tor-browser

ftstroke.h (21773B)

---

/****************************************************************************
*
* ftstroke.h
*
*   FreeType path stroker (specification).
*
* Copyright (C) 2002-2025 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 FTSTROKE_H_
#define FTSTROKE_H_

#include <freetype/ftoutln.h>
#include <freetype/ftglyph.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 colored (and anti-aliased) border around their
  *    shape.
  *
  * @order:
  *    FT_Stroker
  *
  *    FT_Stroker_LineJoin
  *    FT_Stroker_LineCap
  *    FT_StrokerBorder
  *
  *    FT_Outline_GetInsideBorder
  *    FT_Outline_GetOutsideBorder
  *
  *    FT_Glyph_Stroke
  *    FT_Glyph_StrokeBorder
  *
  *    FT_Stroker_New
  *    FT_Stroker_Set
  *    FT_Stroker_Rewind
  *    FT_Stroker_ParseOutline
  *    FT_Stroker_Done
  *
  *    FT_Stroker_BeginSubPath
  *    FT_Stroker_EndSubPath
  *
  *    FT_Stroker_LineTo
  *    FT_Stroker_ConicTo
  *    FT_Stroker_CubicTo
  *
  *    FT_Stroker_GetBorderCounts
  *    FT_Stroker_ExportBorder
  *    FT_Stroker_GetCounts
  *    FT_Stroker_Export
  *
  */


 /**************************************************************************
  *
  * @type:
  *   FT_Stroker
  *
  * @description:
  *   Opaque handle 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.  The outer corner of the joined
  *     lines is filled by enclosing the triangular region of the corner
  *     with a straight line between the outer corners of each stroke.
  *
  *   FT_STROKER_LINEJOIN_MITER_FIXED ::
  *     Used to render mitered line joins, with fixed bevels if the miter
  *     limit is exceeded.  The outer edges of the strokes for the two
  *     segments are extended until they meet at an angle.  A bevel join
  *     (see above) is used if the segments meet at too sharp an angle and
  *     the outer edges meet beyond a distance corresponding to the meter
  *     limit.  This prevents long spikes being created.
  *     `FT_STROKER_LINEJOIN_MITER_FIXED` generates a miter line join as
  *     used in PostScript and PDF.
  *
  *   FT_STROKER_LINEJOIN_MITER_VARIABLE ::
  *   FT_STROKER_LINEJOIN_MITER ::
  *     Used to render mitered line joins, with variable bevels if the miter
  *     limit is exceeded.  The intersection of the strokes is clipped
  *     perpendicularly to the bisector, at a distance corresponding to
  *     the miter limit. This prevents long spikes being created.
  *     `FT_STROKER_LINEJOIN_MITER_VARIABLE` generates a mitered line join
  *     as used in XPS.  `FT_STROKER_LINEJOIN_MITER` is an alias for
  *     `FT_STROKER_LINEJOIN_MITER_VARIABLE`, retained for backward
  *     compatibility.
  */
 typedef enum  FT_Stroker_LineJoin_
 {
   FT_STROKER_LINEJOIN_ROUND          = 0,
   FT_STROKER_LINEJOIN_BEVEL          = 1,
   FT_STROKER_LINEJOIN_MITER_VARIABLE = 2,
   FT_STROKER_LINEJOIN_MITER          = FT_STROKER_LINEJOIN_MITER_VARIABLE,
   FT_STROKER_LINEJOIN_MITER_FIXED    = 3

 } 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_
 {
   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' and '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_StrokerBorder_
 {
   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_RIGHT 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:
  *   library ::
  *     FreeType library handle.
  *
  * @output:
  *   astroker ::
  *     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_Library   library,
                 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 maximum reciprocal sine of half-angle at the miter join,
  *     expressed as 16.16 fixed-point value.
  *
  * @note:
  *   The `radius` is expressed in the same units as the outline
  *   coordinates.
  *
  *   The `miter_limit` multiplied by the `radius` gives the maximum size
  *   of a miter spike, at which it is clipped for
  *   @FT_STROKER_LINEJOIN_MITER_VARIABLE or replaced with a bevel join for
  *   @FT_STROKER_LINEJOIN_MITER_FIXED.
  *
  *   This function calls @FT_Stroker_Rewind automatically.
  */
 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~1, 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 generates two distinct 'border' outlines.
  *
  *   If `opened` is~1, the outline is processed as an open path, and the
  *   stroker generates 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~1, 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 an @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 'draws' 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 Bezier 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 Bezier in the stroker's current sub-path, from
  *   the last position.
  *
  * @input:
  *   stroker ::
  *     The target stroker handle.
  *
  *   control1 ::
  *     A pointer to the first Bezier control point.
  *
  *   control2 ::
  *     A pointer to second Bezier 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:
  *   Call this function once you have finished parsing your paths with the
  *   stroker.  It returns 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 appends the border points and contours to your
  *   outline, but does 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 all
  *   borders to your own @FT_Outline structure.
  *
  *   Note that this function appends the border points and contours to your
  *   outline, but does 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~1, 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.
  *
  *   Adding stroke may yield a significantly wider and taller glyph
  *   depending on how large of a radius was used to stroke the glyph.  You
  *   may need to manually adjust horizontal and vertical advance amounts to
  *   account for this added size.
  */
 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~1, return the inside border, otherwise the outside
  *     border.
  *
  *   destroy ::
  *     A Boolean.  If~1, 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.
  *
  *   Adding stroke may yield a significantly wider and taller glyph
  *   depending on how large of a radius was used to stroke the glyph.  You
  *   may need to manually adjust horizontal and vertical advance amounts to
  *   account for this added size.
  */
 FT_EXPORT( FT_Error )
 FT_Glyph_StrokeBorder( FT_Glyph    *pglyph,
                        FT_Stroker   stroker,
                        FT_Bool      inside,
                        FT_Bool      destroy );

 /* */

FT_END_HEADER

#endif /* FTSTROKE_H_ */


/* END */


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