1 /***************************************************************************/

     2 /*                                                                         */

     3 /*  ftgasp.h                                                               */

     4 /*                                                                         */

     5 /*    Access of TrueType's `gasp' table (specification).                   */

     6 /*                                                                         */

     7 /*  Copyright 2007, 2008, 2011 by                                          */

     8 /*  David Turner, Robert Wilhelm, and Werner Lemberg.                      */

     9 /*                                                                         */

    10 /*  This file is part of the FreeType project, and may only be used,       */

    11 /*  modified, and distributed under the terms of the FreeType project      */

    12 /*  license, LICENSE.TXT.  By continuing to use, modify, or distribute     */

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

    14 /*  understand and accept it fully.                                        */

    15 /*                                                                         */

    16 /***************************************************************************/

    17 

    18 

    19 #ifndef _FT_GASP_H_

    20 #define _FT_GASP_H_

    21 

    22 #include <ft2build.h>

    23 #include FT_FREETYPE_H

    24 

    25 #ifdef FREETYPE_H

    26 #error "freetype.h of FreeType 1 has been loaded!"

    27 #error "Please fix the directory search order for header files"

    28 #error "so that freetype.h of FreeType 2 is found first."

    29 #endif

    30 

    31 

    32   /***************************************************************************

    33    *

    34    * @section:

    35    *   gasp_table

    36    *

    37    * @title:

    38    *   Gasp Table

    39    *

    40    * @abstract:

    41    *   Retrieving TrueType `gasp' table entries.

    42    *

    43    * @description:

    44    *   The function @FT_Get_Gasp can be used to query a TrueType or OpenType

    45    *   font for specific entries in its `gasp' table, if any.  This is

    46    *   mainly useful when implementing native TrueType hinting with the

    47    *   bytecode interpreter to duplicate the Windows text rendering results.

    48    */

    49 

    50   /*************************************************************************

    51    *

    52    * @enum:

    53    *   FT_GASP_XXX

    54    *

    55    * @description:

    56    *   A list of values and/or bit-flags returned by the @FT_Get_Gasp

    57    *   function.

    58    *

    59    * @values:

    60    *   FT_GASP_NO_TABLE ::

    61    *     This special value means that there is no GASP table in this face.

    62    *     It is up to the client to decide what to do.

    63    *

    64    *   FT_GASP_DO_GRIDFIT ::

    65    *     Grid-fitting and hinting should be performed at the specified ppem. 

    66    *     This *really* means TrueType bytecode interpretation.  If this bit

    67    *     is not set, no hinting gets applied.

    68    *

    69    *   FT_GASP_DO_GRAY ::

    70    *     Anti-aliased rendering should be performed at the specified ppem. 

    71    *     If not set, do monochrome rendering.

    72    *

    73    *   FT_GASP_SYMMETRIC_SMOOTHING ::

    74    *     If set, smoothing along multiple axes must be used with ClearType.

    75    *

    76    *   FT_GASP_SYMMETRIC_GRIDFIT ::

    77    *     Grid-fitting must be used with ClearType's symmetric smoothing.

    78    *

    79    * @note:

    80    *   The bit-flags `FT_GASP_DO_GRIDFIT' and `FT_GASP_DO_GRAY' are to be

    81    *   used for standard font rasterization only.  Independently of that,

    82    *   `FT_GASP_SYMMETRIC_SMOOTHING' and `FT_GASP_SYMMETRIC_GRIDFIT' are to

    83    *   be used if ClearType is enabled (and `FT_GASP_DO_GRIDFIT' and

    84    *   `FT_GASP_DO_GRAY' are consequently ignored).

    85    *

    86    *   `ClearType' is Microsoft's implementation of LCD rendering, partly

    87    *   protected by patents.

    88    *

    89    * @since:

    90    *   2.3.0

    91    */

    92 #define FT_GASP_NO_TABLE               -1

    93 #define FT_GASP_DO_GRIDFIT           0x01

    94 #define FT_GASP_DO_GRAY              0x02

    95 #define FT_GASP_SYMMETRIC_SMOOTHING  0x08

    96 #define FT_GASP_SYMMETRIC_GRIDFIT    0x10

    97 

    98 

    99   /*************************************************************************

   100    *

   101    * @func:

   102    *   FT_Get_Gasp

   103    *

   104    * @description:

   105    *   Read the `gasp' table from a TrueType or OpenType font file and

   106    *   return the entry corresponding to a given character pixel size.

   107    *

   108    * @input:

   109    *   face :: The source face handle.

   110    *   ppem :: The vertical character pixel size.

   111    *

   112    * @return:

   113    *   Bit flags (see @FT_GASP_XXX), or @FT_GASP_NO_TABLE if there is no

   114    *   `gasp' table in the face.

   115    *

   116    * @since:

   117    *   2.3.0

   118    */

   119   FT_EXPORT( FT_Int )

   120   FT_Get_Gasp( FT_Face  face,

   121                FT_UInt  ppem );

   122 

   123 /* */

   124 

   125 #endif /* _FT_GASP_H_ */

   126 

   127 

   128 /* END */