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freetype2/include/freetype/ftstroke.h

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/***************************************************************************/
/* */
/* ftstroke.h */
/* */
/* FreeType path stroker (specification). */
/* */
/* Copyright 2002, 2003, 2004 by */
/* David Turner, Robert Wilhelm, and Werner Lemberg. */
/* */
/* This file is part of the FreeType project, and may only be used, */
/* modified, and distributed under the terms of the FreeType project */
/* license, LICENSE.TXT. By continuing to use, modify, or distribute */
/* this file you indicate that you have read the license and */
/* understand and accept it fully. */
/* */
/***************************************************************************/
#ifndef __FT_STROKE_H__
#define __FT_STROKE_H__
#include <ft2build.h>
#include FT_OUTLINE_H
#include FT_GLYPH_H
FT_BEGIN_HEADER
/************************************************************************
*
* <Section>
* glyph_stroker
*
* <Title>
* Glyph Stroker
*
* <Abstract>
* Generating bordered and stroked glyphs.
*
* <Description>
* This component generates stroked outlines of a given vectorial
* glyph. It also allows you to retrieve the `outside' and/or the
* `inside' borders of the stroke.
*
* This can be useful to generate `bordered' glyph, i.e., glyphs
* displayed with a coloured (and anti-aliased) border around their
* shape.
*/
/**************************************************************
*
* @type:
* FT_Stroker
*
* @description:
* Opaque handler to a path stroker object.
*/
typedef struct FT_StrokerRec_* FT_Stroker;
/**************************************************************
*
* @enum:
* FT_Stroker_LineJoin
*
* @description:
* These values determine how two joining lines are rendered
* in a stroker.
*
* @values:
* FT_STROKER_LINEJOIN_ROUND ::
* Used to render rounded line joins. Circular arcs are used
* to join two lines smoothly.
*
* FT_STROKER_LINEJOIN_BEVEL ::
* Used to render beveled line joins; i.e., the two joining lines
* are extended until they intersect.
*
* FT_STROKER_LINEJOIN_MITER ::
* Same as beveled rendering, except that an additional line
* break is added if the angle between the two joining lines
* is too closed (this is useful to avoid unpleasant spikes
* in beveled rendering).
*/
typedef enum
{
FT_STROKER_LINEJOIN_ROUND = 0,
FT_STROKER_LINEJOIN_BEVEL,
FT_STROKER_LINEJOIN_MITER
} FT_Stroker_LineJoin;
/**************************************************************
*
* @enum:
* FT_Stroker_LineCap
*
* @description:
* These values determine how the end of opened sub-paths are
* rendered in a stroke.
*
* @values:
* FT_STROKER_LINECAP_BUTT ::
* The end of lines is rendered as a full stop on the last
* point itself.
*
* FT_STROKER_LINECAP_ROUND ::
* The end of lines is rendered as a half-circle around the
* last point.
*
* FT_STROKER_LINECAP_SQUARE ::
* The end of lines is rendered as a square around the
* last point.
*/
typedef enum
{
FT_STROKER_LINECAP_BUTT = 0,
FT_STROKER_LINECAP_ROUND,
FT_STROKER_LINECAP_SQUARE
} FT_Stroker_LineCap;
/**************************************************************
*
* @enum:
* FT_StrokerBorder
*
* @description:
* These values are used to select a given stroke border
* in @FT_Stroker_GetBorderCounts and @FT_Stroker_ExportBorder.
*
* @values:
* FT_STROKER_BORDER_LEFT ::
* Select the left border, relative to the drawing direction.
*
* FT_STROKER_BORDER_RIGHT ::
* Select the right border, relative to the drawing direction.
*
* @note:
* Applications are generally interested in the `inside' and `outside'
* borders. However, there is no direct mapping between these and
* the `left' / `right' ones, since this really depends on the glyph's
* drawing orientation, which varies between font formats.
*
* You can however use @FT_Outline_GetInsideBorder and
* @FT_Outline_GetOutsideBorder to get these.
