the face at any time that will be used by functions like FT_Load_Glyph, FT_Get_Kerning, etc. You can use the FT_Activate_Size API to change the current active size of any given face.

also
The FT_SizeRec structure details the publicly accessible fields of a given face object.

#### FT_GlyphSlot

      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 one 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.

also
FT_GlyphSlotRec details the publicly accessible glyph fields.

#### FT_CharMap

      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.

note
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.

also
The FT_CharMapRec details the publicly accessible fields of a given character map.

#### FT_Encoding

      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 encodings supported by charmaps. Used in the FT_Select_Charmap API function.

note
Because of 32-bit charcodes defined in Unicode (i.e., surrogates), all character codes must be expressed as FT_Longs. The values of this type correspond to specific character repertories (i.e. charsets), and not to text encoding methods (like UTF-8, UTF-16, GB2312_EUC, etc.). Other encodings might be defined in the future.

values

FT_ENCODING_NONE | The encoding value 0 is reserved.
FT_ENCODING_UNICODE | Corresponds to the Unicode character set. This value covers all versions of the Unicode repertoire, including ASCII and Latin-1. Most fonts include a Unicode charmap, but not all of them.
FT_ENCODING_MS_SYMBOL | Corresponds to the Microsoft Symbol encoding, used to encode mathematical symbols in the 32..255 character code range. For more information, see `http://www.ceviz.net/symbol.htm'.
FT_ENCODING_SJIS | Corresponds to Japanese SJIS encoding. More info at at `http://langsupport.japanreference.com/encoding.shtml'. See note on multi-byte encodings below.
FT_ENCODING_GB2312 | Corresponds to an encoding system for Simplified Chinese as used used in mainland China.
FT_ENCODING_BIG5 | Corresponds to an encoding system for Traditional Chinese as used in Taiwan and Hong Kong.
FT_ENCODING_WANSUNG | Corresponds to the Korean encoding system known as Wansung. For more information see `http://www.microsoft.com/typography/unicode/949.txt'.
FT_ENCODING_JOHAB | The Korean standard character set (KS C-5601-1992), which corresponds to MS Windows code page 1361. This character set includes all possible Hangeul character combinations.
FT_ENCODING_ADOBE_LATIN_1 | Corresponds to a Latin-1 encoding as defined in a Type 1 Postscript font. It is limited to 256 character codes.
FT_ENCODING_ADOBE_STANDARD | Corresponds to the Adobe Standard encoding, as found in Type 1, CFF, and OpenType/CFF fonts. It is limited to 256 character codes.
FT_ENCODING_ADOBE_EXPERT | Corresponds to the Adobe Expert encoding, as found in Type 1, CFF, and OpenType/CFF fonts. It is limited to 256 character codes.
FT_ENCODING_ADOBE_CUSTOM | Corresponds to a custom encoding, as found in Type 1, CFF, and OpenType/CFF fonts. It is limited to 256 character codes.
FT_ENCODING_APPLE_ROMAN | Corresponds to the 8-bit Apple roman encoding. Many TrueType and OpenType fonts contain a charmap for this encoding, since older versions of Mac OS are able to use it.
FT_ENCODING_OLD_LATIN_2 | This value is deprecated and was never used nor reported by FreeType. Don't use or test for it.
FT_ENCODING_MS_SJIS | Same as FT_ENCODING_SJIS. Deprecated.
FT_ENCODING_MS_GB2312 | Same as FT_ENCODING_GB2312. Deprecated.
FT_ENCODING_MS_BIG5 | Same as FT_ENCODING_BIG5. Deprecated.
FT_ENCODING_MS_WANSUNG | Same as FT_ENCODING_WANSUNG. Deprecated.
FT_ENCODING_MS_JOHAB | Same as FT_ENCODING_JOHAB. Deprecated.

note

By default, FreeType automatically synthetizes a Unicode charmap for Postscript fonts, using their glyph names dictionaries. However, it will also report 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, dont 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.

#### FT_Glyph_Metrics

      typedef struct  FT_Glyph_Metrics_
      {
        FT_Pos  width;         /* glyph width  */
        FT_Pos  height;        /* glyph height */

        FT_Pos  horiBearingX;  /* left side bearing in horizontal layouts */
        FT_Pos  horiBearingY;  /* top side bearing in horizontal layouts  */
        FT_Pos  horiAdvance;   /* advance width for horizontal layout     */

        FT_Pos  vertBearingX;  /* left side bearing in vertical layouts */
        FT_Pos  vertBearingY;  /* top side bearing in vertical layouts  */
        FT_Pos  vertAdvance;   /* advance height for vertical layout    */

      } 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 is used, values are returned in font units instead.

fields

width | The glyph's width.
height | The glyph's height.
horiBearingX | Horizontal left side bearing.
horiBearingY | Horizontal top side bearing.
horiAdvance | Horizontal advance width.
vertBearingX | Vertical left side bearing.
vertBearingY | Vertical top side bearing.
vertAdvance | Vertical advance height.

