pshints.h

Go to the documentation of this file.

/***************************************************************************/
/*                                                                         */
/*  pshints.h                                                              */
/*                                                                         */
/*    Interface to Postscript-specific (Type 1 and Type 2) hints           */
/*    recorders (specification only).  These are used to support native    */
/*    T1/T2 hints in the `type1', `cid', and `cff' font drivers.           */
/*                                                                         */
/*  Copyright 2001-2003, 2005-2007, 2009, 2012 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 __PSHINTS_H__
#define __PSHINTS_H__


#include <ft2build.h>
#include FT_FREETYPE_H
#include FT_TYPE1_TABLES_H


FT_BEGIN_HEADER


  /*************************************************************************/
  /*************************************************************************/
  /*****                                                               *****/
  /*****               INTERNAL REPRESENTATION OF GLOBALS              *****/
  /*****                                                               *****/
  /*************************************************************************/
  /*************************************************************************/

  typedef struct PSH_GlobalsRec_*  PSH_Globals;

  typedef FT_Error
  (*PSH_Globals_NewFunc)( FT_Memory     memory,
                          T1_Private*   private_dict,
                          PSH_Globals*  aglobals );

  typedef FT_Error
  (*PSH_Globals_SetScaleFunc)( PSH_Globals  globals,
                               FT_Fixed     x_scale,
                               FT_Fixed     y_scale,
                               FT_Fixed     x_delta,
                               FT_Fixed     y_delta );

  typedef void
  (*PSH_Globals_DestroyFunc)( PSH_Globals  globals );


  typedef struct  PSH_Globals_FuncsRec_
  {
    PSH_Globals_NewFunc       create;
    PSH_Globals_SetScaleFunc  set_scale;
    PSH_Globals_DestroyFunc   destroy;

  } PSH_Globals_FuncsRec, *PSH_Globals_Funcs;


  /*************************************************************************/
  /*************************************************************************/
  /*****                                                               *****/
  /*****                  PUBLIC TYPE 1 HINTS RECORDER                 *****/
  /*****                                                               *****/
  /*************************************************************************/
  /*************************************************************************/

  /*************************************************************************
   *
   * @type:
   *   T1_Hints
   *
   * @description:
   *   This is a handle to an opaque structure used to record glyph hints
   *   from a Type 1 character glyph character string.
   *
   *   The methods used to operate on this object are defined by the
   *   @T1_Hints_FuncsRec structure.  Recording glyph hints is normally
   *   achieved through the following scheme:
   *
   *   - Open a new hint recording session by calling the `open' method.
   *     This rewinds the recorder and prepare it for new input.
   *
   *   - For each hint found in the glyph charstring, call the corresponding
   *     method (`stem', `stem3', or `reset').  Note that these functions do
   *     not return an error code.
   *
   *   - Close the recording session by calling the `close' method.  It
   *     returns an error code if the hints were invalid or something
   *     strange happened (e.g., memory shortage).
   *
   *   The hints accumulated in the object can later be used by the
   *   PostScript hinter.
   *
   */
  typedef struct T1_HintsRec_*  T1_Hints;


  /*************************************************************************
   *
   * @type:
   *   T1_Hints_Funcs
   *
   * @description:
   *   A pointer to the @T1_Hints_FuncsRec structure that defines the API of
   *   a given @T1_Hints object.
   *
   */
  typedef const struct T1_Hints_FuncsRec_*  T1_Hints_Funcs;


  /*************************************************************************
   *
   * @functype:
   *   T1_Hints_OpenFunc
   *
   * @description:
   *   A method of the @T1_Hints class used to prepare it for a new Type 1
   *   hints recording session.
   *
   * @input:
   *   hints ::
   *     A handle to the Type 1 hints recorder.
   *
   * @note:
   *   You should always call the @T1_Hints_CloseFunc method in order to
   *   close an opened recording session.
   *
   */
  typedef void
  (*T1_Hints_OpenFunc)( T1_Hints  hints );


