FreeType-2.1.10 API Reference
Outline Processing
Synopsis
#FT_Outline
FT_Outline
#FT_Outline_MoveToFunc
FT_Outline_MoveToFunc
#FT_OUTLINE_FLAGS
FT_OUTLINE_FLAGS
#FT_Outline_LineToFunc
FT_Outline_LineToFunc
#FT_Outline_New
FT_Outline_New
#FT_Outline_ConicToFunc
FT_Outline_ConicToFunc
#FT_Outline_Done
FT_Outline_Done
#FT_Outline_CubicToFunc
FT_Outline_CubicToFunc
#FT_Outline_Copy
FT_Outline_Copy
#FT_Outline_Funcs
FT_Outline_Funcs
#FT_Outline_Translate
FT_Outline_Translate
#FT_Outline_Decompose
FT_Outline_Decompose
#FT_Outline_Transform
FT_Outline_Transform
#FT_Outline_Get_CBox
FT_Outline_Get_CBox
#FT_Outline_Embolden
FT_Outline_Embolden
#FT_Outline_Get_Bitmap
FT_Outline_Get_Bitmap
#FT_Outline_Reverse
FT_Outline_Reverse
#FT_Outline_Render
FT_Outline_Render
#FT_Outline_Check
FT_Outline_Check
#FT_Orientation
FT_Orientation
#FT_Outline_Get_BBox
FT_Outline_Get_BBox
#FT_Outline_Get_Orientation
FT_Outline_Get_Orientation
#ft_outline_flags
ft_outline_flags
This section contains routines used to create and destroy scalable glyph images known as `outlines'. These can also be measured, transformed, and converted into bitmaps and pixmaps.
FT_Outline
typedef
struct
FT_Outline_
{
short
n_contours;      /* number of contours in glyph        */
short
n_points;        /* number of points in the glyph      */
ft2-basic_types.html#FT_Vector
FT_Vector
*  points;          /* the outline's points               */
char
*       tags;            /* the points flags                   */
short
*      contours;        /* the contour end points             */
int
flags;           /* outline masks                      */
}
FT_Outline
;
This structure is used to describe an outline to the scan-line converter.
fields
n_contours
The number of contours in the outline.
n_points
The number of points in the outline.
points
A pointer to an array of `n_points' FT_Vector elements, giving the outline's point coordinates.
tags
A pointer to an array of `n_points' chars, giving each outline point's type. If bit 0 is unset, the point is `off' the curve, i.e. a Bezier control point, while it is `on' when set.
Bit 1 is meaningful for `off' points only. If set, it indicates a third-order Bezier arc control point; and a second-order control point if unset.
contours
An array of `n_contours' shorts, giving the end point of each contour within the outline. For example, the first contour is defined by the points `0' to `contours[0]', the second one is defined by the points `contours[0]+1' to `contours[1]', etc.
flags
A set of bit flags used to characterize the outline and give hints to the scan-converter and hinter on how to convert/grid-fit it. See FT_Outline_Flags.
FT_OUTLINE_FLAGS
#define
ft2-outline_processing.html#FT_OUTLINE_FLAGS
FT_OUTLINE_NONE
0x0
#define
ft2-outline_processing.html#FT_OUTLINE_FLAGS
FT_OUTLINE_OWNER
0x1
#define
ft2-outline_processing.html#FT_OUTLINE_FLAGS
FT_OUTLINE_EVEN_ODD_FILL
0x2
#define
ft2-outline_processing.html#FT_OUTLINE_FLAGS
FT_OUTLINE_REVERSE_FILL
0x4
#define
ft2-outline_processing.html#FT_OUTLINE_FLAGS
FT_OUTLINE_IGNORE_DROPOUTS
0x8
#define
ft2-outline_processing.html#FT_OUTLINE_FLAGS
FT_OUTLINE_HIGH_PRECISION
0x100
#define
ft2-outline_processing.html#FT_OUTLINE_FLAGS
FT_OUTLINE_SINGLE_PASS
0x200
A list of bit-field constants use for the flags in an outline's `flags' field.
values
FT_OUTLINE_NONE
Value 0 is reserved.
