FreeType-2.5.4 API Reference

Base Interface

Synopsis

FT_LibraryFT_Glyph_MetricsFT_LOAD_COLOR
FT_FaceFT_SubGlyph 
FT_Size FT_LOAD_VERTICAL_LAYOUT
FT_GlyphSlotFT_Bitmap_SizeFT_LOAD_IGNORE_TRANSFORM
FT_CharMap FT_LOAD_FORCE_AUTOHINT
FT_EncodingFT_Init_FreeTypeFT_LOAD_NO_RECURSE
FT_ENC_TAGFT_Done_FreeTypeFT_LOAD_PEDANTIC
   
FT_FaceRecFT_New_FaceFT_LOAD_TARGET_NORMAL
 FT_Done_FaceFT_LOAD_TARGET_LIGHT
FT_FACE_FLAG_SCALABLEFT_Reference_FaceFT_LOAD_TARGET_MONO
FT_FACE_FLAG_FIXED_SIZESFT_New_Memory_FaceFT_LOAD_TARGET_LCD
FT_FACE_FLAG_FIXED_WIDTHFT_Open_FaceFT_LOAD_TARGET_LCD_V
FT_FACE_FLAG_HORIZONTALFT_Open_Args 
FT_FACE_FLAG_VERTICALFT_ParameterFT_LOAD_TARGET_MODE
FT_FACE_FLAG_COLORFT_Attach_File 
FT_FACE_FLAG_SFNTFT_Attach_StreamFT_Render_Glyph
FT_FACE_FLAG_CID_KEYED FT_Render_Mode
FT_FACE_FLAG_TRICKYFT_Set_Char_SizeFT_Get_Kerning
FT_FACE_FLAG_KERNINGFT_Set_Pixel_SizesFT_Kerning_Mode
FT_FACE_FLAG_MULTIPLE_MASTERSFT_Request_SizeFT_Get_Track_Kerning
FT_FACE_FLAG_GLYPH_NAMESFT_Select_SizeFT_Get_Glyph_Name
FT_FACE_FLAG_EXTERNAL_STREAMFT_Size_Request_TypeFT_Get_Postscript_Name
FT_FACE_FLAG_HINTERFT_Size_RequestRec 
FT_FACE_FLAG_TRICKYFT_Size_RequestFT_CharMapRec
 FT_Set_TransformFT_Select_Charmap
FT_HAS_HORIZONTALFT_Load_GlyphFT_Set_Charmap
FT_HAS_VERTICALFT_Get_Char_IndexFT_Get_Charmap_Index
FT_HAS_KERNINGFT_Get_First_Char 
FT_HAS_FIXED_SIZESFT_Get_Next_CharFT_Get_FSType_Flags
FT_HAS_GLYPH_NAMESFT_Get_Name_IndexFT_Get_SubGlyph_Info
FT_HAS_MULTIPLE_MASTERSFT_Load_Char 
FT_HAS_COLOR FT_Face_Internal
 FT_OPEN_MEMORYFT_Size_Internal
FT_IS_SFNTFT_OPEN_STREAMFT_Slot_Internal
FT_IS_SCALABLEFT_OPEN_PATHNAME 
FT_IS_FIXED_WIDTHFT_OPEN_DRIVERFT_FACE_FLAG_XXX
FT_IS_CID_KEYEDFT_OPEN_PARAMSFT_STYLE_FLAG_XXX
FT_IS_TRICKY FT_OPEN_XXX
 FT_LOAD_DEFAULTFT_LOAD_XXX
FT_STYLE_FLAG_BOLDFT_LOAD_RENDERFT_LOAD_TARGET_XXX
FT_STYLE_FLAG_ITALICFT_LOAD_MONOCHROMEFT_SUBGLYPH_FLAG_XXX
 FT_LOAD_LINEAR_DESIGNFT_FSTYPE_XXX
FT_SizeRecFT_LOAD_NO_SCALE 
FT_Size_MetricsFT_LOAD_NO_HINTINGFT_HAS_FAST_GLYPHS
 FT_LOAD_NO_BITMAP
FT_GlyphSlotRecFT_LOAD_NO_AUTOHINT

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

FT_Library

Defined in FT_FREETYPE_H (freetype.h).

  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).

In multi-threaded applications, make sure that the same FT_Library object or any of its children doesn't get accessed in parallel.

note

Library objects are normally created by FT_Init_FreeType, and destroyed with FT_Done_FreeType. If you need reference-counting (cf. FT_Reference_Library), use FT_New_Library and FT_Done_Library.


FT_Face

Defined in FT_FREETYPE_H (freetype.h).

