574 lines
20 KiB
C
574 lines
20 KiB
C
/****************************************************************************
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*
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* aftypes.h
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*
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* Auto-fitter types (specification only).
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*
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* Copyright (C) 2003-2020 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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/*************************************************************************
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*
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* The auto-fitter is a complete rewrite of the old auto-hinter.
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* Its main feature is the ability to differentiate between different
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* writing systems and scripts in order to apply specific rules.
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*
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* The code has also been compartmentalized into several entities that
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* should make algorithmic experimentation easier than with the old
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* code.
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*
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*************************************************************************/
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#ifndef AFTYPES_H_
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#define AFTYPES_H_
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#include <ft2build.h>
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#include FT_FREETYPE_H
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#include FT_OUTLINE_H
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#include FT_INTERNAL_OBJECTS_H
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#include FT_INTERNAL_DEBUG_H
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#include "afblue.h"
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#ifdef FT_DEBUG_AUTOFIT
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#include FT_CONFIG_STANDARD_LIBRARY_H
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#endif
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FT_BEGIN_HEADER
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/*************************************************************************/
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/*************************************************************************/
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/***** *****/
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/***** D E B U G G I N G *****/
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/***** *****/
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/*************************************************************************/
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/*************************************************************************/
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#ifdef FT_DEBUG_AUTOFIT
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extern int _af_debug_disable_horz_hints;
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extern int _af_debug_disable_vert_hints;
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extern int _af_debug_disable_blue_hints;
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extern void* _af_debug_hints;
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#endif /* FT_DEBUG_AUTOFIT */
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/*************************************************************************/
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/*************************************************************************/
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/***** *****/
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/***** U T I L I T Y S T U F F *****/
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/***** *****/
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/*************************************************************************/
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/*************************************************************************/
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typedef struct AF_WidthRec_
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{
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FT_Pos org; /* original position/width in font units */
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FT_Pos cur; /* current/scaled position/width in device subpixels */
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FT_Pos fit; /* current/fitted position/width in device subpixels */
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} AF_WidthRec, *AF_Width;
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FT_LOCAL( void )
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af_sort_pos( FT_UInt count,
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FT_Pos* table );
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FT_LOCAL( void )
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af_sort_and_quantize_widths( FT_UInt* count,
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AF_Width widths,
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FT_Pos threshold );
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/*************************************************************************/
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/*************************************************************************/
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/***** *****/
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/***** A N G L E T Y P E S *****/
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/***** *****/
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/*************************************************************************/
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/*************************************************************************/
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/*
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* The auto-fitter doesn't need a very high angular accuracy;
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* this allows us to speed up some computations considerably with a
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* light Cordic algorithm (see afangles.c).
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*/
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typedef FT_Int AF_Angle;
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#define AF_ANGLE_PI 256
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#define AF_ANGLE_2PI ( AF_ANGLE_PI * 2 )
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#define AF_ANGLE_PI2 ( AF_ANGLE_PI / 2 )
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#define AF_ANGLE_PI4 ( AF_ANGLE_PI / 4 )
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#if 0
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/*
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* compute the angle of a given 2-D vector
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*/
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FT_LOCAL( AF_Angle )
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af_angle_atan( FT_Pos dx,
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FT_Pos dy );
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/*
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* compute `angle2 - angle1'; the result is always within
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* the range [-AF_ANGLE_PI .. AF_ANGLE_PI - 1]
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*/
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FT_LOCAL( AF_Angle )
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af_angle_diff( AF_Angle angle1,
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AF_Angle angle2 );
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#endif /* 0 */
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#define AF_ANGLE_DIFF( result, angle1, angle2 ) \
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FT_BEGIN_STMNT \
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AF_Angle _delta = (angle2) - (angle1); \
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\
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\
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while ( _delta <= -AF_ANGLE_PI ) \
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_delta += AF_ANGLE_2PI; \
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\
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while ( _delta > AF_ANGLE_PI ) \
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_delta -= AF_ANGLE_2PI; \
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\
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result = _delta; \
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FT_END_STMNT
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/*
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* opaque handle to glyph-specific hints -- see `afhints.h' for more
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* details
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*/
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typedef struct AF_GlyphHintsRec_* AF_GlyphHints;
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/*************************************************************************/
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/*************************************************************************/
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/***** *****/
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/***** S C A L E R S *****/
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/***** *****/
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/*************************************************************************/
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/*************************************************************************/
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/*
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* A scaler models the target pixel device that will receive the
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* auto-hinted glyph image.
