326 lines
10 KiB
C
326 lines
10 KiB
C
#ifndef SW_FT_STROKER_H
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#define SW_FT_STROKER_H
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/***************************************************************************/
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/* */
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/* ftstroke.h */
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/* */
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/* FreeType path stroker (specification). */
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/* */
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/* Copyright 2002-2006, 2008, 2009, 2011-2012 by */
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/* David Turner, Robert Wilhelm, and Werner Lemberg. */
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/* */
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/* This file is part of the FreeType project, and may only be used, */
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/* modified, and distributed under the terms of the FreeType project */
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/* license, LICENSE.TXT. By continuing to use, modify, or distribute */
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/* this file you indicate that you have read the license and */
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/* understand and accept it fully. */
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/* */
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/***************************************************************************/
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#include "sw_ft_raster.h"
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/**************************************************************
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*
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* @type:
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* SW_FT_Stroker
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*
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* @description:
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* Opaque handler to a path stroker object.
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*/
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typedef struct SW_FT_StrokerRec_* SW_FT_Stroker;
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/**************************************************************
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*
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* @enum:
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* SW_FT_Stroker_LineJoin
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*
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* @description:
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* These values determine how two joining lines are rendered
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* in a stroker.
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*
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* @values:
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* SW_FT_STROKER_LINEJOIN_ROUND ::
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* Used to render rounded line joins. Circular arcs are used
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* to join two lines smoothly.
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*
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* SW_FT_STROKER_LINEJOIN_BEVEL ::
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* Used to render beveled line joins. The outer corner of
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* the joined lines is filled by enclosing the triangular
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* region of the corner with a straight line between the
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* outer corners of each stroke.
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*
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* SW_FT_STROKER_LINEJOIN_MITER_FIXED ::
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* Used to render mitered line joins, with fixed bevels if the
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* miter limit is exceeded. The outer edges of the strokes
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* for the two segments are extended until they meet at an
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* angle. If the segments meet at too sharp an angle (such
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* that the miter would extend from the intersection of the
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* segments a distance greater than the product of the miter
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* limit value and the border radius), then a bevel join (see
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* above) is used instead. This prevents long spikes being
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* created. SW_FT_STROKER_LINEJOIN_MITER_FIXED generates a miter
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* line join as used in PostScript and PDF.
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*
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* SW_FT_STROKER_LINEJOIN_MITER_VARIABLE ::
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* SW_FT_STROKER_LINEJOIN_MITER ::
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* Used to render mitered line joins, with variable bevels if
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* the miter limit is exceeded. The intersection of the
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* strokes is clipped at a line perpendicular to the bisector
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* of the angle between the strokes, at the distance from the
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* intersection of the segments equal to the product of the
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* miter limit value and the border radius. This prevents
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* long spikes being created.
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* SW_FT_STROKER_LINEJOIN_MITER_VARIABLE generates a mitered line
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* join as used in XPS. SW_FT_STROKER_LINEJOIN_MITER is an alias
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* for SW_FT_STROKER_LINEJOIN_MITER_VARIABLE, retained for
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* backwards compatibility.
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*/
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typedef enum SW_FT_Stroker_LineJoin_
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{
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SW_FT_STROKER_LINEJOIN_ROUND = 0,
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SW_FT_STROKER_LINEJOIN_BEVEL = 1,
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SW_FT_STROKER_LINEJOIN_MITER_VARIABLE = 2,
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SW_FT_STROKER_LINEJOIN_MITER = SW_FT_STROKER_LINEJOIN_MITER_VARIABLE,
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SW_FT_STROKER_LINEJOIN_MITER_FIXED = 3
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} SW_FT_Stroker_LineJoin;
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/**************************************************************
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*
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* @enum:
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* SW_FT_Stroker_LineCap
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*
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* @description:
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* These values determine how the end of opened sub-paths are
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* rendered in a stroke.
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*
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* @values:
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* SW_FT_STROKER_LINECAP_BUTT ::
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* The end of lines is rendered as a full stop on the last
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* point itself.
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*
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* SW_FT_STROKER_LINECAP_ROUND ::
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* The end of lines is rendered as a half-circle around the
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* last point.
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*
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* SW_FT_STROKER_LINECAP_SQUARE ::
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* The end of lines is rendered as a square around the
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* last point.
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*/
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typedef enum SW_FT_Stroker_LineCap_
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{
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SW_FT_STROKER_LINECAP_BUTT = 0,
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SW_FT_STROKER_LINECAP_ROUND,
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SW_FT_STROKER_LINECAP_SQUARE
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} SW_FT_Stroker_LineCap;
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/**************************************************************
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*
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* @enum:
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* SW_FT_StrokerBorder
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*
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* @description:
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* These values are used to select a given stroke border
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* in @SW_FT_Stroker_GetBorderCounts and @SW_FT_Stroker_ExportBorder.
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*
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* @values:
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* SW_FT_STROKER_BORDER_LEFT ::
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* Select the left border, relative to the drawing direction.