#### FT_Bitmap_Size

      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 size of a bitmap strike (i.e., a bitmap instance of the font for a given resolution) in a fixed-size font face. It is used for the `available_sizes' field of the FT_FaceRec structure.

fields

height | The (vertical) baseline-to-baseline distance in pixels. It makes most sense to define the height of a bitmap font in this way.
width | The average width of the font (in pixels). Since the algorithms to compute this value are different for the various bitmap formats, it can only give an additional hint if the `height' value isn't sufficient to select the proper font. For monospaced fonts the average width is the same as the maximum width.
size | The point size in 26.6 fractional format this font shall represent (for a given vertical resolution).
x_ppem | The horizontal ppem value (in 26.6 fractional format).
y_ppem | The vertical ppem value (in 26.6 fractional format).

note

The values in this structure are taken from the bitmap font. If the font doesn't provide a parameter it is set to zero to indicate that the information is not available.

The following formula converts from dpi to ppem:

ppem = size * dpi / 72

where `size' is in points.

Windows FNT: The `size', `x_ppem', and `y_ppem' parameters are not reliable: There exist fonts (e.g. app850.fon) which have a wrong size for some subfonts; since FNT files don't contain ppem but dpi values the computed x_ppem and y_ppem numbers are thus wrong also.

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

#### FT_Module

      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.

#### FT_Driver

      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.

#### FT_Renderer

      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.

#### FT_ENC_TAG

    #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).

note
Since many 16bit compilers don't like 32bit 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.

#### ft_encoding_xxx

    #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.

values

ft_encoding_none | see FT_ENCODING_NONE
ft_encoding_unicode | see FT_ENCODING_UNICODE
ft_encoding_latin_2 | see FT_ENCODING_OLD_LATIN_2
ft_encoding_symbol | see FT_ENCODING_MS_SYMBOL
ft_encoding_sjis | see FT_ENCODING_SJIS
ft_encoding_gb2312 | see FT_ENCODING_GB2312
ft_encoding_big5 | see FT_ENCODING_BIG5
ft_encoding_wansung | see FT_ENCODING_WANSUNG
ft_encoding_johab | see FT_ENCODING_JOHAB
ft_encoding_adobe_standard | see FT_ENCODING_ADOBE_STANDARD
ft_encoding_adobe_expert | see FT_ENCODING_ADOBE_EXPERT
ft_encoding_adobe_custom | see FT_ENCODING_ADOBE_CUSTOM
ft_encoding_latin_1 | see FT_ENCODING_ADOBE_LATIN_1
ft_encoding_apple_roman | see FT_ENCODING_APPLE_ROMAN

#### FT_CharMapRec

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

      } FT_CharMapRec;

The base charmap structure.

fields

face | A handle to the parent face object.
encoding | An FT_Encoding tag identifying the charmap. Use this with FT_Select_Charmap.
platform_id | An ID number describing the platform for the following encoding ID. This comes directly from the TrueType specification and should be emulated for other formats.
encoding_id | A platform specific encoding number. This also comes from the TrueType specification and should be emulated similarly.

#### FT_Face_Internal

      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.

#### FT_FaceRec

      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 are only relevant to scalable outlines */
        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;
        void*             extensions;

        FT_Face_Internal  internal;

        /*@private end */

      } FT_FaceRec;

FreeType root face class structure. A face object models the resolution and point-size independent data found in a font file.

fields

num_faces | In the case where the face is located in a collection (i.e., a file which embeds several faces), this is the total number of faces found in the resource. 1 by default. Accessing non-existent face indices causes an error.
face_index | The index of the face in its font file. Usually, this is 0 for all normal font formats. It can be > 0 in the case of collections (which embed several fonts in a single resource/file).
face_flags | A set of bit flags that give important information about the face; see the FT_FACE_FLAG_XXX constants for details.
style_flags | A set of bit flags indicating the style of the face (i.e., italic, bold, underline, etc). See the FT_STYLE_FLAG_XXX constants.
num_glyphs | The total number of glyphs in the face.
family_name | The face's family name. This is an ASCII string, usually in English, which describes the typeface's family (like `Times New Roman', `Bodoni', `Garamond', etc). This is a least common denominator used to list fonts. Some formats (TrueType & OpenType) provide localized and Unicode versions of this string. Applications should use the format specific interface to access them.

style_name

The face's style name. This is an ASCII string, usually in English, which describes the typeface's style (like `Italic', `Bold', `Condensed', etc). Not all font formats provide a style name, so this field is optional, and can be set to NULL. As for `family_name', some formats provide localized/Unicode versions of this string. Applications should use the format specific interface to access them.

