189 lines
5.4 KiB
C
189 lines
5.4 KiB
C
/****************************************************************************
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*
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* ftadvanc.h
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*
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* Quick computation of advance widths (specification only).
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*
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* Copyright (C) 2008-2020 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 FTADVANC_H_
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#define FTADVANC_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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* quick_advance
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*
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* @title:
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* Quick retrieval of advance values
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*
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* @abstract:
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* Retrieve horizontal and vertical advance values without processing
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* glyph outlines, if possible.
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*
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* @description:
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* This section contains functions to quickly extract advance values
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* without handling glyph outlines, if possible.
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*
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* @order:
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* FT_Get_Advance
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* FT_Get_Advances
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*
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*/
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/**************************************************************************
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*
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* @enum:
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* FT_ADVANCE_FLAG_FAST_ONLY
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*
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* @description:
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* A bit-flag to be OR-ed with the `flags` parameter of the
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* @FT_Get_Advance and @FT_Get_Advances functions.
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*
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* If set, it indicates that you want these functions to fail if the
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* corresponding hinting mode or font driver doesn't allow for very quick
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* advance computation.
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*
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* Typically, glyphs that are either unscaled, unhinted, bitmapped, or
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* light-hinted can have their advance width computed very quickly.
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*
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* Normal and bytecode hinted modes that require loading, scaling, and
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* hinting of the glyph outline, are extremely slow by comparison.
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*/
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#define FT_ADVANCE_FLAG_FAST_ONLY 0x20000000L
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/**************************************************************************
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*
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* @function:
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* FT_Get_Advance
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*
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* @description:
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* Retrieve the advance value of a given glyph outline in an @FT_Face.
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*
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* @input:
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* face ::
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* The source @FT_Face handle.
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*
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* gindex ::
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* The glyph index.
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*
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* load_flags ::
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* A set of bit flags similar to those used when calling
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* @FT_Load_Glyph, used to determine what kind of advances you need.
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* @output:
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* padvance ::
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* The advance value. If scaling is performed (based on the value of
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* `load_flags`), the advance value is in 16.16 format. Otherwise, it
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* is in font units.
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*
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* If @FT_LOAD_VERTICAL_LAYOUT is set, this is the vertical advance
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* corresponding to a vertical layout. Otherwise, it is the horizontal
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* advance in a horizontal layout.
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*
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* @return:
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* FreeType error code. 0 means success.
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*
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* @note:
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* This function may fail if you use @FT_ADVANCE_FLAG_FAST_ONLY and if
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* the corresponding font backend doesn't have a quick way to retrieve
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* the advances.
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*
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* A scaled advance is returned in 16.16 format but isn't transformed by
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* the affine transformation specified by @FT_Set_Transform.
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*/
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FT_EXPORT( FT_Error )
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FT_Get_Advance( FT_Face face,
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FT_UInt gindex,
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FT_Int32 load_flags,
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FT_Fixed *padvance );
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/**************************************************************************
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*
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* @function:
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* FT_Get_Advances
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*
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* @description:
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* Retrieve the advance values of several glyph outlines in an @FT_Face.
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*
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* @input:
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* face ::
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* The source @FT_Face handle.
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*
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* start ::
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* The first glyph index.
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*
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* count ::
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* The number of advance values you want to retrieve.
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*
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* load_flags ::
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* A set of bit flags similar to those used when calling
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* @FT_Load_Glyph.
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*
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* @output:
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* padvance ::
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* The advance values. This array, to be provided by the caller, must
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* contain at least `count` elements.
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*
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* If scaling is performed (based on the value of `load_flags`), the
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* advance values are in 16.16 format. Otherwise, they are in font
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* units.
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*
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* If @FT_LOAD_VERTICAL_LAYOUT is set, these are the vertical advances
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* corresponding to a vertical layout. Otherwise, they are the
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* horizontal advances in a horizontal layout.
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*
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* @return:
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* FreeType error code. 0 means success.
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*
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* @note:
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* This function may fail if you use @FT_ADVANCE_FLAG_FAST_ONLY and if
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* the corresponding font backend doesn't have a quick way to retrieve
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* the advances.
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*
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* Scaled advances are returned in 16.16 format but aren't transformed by
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* the affine transformation specified by @FT_Set_Transform.
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*/
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FT_EXPORT( FT_Error )
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FT_Get_Advances( FT_Face face,
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FT_UInt start,
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FT_UInt count,
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FT_Int32 load_flags,
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FT_Fixed *padvances );
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/* */
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FT_END_HEADER
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#endif /* FTADVANC_H_ */
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/* END */
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