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FreeType-2.4.10 API Reference

Basic Data Types

Synopsis

FT_ByteFT_OffsetFT_UnitVector
FT_BytesFT_PtrDistFT_F26Dot6
FT_CharFT_StringFT_Pixel_Mode
FT_IntFT_Tagft_pixel_mode_xxx
FT_UIntFT_ErrorFT_Palette_Mode
FT_Int16FT_FixedFT_Bitmap
FT_UInt16FT_PointerFT_IMAGE_TAG
FT_Int32FT_PosFT_Glyph_Format
FT_UInt32FT_Vectorft_glyph_format_xxx
FT_ShortFT_BBoxFT_Data
FT_UShortFT_MatrixFT_Generic_Finalizer
FT_LongFT_FWordFT_Generic
FT_ULongFT_UFWordFT_MAKE_TAG
FT_BoolFT_F2Dot14


This section contains the basic data types defined by FreeType 2, ranging from simple scalar types to bitmap descriptors. More font-specific structures are defined in a different section.


FT_Byte

Defined in FT_TYPES_H (freetype/fttypes.h).


  typedef unsigned char  FT_Byte;


A simple typedef for the unsigned char type.



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FT_Bytes

Defined in FT_TYPES_H (freetype/fttypes.h).


  typedef const FT_Byte*  FT_Bytes;


A typedef for constant memory areas.



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FT_Char

Defined in FT_TYPES_H (freetype/fttypes.h).


  typedef signed char  FT_Char;


A simple typedef for the signed char type.



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FT_Int

Defined in FT_TYPES_H (freetype/fttypes.h).


  typedef signed int  FT_Int;


A typedef for the int type.



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FT_UInt

Defined in FT_TYPES_H (freetype/fttypes.h).


  typedef unsigned int  FT_UInt;


A typedef for the unsigned int type.



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FT_Int16

Defined in FT_CONFIG_CONFIG_H (freetype/config/ftconfig.h).


  typedef signed short  FT_Int16;


A typedef for a 16bit signed integer type.



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FT_UInt16

Defined in FT_CONFIG_CONFIG_H (freetype/config/ftconfig.h).


  typedef unsigned short  FT_UInt16;


A typedef for a 16bit unsigned integer type.



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FT_Int32

Defined in FT_CONFIG_CONFIG_H (freetype/config/ftconfig.h).


  typedef signed XXX  FT_Int32;


A typedef for a 32bit signed integer type. The size depends on the configuration.



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FT_UInt32

Defined in FT_CONFIG_CONFIG_H (freetype/config/ftconfig.h).


  typedef unsigned XXX  FT_UInt32;



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FT_Short

Defined in FT_TYPES_H (freetype/fttypes.h).


  typedef signed short  FT_Short;


A typedef for signed short.



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FT_UShort

Defined in FT_TYPES_H (freetype/fttypes.h).


  typedef unsigned short  FT_UShort;


A typedef for unsigned short.



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FT_Long

Defined in FT_TYPES_H (freetype/fttypes.h).


  typedef signed long  FT_Long;


A typedef for signed long.



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FT_ULong

Defined in FT_TYPES_H (freetype/fttypes.h).


  typedef unsigned long  FT_ULong;


A typedef for unsigned long.



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FT_Bool

Defined in FT_TYPES_H (freetype/fttypes.h).


  typedef unsigned char  FT_Bool;


A typedef of unsigned char, used for simple booleans. As usual, values 1 and 0 represent true and false, respectively.



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FT_Offset

Defined in FT_TYPES_H (freetype/fttypes.h).


  typedef size_t  FT_Offset;


This is equivalent to the ANSI C ‘size_t’ type, i.e., the largest unsigned integer type used to express a file size or position, or a memory block size.



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FT_PtrDist

Defined in FT_TYPES_H (freetype/fttypes.h).


  typedef ft_ptrdiff_t  FT_PtrDist;


This is equivalent to the ANSI C ‘ptrdiff_t’ type, i.e., the largest signed integer type used to express the distance between two pointers.