  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

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


FT_Size

Defined in FT_FREETYPE_H (freetype.h).

  typedef struct FT_SizeRec_*  FT_Size;

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

note

Each FT_Face has an active FT_Size object that is used by functions like FT_Load_Glyph to determine the scaling transformation that in turn 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.

also

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


FT_GlyphSlot

Defined in FT_FREETYPE_H (freetype.h).

  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.

also

See FT_GlyphSlotRec for the publicly accessible glyph fields.


FT_CharMap

Defined in FT_FREETYPE_H (freetype.h).

  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

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


FT_Encoding

Defined in FT_FREETYPE_H (freetype.h).

  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;


  /* these constants are deprecated; use the corresponding `FT_Encoding' */
  /* values instead                                                      */
#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

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

note

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.

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.

For example, if you want to access Unicode value U+1F028 (and the font contains it), use value 0x1F028 as the input value for FT_Get_Char_Index.

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.kostis.net/charsets/symbol.htm’.

FT_ENCODING_SJIS

Corresponds to Japanese SJIS encoding. More info at at ‘http://en.wikipedia.org/wiki/Shift_JIS’. 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://msdn.microsoft.com/en-US/goglobal/cc305154’.

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 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 that 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.


FT_ENC_TAG

Defined in FT_FREETYPE_H (freetype.h).

#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 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.


FT_FaceRec

Defined in FT_FREETYPE_H (freetype.h).

  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

num_faces

The number of faces in the font file. Some font formats can have multiple faces in a font file.

face_index

The index of the face in the font file. It is set to 0 if there is only one face in the font file.

face_flags

A set of bit flags that give important information about the face; see FT_FACE_FLAG_XXX for the details.

style_flags

A set of bit flags indicating the style of the face; see FT_STYLE_FLAG_XXX for the details.

num_glyphs

The number of glyphs in the face. If the face is scalable and has sbits (see ‘num_fixed_sizes’), it is set to the number of outline glyphs.

For CID-keyed fonts, this value gives the highest CID used in the font.

family_name

The face's family name. This is an ASCII string, usually in English, that 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. Can be NULL (e.g., in fonts embedded in a PDF file).

style_name

The face's style name. This is an ASCII string, usually in English, that 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 and Unicode versions of this string. Applications should use the format specific interface to access them.

num_fixed_sizes

The number of bitmap strikes in the face. Even if the face is scalable, there might still be bitmap strikes, which are called ‘sbits’ in that case.

available_sizes

An array of FT_Bitmap_Size for all bitmap strikes in the face. It is set to NULL if there is no bitmap strike.

num_charmaps

The number of charmaps in the face.

charmaps

An array of the charmaps of the face.

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 ‘maximum ascender’, and ‘bbox.yMin’ as the ‘minimum descender’. Only relevant for scalable formats.

Note that the bounding box might be off by (at least) one pixel for hinted fonts. See FT_Size_Metrics for further discussion.

units_per_EM

The number of font units per EM square for this face. This is typically 2048 for TrueType fonts, and 1000 for Type 1 fonts. Only relevant for scalable formats.

ascender

The typographic ascender of the face, expressed in font units. For font formats not having this information, it is set to ‘bbox.yMax’. Only relevant for scalable formats.

descender

The typographic descender of the face, expressed in font units. For font formats not having this information, it is set to ‘bbox.yMin’. Note that this field is usually negative. Only relevant for scalable formats.

height

This value is the vertical distance between two consecutive baselines, expressed in font units. It is always positive. Only relevant for scalable formats.

If you want the global glyph height, use ‘ascender - descender’.

max_advance_width

The maximum 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 maximum advance height, in font units, for all glyphs in this face. This is only relevant for vertical layouts, and is set to ‘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 is 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).

size

The current active size for this face.

charmap

The current active charmap for this face.

note

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


FT_HAS_HORIZONTAL

Defined in FT_FREETYPE_H (freetype.h).

#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

Defined in FT_FREETYPE_H (freetype.h).

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

A macro that returns true whenever a face object contains real vertical metrics (and not only synthesized ones).


FT_HAS_KERNING

Defined in FT_FREETYPE_H (freetype.h).

#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_HAS_FIXED_SIZES

Defined in FT_FREETYPE_H (freetype.h).

#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_GLYPH_NAMES

Defined in FT_FREETYPE_H (freetype.h).

#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

Defined in FT_FREETYPE_H (freetype.h).

#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_HAS_COLOR

Defined in FT_FREETYPE_H (freetype.h).

#define FT_HAS_COLOR( face ) \
          ( face->face_flags & FT_FACE_FLAG_COLOR )

A macro that returns true whenever a face object contains tables for color glyphs.


