FreeType-2.1.10 API Reference
Glyph Management
Synopsis
#FT_Glyph
FT_Glyph
#FT_OutlineGlyphRec
FT_OutlineGlyphRec
#ft_glyph_bbox_xxx
ft_glyph_bbox_xxx
#FT_GlyphRec
FT_GlyphRec
#FT_Get_Glyph
FT_Get_Glyph
#FT_Glyph_Get_CBox
FT_Glyph_Get_CBox
#FT_BitmapGlyph
FT_BitmapGlyph
#FT_Glyph_Copy
FT_Glyph_Copy
#FT_Glyph_To_Bitmap
FT_Glyph_To_Bitmap
#FT_BitmapGlyphRec
FT_BitmapGlyphRec
#FT_Glyph_Transform
FT_Glyph_Transform
#FT_Done_Glyph
FT_Done_Glyph
#FT_OutlineGlyph
FT_OutlineGlyph
#FT_Glyph_BBox_Mode
FT_Glyph_BBox_Mode
This section contains definitions used to manage glyph data through generic FT_Glyph objects. Each of them can contain a bitmap, a vector outline, or even images in other formats.
FT_Glyph
typedef
struct
FT_GlyphRec_*
FT_Glyph
;
Handle to an object used to model generic glyph images. It is a pointer to the
ft2-glyph_management.html#FT_GlyphRec
FT_GlyphRec
structure and can contain a glyph bitmap or pointer.
note
Glyph objects are not owned by the library. You must thus release them manually (through
ft2-glyph_management.html#FT_Done_Glyph
FT_Done_Glyph
)
before
calling
ft2-base_interface.html#FT_Done_FreeType
FT_Done_FreeType
.
FT_GlyphRec
typedef
struct
FT_GlyphRec_
{
ft2-base_interface.html#FT_Library
FT_Library
library;
const
FT_Glyph_Class*  clazz;
ft2-basic_types.html#FT_Glyph_Format
FT_Glyph_Format
format;
ft2-basic_types.html#FT_Vector
FT_Vector
advance;
}
FT_GlyphRec
;
The root glyph structure contains a given glyph image plus its advance width in 16.16 fixed float format.
fields
library
A handle to the FreeType library object.
clazz
A pointer to the glyph's class. Private.
format
The format of the glyph's image.
advance
A 16.16 vector that gives the glyph's advance width.
FT_BitmapGlyph
typedef
struct
FT_BitmapGlyphRec_*
FT_BitmapGlyph
;
A handle to an object used to model a bitmap glyph image. This is a sub-class of
ft2-glyph_management.html#FT_Glyph
FT_Glyph
, and a pointer to
ft2-glyph_management.html#FT_BitmapGlyphRec
FT_BitmapGlyphRec
.
FT_BitmapGlyphRec
typedef
struct
FT_BitmapGlyphRec_
{
ft2-glyph_management.html#FT_GlyphRec
FT_GlyphRec
root;
ft2-basic_types.html#FT_Int
FT_Int
left;
ft2-basic_types.html#FT_Int
FT_Int
top;
ft2-basic_types.html#FT_Bitmap
FT_Bitmap
bitmap;
}
FT_BitmapGlyphRec
;
A structure used for bitmap glyph images. This really is a `sub-class' of `FT_GlyphRec'.
fields
root
The root FT_Glyph fields.
left
The left-side bearing, i.e., the horizontal distance from the current pen position to the left border of the glyph bitmap.
top
The top-side bearing, i.e., the vertical distance from the current pen position to the top border of the glyph bitmap. This distance is positive for upwards-y!
bitmap
A descriptor for the bitmap.
note
You can typecast FT_Glyph to FT_BitmapGlyph if you have glyph->format == FT_GLYPH_FORMAT_BITMAP. This lets you access the bitmap's contents easily.
The corresponding pixel buffer is always owned by the BitmapGlyph and is thus created and destroyed with it.
FT_OutlineGlyph
typedef
struct
FT_OutlineGlyphRec_*
FT_OutlineGlyph
;
A handle to an object used to model an outline glyph image. This is a sub-class of
ft2-glyph_management.html#FT_Glyph
FT_Glyph
, and a pointer to
ft2-glyph_management.html#FT_OutlineGlyphRec
FT_OutlineGlyphRec
.
FT_OutlineGlyphRec
typedef
struct
FT_OutlineGlyphRec_
{
ft2-glyph_management.html#FT_GlyphRec
FT_GlyphRec
root;
ft2-outline_processing.html#FT_Outline
FT_Outline
outline;
}
FT_OutlineGlyphRec
;
A structure used for outline (vectorial) glyph images. This really is a `sub-class' of `FT_GlyphRec'.
fields
root
The root FT_Glyph fields.
outline
A descriptor for the outline.
note
You can typecast FT_Glyph to FT_OutlineGlyph if you have glyph->format == FT_GLYPH_FORMAT_OUTLINE. This lets you access the outline's content easily.
As the outline is extracted from a glyph slot, its coordinates are expressed normally in 26.6 pixels, unless the flag FT_LOAD_NO_SCALE was used in FT_Load_Glyph() or FT_Load_Char().
