143 lines
4.7 KiB
C
143 lines
4.7 KiB
C
/***************************************************************************/
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/* */
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/* ftgasp.h */
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/* */
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/* Access of TrueType's `gasp' table (specification). */
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/* */
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/* Copyright 2007-2018 by */
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/* David Turner, Robert Wilhelm, and Werner Lemberg. */
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/* */
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/* This file is part of the FreeType project, and may only be used, */
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/* modified, and distributed under the terms of the FreeType project */
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/* license, LICENSE.TXT. By continuing to use, modify, or distribute */
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/* this file you indicate that you have read the license and */
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/* understand and accept it fully. */
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/* */
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/***************************************************************************/
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#ifndef FTGASP_H_
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#define FTGASP_H_
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#include <ft2build.h>
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#include FT_FREETYPE_H
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#ifdef FREETYPE_H
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#error "freetype.h of FreeType 1 has been loaded!"
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#error "Please fix the directory search order for header files"
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#error "so that freetype.h of FreeType 2 is found first."
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#endif
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FT_BEGIN_HEADER
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/***************************************************************************
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*
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* @section:
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* gasp_table
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*
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* @title:
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* Gasp Table
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*
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* @abstract:
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* Retrieving TrueType `gasp' table entries.
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*
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* @description:
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* The function @FT_Get_Gasp can be used to query a TrueType or OpenType
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* font for specific entries in its `gasp' table, if any. This is
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* mainly useful when implementing native TrueType hinting with the
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* bytecode interpreter to duplicate the Windows text rendering results.
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*/
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/*************************************************************************
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*
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* @enum:
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* FT_GASP_XXX
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*
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* @description:
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* A list of values and/or bit-flags returned by the @FT_Get_Gasp
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* function.
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*
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* @values:
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* FT_GASP_NO_TABLE ::
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* This special value means that there is no GASP table in this face.
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* It is up to the client to decide what to do.
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*
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* FT_GASP_DO_GRIDFIT ::
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* Grid-fitting and hinting should be performed at the specified ppem.
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* This *really* means TrueType bytecode interpretation. If this bit
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* is not set, no hinting gets applied.
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*
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* FT_GASP_DO_GRAY ::
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* Anti-aliased rendering should be performed at the specified ppem.
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* If not set, do monochrome rendering.
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*
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* FT_GASP_SYMMETRIC_SMOOTHING ::
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* If set, smoothing along multiple axes must be used with ClearType.
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*
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* FT_GASP_SYMMETRIC_GRIDFIT ::
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* Grid-fitting must be used with ClearType's symmetric smoothing.
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*
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* @note:
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* The bit-flags `FT_GASP_DO_GRIDFIT' and `FT_GASP_DO_GRAY' are to be
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* used for standard font rasterization only. Independently of that,
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* `FT_GASP_SYMMETRIC_SMOOTHING' and `FT_GASP_SYMMETRIC_GRIDFIT' are to
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* be used if ClearType is enabled (and `FT_GASP_DO_GRIDFIT' and
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* `FT_GASP_DO_GRAY' are consequently ignored).
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*
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* `ClearType' is Microsoft's implementation of LCD rendering, partly
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* protected by patents.
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*
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* @since:
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* 2.3.0
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*/
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#define FT_GASP_NO_TABLE -1
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#define FT_GASP_DO_GRIDFIT 0x01
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#define FT_GASP_DO_GRAY 0x02
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#define FT_GASP_SYMMETRIC_GRIDFIT 0x04
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#define FT_GASP_SYMMETRIC_SMOOTHING 0x08
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/*************************************************************************
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*
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* @func:
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* FT_Get_Gasp
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*
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* @description:
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* For a TrueType or OpenType font file, return the rasterizer behaviour
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* flags from the font's `gasp' table corresponding to a given
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* character pixel size.
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*
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* @input:
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* face :: The source face handle.
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*
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* ppem :: The vertical character pixel size.
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*
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* @return:
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* Bit flags (see @FT_GASP_XXX), or @FT_GASP_NO_TABLE if there is no
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* `gasp' table in the face.
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*
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* @note:
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* If you want to use the MM functionality of OpenType variation fonts
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* (i.e., using @FT_Set_Var_Design_Coordinates and friends), call this
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* function *after* setting an instance since the return values can
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* change.
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*
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* @since:
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* 2.3.0
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*/
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FT_EXPORT( FT_Int )
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FT_Get_Gasp( FT_Face face,
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FT_UInt ppem );
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/* */
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FT_END_HEADER
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#endif /* FTGASP_H_ */
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/* END */
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