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FT_String

Defined in FT_TYPES_H (freetype/fttypes.h).


  typedef char  FT_String;


A simple typedef for the char type, usually used for strings.



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FT_Tag

Defined in FT_TYPES_H (freetype/fttypes.h).


  typedef FT_UInt32  FT_Tag;


A typedef for 32-bit tags (as used in the SFNT format).



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FT_Error

Defined in FT_TYPES_H (freetype/fttypes.h).


  typedef int  FT_Error;


The FreeType error code type. A value of 0 is always interpreted as a successful operation.



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FT_Fixed

Defined in FT_TYPES_H (freetype/fttypes.h).


  typedef signed long  FT_Fixed;


This type is used to store 16.16 fixed float values, like scaling values or matrix coefficients.



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FT_Pointer

Defined in FT_TYPES_H (freetype/fttypes.h).


  typedef void*  FT_Pointer;


A simple typedef for a typeless pointer.



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FT_Pos

Defined in FT_IMAGE_H (freetype/ftimage.h).


  typedef signed long  FT_Pos;


The type FT_Pos is used to store vectorial coordinates. Depending on the context, these can represent distances in integer font units, or 16.16, or 26.6 fixed float pixel coordinates.



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FT_Vector

Defined in FT_IMAGE_H (freetype/ftimage.h).


  typedef struct  FT_Vector_
  {
    FT_Pos  x;
    FT_Pos  y;

  } FT_Vector;


A simple structure used to store a 2D vector; coordinates are of the FT_Pos type.


fields

x

The horizontal coordinate.

y

The vertical coordinate.


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FT_BBox

Defined in FT_IMAGE_H (freetype/ftimage.h).


  typedef struct  FT_BBox_
  {
    FT_Pos  xMin, yMin;
    FT_Pos  xMax, yMax;

  } FT_BBox;


A structure used to hold an outline's bounding box, i.e., the coordinates of its extrema in the horizontal and vertical directions.


fields

xMin

The horizontal minimum (left-most).

yMin

The vertical minimum (bottom-most).

xMax

The horizontal maximum (right-most).

yMax

The vertical maximum (top-most).

note

The bounding box is specified with the coordinates of the lower left and the upper right corner. In PostScript, those values are often called (llx,lly) and (urx,ury), respectively.

If ‘yMin’ is negative, this value gives the glyph's descender. Otherwise, the glyph doesn't descend below the baseline. Similarly, if ‘ymax’ is positive, this value gives the glyph's ascender.

‘xMin’ gives the horizontal distance from the glyph's origin to the left edge of the glyph's bounding box. If ‘xMin’ is negative, the glyph extends to the left of the origin.


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FT_Matrix

Defined in FT_TYPES_H (freetype/fttypes.h).


  typedef struct  FT_Matrix_
  {
    FT_Fixed  xx, xy;
    FT_Fixed  yx, yy;

  } FT_Matrix;


A simple structure used to store a 2x2 matrix. Coefficients are in 16.16 fixed float format. The computation performed is:

   x' = x*xx + y*xy                                             
   y' = x*yx + y*yy                                             

fields

xx

Matrix coefficient.

xy

Matrix coefficient.

yx

Matrix coefficient.

yy

Matrix coefficient.


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FT_FWord

Defined in FT_TYPES_H (freetype/fttypes.h).


  typedef signed short  FT_FWord;   /* distance in FUnits */


A signed 16-bit integer used to store a distance in original font units.



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FT_UFWord

Defined in FT_TYPES_H (freetype/fttypes.h).


  typedef unsigned short  FT_UFWord;  /* unsigned distance */


An unsigned 16-bit integer used to store a distance in original font units.



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FT_F2Dot14

Defined in FT_TYPES_H (freetype/fttypes.h).


  typedef signed short  FT_F2Dot14;


A signed 2.14 fixed float type used for unit vectors.



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FT_UnitVector

Defined in FT_TYPES_H (freetype/fttypes.h).


  typedef struct  FT_UnitVector_
  {
    FT_F2Dot14  x;
    FT_F2Dot14  y;

  } FT_UnitVector;


A simple structure used to store a 2D vector unit vector. Uses FT_F2Dot14 types.


fields

x

Horizontal coordinate.

y

Vertical coordinate.