  /*************************************************************************
   *
   * @functype:
   *   T1_Hints_SetStemFunc
   *
   * @description:
   *   A method of the @T1_Hints class used to record a new horizontal or
   *   vertical stem.  This corresponds to the Type 1 `hstem' and `vstem'
   *   operators.
   *
   * @input:
   *   hints ::
   *     A handle to the Type 1 hints recorder.
   *
   *   dimension ::
   *     0 for horizontal stems (hstem), 1 for vertical ones (vstem).
   *
   *   coords ::
   *     Array of 2 coordinates in 16.16 format, used as (position,length)
   *     stem descriptor.
   *
   * @note:
   *   Use vertical coordinates (y) for horizontal stems (dim=0).  Use
   *   horizontal coordinates (x) for vertical stems (dim=1).
   *
   *   `coords[0]' is the absolute stem position (lowest coordinate);
   *   `coords[1]' is the length.
   *
   *   The length can be negative, in which case it must be either -20 or
   *   -21.  It is interpreted as a `ghost' stem, according to the Type 1
   *   specification.
   *
   *   If the length is -21 (corresponding to a bottom ghost stem), then
   *   the real stem position is `coords[0]+coords[1]'.
   *
   */
  typedef void
  (*T1_Hints_SetStemFunc)( T1_Hints   hints,
                           FT_UInt    dimension,
                           FT_Fixed*  coords );


  /*************************************************************************
   *
   * @functype:
   *   T1_Hints_SetStem3Func
   *
   * @description:
   *   A method of the @T1_Hints class used to record three
   *   counter-controlled horizontal or vertical stems at once.
   *
   * @input:
   *   hints ::
   *     A handle to the Type 1 hints recorder.
   *
   *   dimension ::
   *     0 for horizontal stems, 1 for vertical ones.
   *
   *   coords ::
   *     An array of 6 values in 16.16 format, holding 3 (position,length)
   *     pairs for the counter-controlled stems.
   *
   * @note:
   *   Use vertical coordinates (y) for horizontal stems (dim=0).  Use
   *   horizontal coordinates (x) for vertical stems (dim=1).
   *
   *   The lengths cannot be negative (ghost stems are never
   *   counter-controlled).
   *
   */
  typedef void
  (*T1_Hints_SetStem3Func)( T1_Hints   hints,
                            FT_UInt    dimension,
                            FT_Fixed*  coords );


  /*************************************************************************
   *
   * @functype:
   *   T1_Hints_ResetFunc
   *
   * @description:
   *   A method of the @T1_Hints class used to reset the stems hints in a
   *   recording session.
   *
   * @input:
   *   hints ::
   *     A handle to the Type 1 hints recorder.
   *
   *   end_point ::
   *     The index of the last point in the input glyph in which the
   *     previously defined hints apply.
   *
   */
  typedef void
  (*T1_Hints_ResetFunc)( T1_Hints  hints,
                         FT_UInt   end_point );


  /*************************************************************************
   *
   * @functype:
   *   T1_Hints_CloseFunc
   *
   * @description:
   *   A method of the @T1_Hints class used to close a hint recording
   *   session.
   *
   * @input:
   *   hints ::
   *     A handle to the Type 1 hints recorder.
   *
   *   end_point ::
   *     The index of the last point in the input glyph.
   *
   * @return:
   *   FreeType error code.  0 means success.
   *
   * @note:
   *   The error code is set to indicate that an error occurred during the
   *   recording session.
   *
   */
  typedef FT_Error
  (*T1_Hints_CloseFunc)( T1_Hints  hints,
                         FT_UInt   end_point );