FT_OUTLINE_OWNER
If set, this flag indicates that the outline's field arrays (i.e. `points', `flags' & `contours') are `owned' by the outline object, and should thus be freed when it is destroyed.
FT_OUTLINE_EVEN_ODD_FILL
By default, outlines are filled using the non-zero winding rule. If set to 1, the outline will be filled using the even-odd fill rule (only works with the smooth raster).
FT_OUTLINE_REVERSE_FILL
By default, outside contours of an outline are oriented in clock-wise direction, as defined in the TrueType specification. This flag is set if the outline uses the opposite direction (typically for Type 1 fonts). This flag is ignored by the scan-converter. However, it is very important for the auto-hinter.
FT_OUTLINE_IGNORE_DROPOUTS
By default, the scan converter will try to detect drop-outs in an outline and correct the glyph bitmap to ensure consistent shape continuity. If set, this flag hints the scan-line converter to ignore such cases.
FT_OUTLINE_HIGH_PRECISION
This flag indicates that the scan-line converter should try to convert this outline to bitmaps with the highest possible quality. It is typically set for small character sizes. Note that this is only a hint, that might be completely ignored by a given scan-converter.
FT_OUTLINE_SINGLE_PASS
This flag is set to force a given scan-converter to only use a single pass over the outline to render a bitmap glyph image. Normally, it is set for very large character sizes. It is only a hint, that might be completely ignored by a given scan-converter.
FT_Outline_New
FT_EXPORT(
ft2-basic_types.html#FT_Error
FT_Error
)
FT_Outline_New
(
ft2-base_interface.html#FT_Library
FT_Library
library,
ft2-basic_types.html#FT_UInt
FT_UInt
numPoints,
ft2-basic_types.html#FT_Int
FT_Int
numContours,
ft2-outline_processing.html#FT_Outline
FT_Outline
*anoutline );
FT_EXPORT(
ft2-basic_types.html#FT_Error
FT_Error
)
FT_Outline_New_Internal(
ft2-system_interface.html#FT_Memory
FT_Memory
memory,
ft2-basic_types.html#FT_UInt
FT_UInt
numPoints,
ft2-basic_types.html#FT_Int
FT_Int
numContours,
ft2-outline_processing.html#FT_Outline
FT_Outline
*anoutline );
Creates a new outline of a given size.
input
library
A handle to the library object from where the outline is allocated. Note however that the new outline will NOT necessarily be FREED, when destroying the library, by FT_Done_FreeType().
numPoints
The maximal number of points within the outline.
numContours
The maximal number of contours within the outline.
output
anoutline
A handle to the new outline. NULL in case of error.
return
FreeType error code. 0 means success.
note
The reason why this function takes a `library' parameter is simply to use the library's memory allocator.
FT_Outline_Done
FT_EXPORT(
ft2-basic_types.html#FT_Error
FT_Error
)
FT_Outline_Done
(
ft2-base_interface.html#FT_Library
FT_Library
library,
ft2-outline_processing.html#FT_Outline
FT_Outline
*  outline );
FT_EXPORT(
ft2-basic_types.html#FT_Error
FT_Error
)
FT_Outline_Done_Internal(
ft2-system_interface.html#FT_Memory
FT_Memory
memory,
ft2-outline_processing.html#FT_Outline
FT_Outline
*  outline );
Destroys an outline created with FT_Outline_New().
input
library
A handle of the library object used to allocate the outline.
outline
A pointer to the outline object to be discarded.
return
FreeType error code. 0 means success.
note
If the outline's `owner' field is not set, only the outline descriptor will be released.
The reason why this function takes an `library' parameter is simply to use FT_Free().