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FT_F26Dot6

Defined in FT_TYPES_H (freetype/fttypes.h).


  typedef signed long  FT_F26Dot6;


A signed 26.6 fixed float type used for vectorial pixel coordinates.



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FT_Pixel_Mode

Defined in FT_IMAGE_H (freetype/ftimage.h).


  typedef enum  FT_Pixel_Mode_
  {
    FT_PIXEL_MODE_NONE = 0,
    FT_PIXEL_MODE_MONO,
    FT_PIXEL_MODE_GRAY,
    FT_PIXEL_MODE_GRAY2,
    FT_PIXEL_MODE_GRAY4,
    FT_PIXEL_MODE_LCD,
    FT_PIXEL_MODE_LCD_V,

    FT_PIXEL_MODE_MAX      /* do not remove */

  } FT_Pixel_Mode;


An enumeration type used to describe the format of pixels in a given bitmap. Note that additional formats may be added in the future.


values

FT_PIXEL_MODE_NONE

Value 0 is reserved.

FT_PIXEL_MODE_MONO

A monochrome bitmap, using 1 bit per pixel. Note that pixels are stored in most-significant order (MSB), which means that the left-most pixel in a byte has value 128.

FT_PIXEL_MODE_GRAY

An 8-bit bitmap, generally used to represent anti-aliased glyph images. Each pixel is stored in one byte. Note that the number of ‘gray’ levels is stored in the ‘num_grays’ field of the FT_Bitmap structure (it generally is 256).

FT_PIXEL_MODE_GRAY2

A 2-bit per pixel bitmap, used to represent embedded anti-aliased bitmaps in font files according to the OpenType specification. We haven't found a single font using this format, however.

FT_PIXEL_MODE_GRAY4

A 4-bit per pixel bitmap, representing embedded anti-aliased bitmaps in font files according to the OpenType specification. We haven't found a single font using this format, however.

FT_PIXEL_MODE_LCD

An 8-bit bitmap, representing RGB or BGR decimated glyph images used for display on LCD displays; the bitmap is three times wider than the original glyph image. See also FT_RENDER_MODE_LCD.

FT_PIXEL_MODE_LCD_V

An 8-bit bitmap, representing RGB or BGR decimated glyph images used for display on rotated LCD displays; the bitmap is three times taller than the original glyph image. See also FT_RENDER_MODE_LCD_V.


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ft_pixel_mode_xxx

Defined in FT_IMAGE_H (freetype/ftimage.h).


#define ft_pixel_mode_none   FT_PIXEL_MODE_NONE
#define ft_pixel_mode_mono   FT_PIXEL_MODE_MONO
#define ft_pixel_mode_grays  FT_PIXEL_MODE_GRAY
#define ft_pixel_mode_pal2   FT_PIXEL_MODE_GRAY2
#define ft_pixel_mode_pal4   FT_PIXEL_MODE_GRAY4


A list of deprecated constants. Use the corresponding FT_Pixel_Mode values instead.


values

ft_pixel_mode_none

See FT_PIXEL_MODE_NONE.

ft_pixel_mode_mono

See FT_PIXEL_MODE_MONO.

ft_pixel_mode_grays

See FT_PIXEL_MODE_GRAY.

ft_pixel_mode_pal2

See FT_PIXEL_MODE_GRAY2.

ft_pixel_mode_pal4

See FT_PIXEL_MODE_GRAY4.


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FT_Palette_Mode

Defined in FT_IMAGE_H (freetype/ftimage.h).


  typedef enum  FT_Palette_Mode_
  {
    ft_palette_mode_rgb = 0,
    ft_palette_mode_rgba,

    ft_palette_mode_max   /* do not remove */

  } FT_Palette_Mode;


THIS TYPE IS DEPRECATED. DO NOT USE IT!

An enumeration type to describe the format of a bitmap palette, used with ft_pixel_mode_pal4 and ft_pixel_mode_pal8.


values

ft_palette_mode_rgb

The palette is an array of 3-byte RGB records.

ft_palette_mode_rgba

The palette is an array of 4-byte RGBA records.

note

As ft_pixel_mode_pal2, pal4 and pal8 are currently unused by FreeType, these types are not handled by the library itself.