  /*************************************************************************
   *
   * @functype:
   *   T1_Hints_ApplyFunc
   *
   * @description:
   *   A method of the @T1_Hints class used to apply hints to the
   *   corresponding glyph outline.  Must be called once all hints have been
   *   recorded.
   *
   * @input:
   *   hints ::
   *     A handle to the Type 1 hints recorder.
   *
   *   outline ::
   *     A pointer to the target outline descriptor.
   *
   *   globals ::
   *     The hinter globals for this font.
   *
   *   hint_mode ::
   *     Hinting information.
   *
   * @return:
   *   FreeType error code.  0 means success.
   *
   * @note:
   *   On input, all points within the outline are in font coordinates. On
   *   output, they are in 1/64th of pixels.
   *
   *   The scaling transformation is taken from the `globals' object which
   *   must correspond to the same font as the glyph.
   *
   */
  typedef FT_Error
  (*T1_Hints_ApplyFunc)( T1_Hints        hints,
                         FT_Outline*     outline,
                         PSH_Globals     globals,
                         FT_Render_Mode  hint_mode );


  /*************************************************************************
   *
   * @struct:
   *   T1_Hints_FuncsRec
   *
   * @description:
   *   The structure used to provide the API to @T1_Hints objects.
   *
   * @fields:
   *   hints ::
   *     A handle to the T1 Hints recorder.
   *
   *   open ::
   *     The function to open a recording session.
   *
   *   close ::
   *     The function to close a recording session.
   *
   *   stem ::
   *     The function to set a simple stem.
   *
   *   stem3 ::
   *     The function to set counter-controlled stems.
   *
   *   reset ::
   *     The function to reset stem hints.
   *
   *   apply ::
   *     The function to apply the hints to the corresponding glyph outline.
   *
   */
  typedef struct  T1_Hints_FuncsRec_
  {
    T1_Hints               hints;
    T1_Hints_OpenFunc      open;
    T1_Hints_CloseFunc     close;
    T1_Hints_SetStemFunc   stem;
    T1_Hints_SetStem3Func  stem3;
    T1_Hints_ResetFunc     reset;
    T1_Hints_ApplyFunc     apply;

  } T1_Hints_FuncsRec;


  /*************************************************************************/
  /*************************************************************************/
  /*****                                                               *****/
  /*****                  PUBLIC TYPE 2 HINTS RECORDER                 *****/
  /*****                                                               *****/
  /*************************************************************************/
  /*************************************************************************/

  /*************************************************************************
   *
   * @type:
   *   T2_Hints
   *
   * @description:
   *   This is a handle to an opaque structure used to record glyph hints
   *   from a Type 2 character glyph character string.
   *
   *   The methods used to operate on this object are defined by the
   *   @T2_Hints_FuncsRec structure.  Recording glyph hints is normally
   *   achieved through the following scheme:
   *
   *   - Open a new hint recording session by calling the `open' method.
   *     This rewinds the recorder and prepare it for new input.
   *
   *   - For each hint found in the glyph charstring, call the corresponding
   *     method (`stems', `hintmask', `counters').  Note that these
   *     functions do not return an error code.
   *
   *   - Close the recording session by calling the `close' method.  It
   *     returns an error code if the hints were invalid or something
   *     strange happened (e.g., memory shortage).
   *
   *   The hints accumulated in the object can later be used by the
   *   Postscript hinter.
   *
   */
  typedef struct T2_HintsRec_*  T2_Hints;


  /*************************************************************************
   *
   * @type:
   *   T2_Hints_Funcs
   *
   * @description:
   *   A pointer to the @T2_Hints_FuncsRec structure that defines the API of
   *   a given @T2_Hints object.
   *
   */
  typedef const struct T2_Hints_FuncsRec_*  T2_Hints_Funcs;


  /*************************************************************************
   *
   * @functype:
   *   T2_Hints_OpenFunc
   *
   * @description:
   *   A method of the @T2_Hints class used to prepare it for a new Type 2
   *   hints recording session.
   *
   * @input:
   *   hints ::
   *     A handle to the Type 2 hints recorder.
   *
   * @note:
   *   You should always call the @T2_Hints_CloseFunc method in order to
   *   close an opened recording session.
   *
   */
  typedef void
  (*T2_Hints_OpenFunc)( T2_Hints  hints );