FT_Outline_Copy
FT_EXPORT(
ft2-basic_types.html#FT_Error
FT_Error
)
FT_Outline_Copy
(
const
ft2-outline_processing.html#FT_Outline
FT_Outline
*  source,
ft2-outline_processing.html#FT_Outline
FT_Outline
*target );
Copies an outline into another one. Both objects must have the same sizes (number of points & number of contours) when this function is called.
input
source
A handle to the source outline.
output
target
A handle to the target outline.
return
FreeType error code. 0 means success.
FT_Outline_Translate
FT_EXPORT(
void
)
FT_Outline_Translate
(
const
ft2-outline_processing.html#FT_Outline
FT_Outline
*  outline,
ft2-basic_types.html#FT_Pos
FT_Pos
xOffset,
ft2-basic_types.html#FT_Pos
FT_Pos
yOffset );
Applies a simple translation to the points of an outline.
inout
outline
A pointer to the target outline descriptor.
input
xOffset
The horizontal offset.
yOffset
The vertical offset.
FT_Outline_Transform
FT_EXPORT(
void
)
FT_Outline_Transform
(
const
ft2-outline_processing.html#FT_Outline
FT_Outline
*  outline,
const
ft2-basic_types.html#FT_Matrix
FT_Matrix
*   matrix );
Applies a simple 2x2 matrix to all of an outline's points. Useful for applying rotations, slanting, flipping, etc.
inout
outline
A pointer to the target outline descriptor.
input
matrix
A pointer to the transformation matrix.
note
You can use FT_Outline_Translate() if you need to translate the outline's points.
FT_Outline_Embolden
FT_EXPORT_DEF(
ft2-basic_types.html#FT_Error
FT_Error
)
FT_Outline_Embolden
(
ft2-outline_processing.html#FT_Outline
FT_Outline
*  outline,
ft2-basic_types.html#FT_Pos
FT_Pos
strength );
Emboldens an outline. The new outline will be at most 4 times `strength' pixels wider and higher. You may think of the left and bottom borders as unchanged.
inout
outline
A handle to the target outline.
input
strength
How strong the glyph is emboldened. Expressed in 26.6 pixel format.
return
FreeType error code. 0 means success.
FT_Outline_Reverse
FT_EXPORT(
void
)
FT_Outline_Reverse
(
ft2-outline_processing.html#FT_Outline
FT_Outline
*  outline );
Reverses the drawing direction of an outline. This is used to ensure consistent fill conventions for mirrored glyphs.
inout
outline
A pointer to the target outline descriptor.
note
This functions toggles the bit flag `FT_OUTLINE_REVERSE_FILL' in the outline's `flags' field.
It shouldn't be used by a normal client application, unless it knows what it is doing.
FT_Outline_Check
FT_EXPORT(
ft2-basic_types.html#FT_Error
FT_Error
)
FT_Outline_Check
(
ft2-outline_processing.html#FT_Outline
FT_Outline
*  outline );
Check the contents of an outline descriptor.
input
outline
A handle to a source outline.
return
FreeType error code. 0 means success.
FT_Outline_Get_BBox
FT_EXPORT(
ft2-basic_types.html#FT_Error
FT_Error
)
FT_Outline_Get_BBox
(
ft2-outline_processing.html#FT_Outline
FT_Outline
*  outline,
ft2-basic_types.html#FT_BBox
FT_BBox
*abbox );
Computes the exact bounding box of an outline. This is slower than computing the control box. However, it uses an advanced algorithm which returns
very
quickly when the two boxes coincide. Otherwise, the outline Bezier arcs are walked over to extract their extrema.
input
outline
A pointer to the source outline.
output
abbox
The outline's exact bounding box.
return
FreeType error code. 0 means success.
