ref: bee8886408a82c244956b76db4ab7b79cdca9079
dir: /src/autofit/aftypes.h/
/****************************************************************************
*
* aftypes.h
*
* Auto-fitter types (specification only).
*
* Copyright (C) 2003-2022 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.
*
*/
/*************************************************************************
*
* The auto-fitter is a complete rewrite of the old auto-hinter.
* Its main feature is the ability to differentiate between different
* writing systems and scripts in order to apply specific rules.
*
* The code has also been compartmentalized into several entities that
* should make algorithmic experimentation easier than with the old
* code.
*
*************************************************************************/
#ifndef AFTYPES_H_
#define AFTYPES_H_
#include <freetype/freetype.h>
#include <freetype/ftoutln.h>
#include <freetype/internal/ftobjs.h>
#include <freetype/internal/ftdebug.h>
#include "afblue.h"
#ifdef FT_DEBUG_AUTOFIT
#include FT_CONFIG_STANDARD_LIBRARY_H
#endif
FT_BEGIN_HEADER
/*************************************************************************/
/*************************************************************************/
/***** *****/
/***** D E B U G G I N G *****/
/***** *****/
/*************************************************************************/
/*************************************************************************/
#ifdef FT_DEBUG_AUTOFIT
extern int _af_debug_disable_horz_hints;
extern int _af_debug_disable_vert_hints;
extern int _af_debug_disable_blue_hints;
extern void* _af_debug_hints;
#endif /* FT_DEBUG_AUTOFIT */
/*************************************************************************/
/*************************************************************************/
/***** *****/
/***** U T I L I T Y S T U F F *****/
/***** *****/
/*************************************************************************/
/*************************************************************************/
typedef struct AF_WidthRec_
{
FT_Pos org; /* original position/width in font units */
FT_Pos cur; /* current/scaled position/width in device subpixels */
FT_Pos fit; /* current/fitted position/width in device subpixels */
} AF_WidthRec, *AF_Width;
FT_LOCAL( void )
af_sort_pos( FT_UInt count,
FT_Pos* table );
FT_LOCAL( void )
af_sort_and_quantize_widths( FT_UInt* count,
AF_Width widths,
FT_Pos threshold );
/*
* opaque handle to glyph-specific hints -- see `afhints.h' for more
* details
*/
typedef struct AF_GlyphHintsRec_* AF_GlyphHints;
/*************************************************************************/
/*************************************************************************/
/***** *****/
/***** S C A L E R S *****/
/***** *****/
/*************************************************************************/
/*************************************************************************/
/*
* A scaler models the target pixel device that will receive the
* auto-hinted glyph image.
*/
#define AF_SCALER_FLAG_NO_HORIZONTAL 1U /* disable horizontal hinting */
#define AF_SCALER_FLAG_NO_VERTICAL 2U /* disable vertical hinting */
#define AF_SCALER_FLAG_NO_ADVANCE 4U /* disable advance hinting */
typedef struct AF_ScalerRec_
{
FT_Face face; /* source font face */
FT_Fixed x_scale; /* from font units to 1/64th device pixels */
FT_Fixed y_scale; /* from font units to 1/64th device pixels */
FT_Pos x_delta; /* in 1/64th device pixels */
FT_Pos y_delta; /* in 1/64th device pixels */
FT_Render_Mode render_mode; /* monochrome, anti-aliased, LCD, etc. */
FT_UInt32 flags; /* additional control flags, see above */
} AF_ScalerRec, *AF_Scaler;
#define AF_SCALER_EQUAL_SCALES( a, b ) \
( (a)->x_scale == (b)->x_scale && \
(a)->y_scale == (b)->y_scale && \
(a)->x_delta == (b)->x_delta && \
(a)->y_delta == (b)->y_delta )
typedef struct AF_StyleMetricsRec_* AF_StyleMetrics;
/*
* This function parses an FT_Face to compute global metrics for
* a specific style.
*/
typedef FT_Error
(*AF_WritingSystem_InitMetricsFunc)( AF_StyleMetrics metrics,
FT_Face face );
typedef void
(*AF_WritingSystem_ScaleMetricsFunc)( AF_StyleMetrics metrics,
AF_Scaler scaler );
typedef void
(*AF_WritingSystem_DoneMetricsFunc)( AF_StyleMetrics metrics );
typedef void
(*AF_WritingSystem_GetStdWidthsFunc)( AF_StyleMetrics metrics,
FT_Pos* stdHW,
FT_Pos* stdVW );
typedef FT_Error
(*AF_WritingSystem_InitHintsFunc)( AF_GlyphHints hints,
AF_StyleMetrics metrics );
typedef FT_Error
(*AF_WritingSystem_ApplyHintsFunc)( FT_UInt glyph_index,
AF_GlyphHints hints,
FT_Outline* outline,
AF_StyleMetrics metrics );
/*************************************************************************/
/*************************************************************************/
/***** *****/
/***** W R I T I N G S Y S T E M S *****/
/***** *****/
/*************************************************************************/
/*************************************************************************/
/*
* For the auto-hinter, a writing system consists of multiple scripts that
* can be handled similarly *in a typographical way*; the relationship is
* not based on history. For example, both the Greek and the unrelated
* Armenian scripts share the same features like ascender, descender,
* x-height, etc. Essentially, a writing system is covered by a
* submodule of the auto-fitter; it contains
*
* - a specific global analyzer that computes global metrics specific to
* the script (based on script-specific characters to identify ascender
* height, x-height, etc.),
*
* - a specific glyph analyzer that computes segments and edges for each
* glyph covered by the script,
*
* - a specific grid-fitting algorithm that distorts the scaled glyph
* outline according to the results of the glyph analyzer.