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*/
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#define AF_SCALER_FLAG_NO_HORIZONTAL 1U /* disable horizontal hinting */
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#define AF_SCALER_FLAG_NO_VERTICAL 2U /* disable vertical hinting */
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#define AF_SCALER_FLAG_NO_ADVANCE 4U /* disable advance hinting */
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#define AF_SCALER_FLAG_NO_WARPER 8U /* disable warper */
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typedef struct AF_ScalerRec_
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{
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FT_Face face; /* source font face */
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FT_Fixed x_scale; /* from font units to 1/64th device pixels */
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FT_Fixed y_scale; /* from font units to 1/64th device pixels */
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FT_Pos x_delta; /* in 1/64th device pixels */
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FT_Pos y_delta; /* in 1/64th device pixels */
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FT_Render_Mode render_mode; /* monochrome, anti-aliased, LCD, etc. */
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FT_UInt32 flags; /* additional control flags, see above */
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} AF_ScalerRec, *AF_Scaler;
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#define AF_SCALER_EQUAL_SCALES( a, b ) \
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( (a)->x_scale == (b)->x_scale && \
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(a)->y_scale == (b)->y_scale && \
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(a)->x_delta == (b)->x_delta && \
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(a)->y_delta == (b)->y_delta )
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typedef struct AF_StyleMetricsRec_* AF_StyleMetrics;
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/*
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* This function parses an FT_Face to compute global metrics for
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* a specific style.
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*/
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typedef FT_Error
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(*AF_WritingSystem_InitMetricsFunc)( AF_StyleMetrics metrics,
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FT_Face face );
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typedef void
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(*AF_WritingSystem_ScaleMetricsFunc)( AF_StyleMetrics metrics,
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AF_Scaler scaler );
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typedef void
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(*AF_WritingSystem_DoneMetricsFunc)( AF_StyleMetrics metrics );
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typedef void
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(*AF_WritingSystem_GetStdWidthsFunc)( AF_StyleMetrics metrics,
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FT_Pos* stdHW,
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FT_Pos* stdVW );
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typedef FT_Error
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(*AF_WritingSystem_InitHintsFunc)( AF_GlyphHints hints,
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AF_StyleMetrics metrics );
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typedef FT_Error
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(*AF_WritingSystem_ApplyHintsFunc)( FT_UInt glyph_index,
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AF_GlyphHints hints,
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FT_Outline* outline,
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AF_StyleMetrics metrics );
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/*************************************************************************/
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/*************************************************************************/
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/***** *****/
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/***** W R I T I N G S Y S T E M S *****/
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/***** *****/
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/*************************************************************************/
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/*************************************************************************/
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/*
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* For the auto-hinter, a writing system consists of multiple scripts that
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* can be handled similarly *in a typographical way*; the relationship is
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* not based on history. For example, both the Greek and the unrelated
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* Armenian scripts share the same features like ascender, descender,
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* x-height, etc. Essentially, a writing system is covered by a
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* submodule of the auto-fitter; it contains
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*
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* - a specific global analyzer that computes global metrics specific to
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* the script (based on script-specific characters to identify ascender
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* height, x-height, etc.),
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*
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* - a specific glyph analyzer that computes segments and edges for each
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* glyph covered by the script,
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*
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* - a specific grid-fitting algorithm that distorts the scaled glyph
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* outline according to the results of the glyph analyzer.