ft_outline_flags
#define
ft2-outline_processing.html#ft_outline_flags
ft_outline_none
ft2-outline_processing.html#FT_OUTLINE_FLAGS
FT_OUTLINE_NONE
#define
ft2-outline_processing.html#ft_outline_flags
ft_outline_owner
ft2-outline_processing.html#FT_OUTLINE_FLAGS
FT_OUTLINE_OWNER
#define
ft2-outline_processing.html#ft_outline_flags
ft_outline_even_odd_fill
ft2-outline_processing.html#FT_OUTLINE_FLAGS
FT_OUTLINE_EVEN_ODD_FILL
#define
ft2-outline_processing.html#ft_outline_flags
ft_outline_reverse_fill
ft2-outline_processing.html#FT_OUTLINE_FLAGS
FT_OUTLINE_REVERSE_FILL
#define
ft2-outline_processing.html#ft_outline_flags
ft_outline_ignore_dropouts
ft2-outline_processing.html#FT_OUTLINE_FLAGS
FT_OUTLINE_IGNORE_DROPOUTS
#define
ft2-outline_processing.html#ft_outline_flags
ft_outline_high_precision
ft2-outline_processing.html#FT_OUTLINE_FLAGS
FT_OUTLINE_HIGH_PRECISION
#define
ft2-outline_processing.html#ft_outline_flags
ft_outline_single_pass
ft2-outline_processing.html#FT_OUTLINE_FLAGS
FT_OUTLINE_SINGLE_PASS
These constants are deprecated. Please use the corresponding
ft2-outline_processing.html#FT_OUTLINE_FLAGS
FT_OUTLINE_FLAGS
values.
values
ft_outline_none
See
ft2-outline_processing.html#FT_OUTLINE_FLAGS
FT_OUTLINE_NONE
.
ft_outline_owner
See
ft2-outline_processing.html#FT_OUTLINE_FLAGS
FT_OUTLINE_OWNER
.
ft_outline_even_odd_fill
See
ft2-outline_processing.html#FT_OUTLINE_FLAGS
FT_OUTLINE_EVEN_ODD_FILL
.
ft_outline_reverse_fill
See
ft2-outline_processing.html#FT_OUTLINE_FLAGS
FT_OUTLINE_REVERSE_FILL
.
ft_outline_ignore_dropouts
See
ft2-outline_processing.html#FT_OUTLINE_FLAGS
FT_OUTLINE_IGNORE_DROPOUTS
.
ft_outline_high_precision
See
ft2-outline_processing.html#FT_OUTLINE_FLAGS
FT_OUTLINE_HIGH_PRECISION
.
ft_outline_single_pass
See
ft2-outline_processing.html#FT_OUTLINE_FLAGS
FT_OUTLINE_SINGLE_PASS
.
FT_Outline_MoveToFunc
typedef
int
(*
FT_Outline_MoveToFunc
)(
ft2-basic_types.html#FT_Vector
FT_Vector
*  to,
void
*       user );
#define FT_Outline_MoveTo_Func
FT_Outline_MoveToFunc
A function pointer type used to describe the signature of a `move to' function during outline walking/decomposition.
A `move to' is emitted to start a new contour in an outline.
input
to
A pointer to the target point of the `move to'.
user
A typeless pointer which is passed from the caller of the decomposition function.
return
Error code. 0 means success.
FT_Outline_LineToFunc
typedef
int
(*
FT_Outline_LineToFunc
)(
ft2-basic_types.html#FT_Vector
FT_Vector
*  to,
void
*       user );
#define  FT_Outline_LineTo_Func
FT_Outline_LineToFunc
A function pointer type used to describe the signature of a `line to' function during outline walking/decomposition.
A `line to' is emitted to indicate a segment in the outline.
input
to
A pointer to the target point of the `line to'.
user
A typeless pointer which is passed from the caller of the decomposition function.
return
Error code. 0 means success.
FT_Outline_ConicToFunc
typedef
int
(*
FT_Outline_ConicToFunc
)(
ft2-basic_types.html#FT_Vector
FT_Vector
*  control,
ft2-basic_types.html#FT_Vector
FT_Vector
*  to,
void
*       user );
#define  FT_Outline_ConicTo_Func
FT_Outline_ConicToFunc
A function pointer type use to describe the signature of a `conic to' function during outline walking/decomposition.