*/
typedef enum
{
FT_STROKER_BORDER_LEFT = 0,
FT_STROKER_BORDER_RIGHT
} FT_StrokerBorder;
/**************************************************************
*
* @function:
* FT_Outline_GetInsideBorder
*
* @description:
* Retrieve the @FT_StrokerBorder value corresponding to the
* `inside' borders of a given outline.
*
* @input:
* outline ::
* The source outline handle.
*
* @return:
* The border index. @FT_STROKER_BORDER_LEFT for empty or invalid
* outlines.
*/
FT_EXPORT( FT_StrokerBorder )
FT_Outline_GetInsideBorder( FT_Outline* outline );
/**************************************************************
*
* @function:
* FT_Outline_GetOutsideBorder
*
* @description:
* Retrieve the @FT_StrokerBorder value corresponding to the
* `outside' borders of a given outline.
*
* @input:
* outline ::
* The source outline handle.
*
* @return:
* The border index. @FT_STROKER_BORDER_LEFT for empty or invalid
* outlines.
*/
FT_EXPORT( FT_StrokerBorder )
FT_Outline_GetOutsideBorder( FT_Outline* outline );
/**************************************************************
*
* @function:
* FT_Stroker_New
*
* @description:
* Create a new stroker object.
*
* @input:
* memory ::
* The memory manager handle.
*
* @output:
* A new stroker object handle. NULL in case of error.
*
* @return:
* FreeType error code. 0 means success.
*/
FT_EXPORT( FT_Error )
FT_Stroker_New( FT_Memory memory,
FT_Stroker *astroker );
/**************************************************************
*
* @function:
* FT_Stroker_Set
*
* @description:
* Reset a stroker object's attributes.
*
* @input:
* stroker ::
* The target stroker handle.
*
* radius ::
* The border radius.
*
* line_cap ::
* The line cap style.
*
* line_join ::
* The line join style.
*
* miter_limit ::
* The miter limit for the FT_STROKER_LINEJOIN_MITER style,
* expressed as 16.16 fixed point value.
*
* @note:
* The radius is expressed in the same units that the outline
* coordinates.
*/
FT_EXPORT( void )
FT_Stroker_Set( FT_Stroker stroker,
FT_Fixed radius,
FT_Stroker_LineCap line_cap,
FT_Stroker_LineJoin line_join,
FT_Fixed miter_limit );
/**************************************************************
*
* @function:
* FT_Stroker_Rewind
*
* @description:
* Reset a stroker object without changing its attributes.
* You should call this function before beginning a new
* series of calls to @FT_Stroker_BeginSubPath or
* @FT_Stroker_EndSubPath.
*
* @input:
* stroker ::
* The target stroker handle.
*/
FT_EXPORT( void )
FT_Stroker_Rewind( FT_Stroker stroker );
/**************************************************************
*
* @function:
* FT_Stroker_ParseOutline
*
* @description:
* A convenience function used to parse a whole outline with
* the stroker. The resulting outline(s) can be retrieved
* later by functions like @FT_Stroker_GetCounts and @FT_Stroker_Export.
*
* @input:
* stroker ::
* The target stroker handle.
*
* outline ::
* The source outline.
*
* opened ::
* A boolean. If TRUE, the outline is treated as an open path
* instead of a closed one.
*
* @return:
* FreeType error code. 0 means success.
*
* @note:
* If `opened' is 0 (the default), the outline is treated as a closed
* path, and the stroker will generate two distinct `border' outlines.
*
* If `opened' is 1, the outline is processed as an open path, and the
* stroker will generate a single `stroke' outline.
*
* This function calls @FT_Stroker_Rewind automatically.
*/
FT_EXPORT( FT_Error )
FT_Stroker_ParseOutline( FT_Stroker stroker,
FT_Outline* outline,
FT_Bool opened );
/**************************************************************
*
* @function:
* FT_Stroker_BeginSubPath
*
* @description:
* Start a new sub-path in the stroker.
*
* @input:
* stroker ::
* The target stroker handle.
*
* to ::
* A pointer to the start vector.
*
* open ::
* A boolean. If TRUE, the sub-path is treated as an open one.
*
* @return:
* FreeType error code. 0 means success.