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FT_Bitmap

Defined in FT_IMAGE_H (freetype/ftimage.h).


  typedef struct  FT_Bitmap_
  {
    int             rows;
    int             width;
    int             pitch;
    unsigned char*  buffer;
    short           num_grays;
    char            pixel_mode;
    char            palette_mode;
    void*           palette;

  } FT_Bitmap;


A structure used to describe a bitmap or pixmap to the raster. Note that we now manage pixmaps of various depths through the ‘pixel_mode’ field.


fields

rows

The number of bitmap rows.

width

The number of pixels in bitmap row.

pitch

The pitch's absolute value is the number of bytes taken by one bitmap row, including padding. However, the pitch is positive when the bitmap has a ‘down’ flow, and negative when it has an ‘up’ flow. In all cases, the pitch is an offset to add to a bitmap pointer in order to go down one row.

Note that ‘padding’ means the alignment of a bitmap to a byte border, and FreeType functions normally align to the smallest possible integer value.

For the B/W rasterizer, ‘pitch’ is always an even number.

To change the pitch of a bitmap (say, to make it a multiple of 4), use FT_Bitmap_Convert. Alternatively, you might use callback functions to directly render to the application's surface; see the file ‘example2.cpp’ in the tutorial for a demonstration.

buffer

A typeless pointer to the bitmap buffer. This value should be aligned on 32-bit boundaries in most cases.

num_grays

This field is only used with FT_PIXEL_MODE_GRAY; it gives the number of gray levels used in the bitmap.

pixel_mode

The pixel mode, i.e., how pixel bits are stored. See FT_Pixel_Mode for possible values.

palette_mode

This field is intended for paletted pixel modes; it indicates how the palette is stored. Not used currently.

palette

A typeless pointer to the bitmap palette; this field is intended for paletted pixel modes. Not used currently.

note

For now, the only pixel modes supported by FreeType are mono and grays. However, drivers might be added in the future to support more ‘colorful’ options.


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FT_IMAGE_TAG

Defined in FT_IMAGE_H (freetype/ftimage.h).


#ifndef FT_IMAGE_TAG
#define FT_IMAGE_TAG( value, _x1, _x2, _x3, _x4 )  \
          value = ( ( (unsigned long)_x1 << 24 ) | \
                    ( (unsigned long)_x2 << 16 ) | \
                    ( (unsigned long)_x3 << 8  ) | \
                      (unsigned long)_x4         )
#endif /* FT_IMAGE_TAG */


This macro converts four-letter tags to an unsigned long type.


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_IMAGE_TAG( value, _x1, _x2, _x3, _x4 )  value         

to get a simple enumeration without assigning special numbers.


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FT_Glyph_Format

Defined in FT_IMAGE_H (freetype/ftimage.h).


  typedef enum  FT_Glyph_Format_
  {
    FT_IMAGE_TAG( FT_GLYPH_FORMAT_NONE, 0, 0, 0, 0 ),

    FT_IMAGE_TAG( FT_GLYPH_FORMAT_COMPOSITE, 'c', 'o', 'm', 'p' ),
    FT_IMAGE_TAG( FT_GLYPH_FORMAT_BITMAP,    'b', 'i', 't', 's' ),
    FT_IMAGE_TAG( FT_GLYPH_FORMAT_OUTLINE,   'o', 'u', 't', 'l' ),
    FT_IMAGE_TAG( FT_GLYPH_FORMAT_PLOTTER,   'p', 'l', 'o', 't' )

  } FT_Glyph_Format;


An enumeration type used to describe the format of a given glyph image. Note that this version of FreeType only supports two image formats, even though future font drivers will be able to register their own format.


values

FT_GLYPH_FORMAT_NONE

The value 0 is reserved.

FT_GLYPH_FORMAT_COMPOSITE

The glyph image is a composite of several other images. This format is only used with FT_LOAD_NO_RECURSE, and is used to report compound glyphs (like accented characters).

