ftstroke.h

奇趣公司比较新的qt/emd版本

/***************************************************************************/
/*                                                                         */
/*  ftstroke.h                                                             */
/*                                                                         */
/*    FreeType path stroker (specification).                               */
/*                                                                         */
/*  Copyright 2002, 2003, 2004, 2005, 2006 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' 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_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:
   *   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 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 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.
   *