/***************************************************************************/

/*                                                                         */

/*  autohint.h                                                             */

/*                                                                         */

/*    High-level `autohint' module-specific interface (specification).     */

/*                                                                         */

/*  Copyright 1996-2001, 2002 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, FTL.TXT.  By continuing to use, modify, or distribute     */

/*  this file you indicate that you have read the license and              */

/*  understand and accept it fully.                                        */

/*                                                                         */

/***************************************************************************/

  /*************************************************************************/

  /*                                                                       */

  /* The auto-hinter is used to load and automatically hint glyphs if a    */

  /* format-specific hinter isn't available.                               */

  /*                                                                       */

  /*************************************************************************/

#ifndef __AUTOHINT_H__

#define __AUTOHINT_H__

  /*************************************************************************/

  /*                                                                       */

  /* A small technical note regarding automatic hinting in order to        */

  /* clarify this module interface.                                        */

  /*                                                                       */

  /* An automatic hinter might compute two kinds of data for a given face: */

  /*                                                                       */

  /* - global hints: Usually some metrics that describe global properties  */

  /*                 of the face.  It is computed by scanning more or less */

  /*                 agressively the glyphs in the face, and thus can be   */

  /*                 very slow to compute (even if the size of global      */

  /*                 hints is really small).                               */

  /*                                                                       */

  /* - glyph hints:  These describe some important features of the glyph   */

  /*                 outline, as well as how to align them.  They are      */

  /*                 generally much faster to compute than global hints.   */

  /*                                                                       */

  /* The current FreeType auto-hinter does a pretty good job while         */

  /* performing fast computations for both global and glyph hints.         */

  /* However, we might be interested in introducing more complex and       */

  /* powerful algorithms in the future, like the one described in the John */

  /* D. Hobby paper, which unfortunately requires a lot more horsepower.   */

  /*                                                                       */

  /* Because a sufficiently sophisticated font management system would     */

  /* typically implement an LRU cache of opened face objects to reduce     */

  /* memory usage, it is a good idea to be able to avoid recomputing       */

  /* global hints every time the same face is re-opened.                   */

  /*                                                                       */

  /* We thus provide the ability to cache global hints outside of the face */

  /* object, in order to speed up font re-opening time.  Of course, this   */

  /* feature is purely optional, so most client programs won't even notice */

  /* it.                                                                   */

  /*                                                                       */

  /* I initially thought that it would be a good idea to cache the glyph   */

  /* hints too.  However, my general idea now is that if you really need   */

  /* to cache these too, you are simply in need of a new font format,      */

  /* where all this information could be stored within the font file and   */

  /* decoded on the fly.                                                   */

  /*                                                                       */

  /*************************************************************************/

#include <ft2build.h>

#include FT_FREETYPE_H

FT_BEGIN_HEADER

  typedef struct FT_AutoHinterRec_  *FT_AutoHinter;

  /*************************************************************************/

  /*                                                                       */

  /* <FuncType>                                                            */

  /*    FT_AutoHinter_GlobalGetFunc                                        */

  /*                                                                       */

  /* <Description>                                                         */

  /*    Retrieves the global hints computed for a given face object the    */

  /*    resulting data is dissociated from the face and will survive a     */

  /*    call to FT_Done_Face().  It must be discarded through the API      */

  /*    FT_AutoHinter_GlobalDoneFunc().                                    */

  /*                                                                       */

  /* <Input>                                                               */

  /*    hinter        :: A handle to the source auto-hinter.               */

  /*                                                                       */

  /*    face          :: A handle to the source face object.               */

  /*                                                                       */

  /* <Output>                                                              */

  /*    global_hints  :: A typeless pointer to the global hints.           */

  /*                                                                       */

  /*    global_len    :: The size in bytes of the global hints.            */

  /*                                                                       */

  typedef void

  (*FT_AutoHinter_GlobalGetFunc)( FT_AutoHinter  hinter,

                                  FT_Face        face,

                                  void**         global_hints,

                                  long*          global_len );

  /*************************************************************************/

  /*                                                                       */

  /* <FuncType>                                                            */

  /*    FT_AutoHinter_GlobalDoneFunc                                       */

  /*                                                                       */

  /* <Description>                                                         */

  /*    Discards the global hints retrieved through                        */

  /*    FT_AutoHinter_GlobalGetFunc().  This is the only way these hints   */

  /*    are freed from memory.                                             */

  /*                                                                       */

  /* <Input>                                                               */

  /*    hinter :: A handle to the auto-hinter module.                      */

  /*                                                                       */

  /*    global :: A pointer to retrieved global hints to discard.          */

  /*                                                                       */

  typedef void

  (*FT_AutoHinter_GlobalDoneFunc)( FT_AutoHinter  hinter,

                                   void*          global );

  /*************************************************************************/

  /*                                                                       */

  /* <FuncType>                                                            */

  /*    FT_AutoHinter_GlobalResetFunc                                      */

  /*                                                                       */

  /* <Description>                                                         */

  /*    This function is used to recompute the global metrics in a given   */

  /*    font.  This is useful when global font data changes (e.g. Multiple */

  /*    Masters fonts where blend coordinates change).                     */

  /*                                                                       */

  /* <Input>                                                               */

  /*    hinter :: A handle to the source auto-hinter.                      */

  /*                                                                       */

  /*    face   :: A handle to the face.                                    */

  /*                                                                       */

  typedef void

  (*FT_AutoHinter_GlobalResetFunc)( FT_AutoHinter  hinter,

                                    FT_Face        face );

  /*************************************************************************/

  /*                                                                       */

  /* <FuncType>                                                            */

  /*    FT_AutoHinter_GlyphLoadFunc                                        */

  /*                                                                       */

  /* <Description>                                                         */

  /*    This function is used to load, scale, and automatically hint a     */

  /*    glyph from a given face.                                           */

  /*                                                                       */

  /* <Input>                                                               */

  /*    face        :: A handle to the face.                               */

  /*                                                                       */

  /*    glyph_index :: The glyph index.                                    */

  /*                                                                       */

  /*    load_flags  :: The load flags.                                     */

  /*                                                                       */

  /* <Note>                                                                */

  /*    This function is capable of loading composite glyphs by hinting    */

  /*    each sub-glyph independently (which improves quality).             */

  /*                                                                       */

  /*    It will call the font driver with FT_Load_Glyph(), with            */

  /*    FT_LOAD_NO_SCALE set.                                              */

  /*                                                                       */

  typedef FT_Error

  (*FT_AutoHinter_GlyphLoadFunc)( FT_AutoHinter  hinter,

                                  FT_GlyphSlot   slot,

                                  FT_Size        size,

                                  FT_UInt        glyph_index,

                                  FT_Int32       load_flags );

  /*************************************************************************/

  /*                                                                       */

  /* <Struct>                                                              */

  /*    FT_AutoHinter_ServiceRec                                           */

  /*                                                                       */

  /* <Description>                                                         */

  /*    The auto-hinter module's interface.                                */

  /*                                                                       */

  typedef struct  FT_AutoHinter_ServiceRec_

  {

    FT_AutoHinter_GlobalResetFunc  reset_face;

    FT_AutoHinter_GlobalGetFunc    get_global_hints;

    FT_AutoHinter_GlobalDoneFunc   done_global_hints;

    FT_AutoHinter_GlyphLoadFunc    load_glyph;

  } FT_AutoHinter_ServiceRec, *FT_AutoHinter_Service;

FT_END_HEADER

#endif /* __AUTOHINT_H__ */

/* END */