The outline's tables are always owned by the object and are destroyed with it.
FT_Get_Glyph
FT_EXPORT(
ft2-basic_types.html#FT_Error
FT_Error
)
FT_Get_Glyph
(
ft2-base_interface.html#FT_GlyphSlot
FT_GlyphSlot
slot,
ft2-glyph_management.html#FT_Glyph
FT_Glyph
*aglyph );
A function used to extract a glyph image from a slot.
input
slot
A handle to the source glyph slot.
output
aglyph
A handle to the glyph object.
return
FreeType error code. 0 means success.
FT_Glyph_Copy
FT_EXPORT(
ft2-basic_types.html#FT_Error
FT_Error
)
FT_Glyph_Copy
(
ft2-glyph_management.html#FT_Glyph
FT_Glyph
source,
ft2-glyph_management.html#FT_Glyph
FT_Glyph
*target );
A function used to copy a glyph image. Note that the created
ft2-glyph_management.html#FT_Glyph
FT_Glyph
object must be released with
ft2-glyph_management.html#FT_Done_Glyph
FT_Done_Glyph
.
input
source
A handle to the source glyph object.
output
target
A handle to the target glyph object. 0 in case of error.
return
FreeType error code. 0 means success.
FT_Glyph_Transform
FT_EXPORT(
ft2-basic_types.html#FT_Error
FT_Error
)
FT_Glyph_Transform
(
ft2-glyph_management.html#FT_Glyph
FT_Glyph
glyph,
ft2-basic_types.html#FT_Matrix
FT_Matrix
*  matrix,
ft2-basic_types.html#FT_Vector
FT_Vector
*  delta );
Transforms a glyph image if its format is scalable.
inout
glyph
A handle to the target glyph object.
input
matrix
A pointer to a 2x2 matrix to apply.
delta
A pointer to a 2d vector to apply. Coordinates are expressed in 1/64th of a pixel.
return
FreeType error code (the glyph format is not scalable if it is not zero).
note
The 2x2 transformation matrix is also applied to the glyph's advance vector.
FT_Glyph_BBox_Mode
typedef
enum
FT_Glyph_BBox_Mode_
{
ft2-glyph_management.html#FT_Glyph_BBox_Mode
FT_GLYPH_BBOX_UNSCALED
= 0,
ft2-glyph_management.html#FT_Glyph_BBox_Mode
FT_GLYPH_BBOX_SUBPIXELS
= 0,
ft2-glyph_management.html#FT_Glyph_BBox_Mode
FT_GLYPH_BBOX_GRIDFIT
= 1,
ft2-glyph_management.html#FT_Glyph_BBox_Mode
FT_GLYPH_BBOX_TRUNCATE
= 2,
ft2-glyph_management.html#FT_Glyph_BBox_Mode
FT_GLYPH_BBOX_PIXELS
= 3
}
FT_Glyph_BBox_Mode
;
The mode how the values of
ft2-glyph_management.html#FT_Glyph_Get_CBox
FT_Glyph_Get_CBox
are returned.
values
FT_GLYPH_BBOX_UNSCALED
Return unscaled font units.
FT_GLYPH_BBOX_SUBPIXELS
Return unfitted 26.6 coordinates.
FT_GLYPH_BBOX_GRIDFIT
Return grid-fitted 26.6 coordinates.
FT_GLYPH_BBOX_TRUNCATE
Return coordinates in integer pixels.
FT_GLYPH_BBOX_PIXELS
Return grid-fitted pixel coordinates.
ft_glyph_bbox_xxx
#define
ft2-glyph_management.html#ft_glyph_bbox_xxx
ft_glyph_bbox_unscaled
ft2-glyph_management.html#FT_Glyph_BBox_Mode
FT_GLYPH_BBOX_UNSCALED
#define
ft2-glyph_management.html#ft_glyph_bbox_xxx
ft_glyph_bbox_subpixels
ft2-glyph_management.html#FT_Glyph_BBox_Mode
FT_GLYPH_BBOX_SUBPIXELS
#define
ft2-glyph_management.html#ft_glyph_bbox_xxx
ft_glyph_bbox_gridfit
ft2-glyph_management.html#FT_Glyph_BBox_Mode
FT_GLYPH_BBOX_GRIDFIT
#define
ft2-glyph_management.html#ft_glyph_bbox_xxx
ft_glyph_bbox_truncate
ft2-glyph_management.html#FT_Glyph_BBox_Mode
FT_GLYPH_BBOX_TRUNCATE
#define
ft2-glyph_management.html#ft_glyph_bbox_xxx
ft_glyph_bbox_pixels
ft2-glyph_management.html#FT_Glyph_BBox_Mode
FT_GLYPH_BBOX_PIXELS
These constants are deprecated. Use the corresponding
ft2-glyph_management.html#FT_Glyph_BBox_Mode
FT_Glyph_BBox_Mode
values instead.