num_fixed_sizes | The number of fixed sizes available in this face. This should be set to 0 for scalable fonts, unless its face includes a set of glyphs (called a `strike') for the specified sizes.
available_sizes | An array of sizes specifying the available bitmap/graymap sizes that are contained in in the font face. Should be set to NULL if the field `num_fixed_sizes' is set to 0.
num_charmaps | The total number of character maps in the face.
charmaps | A table of pointers to the face's charmaps. Used to scan the list of available charmaps -- this table might change after a call to FT_Attach_File or FT_Attach_Stream (e.g. if used to hook an additional encoding or CMap to the face object).
generic | A field reserved for client uses. See the FT_Generic type description.
bbox | The font bounding box. Coordinates are expressed in font units (see units_per_EM). The box is large enough to contain any glyph from the font. Thus, bbox.yMax can be seen as the `maximal ascender', bbox.yMin as the `minimal descender', and the maximal glyph width is given by `bbox.xMax-bbox.xMin' (not to be confused with the maximal advance_width Only relevant for scalable formats.
units_per_EM | The number of font units per EM square for this face. This is typically 2048 for TrueType fonts, 1000 for Type1 fonts, and should be set to the (unrealistic) value 1 for fixed-sizes fonts. Only relevant for scalable formats.
ascender | The face's ascender is the vertical distance from the baseline to the topmost point of any glyph in the face. This field's value is positive, expressed in font units. Some font designs use a value different from `bbox.yMax'. Only relevant for scalable formats.
descender | The face's descender is the vertical distance from the baseline to the bottommost point of any glyph in the face. This field's value is negative for values below the baseline. It is expressed in font units. Some font designs use a value different from `bbox.yMin'. Only relevant for scalable formats.
height | The face's height is the vertical distance from one baseline to the next when writing several lines of text. Its value is always positive, expressed in font units. The value can be computed as `ascender+descender+line_gap' where the value of `line_gap' is also called `external leading'. Only relevant for scalable formats.
max_advance_width | The maximal advance width, in font units, for all glyphs in this face. This can be used to make word wrapping computations faster. Only relevant for scalable formats.
max_advance_height | The maximal advance height, in font units, for all glyphs in this face. This is only relevant for vertical layouts, and should be set to the `height' for fonts that do not provide vertical metrics. Only relevant for scalable formats.
underline_position | The position, in font units, of the underline line for this face. It's the center of the underlining stem. Only relevant for scalable formats.
underline_thickness | The thickness, in font units, of the underline for this face. Only relevant for scalable formats.
glyph | The face's associated glyph slot(s). This object is created automatically with a new face object. However, certain kinds of applications (mainly tools like converters) can need more than one slot to ease their task.
size | The current active size for this face.
charmap | The current active charmap for this face.

#### FT_FACE_FLAG_XXX

    #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 )

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.

values

FT_FACE_FLAG_SCALABLE | Indicates that the face provides vectorial outlines. This doesn't prevent embedded bitmaps, i.e., a face can have both this bit and FT_FACE_FLAG_FIXED_SIZES set.
FT_FACE_FLAG_FIXED_SIZES | Indicates that the face contains `fixed sizes', i.e., bitmap strikes for some given pixel sizes. See the `num_fixed_sizes' and `available_sizes' fields of FT_FaceRec.
FT_FACE_FLAG_FIXED_WIDTH | Indicates that the face contains fixed-width characters (like Courier, Lucido, MonoType, etc.).
FT_FACE_FLAG_SFNT | Indicates that the face uses the `sfnt' storage scheme. For now, this means TrueType and OpenType.
FT_FACE_FLAG_HORIZONTAL | Indicates that the face contains horizontal glyph metrics. This should be set for all common formats.
FT_FACE_FLAG_VERTICAL | Indicates that the face contains vertical glyph metrics. This is only available in some formats, not all of them.
FT_FACE_FLAG_KERNING | Indicates that the face contains kerning information. If set, the kerning distance can be retrieved through the function FT_Get_Kerning. Note that if unset, this function will always return the vector (0,0).
FT_FACE_FLAG_FAST_GLYPHS | THIS FLAG IS DEPRECATED. DO NOT USE OR TEST IT.
FT_FACE_FLAG_MULTIPLE_MASTERS | Indicates that the font contains multiple masters and is capable of interpolating between them. See the multiple-masters specific API for details.
FT_FACE_FLAG_GLYPH_NAMES | Indicates that the font contains glyph names that can be retrieved through FT_Get_Glyph_Name. Note that some TrueType fonts contain broken glyph name tables. Use the function FT_Has_PS_Glyph_Names when needed.
FT_FACE_FLAG_EXTERNAL_STREAM | Used internally by FreeType to indicate that a face's stream was provided by the client application and should not be destroyed when FT_Done_Face is called. Don't read or test this flag.

#### FT_HAS_HORIZONTAL

    #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).

also
FT_HAS_VERTICAL can be used to check for vertical metrics.

#### FT_HAS_VERTICAL

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

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

#### FT_HAS_KERNING

    #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.

#### FT_IS_SCALABLE

    #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, CID, and OpenType/CFF font formats.

#### FT_IS_SFNT

    #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.

#### FT_IS_FIXED_WIDTH

    #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.

#### FT_HAS_FIXED_SIZES

    #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.

#### FT_HAS_FAST_GLYPHS

    #define FT_HAS_FAST_GLYPHS( face ) \
              ( face->face_flags & FT_FACE_FLAG_FAST_GLYPHS )

Deprecated; indicates that the face contains so-called "fast" glyph bitmaps.

#### FT_HAS_GLYPH_NAMES

    #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.

#### FT_HAS_MULTIPLE_MASTERS

    #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.

#### FT_STYLE_FLAG_XXX

    #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.

values

FT_STYLE_FLAG_ITALIC | Indicates that a given face is italicized.
FT_STYLE_FLAG_BOLD | Indicates that a given face is bold.

#### FT_Size_Internal

      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.