FT_GLYPH_FORMAT_BITMAP

The glyph image is a bitmap, and can be described as an FT_Bitmap. You generally need to access the ‘bitmap’ field of the FT_GlyphSlotRec structure to read it.

FT_GLYPH_FORMAT_OUTLINE

The glyph image is a vectorial outline made of line segments and B├ęzier arcs; it can be described as an FT_Outline; you generally want to access the ‘outline’ field of the FT_GlyphSlotRec structure to read it.

FT_GLYPH_FORMAT_PLOTTER

The glyph image is a vectorial path with no inside and outside contours. Some Type 1 fonts, like those in the Hershey family, contain glyphs in this format. These are described as FT_Outline, but FreeType isn't currently capable of rendering them correctly.


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ft_glyph_format_xxx

Defined in FT_IMAGE_H (freetype/ftimage.h).


#define ft_glyph_format_none       FT_GLYPH_FORMAT_NONE
#define ft_glyph_format_composite  FT_GLYPH_FORMAT_COMPOSITE
#define ft_glyph_format_bitmap     FT_GLYPH_FORMAT_BITMAP
#define ft_glyph_format_outline    FT_GLYPH_FORMAT_OUTLINE
#define ft_glyph_format_plotter    FT_GLYPH_FORMAT_PLOTTER


A list of deprecated constants. Use the corresponding FT_Glyph_Format values instead.


values

ft_glyph_format_none

See FT_GLYPH_FORMAT_NONE.

ft_glyph_format_composite

See FT_GLYPH_FORMAT_COMPOSITE.

ft_glyph_format_bitmap

See FT_GLYPH_FORMAT_BITMAP.

ft_glyph_format_outline

See FT_GLYPH_FORMAT_OUTLINE.

ft_glyph_format_plotter

See FT_GLYPH_FORMAT_PLOTTER.


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FT_Data

Defined in FT_TYPES_H (freetype/fttypes.h).


  typedef struct  FT_Data_
  {
    const FT_Byte*  pointer;
    FT_Int          length;

  } FT_Data;


Read-only binary data represented as a pointer and a length.


fields

pointer

The data.

length

The length of the data in bytes.


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FT_Generic_Finalizer

Defined in FT_TYPES_H (freetype/fttypes.h).


  typedef void  (*FT_Generic_Finalizer)(void*  object);


Describe a function used to destroy the ‘client’ data of any FreeType object. See the description of the FT_Generic type for details of usage.


input

The address of the FreeType object which is under finalization. Its client data is accessed through its ‘generic’ field.


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FT_Generic

Defined in FT_TYPES_H (freetype/fttypes.h).


  typedef struct  FT_Generic_
  {
    void*                 data;
    FT_Generic_Finalizer  finalizer;

  } FT_Generic;


Client applications often need to associate their own data to a variety of FreeType core objects. For example, a text layout API might want to associate a glyph cache to a given size object.

Some FreeType object contains a ‘generic’ field, of type FT_Generic, which usage is left to client applications and font servers.

It can be used to store a pointer to client-specific data, as well as the address of a ‘finalizer’ function, which will be called by FreeType when the object is destroyed (for example, the previous client example would put the address of the glyph cache destructor in the ‘finalizer’ field).


fields

data

A typeless pointer to any client-specified data. This field is completely ignored by the FreeType library.

finalizer

A pointer to a ‘generic finalizer’ function, which will be called when the object is destroyed. If this field is set to NULL, no code will be called.


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FT_MAKE_TAG

Defined in FT_TYPES_H (freetype/fttypes.h).


#define FT_MAKE_TAG( _x1, _x2, _x3, _x4 ) \
          (FT_Tag)                        \
          ( ( (FT_ULong)_x1 << 24 ) |     \
            ( (FT_ULong)_x2 << 16 ) |     \
            ( (FT_ULong)_x3 <<  8 ) |     \
              (FT_ULong)_x4         )


This macro converts four-letter tags which are used to label TrueType tables into an unsigned long to be used within FreeType.


note

The produced values must be 32-bit integers. Don't redefine this macro.


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