FT_IS_SFNT

Defined in FT_FREETYPE_H (freetype.h).

#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_SCALABLE

Defined in FT_FREETYPE_H (freetype.h).

#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.


FT_IS_FIXED_WIDTH

Defined in FT_FREETYPE_H (freetype.h).

#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_IS_CID_KEYED

Defined in FT_FREETYPE_H (freetype.h).

#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.


FT_IS_TRICKY

Defined in FT_FREETYPE_H (freetype.h).

#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.


FT_SizeRec

Defined in FT_FREETYPE_H (freetype.h).

  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.

fields

face

Handle to the parent face object.

generic

A typeless pointer, 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_Size_Metrics

Defined in FT_FREETYPE_H (freetype.h).

  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.

fields

x_ppem

The width of the scaled EM square in pixels, hence the term ‘ppem’ (pixels per EM). It is also referred to as ‘nominal width’.

y_ppem

The height of the scaled EM square in pixels, hence the term ‘ppem’ (pixels per EM). It is also referred to as ‘nominal height’.

x_scale

A 16.16 fractional scaling value used to convert horizontal metrics from font units to 26.6 fractional pixels. Only relevant for scalable font formats.

y_scale

A 16.16 fractional scaling value used to convert vertical metrics from font units to 26.6 fractional pixels. Only relevant for scalable font formats.

ascender

The ascender in 26.6 fractional pixels. See FT_FaceRec for the details.

descender

The descender in 26.6 fractional pixels. See FT_FaceRec for the details.

height

The height in 26.6 fractional pixels. See FT_FaceRec for the details.

max_advance

The maximum advance width in 26.6 fractional pixels. See FT_FaceRec for the details.

note

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.


FT_GlyphSlotRec

Defined in FT_FREETYPE_H (freetype.h).

  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.

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 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

The advance width of the unhinted glyph. Its value is expressed in 16.16 fractional pixels, unless FT_LOAD_LINEAR_DESIGN is set when loading the glyph. This field can be important to perform correct WYSIWYG layout. Only relevant for outline glyphs.

linearVertAdvance

The advance height of the unhinted glyph. Its value is expressed in 16.16 fractional pixels, unless FT_LOAD_LINEAR_DESIGN is set when loading the glyph. This field can be important to perform correct WYSIWYG layout. Only relevant for outline glyphs.

advance

This shorthand is, depending on FT_LOAD_IGNORE_TRANSFORM, the transformed (hinted) advance width for the glyph, in 26.6 fractional pixel format. As specified with FT_LOAD_VERTICAL_LAYOUT, it uses either the ‘horiAdvance’ or the ‘vertAdvance’ value of ‘metrics’ field.

format

This field indicates the format of the image contained in the glyph slot. Typically FT_GLYPH_FORMAT_BITMAP, FT_GLYPH_FORMAT_OUTLINE, or 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

The bitmap's left bearing expressed in integer pixels. Only valid if the format is FT_GLYPH_FORMAT_BITMAP, this is, if the glyph slot contains a bitmap.

bitmap_top

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. Once a glyph is loaded, ‘outline’ can be transformed, distorted, embolded, etc. However, it must not be freed.

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.

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 applications. Note that the application needs to know about the image format.

lsb_delta

The difference between hinted and unhinted left side bearing while autohinting is active. Zero otherwise.

rsb_delta

The difference between hinted and unhinted right side bearing while autohinting is active. Zero otherwise.

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., 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.

note

Here a small pseudo code fragment that 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_Glyph_Metrics

Defined in FT_FREETYPE_H (freetype.h).

  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.

fields

width

The glyph's width.

height

The glyph's height.

horiBearingX

Left side bearing for horizontal layout.

horiBearingY

Top side bearing for horizontal layout.

horiAdvance

Advance width for horizontal layout.

vertBearingX

Left side bearing for vertical layout.

vertBearingY

Top side bearing for vertical layout. Larger positive values mean further below the vertical glyph origin.

vertAdvance

Advance height for vertical layout. Positive values mean the glyph has a positive advance downward.

note

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.


FT_SubGlyph

Defined in FT_FREETYPE_H (freetype.h).

  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.

You can however retrieve subglyph information with FT_Get_SubGlyph_Info.


FT_Bitmap_Size

Defined in FT_FREETYPE_H (freetype.h).

  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.

fields

height

The vertical distance, in pixels, between two consecutive baselines. It is always positive.

width

The average width, in pixels, of all glyphs in the strike.

size

The nominal size of the strike in 26.6 fractional points. This field is not very useful.

x_ppem

The horizontal ppem (nominal width) in 26.6 fractional pixels.

y_ppem

The vertical ppem (nominal height) in 26.6 fractional pixels.

note

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.