#### FT_Size_Metrics

      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;     /* two scales used to convert font units  */
        FT_Fixed   y_scale;     /* to 26.6 frac. pixel coordinates        */

        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 returned scaled important distances for a given size object.

fields

x_ppem | The character width, expressed in integer pixels. This is the width of the EM square expressed in pixels, hence the term `ppem' (pixels per EM).
y_ppem | The character height, expressed in integer pixels. This is the height of the EM square expressed in pixels, hence the term `ppem' (pixels per EM).
x_scale | A simple 16.16 fixed point format coefficient used to scale horizontal distances expressed in font units to fractional (26.6) pixel coordinates.
y_scale | A simple 16.16 fixed point format coefficient used to scale vertical distances expressed in font units to fractional (26.6) pixel coordinates.
ascender | The ascender, expressed in 26.6 fixed point pixels. Positive for ascenders above the baseline.
descender | The descender, expressed in 26.6 fixed point pixels. Negative for descenders below the baseline.
height | The text height, expressed in 26.6 fixed point pixels. Always positive.
max_advance | Maximum horizontal advance, expressed in 26.6 fixed point pixels. Always positive.

note

For scalable fonts, the values of `ascender', `descender', and `height' are scaled versions of `face->ascender', `face->descender', and `face->height', respectively.

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

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

#### FT_SizeRec

      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 the resolution and pointsize dependent data of a given face.

fields

face | Handle to the parent face object.
generic | A typeless pointer, which is unused by the FreeType library or any of its drivers. It can be used by client applications to link their own data to each size object.
metrics | Metrics for this size object. This field is read-only.

#### FT_SubGlyph

      typedef struct FT_SubGlyphRec_*  FT_SubGlyph;

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

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

#### FT_Slot_Internal

      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.

#### FT_GlyphSlotRec

      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;

        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 vectorial or bitmap/graymaps.

fields

library | A handle to the FreeType library instance this slot belongs to.
face | A handle to the parent face object.
next | In some cases (like some font tools), several glyph slots per face object can be a good thing. As this is rare, the glyph slots are listed through a direct, single-linked list using its `next' field.
generic | A typeless pointer which is unused by the FreeType library or any of its drivers. It can be used by client applications to link their own data to each glyph slot object.
metrics | The metrics of the last loaded glyph in the slot. The returned values depend on the last load flags (see the FT_Load_Glyph API function) and can be expressed either in 26.6 fractional pixels or font units. Note that even when the glyph image is transformed, the metrics are not.

linearHoriAdvance

For scalable formats only, this field holds the linearly scaled horizontal advance width for the glyph (i.e. the scaled and unhinted value of the hori advance). This can be important to perform correct WYSIWYG layout.

Note that this value is expressed by default in 16.16 pixels. However, when the glyph is loaded with the FT_LOAD_LINEAR_DESIGN flag, this field contains simply the value of the advance in original font units.

linearVertAdvance | For scalable formats only, this field holds the linearly scaled vertical advance height for the glyph. See linearHoriAdvance for comments.
advance | This is the transformed advance width for the glyph.
format | This field indicates the format of the image contained in the glyph slot. Typically FT_GLYPH_FORMAT_BITMAP, FT_GLYPH_FORMAT_OUTLINE, and FT_GLYPH_FORMAT_COMPOSITE, but others are possible.
bitmap | This field is used as a bitmap descriptor when the slot format is FT_GLYPH_FORMAT_BITMAP. Note that the address and content of the bitmap buffer can change between calls of FT_Load_Glyph and a few other functions.
bitmap_left | This is the bitmap's left bearing expressed in integer pixels. Of course, this is only valid if the format is FT_GLYPH_FORMAT_BITMAP.
bitmap_top | This is the bitmap's top bearing expressed in integer pixels. Remember that this is the distance from the baseline to the top-most glyph scanline, upwards y-coordinates being positive
outline | The outline descriptor for the current glyph image if its format is FT_GLYPH_FORMAT_OUTLINE.
num_subglyphs | The number of subglyphs in a composite glyph. This field is only valid for the composite glyph format that should normally only be loaded with the FT_LOAD_NO_RECURSE flag. For now this is internal to FreeType.
subglyphs | An array of subglyph descriptors for composite glyphs. There are `num_subglyphs' elements in there. Currently internal to FreeType.
control_data | Certain font drivers can also return the control data for a given glyph image (e.g. TrueType bytecode, Type 1 charstrings, etc.). This field is a pointer to such data.
control_len | This is the length in bytes of the control data.
other | Really wicked formats can use this pointer to present their own glyph image to client apps. Note that the app will need to know about the image format.

note

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. a vectorial outline 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 convert 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' .

#### FT_Init_FreeType

      FT_EXPORT( FT_Error )
      FT_Init_FreeType( FT_Library  *alibrary );

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

output

alibrary | A handle to a new library object.

return
FreeType error code. 0 means success.

#### FT_Library_Version

      FT_EXPORT( void )
      FT_Library_Version( FT_Library   library,
                          FT_Int      *amajor,
                          FT_Int      *aminor,
                          FT_Int      *apatch );

Return the version of the FreeType library being used. This is useful when dynamically linking to the library, since one cannot use the macros FT_FREETYPE_MAJOR, FT_FREETYPE_MINOR, and FT_FREETYPE_PATCH.

input

library | A source library handle.

output

amajor | The major version number.
aminor | The minor version number.
apatch | The patch version number.

note
The reason why this function takes a 'library' argument is because certain programs implement library initialization in a custom way that doesn't use `FT_Init_FreeType'. In such cases, the library version might not be available before the library object has been created.