*
* @note:
* This function is useful when you need to stroke a path that is
* not stored as a @FT_Outline object.
*/
FT_EXPORT( FT_Error )
FT_Stroker_BeginSubPath( FT_Stroker stroker,
FT_Vector* to,
FT_Bool open );
/**************************************************************
*
* @function:
* FT_Stroker_EndSubPath
*
* @description:
* Close the current sub-path in the stroker.
*
* @input:
* stroker ::
* The target stroker handle.
*
* @return:
* FreeType error code. 0 means success.
*
* @note:
* You should call this function after @FT_Stroker_BeginSubPath.
* If the subpath was not `opened', this function will `draw' a
* single line segment to the start position when needed.
*/
FT_EXPORT( FT_Error )
FT_Stroker_EndSubPath( FT_Stroker stroker );
/**************************************************************
*
* @function:
* FT_Stroker_LineTo
*
* @description:
* `Draw' a single line segment in the stroker's current sub-path,
* from the last position.
*
* @input:
* stroker ::
* The target stroker handle.
*
* to ::
* A pointer to the destination point.
*
* @return:
* FreeType error code. 0 means success.
*
* @note:
* You should call this function between @FT_Stroker_BeginSubPath and
* @FT_Stroker_EndSubPath.
*/
FT_EXPORT( FT_Error )
FT_Stroker_LineTo( FT_Stroker stroker,
FT_Vector* to );
/**************************************************************
*
* @function:
* FT_Stroker_ConicTo
*
* @description:
* `Draw; a single quadratic bezier in the stroker's current sub-path,
* from the last position.
*
* @input:
* stroker ::
* The target stroker handle.
*
* control ::
* A pointer to a B<>zier control point.
*
* to ::
* A pointer to the destination point.
*
* @return:
* FreeType error code. 0 means success.
*
* @note:
* You should call this function between @FT_Stroker_BeginSubPath and
* @FT_Stroker_EndSubPath.
*/
FT_EXPORT( FT_Error )
FT_Stroker_ConicTo( FT_Stroker stroker,
FT_Vector* control,
FT_Vector* to );
/**************************************************************
*
* @function:
* FT_Stroker_CubicTo
*
* @description:
* `Draw' a single cubic B<>zier in the stroker's current sub-path,
* from the last position.
*
* @input:
* stroker ::
* The target stroker handle.
*
* control1 ::
* A pointer to the first B<>zier control point.
*
* control2 ::
* A pointer to second B<>zier control point.
*
* to ::
* A pointer to the destination point.
*
* @return:
* FreeType error code. 0 means success.
*
* @note:
* You should call this function between @FT_Stroker_BeginSubPath and
* @FT_Stroker_EndSubPath.
*/
FT_EXPORT( FT_Error )
FT_Stroker_CubicTo( FT_Stroker stroker,
FT_Vector* control1,
FT_Vector* control2,
FT_Vector* to );
/**************************************************************
*
* @function:
* FT_Stroker_GetBorderCounts
*
* @description:
* Vall this function once you have finished parsing your paths
* with the stroker. It will return the number of points and
* contours necessary to export one of the `border' or `stroke'
* outlines generated by the stroker.
*
* @input:
* stroker ::
* The target stroker handle.
*
* border ::
* The border index.
*
* @output:
* anum_points ::
* The number of points.
*
* anum_contours ::
* The number of contours.
*
* @return:
* FreeType error code. 0 means success.
*
* @note:
* When an outline, or a sub-path, is `closed', the stroker generates
* two independent `border' outlines, named `left' and `right'.
*
* When the outline, or a sub-path, is `opened', the stroker merges
* the `border' outlines with caps. The `left' border receives all
* points, while the `right' border becomes empty.
*
* Use the function @FT_Stroker_GetCounts instead if you want to
* retrieve the counts associated to both borders.
*/
FT_EXPORT( FT_Error )
FT_Stroker_GetBorderCounts( FT_Stroker stroker,
FT_StrokerBorder border,
FT_UInt *anum_points,
FT_UInt *anum_contours );
/**************************************************************
*
* @function:
* FT_Stroker_ExportBorder
*
* @description:
* Call this function after @FT_Stroker_GetBorderCounts to
* export the corresponding border to your own @FT_Outline
* structure.