FT_Init_FreeType

Defined in FT_FREETYPE_H (freetype.h).

  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.

output

alibrary

A handle to a new library object.

return

FreeType error code. 0 means success.

note

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.

If you need reference-counting (cf. FT_Reference_Library), use FT_New_Library and FT_Done_Library.


FT_Done_FreeType

Defined in FT_FREETYPE_H (freetype.h).

  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.

input

library

A handle to the target library object.

return

FreeType error code. 0 means success.


FT_New_Face

Defined in FT_FREETYPE_H (freetype.h).

  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.

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 font. The first face has index 0.

output

aface

A handle to a new face object. If ‘face_index’ is greater than or equal to zero, it must be non-NULL. See FT_Open_Face for more details.

return

FreeType error code. 0 means success.

note

Use FT_Done_Face to destroy the created FT_Face object (along with its slot and sizes).


FT_Done_Face

Defined in FT_FREETYPE_H (freetype.h).

  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.

input

face

A handle to a target face object.

return

FreeType error code. 0 means success.

note

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


FT_Reference_Face

Defined in FT_FREETYPE_H (freetype.h).

  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 that reference FT_Face objects.

input

face

A handle to a target face object.

return

FreeType error code. 0 means success.

since

2.4.2


FT_New_Memory_Face

Defined in FT_FREETYPE_H (freetype.h).

  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 that has been 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 font. The first face has index 0.

output

aface

A handle to a new face object. If ‘face_index’ is greater than or equal to zero, it must be non-NULL. See FT_Open_Face for more details.

return

FreeType error code. 0 means success.

note

You must not deallocate the memory before calling FT_Done_Face.


FT_Open_Face

Defined in FT_FREETYPE_H (freetype.h).

  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.

inout

library

A handle to the library resource.

input

args

A pointer to an ‘FT_Open_Args’ structure that must be filled by the caller.

face_index

The index of the face within the font. The first face has index 0.

output

aface

A handle to a new face object. If ‘face_index’ is greater than or equal to zero, it must be non-NULL. See note below.

return

FreeType error code. 0 means success.

note

Unlike FreeType 1.x, this function automatically creates a glyph slot for the face object that 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’ that 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_Open_Args

Defined in FT_FREETYPE_H (freetype.h).

  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.

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 tries 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’ that 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_Parameter

Defined in FT_FREETYPE_H (freetype.h).

  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 four-byte identification tag.

data

A pointer to the parameter data.

note

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


FT_Attach_File

Defined in FT_FREETYPE_H (freetype.h).

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

This function calls FT_Attach_Stream to attach a file.

inout

face

The target face object.

input

filepathname

The pathname.

return

FreeType error code. 0 means success.


FT_Attach_Stream

Defined in FT_FREETYPE_H (freetype.h).

  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.

inout

face

The target face object.

input

parameters

A pointer to FT_Open_Args that must be filled by the caller.

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_Set_Char_Size

Defined in FT_FREETYPE_H (freetype.h).

  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).

inout

face

A handle to a target face object.

input

char_width

The nominal width, in 26.6 fractional points.

char_height

The nominal height, in 26.6 fractional points.

horz_resolution

The horizontal resolution in dpi.

vert_resolution

The vertical resolution in dpi.

return

FreeType error code. 0 means success.

note

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_Set_Pixel_Sizes

Defined in FT_FREETYPE_H (freetype.h).

  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).

inout

face

A handle to the target face object.

input

pixel_width

The nominal width, in pixels.

pixel_height

The nominal height, in pixels.

return

FreeType error code. 0 means success.

note

You should not rely on the resulting glyphs matching, or being constrained, to this pixel size. Refer to FT_Request_Size to understand how requested sizes relate to actual sizes.

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


FT_Request_Size

Defined in FT_FREETYPE_H (freetype.h).

  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.

inout

face

A handle to a target face object.

input

req

A pointer to a FT_Size_RequestRec.

return

FreeType error code. 0 means success.

note

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.

The relation between the requested size and the resulting glyph size is dependent entirely on how the size is defined in the source face. The font designer chooses the final size of each glyph relative to this size. For more information refer to ‘http://www.freetype.org/freetype2/docs/glyphs/glyphs-2.html

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


FT_Select_Size

Defined in FT_FREETYPE_H (freetype.h).

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

Select a bitmap strike.

inout

face

A handle to a target face object.

input

strike_index

The index of the bitmap strike in the ‘available_sizes’ field of FT_FaceRec structure.

return

FreeType error code. 0 means success.