#### FT_Done_FreeType

      FT_EXPORT( FT_Error )
      FT_Done_FreeType( FT_Library  library );

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

input

library | A handle to the target library object.

return
FreeType error code. 0 means success.

#### FT_OPEN_XXX

    #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.

values

FT_OPEN_MEMORY | This is a memory-based stream.
FT_OPEN_STREAM | Copy the stream from the `stream' field.
FT_OPEN_PATHNAME | Create a new input stream from a C path name.
FT_OPEN_DRIVER | Use the `driver' field.
FT_OPEN_PARAMS | Use the `num_params' & `params' field.
ft_open_memory | Deprecated; use FT_OPEN_MEMORY instead.
ft_open_stream | Deprecated; use FT_OPEN_STREAM instead.
ft_open_pathname | Deprecated; use FT_OPEN_PATHNAME instead.
ft_open_driver | Deprecated; use FT_OPEN_DRIVER instead.
ft_open_params | Deprecated; use FT_OPEN_PARAMS instead.

note
The `FT_OPEN_MEMORY', `FT_OPEN_STREAM', and `FT_OPEN_PATHNAME' flags are mutually exclusive.

#### FT_Parameter

      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.

fields

tag | A 4-byte identification tag.
data | A pointer to the parameter data.

note
The id and function of parameters are driver-specific.

#### FT_Open_Args

      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/stream. A pointer to such a structure can be used as a parameter for the functions FT_Open_Face and FT_Attach_Stream.

fields

flags | A set of bit flags indicating how to use the structure.
memory_base | The first byte of the file in memory.
memory_size | The size in bytes of the file in memory.
pathname | A pointer to an 8-bit file pathname.
stream | A handle to a source stream object.
driver | This field is exclusively used by FT_Open_Face; it simply specifies the font driver to use to open the face. If set to 0, FreeType will try to load the face with each one of the drivers in its list.
num_params | The number of extra parameters.
params | Extra parameters passed to the font driver when opening a new face.

note

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'.

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 will only try 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' will be used. They are ignored otherwise.

#### FT_New_Face

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

Creates a new face object from a given resource and typeface index using a pathname to the font file.

inout

library | A handle to the library resource.

input

pathname | A path to the font file.
face_index | The index of the face within the resource. The first face has index 0.

output

aface | A handle to a new face object.

return
FreeType error code. 0 means success.

note

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

FT_New_Face can be used to determine and/or check the font format of a given font resource. If the `face_index' field is negative, the function will not return any face handle in `aface'; the return value is 0 if the font format is recognized, or non-zero otherwise.

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

#### FT_New_Memory_Face

      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 );

Creates a new face object from a given resource and typeface index using a font file already loaded into memory.

inout

library | A handle to the library resource.

input

file_base | A pointer to the beginning of the font data.
file_size | The size of the memory chunk used by the font data.
face_index | The index of the face within the resource. The first face has index 0.

output

aface | A handle to a new face object.

return
FreeType error code. 0 means success.

note

The font data bytes are used directly by the FT_Face object. This means that they are not copied, and that the client is responsible for releasing/destroying them after the corresponding call to FT_Done_Face .

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

FT_New_Memory_Face can be used to determine and/or check the font format of a given font resource. If the `face_index' field is negative, the function will not return any face handle in `aface'; the return value is 0 if the font format is recognized, or non-zero otherwise.

#### FT_Open_Face

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

Opens a face object from a given resource and typeface index using an `FT_Open_Args' structure. If the face object doesn't exist, it will be created.

inout

library | A handle to the library resource.

input

args | A pointer to an `FT_Open_Args' structure which must be filled by the caller.
face_index | The index of the face within the resource. The first face has index 0.

output

aface | A handle to a new face object.

return
FreeType error code. 0 means success.

note

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 determine and/or check the font format of a given font resource. If the `face_index' field is negative, the function will not return any face handle in `*face'; the return value is 0 if the font format is recognized, or non-zero otherwise.

#### FT_Attach_File

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

`Attaches' a given font file to an existing face. This is usually to read additional information for a single face object. For example, it is used to read the AFM files that come with Type 1 fonts in order to add kerning data and other metrics.

inout

face | The target face object.

input

filepathname | An 8-bit pathname naming the `metrics' file.

return
FreeType error code. 0 means success.

note

If your font file is in memory, or if you want to provide your own input stream object, use FT_Attach_Stream.

The meaning of the `attach' action (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_Attach_Stream

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

This function is similar to FT_Attach_File with the exception that it reads the attachment from an arbitrary stream.

inout

face | The target face object.

input

parameters | A pointer to an FT_Open_Args structure used to describe the input stream to FreeType.

return
FreeType error code. 0 means success.

note
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_Done_Face

      FT_EXPORT( FT_Error )
      FT_Done_Face( FT_Face  face );

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

input

face | A handle to a target face object.

return
FreeType error code. 0 means success.