*
* Note that this function will append the border points and
* contours to your outline, but will not try to resize its
* arrays.
*
* @input:
* stroker ::
* The target stroker handle.
*
* border ::
* The border index.
*
* outline ::
* The target outline handle.
*
* @note:
* Always call this function after @FT_Stroker_GetBorderCounts to
* get sure that there is enough room in your @FT_Outline object to
* receive all new data.
*
* When an outline, or a sub-path, is `closed', the stroker generates
* two independent `border' outlines, named `left' and `right'
*
* When the outline, or a sub-path, is `opened', the stroker merges
* the `border' outlines with caps. The `left' border receives all
* points, while the `right' border becomes empty.
*
* Use the function @FT_Stroker_Export instead if you want to
* retrieve all borders at once.
*/
FT_EXPORT( void )
FT_Stroker_ExportBorder( FT_Stroker stroker,
FT_StrokerBorder border,
FT_Outline* outline );
/**************************************************************
*
* @function:
* FT_Stroker_GetCounts
*
* @description:
* Call this function once you have finished parsing your paths
* with the stroker. It returns the number of points and
* contours necessary to export all points/borders from the stroked
* outline/path.
*
* @input:
* stroker ::
* The target stroker handle.
*
* @output:
* anum_points ::
* The number of points.
*
* anum_contours ::
* The number of contours.
*
* @return:
* FreeType error code. 0 means success.
*/
FT_EXPORT( FT_Error )
FT_Stroker_GetCounts( FT_Stroker stroker,
FT_UInt *anum_points,
FT_UInt *anum_contours );
/**************************************************************
*
* @function:
* FT_Stroker_Export
*
* @description:
* Call this function after @FT_Stroker_GetBorderCounts to
* export the all borders to your own @FT_Outline structure.
*
* Note that this function will append the border points and
* contours to your outline, but will not try to resize its
* arrays.
*
* @input:
* stroker ::
* The target stroker handle.
*
* outline ::
* The target outline handle.
*/
FT_EXPORT( void )
FT_Stroker_Export( FT_Stroker stroker,
FT_Outline* outline );
/**************************************************************
*
* @function:
* FT_Stroker_Done
*
* @description:
* Destroy a stroker object.
*
* @input:
* stroker ::
* A stroker handle. Can be NULL.
*/
FT_EXPORT( void )
FT_Stroker_Done( FT_Stroker stroker );
/**************************************************************
*
* @function:
* FT_Glyph_Stroke
*
* @description:
* Stroke a given outline glyph object with a given stroker.
*
* @inout:
* pglyph :: Source glyph handle on input, new glyph handle
* on output.
*
* @input:
* stroker ::
* A stroker handle.
*
* destroy ::
* A Boolean. If TRUE, the source glyph object is destroyed
* on success.
*
* @return:
* FreeType error code. 0 means success.
*
* @note:
* The source glyph is untouched in case of error.
*/
FT_EXPORT( FT_Error )
FT_Glyph_Stroke( FT_Glyph *pglyph,
FT_Stroker stroker,
FT_Bool destroy );
/**************************************************************
*
* @function:
* FT_Glyph_StrokeBorder
*
* @description:
* Stroke a given outline glyph object with a given stroker, but
* only return either its inside or outside border.
*
* @inout:
* pglyph ::
* Source glyph handle on input, new glyph handle on output.
*
* @input:
* stroker ::
* A stroker handle.
*
* inside ::
* A Boolean. If TRUE, return the inside border, otherwise
* the outside border.
*
* destroy ::
* A Boolean. If TRUE, the source glyph object is destroyed
* on success.
*
* @return:
* FreeType error code. 0 means success.
*
* @note:
* The source glyph is untouched in case of error.
*/
FT_EXPORT( FT_Error )
FT_Glyph_StrokeBorder( FT_Glyph *pglyph,
FT_Stroker stroker,
FT_Bool inside,
FT_Bool destroy );
/* */
FT_END_HEADER
#endif /* __FT_STROKE_H__ */
/* END */
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