ref: 216e077600a58346bb022d8409fd82e9d914a10a
dir: /include/freetype/ftgasp.h/
/****************************************************************************
*
* ftgasp.h
*
* Access of TrueType's 'gasp' table (specification).
*
* Copyright (C) 2007-2020 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 FTGASP_H_
#define FTGASP_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:
* gasp_table
*
* @title:
* Gasp Table
*
* @abstract:
* Retrieving TrueType 'gasp' table entries.
*
* @description:
* The function @FT_Get_Gasp can be used to query a TrueType or OpenType
* font for specific entries in its 'gasp' table, if any. This is mainly
* useful when implementing native TrueType hinting with the bytecode
* interpreter to duplicate the Windows text rendering results.
*/
/**************************************************************************
*
* @enum:
* FT_GASP_XXX
*
* @description:
* A list of values and/or bit-flags returned by the @FT_Get_Gasp
* function.
*
* @values:
* FT_GASP_NO_TABLE ::
* This special value means that there is no GASP table in this face.
* It is up to the client to decide what to do.
*
* FT_GASP_DO_GRIDFIT ::
* Grid-fitting and hinting should be performed at the specified ppem.
* This **really** means TrueType bytecode interpretation. If this bit
* is not set, no hinting gets applied.
*
* FT_GASP_DO_GRAY ::
* Anti-aliased rendering should be performed at the specified ppem.
* If not set, do monochrome rendering.
*
* FT_GASP_SYMMETRIC_SMOOTHING ::
* If set, smoothing along multiple axes must be used with ClearType.
*
* FT_GASP_SYMMETRIC_GRIDFIT ::
* Grid-fitting must be used with ClearType's symmetric smoothing.
*
* @note:
* The bit-flags `FT_GASP_DO_GRIDFIT` and `FT_GASP_DO_GRAY` are to be
* used for standard font rasterization only. Independently of that,
* `FT_GASP_SYMMETRIC_SMOOTHING` and `FT_GASP_SYMMETRIC_GRIDFIT` are to
* be used if ClearType is enabled (and `FT_GASP_DO_GRIDFIT` and
* `FT_GASP_DO_GRAY` are consequently ignored).
*
* 'ClearType' is Microsoft's implementation of LCD rendering, partly
* protected by patents.
*
* @since:
* 2.3.0
*/
#define FT_GASP_NO_TABLE -1
#define FT_GASP_DO_GRIDFIT 0x01
#define FT_GASP_DO_GRAY 0x02
#define FT_GASP_SYMMETRIC_GRIDFIT 0x04
#define FT_GASP_SYMMETRIC_SMOOTHING 0x08
/**************************************************************************
*
* @function:
* FT_Get_Gasp
*
* @description:
* For a TrueType or OpenType font file, return the rasterizer behaviour
* flags from the font's 'gasp' table corresponding to a given character
* pixel size.
*
* @input:
* face ::
* The source face handle.
*
* ppem ::
* The vertical character pixel size.
*
* @return:
* Bit flags (see @FT_GASP_XXX), or @FT_GASP_NO_TABLE if there is no
* 'gasp' table in the face.
*
* @note:
* If you want to use the MM functionality of OpenType variation fonts
* (i.e., using @FT_Set_Var_Design_Coordinates and friends), call this
* function **after** setting an instance since the return values can
* change.
*
* @since:
* 2.3.0
*/
FT_EXPORT( FT_Int )
FT_Get_Gasp( FT_Face face,
FT_UInt ppem );
/* */
FT_END_HEADER
#endif /* FTGASP_H_ */
/* END */