#### FT_Set_Char_Size

      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 );

Sets the character dimensions of a given face object. The `char_width' and `char_height' values are used for the width and height, respectively, expressed in 26.6 fractional points. If the horizontal or vertical resolution values are zero, a default value of 72dpi is used. Similarly, if one of the character dimensions is zero, its value is set equal to the other.

inout

face | A handle to a target face object.

input

char_width | The character width, in 26.6 fractional points.
char_height | The character height, in 26.6 fractional points.
horz_resolution | The horizontal resolution.
vert_resolution | The vertical resolution.

return
FreeType error code. 0 means success.

note
When dealing with fixed-size faces (i.e., non-scalable formats), FT_Set_Pixel_Sizes provides a more convenient interface.

#### FT_Set_Pixel_Sizes

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

Sets the character dimensions of a given face object. The width and height are expressed in integer pixels. If one of the character dimensions is zero, its value is set equal to the other.

inout

face | A handle to the target face object.

input

pixel_width | The character width, in integer pixels.
pixel_height | The character height, in integer pixels.

return
FreeType error code. 0 means success.

note

The values of `pixel_width' and `pixel_height' correspond to the pixel values of the typographic character size, which are NOT necessarily the same as the dimensions of the glyph `bitmap cells'.

The `character size' is really the size of an abstract square called the `EM', used to design the font. However, depending on the font design, glyphs will be smaller or greater than the EM.

This means that setting the pixel size to, say, 8x8 doesn't guarantee in any way that you will get glyph bitmaps that all fit within an 8x8 cell (sometimes even far from it).

For bitmap fonts, `pixel_height' usually is a reliable value for the height of the bitmap cell. Drivers for bitmap font formats which contain a single bitmap strike only (BDF, PCF, FNT) ignore `pixel_width'.

#### FT_Load_Glyph

      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 within a given glyph slot, for a given size.

inout

face | A handle to the target face object where the glyph will be loaded.

input

glyph_index | The index of the glyph in the font file. For CID-keyed fonts (either in PS or in CFF format) this argument specifies the CID value.
load_flags | A flag indicating what to load for this glyph. The FT_LOAD_XXX constants can be used to control the glyph loading process (e.g., whether the outline should be scaled, whether to load bitmaps or not, whether to hint the outline, etc).

return
FreeType error code. 0 means success.

note
If the glyph image is not a bitmap, and if the bit flag FT_LOAD_IGNORE_TRANSFORM is unset, the glyph image will be transformed with the information passed to a previous call to FT_Set_Transform. Note that this also transforms the `face.glyph.advance' field, but not the values in `face.glyph.metrics'.

#### FT_Load_Char

      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 within a given glyph slot, for a given size, according to its character code.

inout

face | A handle to a target face object where the glyph will be loaded.

input

char_code | The glyph's character code, according to the current charmap used in the face.
load_flags | A flag indicating what to load for this glyph. The FT_LOAD_XXX constants can be used to control the glyph loading process (e.g., whether the outline should be scaled, whether to load bitmaps or not, whether to hint the outline, etc).

return
FreeType error code. 0 means success.

note

If the face has no current charmap, or if the character code is not defined in the charmap, this function will return an error.

If the glyph image is not a bitmap, and if the bit flag FT_LOAD_IGNORE_TRANSFORM is unset, the glyph image will be transformed with the information passed to a previous call to FT_Set_Transform.

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

#### FT_LOAD_XXX

    #define FT_LOAD_DEFAULT                      0x0
    #define FT_LOAD_NO_SCALE                     0x1
    #define FT_LOAD_NO_HINTING                   0x2
    #define FT_LOAD_RENDER                       0x4
    #define FT_LOAD_NO_BITMAP                    0x8
    #define FT_LOAD_VERTICAL_LAYOUT              0x10
    #define FT_LOAD_FORCE_AUTOHINT               0x20
    #define FT_LOAD_CROP_BITMAP                  0x40
    #define FT_LOAD_PEDANTIC                     0x80
    #define FT_LOAD_IGNORE_GLOBAL_ADVANCE_WIDTH  0x200
    #define FT_LOAD_NO_RECURSE                   0x400
    #define FT_LOAD_IGNORE_TRANSFORM             0x800
    #define FT_LOAD_MONOCHROME                   0x1000
    #define FT_LOAD_LINEAR_DESIGN                0x2000

      /* temporary hack! */
    #define FT_LOAD_SBITS_ONLY                   0x4000
    #define FT_LOAD_NO_AUTOHINT                  0x8000U

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

values

FT_LOAD_DEFAULT

Corresponding to 0, this value is used a default glyph load. In this case, the following will happen:

1. FreeType looks for a bitmap for the glyph corresponding to the face's current size. If one is found, the function returns. The bitmap data can be accessed from the glyph slot (see note below).

2. If no embedded bitmap is searched or found, FreeType looks for a scalable outline. If one is found, it is loaded from the font file, scaled to device pixels, then "hinted" to the pixel grid in order to optimize it. The outline data can be accessed from the glyph slot (see note below).

Note that by default, the glyph loader doesn't render outlines into bitmaps. The following flags are used to modify this default behaviour to more specific and useful cases.