FT_Size_Request_Type

Defined in FT_FREETYPE_H (freetype.h).

  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.

values

FT_SIZE_REQUEST_TYPE_NOMINAL

The nominal size. The ‘units_per_EM’ field of FT_FaceRec is used to determine both scaling values.

FT_SIZE_REQUEST_TYPE_REAL_DIM

The real dimension. The sum of the the ‘ascender’ and (minus of) the ‘descender’ fields of FT_FaceRec are used to determine both scaling values.

FT_SIZE_REQUEST_TYPE_BBOX

The font bounding box. The width and height of the ‘bbox’ field of FT_FaceRec are used to determine the horizontal and vertical scaling value, respectively.

FT_SIZE_REQUEST_TYPE_CELL

The ‘max_advance_width’ field of FT_FaceRec is used to determine the horizontal scaling value; the vertical scaling value is determined the same way as FT_SIZE_REQUEST_TYPE_REAL_DIM does. Finally, both scaling values are set to the smaller one. This type is useful if you want to specify the font size for, say, a window of a given dimension and 80x24 cells.

FT_SIZE_REQUEST_TYPE_SCALES

Specify the scaling values directly.

note

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.


FT_Size_RequestRec

Defined in FT_FREETYPE_H (freetype.h).

  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.

fields

type

See FT_Size_Request_Type.

width

The desired width.

height

The desired height.

horiResolution

The horizontal resolution. If set to zero, ‘width’ is treated as a 26.6 fractional pixel value.

vertResolution

The vertical resolution. If set to zero, ‘height’ is treated as a 26.6 fractional pixel value.

note

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


FT_Size_Request

Defined in FT_FREETYPE_H (freetype.h).

  typedef struct FT_Size_RequestRec_  *FT_Size_Request;

A handle to a size request structure.


FT_Set_Transform

Defined in FT_FREETYPE_H (freetype.h).

  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.

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.

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


FT_Load_Glyph

Defined in FT_FREETYPE_H (freetype.h).

  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.

inout

face

A handle to the target face object where the glyph is 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

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 that don't have a corresponding glyph in the font). See the discussion of the FT_FACE_FLAG_CID_KEYED flag for more details.


FT_Get_Char_Index

Defined in FT_FREETYPE_H (freetype.h).

  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.

input

face

A handle to the source face object.

charcode

The character code.

return

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

note

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_Get_First_Char

Defined in FT_FREETYPE_H (freetype.h).

  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.

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’ 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_Get_Next_Char

Defined in FT_FREETYPE_H (freetype.h).

  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 next 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 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_Get_Name_Index

Defined in FT_FREETYPE_H (freetype.h).

  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.

input

face

A handle to the source face object.

glyph_name

The glyph name.

return

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


FT_Load_Char

Defined in FT_FREETYPE_H (freetype.h).

  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.

inout

face

A handle to a target face object where the glyph is 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

This function simply calls FT_Get_Char_Index and FT_Load_Glyph.


FT_LOAD_TARGET_MODE

Defined in FT_FREETYPE_H (freetype.h).

#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_Render_Glyph

Defined in FT_FREETYPE_H (freetype.h).

  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.

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.

note

To get meaningful results, font scaling values must be set with functions like FT_Set_Char_Size before calling FT_Render_Glyph.


FT_Render_Mode

Defined in FT_FREETYPE_H (freetype.h).

  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;


  /* these constants are deprecated; use the corresponding */
  /* `FT_Render_Mode' values instead                       */
#define ft_render_mode_normal  FT_RENDER_MODE_NORMAL
#define ft_render_mode_mono    FT_RENDER_MODE_MONO

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.

values

FT_RENDER_MODE_NORMAL

This is the default render mode; it corresponds to 8-bit anti-aliased bitmaps.

FT_RENDER_MODE_LIGHT

This is equivalent to FT_RENDER_MODE_NORMAL. It is only defined as a separate value because render modes are also used indirectly to define hinting algorithm selectors. See FT_LOAD_TARGET_XXX for details.

FT_RENDER_MODE_MONO

This mode corresponds to 1-bit bitmaps (with 2 levels of opacity).

FT_RENDER_MODE_LCD

This mode corresponds to horizontal RGB and 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 and 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 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.


FT_Get_Kerning

Defined in FT_FREETYPE_H (freetype.h).

  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.