  /*************************************************************************
   *
   * @functype:
   *   T2_Hints_StemsFunc
   *
   * @description:
   *   A method of the @T2_Hints class used to set the table of stems in
   *   either the vertical or horizontal dimension.  Equivalent to the
   *   `hstem', `vstem', `hstemhm', and `vstemhm' Type 2 operators.
   *
   * @input:
   *   hints ::
   *     A handle to the Type 2 hints recorder.
   *
   *   dimension ::
   *     0 for horizontal stems (hstem), 1 for vertical ones (vstem).
   *
   *   count ::
   *     The number of stems.
   *
   *   coords ::
   *     An array of `count' (position,length) pairs in 16.16 format.
   *
   * @note:
   *   Use vertical coordinates (y) for horizontal stems (dim=0).  Use
   *   horizontal coordinates (x) for vertical stems (dim=1).
   *
   *   There are `2*count' elements in the `coords' array.  Each even
   *   element is an absolute position in font units, each odd element is a
   *   length in font units.
   *
   *   A length can be negative, in which case it must be either -20 or
   *   -21.  It is interpreted as a `ghost' stem, according to the Type 1
   *   specification.
   *
   */
  typedef void
  (*T2_Hints_StemsFunc)( T2_Hints   hints,
                         FT_UInt    dimension,
                         FT_UInt    count,
                         FT_Fixed*  coordinates );


  /*************************************************************************
   *
   * @functype:
   *   T2_Hints_MaskFunc
   *
   * @description:
   *   A method of the @T2_Hints class used to set a given hintmask (this
   *   corresponds to the `hintmask' Type 2 operator).
   *
   * @input:
   *   hints ::
   *     A handle to the Type 2 hints recorder.
   *
   *   end_point ::
   *     The glyph index of the last point to which the previously defined
   *     or activated hints apply.
   *
   *   bit_count ::
   *     The number of bits in the hint mask.
   *
   *   bytes ::
   *     An array of bytes modelling the hint mask.
   *
   * @note:
   *   If the hintmask starts the charstring (before any glyph point
   *   definition), the value of `end_point' should be 0.
   *
   *   `bit_count' is the number of meaningful bits in the `bytes' array; it
   *   must be equal to the total number of hints defined so far (i.e.,
   *   horizontal+verticals).
   *
   *   The `bytes' array can come directly from the Type 2 charstring and
   *   respects the same format.
   *
   */
  typedef void
  (*T2_Hints_MaskFunc)( T2_Hints        hints,
                        FT_UInt         end_point,
                        FT_UInt         bit_count,
                        const FT_Byte*  bytes );


  /*************************************************************************
   *
   * @functype:
   *   T2_Hints_CounterFunc
   *
   * @description:
   *   A method of the @T2_Hints class used to set a given counter mask
   *   (this corresponds to the `hintmask' Type 2 operator).
   *
   * @input:
   *   hints ::
   *     A handle to the Type 2 hints recorder.
   *
   *   end_point ::
   *     A glyph index of the last point to which the previously defined or
   *     active hints apply.
   *
   *   bit_count ::
   *     The number of bits in the hint mask.
   *
   *   bytes ::
   *     An array of bytes modelling the hint mask.
   *
   * @note:
   *   If the hintmask starts the charstring (before any glyph point
   *   definition), the value of `end_point' should be 0.
   *
   *   `bit_count' is the number of meaningful bits in the `bytes' array; it
   *   must be equal to the total number of hints defined so far (i.e.,
   *   horizontal+verticals).
   *
   *    The `bytes' array can come directly from the Type 2 charstring and
   *    respects the same format.
   *
   */
  typedef void
  (*T2_Hints_CounterFunc)( T2_Hints        hints,
                           FT_UInt         bit_count,
                           const FT_Byte*  bytes );


  /*************************************************************************
   *
   * @functype:
   *   T2_Hints_CloseFunc
   *
   * @description:
   *   A method of the @T2_Hints class used to close a hint recording
   *   session.
   *
   * @input:
   *   hints ::
   *     A handle to the Type 2 hints recorder.
   *
   *   end_point ::
   *     The index of the last point in the input glyph.
   *
   * @return:
   *   FreeType error code.  0 means success.
   *
   * @note:
   *   The error code is set to indicate that an error occurred during the
   *   recording session.
   *
   */
  typedef FT_Error
  (*T2_Hints_CloseFunc)( T2_Hints  hints,
                         FT_UInt   end_point );