A `conic to' is emitted to indicate a second-order Bezier arc in the outline.
input
control
An intermediate control point between the last position and the new target in `to'.
to
A pointer to the target end point of the conic arc.
user
A typeless pointer which is passed from the caller of the decomposition function.
return
Error code. 0 means success.
FT_Outline_CubicToFunc
typedef
int
(*
FT_Outline_CubicToFunc
)(
ft2-basic_types.html#FT_Vector
FT_Vector
*  control1,
ft2-basic_types.html#FT_Vector
FT_Vector
*  control2,
ft2-basic_types.html#FT_Vector
FT_Vector
*  to,
void
*       user );
#define  FT_Outline_CubicTo_Func
FT_Outline_CubicToFunc
A function pointer type used to describe the signature of a `cubic to' function during outline walking/decomposition.
A `cubic to' is emitted to indicate a third-order Bezier arc.
input
control1
A pointer to the first Bezier control point.
control2
A pointer to the second Bezier control point.
to
A pointer to the target end point.
user
A typeless pointer which is passed from the caller of the decomposition function.
return
Error code. 0 means success.
FT_Outline_Funcs
typedef
struct
FT_Outline_Funcs_
{
ft2-outline_processing.html#FT_Outline_MoveToFunc
FT_Outline_MoveToFunc
move_to;
ft2-outline_processing.html#FT_Outline_LineToFunc
FT_Outline_LineToFunc
line_to;
ft2-outline_processing.html#FT_Outline_ConicToFunc
FT_Outline_ConicToFunc
conic_to;
ft2-outline_processing.html#FT_Outline_CubicToFunc
FT_Outline_CubicToFunc
cubic_to;
int
shift;
ft2-basic_types.html#FT_Pos
FT_Pos
delta;
}
FT_Outline_Funcs
;
A structure to hold various function pointers used during outline decomposition in order to emit segments, conic, and cubic Beziers, as well as `move to' and `close to' operations.
fields
move_to
The `move to' emitter.
line_to
The segment emitter.
conic_to
The second-order Bezier arc emitter.
cubic_to
The third-order Bezier arc emitter.
shift
The shift that is applied to coordinates before they are sent to the emitter.
delta
The delta that is applied to coordinates before they are sent to the emitter, but after the shift.
note
The point coordinates sent to the emitters are the transformed version of the original coordinates (this is important for high accuracy during scan-conversion). The transformation is simple:
x' = (x << shift) - delta y' = (x << shift) - delta
Set the value of `shift' and `delta' to 0 to get the original point coordinates.
FT_Outline_Decompose
FT_EXPORT(
ft2-basic_types.html#FT_Error
FT_Error
)
FT_Outline_Decompose
(
ft2-outline_processing.html#FT_Outline
FT_Outline
*              outline,
const
ft2-outline_processing.html#FT_Outline_Funcs
FT_Outline_Funcs
*  func_interface,
void
*                    user );
Walks over an outline's structure to decompose it into individual segments and Bezier arcs. This function is also able to emit `move to' and `close to' operations to indicate the start and end of new contours in the outline.
input
outline
A pointer to the source target.
func_interface
A table of `emitters', i.e,. function pointers called during decomposition to indicate path operations.
inout
user
A typeless pointer which is passed to each emitter during the decomposition. It can be used to store the state during the decomposition.
return
FreeType error code. 0 means sucess.
FT_Outline_Get_CBox
FT_EXPORT(
void
)
FT_Outline_Get_CBox
(
const
ft2-outline_processing.html#FT_Outline
FT_Outline
*  outline,
ft2-basic_types.html#FT_BBox
FT_BBox
*acbox );
Returns an outline'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
outline
A pointer to the source outline descriptor.
output
acbox
The outline's control box.