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 and dimension of the returned kerning vector.

output

akerning

The kerning vector. This is either in font units or in pixels (26.6 format) 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_Kerning_Mode

Defined in FT_FREETYPE_H (freetype.h).

  typedef enum  FT_Kerning_Mode_
  {
    FT_KERNING_DEFAULT  = 0,
    FT_KERNING_UNFITTED,
    FT_KERNING_UNSCALED

  } FT_Kerning_Mode;


  /* these constants are deprecated; use the corresponding */
  /* `FT_Kerning_Mode' values instead                      */
#define ft_kerning_default   FT_KERNING_DEFAULT
#define ft_kerning_unfitted  FT_KERNING_UNFITTED
#define ft_kerning_unscaled  FT_KERNING_UNSCALED

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_Get_Track_Kerning

Defined in FT_FREETYPE_H (freetype.h).

  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.

input

face

A handle to a source face object.

point_size

The point size in 16.16 fractional points.

degree

The degree of tightness. Increasingly negative values represent tighter track kerning, while increasingly positive values represent looser track kerning. Value zero means no track kerning.

output

akerning

The kerning in 16.16 fractional points, to be uniformly applied between all glyphs.

return

FreeType error code. 0 means success.

note

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_Get_Glyph_Name

Defined in FT_FREETYPE_H (freetype.h).

  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.

input

face

A handle to a source face object.

glyph_index

The glyph index.

buffer_max

The maximum number of bytes available in the buffer.

output

buffer

A pointer to a target buffer where the name is 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’ 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 always returns an error if the config macro ‘FT_CONFIG_OPTION_NO_GLYPH_NAMES’ is not defined in ‘ftoptions.h’.


FT_Get_Postscript_Name

Defined in FT_FREETYPE_H (freetype.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.

input

face

A handle to the source face object.

return

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

note

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


FT_CharMapRec

Defined in FT_FREETYPE_H (freetype.h).

  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_Select_Charmap

Defined in FT_FREETYPE_H (freetype.h).

  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’).

inout

face

A handle to the source face object.

input

encoding

A handle to the selected encoding.

return

FreeType error code. 0 means success.

note

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 that 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_Set_Charmap

Defined in FT_FREETYPE_H (freetype.h).

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

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

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 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_Get_Charmap_Index

Defined in FT_FREETYPE_H (freetype.h).

  FT_EXPORT( FT_Int )
  FT_Get_Charmap_Index( FT_CharMap  charmap );

Retrieve index of a given charmap.

input

charmap

A handle to a charmap.

return

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


FT_Get_FSType_Flags

Defined in FT_FREETYPE_H (freetype.h).

  FT_EXPORT( FT_UShort )
  FT_Get_FSType_Flags( FT_Face  face );

Return the fsType flags for a font.

input

face

A handle to the source face object.

return

The fsType flags, FT_FSTYPE_XXX.

note

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.

since

2.3.8


FT_Get_SubGlyph_Info

Defined in FT_FREETYPE_H (freetype.h).

  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.

input

glyph

The source glyph slot.

sub_index

The index of the subglyph. Must be less than ‘glyph->num_subglyphs’.

output

p_index

The glyph index of the subglyph.

p_flags

The subglyph flags, see FT_SUBGLYPH_FLAG_XXX.

p_arg1

The subglyph's first argument (if any).

p_arg2

The subglyph's second argument (if any).

p_transform

The subglyph transformation (if any).

return

FreeType error code. 0 means success.

note

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.


FT_Face_Internal

Defined in FT_FREETYPE_H (freetype.h).

  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_Size_Internal

Defined in FT_FREETYPE_H (freetype.h).

  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_Slot_Internal

Defined in FT_FREETYPE_H (freetype.h).

  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_FACE_FLAG_XXX

Defined in FT_FREETYPE_H (freetype.h).

#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 )
#define FT_FACE_FLAG_COLOR             ( 1L << 14 )

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 contains outline glyphs. This doesn't prevent bitmap strikes, i.e., a face can have both this and and FT_FACE_FLAG_FIXED_SIZES set.

FT_FACE_FLAG_FIXED_SIZES

Indicates that the face contains bitmap strikes. See also 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. Otherwise the function always return the vector (0,0). Note that FreeType doesn't handle kerning data from the ‘GPOS’ table (as present in some OpenType fonts).

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_FACE_FLAG_HINTER

Set if the font driver has a hinting machine of its own. For example, with TrueType fonts, it makes sense to use data from the SFNT ‘gasp’ table only if the native TrueType hinting engine (with the bytecode interpreter) is available and active.

FT_FACE_FLAG_CID_KEYED

Set if the font is CID-keyed. In that case, the font is not accessed by glyph indices but by CID values. For subsetted CID-keyed fonts this has the consequence that not all index values are a valid argument to FT_Load_Glyph. Only the CID values for which corresponding glyphs in the subsetted font exist make FT_Load_Glyph return successfully; in all other cases you get an ‘FT_Err_Invalid_Argument’ error.