FT_LOAD_NO_SCALE | Don't scale the vector outline being loaded to 26.6 fractional pixels, but kept in font units. Note that this also disables hinting and the loading of embedded bitmaps. You should only use it when you want to retrieve the original glyph outlines in font units.
FT_LOAD_NO_HINTING | Don't hint glyph outlines after their scaling to device pixels. This generally generates "blurrier" glyphs in anti-aliased modes. This flag is ignored if FT_LOAD_NO_SCALE is set.
FT_LOAD_RENDER | Render the glyph outline immediately into a bitmap before the glyph loader returns. By default, the glyph is rendered for the FT_RENDER_MODE_NORMAL mode, which corresponds to 8-bit anti-aliased bitmaps using 256 opacity levels. You can use either FT_LOAD_TARGET_MONO or FT_LOAD_MONOCHROME to render 1-bit monochrome bitmaps. This flag is ignored if FT_LOAD_NO_SCALE is set.
FT_LOAD_NO_BITMAP | Don't look for bitmaps when loading the glyph. Only scalable outlines will be loaded when available, and scaled, hinted, or rendered depending on other bit flags. This does not prevent you from rendering outlines to bitmaps with FT_LOAD_RENDER, however.
FT_LOAD_VERTICAL_LAYOUT | Prepare the glyph image for vertical text layout. This basically means that `face.glyph.advance' will correspond to the vertical advance height (instead of the default horizontal advance width), and that the glyph image will be translated to match the vertical bearings positions.
FT_LOAD_FORCE_AUTOHINT | Force the use of the FreeType auto-hinter when a glyph outline is loaded. You shouldn't need this in a typical application, since it is mostly used to experiment with its algorithm.
FT_LOAD_CROP_BITMAP | Indicates that the glyph loader should try to crop the bitmap (i.e., remove all space around its black bits) when loading it. This is only useful when loading embedded bitmaps in certain fonts, since bitmaps rendered with FT_LOAD_RENDER are always cropped by default.
FT_LOAD_PEDANTIC | Indicates that the glyph loader should perform pedantic verifications during glyph loading, rejecting invalid fonts. This is mostly used to detect broken glyphs in fonts. By default, FreeType tries to handle broken fonts also.
FT_LOAD_IGNORE_GLOBAL_ADVANCE_WIDTH | Indicates that the glyph loader should ignore the global advance width defined in the font. As far as we know, this is only used by the X-TrueType font server, in order to deal correctly with the incorrect metrics contained in DynaLab's TrueType CJK fonts.
FT_LOAD_NO_RECURSE | This flag is only used internally. It merely indicates that the glyph loader should not load composite glyphs recursively. Instead, it should set the `num_subglyph' and `subglyphs' values of the glyph slot accordingly, and set "glyph->format" to FT_GLYPH_FORMAT_COMPOSITE. The description of sub-glyphs is not available to client applications for now.
FT_LOAD_IGNORE_TRANSFORM | Indicates that the glyph loader should not try to transform the loaded glyph image. This doesn't prevent scaling, hinting, or rendering.
FT_LOAD_MONOCHROME | This flag is used with FT_LOAD_RENDER to indicate that you want to render a 1-bit monochrome glyph bitmap from a vectorial outline. Note that this has no effect on the hinting algorithm used by the glyph loader. You should better use FT_LOAD_TARGET_MONO if you want to render monochrome-optimized glyph images instead.
FT_LOAD_LINEAR_DESIGN | Return the linearly scaled metrics expressed in original font units instead of the default 16.16 pixel values.
FT_LOAD_NO_AUTOHINT | Indicates that the auto-hinter should never be used to hint glyph outlines. This doesn't prevent native format-specific hinters from being used. This can be important for certain fonts where unhinted output is better than auto-hinted one.
FT_LOAD_TARGET_NORMAL | Use hinting for FT_RENDER_MODE_NORMAL.
FT_LOAD_TARGET_LIGHT | Use hinting for FT_RENDER_MODE_LIGHT.
FT_LOAD_TARGET_MONO | Use hinting for FT_RENDER_MODE_MONO.
FT_LOAD_TARGET_LCD | Use hinting for FT_RENDER_MODE_LCD.
FT_LOAD_TARGET_LCD_V | Use hinting for FT_RENDER_MODE_LCD_V. /

#### FT_Set_Transform

      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 just before they are converted to bitmaps in a glyph slot when FT_Render_Glyph is called.

inout

face | A handle to the source face object.

input

matrix | A pointer to the transformation's 2x2 matrix. Use 0 for the identity matrix.
delta | A pointer to the translation vector. Use 0 for the null vector.

note
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.

#### FT_Render_Mode

      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, as well as specific hinting optimizations. For bitmap fonts the `bitmap->pixel_mode' field in the FT_GlyphSlotRec structure gives the format of the returned bitmap.

values

FT_RENDER_MODE_NORMAL | This is the default render mode; it corresponds to 8-bit anti-aliased bitmaps, using 256 levels of opacity.
FT_RENDER_MODE_LIGHT | This is similar to FT_RENDER_MODE_NORMAL -- you have to use FT_LOAD_TARGET_LIGHT in calls to FT_Load_Glyph to get any effect since the rendering process no longer influences the positioning of glyph outlines. The resulting glyph shapes are more similar to the original, while being a bit more fuzzy (`better shapes' instead of `better contrast', so to say.
FT_RENDER_MODE_MONO | This mode corresponds to 1-bit bitmaps.
FT_RENDER_MODE_LCD | This mode corresponds to horizontal RGB/BGR sub-pixel displays, like LCD-screens. It produces 8-bit bitmaps that are 3 times the width of the original glyph outline in pixels, and which use the FT_PIXEL_MODE_LCD mode.
FT_RENDER_MODE_LCD_V | This mode corresponds to vertical RGB/BGR sub-pixel displays (like PDA screens, rotated LCD displays, etc.). It produces 8-bit bitmaps that are 3 times the height of the original glyph outline in pixels and use the FT_PIXEL_MODE_LCD_V mode.

note
The LCD-optimized glyph bitmaps produced by FT_Render_Glyph are _not filtered_ to reduce color-fringes. It is up to the caller to perform this pass.