  /*************************************************************************
   *
   * @functype:
   *   T2_Hints_ApplyFunc
   *
   * @description:
   *   A method of the @T2_Hints class used to apply hints to the
   *   corresponding glyph outline.  Must be called after the `close'
   *   method.
   *
   * @input:
   *   hints ::
   *     A handle to the Type 2 hints recorder.
   *
   *   outline ::
   *     A pointer to the target outline descriptor.
   *
   *   globals ::
   *     The hinter globals for this font.
   *
   *   hint_mode ::
   *     Hinting information.
   *
   * @return:
   *   FreeType error code.  0 means success.
   *
   * @note:
   *   On input, all points within the outline are in font coordinates. On
   *   output, they are in 1/64th of pixels.
   *
   *   The scaling transformation is taken from the `globals' object which
   *   must correspond to the same font than the glyph.
   *
   */
  typedef FT_Error
  (*T2_Hints_ApplyFunc)( T2_Hints        hints,
                         FT_Outline*     outline,
                         PSH_Globals     globals,
                         FT_Render_Mode  hint_mode );


  /*************************************************************************
   *
   * @struct:
   *   T2_Hints_FuncsRec
   *
   * @description:
   *   The structure used to provide the API to @T2_Hints objects.
   *
   * @fields:
   *   hints ::
   *     A handle to the T2 hints recorder object.
   *
   *   open ::
   *     The function to open a recording session.
   *
   *   close ::
   *     The function to close a recording session.
   *
   *   stems ::
   *     The function to set the dimension's stems table.
   *
   *   hintmask ::
   *     The function to set hint masks.
   *
   *   counter ::
   *     The function to set counter masks.
   *
   *   apply ::
   *     The function to apply the hints on the corresponding glyph outline.
   *
   */
  typedef struct  T2_Hints_FuncsRec_
  {
    T2_Hints              hints;
    T2_Hints_OpenFunc     open;
    T2_Hints_CloseFunc    close;
    T2_Hints_StemsFunc    stems;
    T2_Hints_MaskFunc     hintmask;
    T2_Hints_CounterFunc  counter;
    T2_Hints_ApplyFunc    apply;

  } T2_Hints_FuncsRec;


  /* */


  typedef struct  PSHinter_Interface_
  {
    PSH_Globals_Funcs  (*get_globals_funcs)( FT_Module  module );
    T1_Hints_Funcs     (*get_t1_funcs)     ( FT_Module  module );
    T2_Hints_Funcs     (*get_t2_funcs)     ( FT_Module  module );

  } PSHinter_Interface;

  typedef PSHinter_Interface*  PSHinter_Service;


#ifndef FT_CONFIG_OPTION_PIC

#define FT_DEFINE_PSHINTER_INTERFACE(        \
          class_,                            \
          get_globals_funcs_,                \
          get_t1_funcs_,                     \
          get_t2_funcs_ )                    \
  static const PSHinter_Interface  class_ =  \
  {                                          \
    get_globals_funcs_,                      \
    get_t1_funcs_,                           \
    get_t2_funcs_                            \
  };

#else /* FT_CONFIG_OPTION_PIC */

#define FT_DEFINE_PSHINTER_INTERFACE(                      \
          class_,                                          \
          get_globals_funcs_,                              \
          get_t1_funcs_,                                   \
          get_t2_funcs_ )                                  \
  void                                                     \
  FT_Init_Class_ ## class_( FT_Library           library,  \
                            PSHinter_Interface*  clazz )   \
  {                                                        \
    FT_UNUSED( library );                                  \
                                                           \
    clazz->get_globals_funcs = get_globals_funcs_;         \
    clazz->get_t1_funcs      = get_t1_funcs_;              \
    clazz->get_t2_funcs      = get_t2_funcs_;              \
  }

#endif /* FT_CONFIG_OPTION_PIC */

FT_END_HEADER

#endif /* __PSHINTS_H__ */


/* END */