FT_Outline_Get_Bitmap
FT_EXPORT(
ft2-basic_types.html#FT_Error
FT_Error
)
FT_Outline_Get_Bitmap
(
ft2-base_interface.html#FT_Library
FT_Library
library,
ft2-outline_processing.html#FT_Outline
FT_Outline
*       outline,
const
ft2-basic_types.html#FT_Bitmap
FT_Bitmap
*abitmap );
Renders an outline within a bitmap. The outline's image is simply OR-ed to the target bitmap.
input
library
A handle to a FreeType library object.
outline
A pointer to the source outline descriptor.
output
abitmap
A pointer to the target bitmap descriptor.
return
FreeType error code. 0 means success.
note
This function does NOT CREATE the bitmap, it only renders an outline image within the one you pass to it!
It will use the raster correponding to the default glyph format.
FT_Outline_Render
FT_EXPORT(
ft2-basic_types.html#FT_Error
FT_Error
)
FT_Outline_Render
(
ft2-base_interface.html#FT_Library
FT_Library
library,
ft2-outline_processing.html#FT_Outline
FT_Outline
*        outline,
ft2-raster.html#FT_Raster_Params
FT_Raster_Params
*  params );
Renders an outline within a bitmap using the current scan-convert. This functions uses an FT_Raster_Params structure as an argument, allowing advanced features like direct composition, translucency, etc.
input
library
A handle to a FreeType library object.
outline
A pointer to the source outline descriptor.
inout
params
A pointer to a FT_Raster_Params structure used to describe the rendering operation.
return
FreeType error code. 0 means success.
note
You should know what you are doing and how FT_Raster_Params works to use this function.
The field `params.source' will be set to `outline' before the scan converter is called, which means that the value you give to it is actually ignored.
FT_Orientation
typedef
enum
{
ft2-outline_processing.html#FT_Orientation
FT_ORIENTATION_TRUETYPE
= 0,
ft2-outline_processing.html#FT_Orientation
FT_ORIENTATION_POSTSCRIPT
= 1,
ft2-outline_processing.html#FT_Orientation
FT_ORIENTATION_FILL_RIGHT
=
ft2-outline_processing.html#FT_Orientation
FT_ORIENTATION_TRUETYPE
,
ft2-outline_processing.html#FT_Orientation
FT_ORIENTATION_FILL_LEFT
=
ft2-outline_processing.html#FT_Orientation
FT_ORIENTATION_POSTSCRIPT
}
FT_Orientation
;
A list of values used to describe an outline's contour orientation.
The TrueType and Postscript specifications use different conventions to determine whether outline contours should be filled or unfilled.
values
FT_ORIENTATION_TRUETYPE
According to the TrueType specification, clockwise contours must be filled, and counter-clockwise ones must be unfilled.
FT_ORIENTATION_POSTSCRIPT
According to the Postscript specification, counter-clockwise contours must be filled, and clockwise ones must be unfilled.
FT_ORIENTATION_FILL_RIGHT
This is identical to
ft2-outline_processing.html#FT_Orientation
FT_ORIENTATION_TRUETYPE
, but is used to remember that in TrueType, everything that is to the right of the drawing direction of a contour must be filled.
FT_ORIENTATION_FILL_LEFT
This is identical to
ft2-outline_processing.html#FT_Orientation
FT_ORIENTATION_POSTSCRIPT
, but is used to remember that in Postscript, everything that is to the left of the drawing direction of a contour must be filled.
FT_Outline_Get_Orientation
FT_EXPORT(
ft2-outline_processing.html#FT_Orientation
FT_Orientation
)
FT_Outline_Get_Orientation
(
ft2-outline_processing.html#FT_Outline
FT_Outline
*  outline );
This function analyzes a glyph outline and tries to compute its fill orientation (see
ft2-outline_processing.html#FT_Orientation
FT_Orientation
). This is done by computing the direction of each global horizontal and/or vertical extrema within the outline.
Note that this will return
ft2-outline_processing.html#FT_Orientation
FT_ORIENTATION_TRUETYPE
for empty outlines.
input
outline
A handle to the source outline.
return
The orientation.