#### ft_render_mode_xxx

    #define ft_render_mode_normal  FT_RENDER_MODE_NORMAL
    #define ft_render_mode_mono    FT_RENDER_MODE_MONO

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

values

ft_render_mode_normal | see FT_RENDER_MODE_NORMAL
ft_render_mode_mono | see FT_RENDER_MODE_MONO

#### FT_Render_Glyph

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

Converts a given glyph image to a bitmap. It does so by inspecting the glyph image format, find the relevant renderer, and invoke it.

inout

slot | A handle to the glyph slot containing the image to convert.

input

render_mode | This is the render mode used to render the glyph image into a bitmap. See FT_Render_Mode for a list of possible values.

return
FreeType error code. 0 means success.

#### FT_Kerning_Mode

      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.

values

FT_KERNING_DEFAULT | Return scaled and grid-fitted kerning distances (value is 0).
FT_KERNING_UNFITTED | Return scaled but un-grid-fitted kerning distances.
FT_KERNING_UNSCALED | Return the kerning vector in original font units.

#### ft_kerning_default

    #define ft_kerning_default   FT_KERNING_DEFAULT

This constant is deprecated. Please use FT_KERNING_DEFAULT instead.

#### ft_kerning_unfitted

    #define ft_kerning_unfitted  FT_KERNING_UNFITTED

This constant is deprecated. Please use FT_KERNING_UNFITTED instead.

#### ft_kerning_unscaled

    #define ft_kerning_unscaled  FT_KERNING_UNSCALED

This constant is deprecated. Please use FT_KERNING_UNSCALED instead.

#### FT_Get_Kerning

      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 );

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

input

face | A handle to a source face object.
left_glyph | The index of the left glyph in the kern pair.
right_glyph | The index of the right glyph in the kern pair.
kern_mode | See FT_Kerning_Mode for more information. Determines the scale/dimension of the returned kerning vector.

output

akerning | The kerning vector. This is in font units for scalable formats, and in pixels for fixed-sizes formats.

return
FreeType error code. 0 means success.

note
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_Get_Glyph_Name

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

Retrieves the ASCII name of a given glyph in a face. This only works for those faces where FT_HAS_GLYPH_NAME(face) returns true.

input

face | A handle to a source face object.
glyph_index | The glyph index.
buffer_max | The maximal number of bytes available in the buffer.

output

buffer | A pointer to a target buffer where the name will be copied to.

return
FreeType error code. 0 means success.

note

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' will be 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.

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_Get_Postscript_Name

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

Retrieves the ASCII Postscript name of a given face, if available. This should only work with Postscript and TrueType fonts.

input

face | A handle to the source face object.

return
A pointer to the face's Postscript name. NULL if un-available.

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

#### FT_Select_Charmap

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

Selects a given charmap by its encoding tag (as listed in `freetype.h').

inout

face | A handle to the source face object.

input

encoding | A handle to the selected charmap.

return
FreeType error code. 0 means success.

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

#### FT_Set_Charmap

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

Selects a given charmap for character code to glyph index decoding.

inout

face | A handle to the source face object.

input

charmap | A handle to the selected charmap.

return
FreeType error code. 0 means success.

note
This function will return an error if the charmap is not part of the face (i.e., if it is not listed in the face->charmaps[] table).

#### FT_Get_Char_Index

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

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

input

face | A handle to the source face object.
charcode | The character code.

return
The glyph index. 0 means `undefined character code'.

note
FreeType computes its own glyph indices which are not necessarily the same as used in the font in case the font is based on glyph indices. Reason for this behaviour is to assure that index 0 is never used, representing the missing glyph.

#### FT_Get_First_Char

      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 will also return the corresponding glyph index.

input

face | A handle to the source face object.

output

agindex | Glyph index of first character code. 0 if charmap is empty.

return
The charmap's first character code.

note

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' will be set to 0 if the charmap is empty. The result itself can be 0 in two cases: if the charmap is empty or when the value 0 is the first valid character code.

#### FT_Get_Next_Char

      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.

input

face | A handle to the source face object.
char_code | The starting character code.

output

agindex | Glyph index of first character code. 0 if charmap is empty.

return
The charmap's next character code.

note
You should use this function with FT_Get_First_Char to walk through all character codes available in a given charmap. See the note for this function for a simple code example. Note that `*agindex' will be set to 0 when there are no more codes in the charmap.

#### FT_Get_Name_Index

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

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

input

face | A handle to the source face object.
glyph_name | The glyph name.

return
The glyph index. 0 means `undefined character code'.