values
ft_glyph_bbox_unscaled
see
ft2-glyph_management.html#FT_Glyph_BBox_Mode
FT_GLYPH_BBOX_UNSCALED
ft_glyph_bbox_subpixels
see
ft2-glyph_management.html#FT_Glyph_BBox_Mode
FT_GLYPH_BBOX_SUBPIXELS
ft_glyph_bbox_gridfit
see
ft2-glyph_management.html#FT_Glyph_BBox_Mode
FT_GLYPH_BBOX_GRIDFIT
ft_glyph_bbox_truncate
see
ft2-glyph_management.html#FT_Glyph_BBox_Mode
FT_GLYPH_BBOX_TRUNCATE
ft_glyph_bbox_pixels
see
ft2-glyph_management.html#FT_Glyph_BBox_Mode
FT_GLYPH_BBOX_PIXELS
FT_Glyph_Get_CBox
FT_EXPORT(
void
)
FT_Glyph_Get_CBox
(
ft2-glyph_management.html#FT_Glyph
FT_Glyph
glyph,
ft2-basic_types.html#FT_UInt
FT_UInt
bbox_mode,
ft2-basic_types.html#FT_BBox
FT_BBox
*acbox );
Returns a glyph's `control box'. The control box encloses all the outline's points, including Bezier control points. Though it coincides with the exact bounding box for most glyphs, it can be slightly larger in some situations (like when rotating an outline which contains Bezier outside arcs).
Computing the control box is very fast, while getting the bounding box can take much more time as it needs to walk over all segments and arcs in the outline. To get the latter, you can use the `ftbbox' component which is dedicated to this single task.
input
glyph
A handle to the source glyph object.
mode
The mode which indicates how to interpret the returned bounding box values.
output
acbox
The glyph coordinate bounding box. Coordinates are expressed in 1/64th of pixels if it is grid-fitted.
note
Coordinates are relative to the glyph origin, using the Y-upwards convention.
If the glyph has been loaded with FT_LOAD_NO_SCALE, `bbox_mode' must be set to `FT_GLYPH_BBOX_UNSCALED' to get unscaled font units in 26.6 pixel format. The value `FT_GLYPH_BBOX_SUBPIXELS' is another name for this constant.
Note that the maximum coordinates are exclusive, which means that one can compute the width and height of the glyph image (be it in integer or 26.6 pixels) as:
width = bbox.xMax - bbox.xMin; height = bbox.yMax - bbox.yMin;
Note also that for 26.6 coordinates, if `bbox_mode' is set to `FT_GLYPH_BBOX_GRIDFIT', the coordinates will also be grid-fitted, which corresponds to:
bbox.xMin = FLOOR(bbox.xMin); bbox.yMin = FLOOR(bbox.yMin); bbox.xMax = CEILING(bbox.xMax); bbox.yMax = CEILING(bbox.yMax);
To get the bbox in pixel coordinates, set `bbox_mode' to `FT_GLYPH_BBOX_TRUNCATE'.
To get the bbox in grid-fitted pixel coordinates, set `bbox_mode' to `FT_GLYPH_BBOX_PIXELS'.
FT_Glyph_To_Bitmap
FT_EXPORT(
ft2-basic_types.html#FT_Error
FT_Error
)
FT_Glyph_To_Bitmap
(
ft2-glyph_management.html#FT_Glyph
FT_Glyph
*       the_glyph,
ft2-base_interface.html#FT_Render_Mode
FT_Render_Mode
render_mode,
ft2-basic_types.html#FT_Vector
FT_Vector
*      origin,
ft2-basic_types.html#FT_Bool
FT_Bool
destroy );
Converts a given glyph object to a bitmap glyph object.
inout
the_glyph
A pointer to a handle to the target glyph.
input
render_mode
An enumeration that describe how the data is rendered.
origin
A pointer to a vector used to translate the glyph image before rendering. Can be 0 (if no translation). The origin is expressed in 26.6 pixels.
destroy
A boolean that indicates that the original glyph image should be destroyed by this function. It is never destroyed in case of error.
return
FreeType error code. 0 means success.
note
The glyph image is translated with the `origin' vector before rendering.
The first parameter is a pointer to a FT_Glyph handle, that will be replaced by this function. Typically, you would use (omitting error handling):
FT_Glyph        glyph;
FT_BitmapGlyph  glyph_bitmap;
// load glyph
error = FT_Load_Char( face, glyph_index, FT_LOAD_DEFAUT );
// extract glyph image
error = FT_Get_Glyph( face->glyph, &glyph );
// convert to a bitmap (default render mode + destroy old)
if ( glyph->format != FT_GLYPH_FORMAT_BITMAP )
{
error = FT_Glyph_To_Bitmap( &glyph, FT_RENDER_MODE_DEFAULT,
0, 1 );
if ( error ) // glyph unchanged
...
}
// access bitmap content by typecasting
glyph_bitmap = (FT_BitmapGlyph)glyph;
// do funny stuff with it, like blitting/drawing
...
// discard glyph image (bitmap or not)
FT_Done_Glyph( glyph );
This function does nothing if the glyph format isn't scalable.
FT_Done_Glyph
FT_EXPORT(
void
)
FT_Done_Glyph
(
ft2-glyph_management.html#FT_Glyph
FT_Glyph
glyph );
/* other helpful functions */
Destroys a given glyph.
input
glyph
A handle to the target glyph object.
