freetype2/include/ftadvanc.h

/***************************************************************************/
/*                                                                         */
/*  ftadvanc.h                                                             */
/*                                                                         */
/*    Quick computation of advance widths (specification only).            */
/*                                                                         */
/*  Copyright 2008-2015 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 __FTADVANC_H__
#define __FTADVANC_H__


#include <ft2build.h>
#include FT_FREETYPE_H

#ifdef FREETYPE_H
#error "freetype.h of FreeType 1 has been loaded!"
#error "Please fix the directory search order for header files"
#error "so that freetype.h of FreeType 2 is found first."
#endif


FT_BEGIN_HEADER


  /**************************************************************************
   *
   * @section:
   *   quick_advance
   *
   * @title:
   *   Quick retrieval of advance values
   *
   * @abstract:
   *   Retrieve horizontal and vertical advance values without processing
   *   glyph outlines, if possible.
   *
   * @description:
   *   This section contains functions to quickly extract advance values
   *   without handling glyph outlines, if possible.
   *
   * @order:
   *   FT_Get_Advance
   *   FT_Get_Advances
   *
   */


  /*************************************************************************/
  /*                                                                       */
  /* <Const>                                                               */
  /*    FT_ADVANCE_FLAG_FAST_ONLY                                          */
  /*                                                                       */
  /* <Description>                                                         */
  /*    A bit-flag to be OR-ed with the `flags' parameter of the           */
  /*    @FT_Get_Advance and @FT_Get_Advances functions.                    */
  /*                                                                       */
  /*    If set, it indicates that you want these functions to fail if the  */
  /*    corresponding hinting mode or font driver doesn't allow for very   */
  /*    quick advance computation.                                         */
  /*                                                                       */
  /*    Typically, glyphs that are either unscaled, unhinted, bitmapped,   */
  /*    or light-hinted can have their advance width computed very         */
  /*    quickly.                                                           */
  /*                                                                       */
  /*    Normal and bytecode hinted modes that require loading, scaling,    */
  /*    and hinting of the glyph outline, are extremely slow by            */
  /*    comparison.                                                        */
  /*                                                                       */
#define FT_ADVANCE_FLAG_FAST_ONLY  0x20000000UL


  /*************************************************************************/
  /*                                                                       */
  /* <Function>                                                            */
  /*    FT_Get_Advance                                                     */
  /*                                                                       */
  /* <Description>                                                         */
  /*    Retrieve the advance value of a given glyph outline in an          */
  /*    @FT_Face.                                                          */
  /*                                                                       */
  /* <Input>                                                               */
  /*    face       :: The source @FT_Face handle.                          */
  /*                                                                       */
  /*    gindex     :: The glyph index.                                     */
  /*                                                                       */
  /*    load_flags :: A set of bit flags similar to those used when        */
  /*                  calling @FT_Load_Glyph, used to determine what kind  */
  /*                  of advances you need.                                */
  /* <Output>                                                              */
  /*    padvance :: The advance value.  If scaling is performed (based on  */
  /*                the value of `load_flags'), the advance value is in    */
  /*                16.16 format.  Otherwise, it is in font units.         */
  /*                                                                       */
  /*                If @FT_LOAD_VERTICAL_LAYOUT is set, this is the        */
  /*                vertical advance corresponding to a vertical layout.   */
  /*                Otherwise, it is the horizontal advance in a           */
  /*                horizontal layout.                                     */
  /*                                                                       */
  /* <Return>                                                              */
  /*    FreeType error code.  0 means success.                             */
  /*                                                                       */
  /* <Note>                                                                */
  /*    This function may fail if you use @FT_ADVANCE_FLAG_FAST_ONLY and   */
  /*    if the corresponding font backend doesn't have a quick way to      */
  /*    retrieve the advances.                                             */
  /*                                                                       */
  /*    A scaled advance is returned in 16.16 format but isn't transformed */
  /*    by the affine transformation specified by @FT_Set_Transform.       */
  /*                                                                       */
  FT_EXPORT( FT_Error )
  FT_Get_Advance( FT_Face    face,
                  FT_UInt    gindex,
                  FT_Int32   load_flags,
                  FT_Fixed  *padvance );


  /*************************************************************************/
  /*                                                                       */
  /* <Function>                                                            */
  /*    FT_Get_Advances                                                    */
  /*                                                                       */
  /* <Description>                                                         */
  /*    Retrieve the advance values of several glyph outlines in an        */
  /*    @FT_Face.                                                          */
  /*                                                                       */
  /* <Input>                                                               */
  /*    face        :: The source @FT_Face handle.                         */
  /*                                                                       */
  /*    start       :: The first glyph index.                              */
  /*                                                                       */
  /*    count       :: The number of advance values you want to retrieve.  */
  /*                                                                       */
  /*    load_flags  :: A set of bit flags similar to those used when       */
  /*                   calling @FT_Load_Glyph.                             */
  /*                                                                       */
  /* <Output>                                                              */
  /*    padvance :: The advance values.  This array, to be provided by the */
  /*                caller, must contain at least `count' elements.        */
  /*                                                                       */
  /*                If scaling is performed (based on the value of         */
  /*                `load_flags'), the advance values are in 16.16 format. */
  /*                Otherwise, they are in font units.                     */
  /*                                                                       */
  /*                If @FT_LOAD_VERTICAL_LAYOUT is set, these are the      */
  /*                vertical advances corresponding to a vertical layout.  */
  /*                Otherwise, they are the horizontal advances in a       */
  /*                horizontal layout.                                     */
  /*                                                                       */
  /* <Return>                                                              */
  /*    FreeType error code.  0 means success.                             */
  /*                                                                       */
  /* <Note>                                                                */
  /*    This function may fail if you use @FT_ADVANCE_FLAG_FAST_ONLY and   */
  /*    if the corresponding font backend doesn't have a quick way to      */
  /*    retrieve the advances.                                             */
  /*                                                                       */
  /*    Scaled advances are returned in 16.16 format but aren't            */
  /*    transformed by the affine transformation specified by              */
  /*    @FT_Set_Transform.                                                 */
  /*                                                                       */
  FT_EXPORT( FT_Error )
  FT_Get_Advances( FT_Face    face,
                   FT_UInt    start,
                   FT_UInt    count,
                   FT_Int32   load_flags,
                   FT_Fixed  *padvances );

  /* */


FT_END_HEADER

#endif /* __FTADVANC_H__ */


/* END */