diff options
Diffstat (limited to 'modules/freetype2/include/freetype/ftstroke.h')
| -rw-r--r-- | modules/freetype2/include/freetype/ftstroke.h | 773 |
1 files changed, 773 insertions, 0 deletions
diff --git a/modules/freetype2/include/freetype/ftstroke.h b/modules/freetype2/include/freetype/ftstroke.h new file mode 100644 index 0000000000..b3d90802a5 --- /dev/null +++ b/modules/freetype2/include/freetype/ftstroke.h @@ -0,0 +1,773 @@ +/**************************************************************************** + * + * ftstroke.h + * + * FreeType path stroker (specification). + * + * Copyright (C) 2002-2023 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 */ + + +/* Local Variables: */ +/* coding: utf-8 */ +/* End: */ |