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*
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* SW_FT_STROKER_BORDER_RIGHT ::
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* Select the right border, relative to the drawing direction.
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*
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* @note:
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* Applications are generally interested in the `inside' and `outside'
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* borders. However, there is no direct mapping between these and the
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* `left' and `right' ones, since this really depends on the glyph's
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* drawing orientation, which varies between font formats.
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*
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* You can however use @SW_FT_Outline_GetInsideBorder and
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* @SW_FT_Outline_GetOutsideBorder to get these.
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*/
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typedef enum SW_FT_StrokerBorder_
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{
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SW_FT_STROKER_BORDER_LEFT = 0,
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SW_FT_STROKER_BORDER_RIGHT
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} SW_FT_StrokerBorder;
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/**************************************************************
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*
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* @function:
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* SW_FT_Stroker_New
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*
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* @description:
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* Create a new stroker object.
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*
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* @input:
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* library ::
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* FreeType library handle.
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*
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* @output:
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* astroker ::
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* A new stroker object handle. NULL in case of error.
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*
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* @return:
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* FreeType error code. 0~means success.
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*/
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SW_FT_Error
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SW_FT_Stroker_New( SW_FT_Stroker *astroker );
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/**************************************************************
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*
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* @function:
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* SW_FT_Stroker_Set
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*
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* @description:
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* Reset a stroker object's attributes.
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*
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* @input:
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* stroker ::
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* The target stroker handle.
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*
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* radius ::
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* The border radius.
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*
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* line_cap ::
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* The line cap style.
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*
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* line_join ::
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* The line join style.
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*
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* miter_limit ::
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* The miter limit for the SW_FT_STROKER_LINEJOIN_MITER_FIXED and
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* SW_FT_STROKER_LINEJOIN_MITER_VARIABLE line join styles,
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* expressed as 16.16 fixed-point value.
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*
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* @note:
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* The radius is expressed in the same units as the outline
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* coordinates.
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*/
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void
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SW_FT_Stroker_Set( SW_FT_Stroker stroker,
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SW_FT_Fixed radius,
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SW_FT_Stroker_LineCap line_cap,
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SW_FT_Stroker_LineJoin line_join,
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SW_FT_Fixed miter_limit );
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/**************************************************************
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*
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* @function:
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* SW_FT_Stroker_ParseOutline
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*
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* @description:
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* A convenience function used to parse a whole outline with
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* the stroker. The resulting outline(s) can be retrieved
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* later by functions like @SW_FT_Stroker_GetCounts and @SW_FT_Stroker_Export.
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*
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* @input:
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* stroker ::
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* The target stroker handle.
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*
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* outline ::
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* The source outline.
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*
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* opened ::
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* A boolean. If~1, the outline is treated as an open path instead
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* of a closed one.
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*
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* @return:
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* FreeType error code. 0~means success.
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*
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* @note:
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* If `opened' is~0 (the default), the outline is treated as a closed
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* path, and the stroker generates two distinct `border' outlines.
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*
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* If `opened' is~1, the outline is processed as an open path, and the
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* stroker generates a single `stroke' outline.
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*
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* This function calls @SW_FT_Stroker_Rewind automatically.
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*/
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SW_FT_Error
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SW_FT_Stroker_ParseOutline( SW_FT_Stroker stroker,
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SW_FT_Outline* outline,
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SW_FT_Bool opened );
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/**************************************************************
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*
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* @function:
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* SW_FT_Stroker_GetCounts
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*
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* @description:
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* Call this function once you have finished parsing your paths
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* with the stroker. It returns the number of points and
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* contours necessary to export all points/borders from the stroked
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* outline/path.
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*
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* @input:
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* stroker ::
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* The target stroker handle.
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*
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* @output:
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* anum_points ::
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* The number of points.
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*
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* anum_contours ::
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* The number of contours.
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*
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* @return:
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* FreeType error code. 0~means success.
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*/
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SW_FT_Error
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SW_FT_Stroker_GetCounts( SW_FT_Stroker stroker,
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SW_FT_UInt *anum_points,
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SW_FT_UInt *anum_contours );
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/**************************************************************
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*
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* @function:
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* SW_FT_Stroker_Export
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*
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* @description:
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* Call this function after @SW_FT_Stroker_GetBorderCounts to
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* export all borders to your own @SW_FT_Outline structure.
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*
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* Note that this function appends the border points and
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* contours to your outline, but does not try to resize its
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* arrays.
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*
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* @input:
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* stroker ::
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* The target stroker handle.
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*
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* outline ::
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* The target outline handle.
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*/
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void
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SW_FT_Stroker_Export( SW_FT_Stroker stroker,
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SW_FT_Outline* outline );
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/**************************************************************
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*
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* @function:
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* SW_FT_Stroker_Done
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*
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* @description:
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* Destroy a stroker object.
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*
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* @input:
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* stroker ::
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* A stroker handle. Can be NULL.
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*/
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void
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SW_FT_Stroker_Done( SW_FT_Stroker stroker );
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#endif // SW_FT_STROKER_H
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