Note that CID-keyed fonts that are in an SFNT wrapper don't have this flag set since the glyphs are accessed in the normal way (using contiguous indices); the ‘CID-ness’ isn't visible to the application.

FT_FACE_FLAG_TRICKY

Set if the font is ‘tricky’, this is, it always needs the font format's native hinting engine to get a reasonable result. A typical example is the Chinese font ‘mingli.ttf’ that uses TrueType bytecode instructions to move and scale all of its subglyphs.

It is not possible to autohint such fonts using FT_LOAD_FORCE_AUTOHINT; it will also ignore FT_LOAD_NO_HINTING. You have to set both FT_LOAD_NO_HINTING and FT_LOAD_NO_AUTOHINT to really disable hinting; however, you probably never want this except for demonstration purposes.

Currently, there are about a dozen TrueType fonts in the list of tricky fonts; they are hard-coded in file ‘ttobjs.c’.

FT_FACE_FLAG_COLOR

Set if the font has color glyph tables. To access color glyphs use FT_LOAD_COLOR.


FT_STYLE_FLAG_XXX

Defined in FT_FREETYPE_H (freetype.h).

#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 style is italic or oblique.

FT_STYLE_FLAG_BOLD

Indicates that a given face is bold.

note

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).


FT_OPEN_XXX

Defined in FT_FREETYPE_H (freetype.h).

#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


  /* these constants are deprecated; use the corresponding `FT_OPEN_XXX' */
  /* values instead                                                      */
#define ft_open_memory    FT_OPEN_MEMORY
#define ft_open_stream    FT_OPEN_STREAM
#define ft_open_pathname  FT_OPEN_PATHNAME
#define ft_open_driver    FT_OPEN_DRIVER
#define ft_open_params    FT_OPEN_PARAMS

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’ and ‘params’ fields.

note

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


FT_LOAD_XXX

Defined in FT_FREETYPE_H (freetype.h).

#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 )
  /* Bits 16..19 are used by `FT_LOAD_TARGET_' */
#define FT_LOAD_COLOR                        ( 1L << 20 )

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 as the default glyph load operation. In this case, the following happens:

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 loaded outline glyph but keep it in font units.

This flag implies FT_LOAD_NO_HINTING and FT_LOAD_NO_BITMAP, and unsets FT_LOAD_RENDER.

If the font is ‘tricky’ (see FT_FACE_FLAG_TRICKY for more), using FT_LOAD_NO_SCALE usually yields meaningless outlines because the subglyphs must be scaled and positioned with hinting instructions. This can be solved by loading the font without FT_LOAD_NO_SCALE and setting the character size to ‘font->units_per_EM’.

FT_LOAD_NO_HINTING

Disable hinting. This generally generates ‘blurrier’ bitmap glyphs when the glyph are rendered in any of the anti-aliased modes. See also the note below.

This flag is implied by FT_LOAD_NO_SCALE.

FT_LOAD_RENDER

Call FT_Render_Glyph after the glyph is loaded. By default, the glyph is rendered in FT_RENDER_MODE_NORMAL mode. This can be overridden by FT_LOAD_TARGET_XXX or FT_LOAD_MONOCHROME.

This flag is unset by FT_LOAD_NO_SCALE.

FT_LOAD_NO_BITMAP

Ignore bitmap strikes when loading. Bitmap-only fonts ignore this flag.

FT_LOAD_NO_SCALE always sets this flag.

FT_LOAD_VERTICAL_LAYOUT

Load the glyph for vertical text layout. In particular, the ‘advance’ value in the FT_GlyphSlotRec structure is set to the ‘vertAdvance’ value of the ‘metrics’ field.

In case FT_HAS_VERTICAL doesn't return true, you shouldn't use this flag currently. Reason is that in this case vertical metrics get synthesized, and those values are not always consistent across various font formats.

FT_LOAD_FORCE_AUTOHINT

Indicates that the auto-hinter is preferred over the font's native hinter. See also the note below.

FT_LOAD_PEDANTIC

Indicates that the font driver should perform pedantic verifications during glyph loading. This is mostly used to detect broken glyphs in fonts. By default, FreeType tries to handle broken fonts also.

In particular, errors from the TrueType bytecode engine are not passed to the application if this flag is not set; this might result in partially hinted or distorted glyphs in case a glyph's bytecode is buggy.

FT_LOAD_NO_RECURSE

Indicate that the font driver 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 subglyphs can then be accessed with FT_Get_SubGlyph_Info.

This flag implies FT_LOAD_NO_SCALE and FT_LOAD_IGNORE_TRANSFORM.