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*/
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#define AFWRTSYS_H_ /* don't load header files */
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#undef WRITING_SYSTEM
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#define WRITING_SYSTEM( ws, WS ) \
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AF_WRITING_SYSTEM_ ## WS,
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/* The list of known writing systems. */
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typedef enum AF_WritingSystem_
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{
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#include "afwrtsys.h"
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AF_WRITING_SYSTEM_MAX /* do not remove */
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} AF_WritingSystem;
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#undef AFWRTSYS_H_
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typedef struct AF_WritingSystemClassRec_
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{
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AF_WritingSystem writing_system;
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FT_Offset style_metrics_size;
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AF_WritingSystem_InitMetricsFunc style_metrics_init;
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AF_WritingSystem_ScaleMetricsFunc style_metrics_scale;
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AF_WritingSystem_DoneMetricsFunc style_metrics_done;
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AF_WritingSystem_GetStdWidthsFunc style_metrics_getstdw;
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AF_WritingSystem_InitHintsFunc style_hints_init;
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AF_WritingSystem_ApplyHintsFunc style_hints_apply;
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} AF_WritingSystemClassRec;
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typedef const AF_WritingSystemClassRec* AF_WritingSystemClass;
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/*************************************************************************/
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/*************************************************************************/
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/***** *****/
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/***** S C R I P T S *****/
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/***** *****/
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/*************************************************************************/
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/*************************************************************************/
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/*
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* Each script is associated with two sets of Unicode ranges to test
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* whether the font face supports the script, and which non-base
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* characters the script contains.
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*
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* We use four-letter script tags from the OpenType specification,
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* extended by `NONE', which indicates `no script'.
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*/
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#undef SCRIPT
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#define SCRIPT( s, S, d, h, H, ss ) \
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AF_SCRIPT_ ## S,
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/* The list of known scripts. */
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typedef enum AF_Script_
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{
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#include "afscript.h"
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AF_SCRIPT_MAX /* do not remove */
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} AF_Script;
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typedef struct AF_Script_UniRangeRec_
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{
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FT_UInt32 first;
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FT_UInt32 last;
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} AF_Script_UniRangeRec;
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#define AF_UNIRANGE_REC( a, b ) { (FT_UInt32)(a), (FT_UInt32)(b) }
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typedef const AF_Script_UniRangeRec* AF_Script_UniRange;
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typedef struct AF_ScriptClassRec_
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{
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AF_Script script;
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/* last element in the ranges must be { 0, 0 } */
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AF_Script_UniRange script_uni_ranges;
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AF_Script_UniRange script_uni_nonbase_ranges;
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FT_Bool top_to_bottom_hinting;
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const char* standard_charstring; /* for default width and height */
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} AF_ScriptClassRec;
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typedef const AF_ScriptClassRec* AF_ScriptClass;
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/*************************************************************************/
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/*************************************************************************/
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/***** *****/
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/***** C O V E R A G E S *****/
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/***** *****/
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/*************************************************************************/
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/*************************************************************************/
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/*
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* Usually, a font contains more glyphs than can be addressed by its
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* character map.
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*
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* In the PostScript font world, encoding vectors specific to a given
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* task are used to select such glyphs, and these glyphs can be often
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* recognized by having a suffix in its glyph names. For example, a
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* superscript glyph `A' might be called `A.sup'. Unfortunately, this
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* naming scheme is not standardized and thus unusable for us.
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*
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* In the OpenType world, a better solution was invented, namely
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* `features', which cleanly separate a character's input encoding from
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* the corresponding glyph's appearance, and which don't use glyph names
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* at all. For our purposes, and slightly generalized, an OpenType
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* feature is a name of a mapping that maps character codes to
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* non-standard glyph indices (features get used for other things also).
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* For example, the `sups' feature provides superscript glyphs, thus
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* mapping character codes like `A' or `B' to superscript glyph
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* representation forms. How this mapping happens is completely
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* uninteresting to us.
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*
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* For the auto-hinter, a `coverage' represents all glyphs of an OpenType
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* feature collected in a set (as listed below) that can be hinted
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* together. To continue the above example, superscript glyphs must not
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* be hinted together with normal glyphs because the blue zones
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* completely differ.
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*
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* Note that FreeType itself doesn't compute coverages; it only provides
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* the glyphs addressable by the default Unicode character map. Instead,
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* we use the HarfBuzz library (if available), which has many functions
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* exactly for this purpose.
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*
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* AF_COVERAGE_DEFAULT is special: It should cover everything that isn't
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* listed separately (including the glyphs addressable by the character
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* map). In case HarfBuzz isn't available, it exactly covers the glyphs
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* addressable by the character map.