FT_LOAD_IGNORE_TRANSFORM

Indicates that the transform matrix set by FT_Set_Transform should be ignored.

FT_LOAD_MONOCHROME

This flag is used with FT_LOAD_RENDER to indicate that you want to render an outline glyph to a 1-bit monochrome bitmap glyph, with 8 pixels packed into each byte of the bitmap data.

Note that this has no effect on the hinting algorithm used. You should rather use FT_LOAD_TARGET_MONO so that the monochrome-optimized hinting algorithm is used.

FT_LOAD_LINEAR_DESIGN

Indicates that the ‘linearHoriAdvance’ and ‘linearVertAdvance’ fields of FT_GlyphSlotRec should be kept in font units. See FT_GlyphSlotRec for details.

FT_LOAD_NO_AUTOHINT

Disable auto-hinter. See also the note below.

FT_LOAD_COLOR

This flag is used to request loading of color embedded-bitmap images. The resulting color bitmaps, if available, will have the FT_PIXEL_MODE_BGRA format. When the flag is not used and color bitmaps are found, they will be converted to 256-level gray bitmaps transparently. Those bitmaps will be in the FT_PIXEL_MODE_GRAY format.

FT_LOAD_CROP_BITMAP

Ignored. Deprecated.

FT_LOAD_IGNORE_GLOBAL_ADVANCE_WIDTH

Ignored. Deprecated.

note

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.


FT_LOAD_TARGET_XXX

Defined in FT_FREETYPE_H (freetype.h).

#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.

values

FT_LOAD_TARGET_NORMAL

This corresponds to the default hinting algorithm, optimized for standard gray-level rendering. For monochrome output, use FT_LOAD_TARGET_MONO instead.

FT_LOAD_TARGET_LIGHT

A lighter hinting algorithm for non-monochrome modes. Many generated glyphs are more fuzzy but better resemble its original shape. A bit like rendering on Mac OS X.

As a special exception, this target implies FT_LOAD_FORCE_AUTOHINT.

FT_LOAD_TARGET_MONO

Strong hinting algorithm that should only be used for monochrome output. The result is probably unpleasant if the glyph is rendered in non-monochrome modes.

FT_LOAD_TARGET_LCD

A variant of FT_LOAD_TARGET_NORMAL optimized for horizontally decimated LCD displays.

FT_LOAD_TARGET_LCD_V

A variant of FT_LOAD_TARGET_NORMAL optimized for vertically decimated LCD displays.

note

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 that 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 );

FT_SUBGLYPH_FLAG_XXX

Defined in FT_FREETYPE_H (freetype.h).

#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.

values

FT_SUBGLYPH_FLAG_ARGS_ARE_WORDS

FT_SUBGLYPH_FLAG_ARGS_ARE_XY_VALUES

FT_SUBGLYPH_FLAG_ROUND_XY_TO_GRID

FT_SUBGLYPH_FLAG_SCALE

FT_SUBGLYPH_FLAG_XY_SCALE

FT_SUBGLYPH_FLAG_2X2

FT_SUBGLYPH_FLAG_USE_MY_METRICS


FT_FSTYPE_XXX

Defined in FT_FREETYPE_H (freetype.h).

#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.

values

FT_FSTYPE_INSTALLABLE_EMBEDDING

Fonts with no fsType bit set may be embedded and permanently installed on the remote system by an application.

FT_FSTYPE_RESTRICTED_LICENSE_EMBEDDING

Fonts that have only this bit set must not be modified, embedded or exchanged in any manner without first obtaining permission of the font software copyright owner.

FT_FSTYPE_PREVIEW_AND_PRINT_EMBEDDING

If this bit is set, the font may be embedded and temporarily loaded on the remote system. Documents containing Preview & Print fonts must be opened ‘read-only’; no edits can be applied to the document.

FT_FSTYPE_EDITABLE_EMBEDDING

If this bit is set, the font may be embedded but must only be installed temporarily on other systems. In contrast to Preview & Print fonts, documents containing editable fonts may be opened for reading, editing is permitted, and changes may be saved.

FT_FSTYPE_NO_SUBSETTING

If this bit is set, the font may not be subsetted prior to embedding.

FT_FSTYPE_BITMAP_EMBEDDING_ONLY

If this bit is set, only bitmaps contained in the font may be embedded; no outline data may be embedded. If there are no bitmaps available in the font, then the font is unembeddable.

note

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_HAS_FAST_GLYPHS

Defined in FT_FREETYPE_H (freetype.h).

#define FT_HAS_FAST_GLYPHS( face )  0

Deprecated.