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*
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*/
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#undef COVERAGE
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#define COVERAGE( name, NAME, description, \
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tag1, tag2, tag3, tag4 ) \
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AF_COVERAGE_ ## NAME,
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typedef enum AF_Coverage_
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{
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#include "afcover.h"
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AF_COVERAGE_DEFAULT
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} AF_Coverage;
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/*************************************************************************/
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/*************************************************************************/
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/***** *****/
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/***** S T Y L E S *****/
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/***** *****/
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/*************************************************************************/
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/*************************************************************************/
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/*
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* The topmost structure for modelling the auto-hinter glyph input data
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* is a `style class', grouping everything together.
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*/
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#undef STYLE
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#define STYLE( s, S, d, ws, sc, ss, c ) \
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AF_STYLE_ ## S,
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/* The list of known styles. */
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typedef enum AF_Style_
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{
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#include "afstyles.h"
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AF_STYLE_MAX /* do not remove */
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} AF_Style;
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typedef struct AF_StyleClassRec_
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{
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AF_Style style;
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AF_WritingSystem writing_system;
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AF_Script script;
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AF_Blue_Stringset blue_stringset;
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AF_Coverage coverage;
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} AF_StyleClassRec;
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typedef const AF_StyleClassRec* AF_StyleClass;
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/*************************************************************************/
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/*************************************************************************/
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/***** *****/
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/***** S T Y L E M E T R I C S *****/
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/***** *****/
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/*************************************************************************/
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/*************************************************************************/
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typedef struct AF_FaceGlobalsRec_* AF_FaceGlobals;
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/* This is the main structure that combines everything. Autofit modules */
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/* specific to writing systems derive their structures from it, for */
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/* example `AF_LatinMetrics'. */
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typedef struct AF_StyleMetricsRec_
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{
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AF_StyleClass style_class;
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AF_ScalerRec scaler;
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FT_Bool digits_have_same_width;
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AF_FaceGlobals globals; /* to access properties */
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} AF_StyleMetricsRec;
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#define AF_HINTING_BOTTOM_TO_TOP 0
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#define AF_HINTING_TOP_TO_BOTTOM 1
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/* Declare and define vtables for classes */
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#define AF_DECLARE_WRITING_SYSTEM_CLASS( writing_system_class ) \
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FT_CALLBACK_TABLE const AF_WritingSystemClassRec \
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writing_system_class;
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#define AF_DEFINE_WRITING_SYSTEM_CLASS( \
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writing_system_class, \
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system, \
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m_size, \
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m_init, \
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m_scale, \
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m_done, \
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m_stdw, \
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h_init, \
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h_apply ) \
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FT_CALLBACK_TABLE_DEF \
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const AF_WritingSystemClassRec writing_system_class = \
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{ \
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system, \
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\
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m_size, \
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\
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m_init, \
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m_scale, \
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m_done, \
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m_stdw, \
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\
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h_init, \
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h_apply \
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};
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#define AF_DECLARE_SCRIPT_CLASS( script_class ) \
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FT_CALLBACK_TABLE const AF_ScriptClassRec \
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script_class;
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#define AF_DEFINE_SCRIPT_CLASS( \
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script_class, \
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script, \
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ranges, \
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nonbase_ranges, \
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top_to_bottom, \
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std_charstring ) \
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FT_CALLBACK_TABLE_DEF \
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const AF_ScriptClassRec script_class = \
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{ \
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script, \
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ranges, \
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nonbase_ranges, \
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top_to_bottom, \
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std_charstring, \
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};
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#define AF_DECLARE_STYLE_CLASS( style_class ) \
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FT_CALLBACK_TABLE const AF_StyleClassRec \
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style_class;
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#define AF_DEFINE_STYLE_CLASS( \
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style_class, \
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style, \
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writing_system, \
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script, \
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blue_stringset, \
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coverage ) \
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FT_CALLBACK_TABLE_DEF \
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const AF_StyleClassRec style_class = \
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{ \
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style, \
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writing_system, \
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script, \
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blue_stringset, \
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coverage \
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};
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/* */
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FT_END_HEADER
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#endif /* AFTYPES_H_ */
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/* END */
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