*/
#undef WRITING_SYSTEM
#define WRITING_SYSTEM( ws, WS ) \
AF_WRITING_SYSTEM_ ## WS,
/* The list of known writing systems. */
typedef enum AF_WritingSystem_
{
#include "afws-iter.h"
AF_WRITING_SYSTEM_MAX /* do not remove */
} AF_WritingSystem;
typedef struct AF_WritingSystemClassRec_
{
AF_WritingSystem writing_system;
FT_Offset style_metrics_size;
AF_WritingSystem_InitMetricsFunc style_metrics_init;
AF_WritingSystem_ScaleMetricsFunc style_metrics_scale;
AF_WritingSystem_DoneMetricsFunc style_metrics_done;
AF_WritingSystem_GetStdWidthsFunc style_metrics_getstdw;
AF_WritingSystem_InitHintsFunc style_hints_init;
AF_WritingSystem_ApplyHintsFunc style_hints_apply;
} AF_WritingSystemClassRec;
typedef const AF_WritingSystemClassRec* AF_WritingSystemClass;
/*************************************************************************/
/*************************************************************************/
/***** *****/
/***** S C R I P T S *****/
/***** *****/
/*************************************************************************/
/*************************************************************************/
/*
* Each script is associated with two sets of Unicode ranges to test
* whether the font face supports the script, and which non-base
* characters the script contains.
*
* We use four-letter script tags from the OpenType specification,
* extended by `NONE', which indicates `no script'.
*/
#undef SCRIPT
#define SCRIPT( s, S, d, h, H, ss ) \
AF_SCRIPT_ ## S,
/* The list of known scripts. */
typedef enum AF_Script_
{
#include "afscript.h"
AF_SCRIPT_MAX /* do not remove */
} AF_Script;
typedef struct AF_Script_UniRangeRec_
{
FT_UInt32 first;
FT_UInt32 last;
} AF_Script_UniRangeRec;
#define AF_UNIRANGE_REC( a, b ) { (FT_UInt32)(a), (FT_UInt32)(b) }
typedef const AF_Script_UniRangeRec* AF_Script_UniRange;
typedef struct AF_ScriptClassRec_
{
AF_Script script;
/* last element in the ranges must be { 0, 0 } */
AF_Script_UniRange script_uni_ranges;
AF_Script_UniRange script_uni_nonbase_ranges;
FT_Bool top_to_bottom_hinting;
const char* standard_charstring; /* for default width and height */
} AF_ScriptClassRec;
typedef const AF_ScriptClassRec* AF_ScriptClass;
/*************************************************************************/
/*************************************************************************/
/***** *****/
/***** C O V E R A G E S *****/
/***** *****/
/*************************************************************************/
/*************************************************************************/
/*
* Usually, a font contains more glyphs than can be addressed by its
* character map.
*
* In the PostScript font world, encoding vectors specific to a given
* task are used to select such glyphs, and these glyphs can be often
* recognized by having a suffix in its glyph names. For example, a
* superscript glyph `A' might be called `A.sup'. Unfortunately, this
* naming scheme is not standardized and thus unusable for us.
*
* In the OpenType world, a better solution was invented, namely
* `features', which cleanly separate a character's input encoding from
* the corresponding glyph's appearance, and which don't use glyph names
* at all. For our purposes, and slightly generalized, an OpenType
* feature is a name of a mapping that maps character codes to
* non-standard glyph indices (features get used for other things also).
* For example, the `sups' feature provides superscript glyphs, thus
* mapping character codes like `A' or `B' to superscript glyph
* representation forms. How this mapping happens is completely
* uninteresting to us.
*
* For the auto-hinter, a `coverage' represents all glyphs of an OpenType
* feature collected in a set (as listed below) that can be hinted
* together. To continue the above example, superscript glyphs must not
* be hinted together with normal glyphs because the blue zones
* completely differ.
*
* Note that FreeType itself doesn't compute coverages; it only provides
* the glyphs addressable by the default Unicode character map. Instead,
* we use the HarfBuzz library (if available), which has many functions
* exactly for this purpose.
*
* AF_COVERAGE_DEFAULT is special: It should cover everything that isn't
* listed separately (including the glyphs addressable by the character
* map). In case HarfBuzz isn't available, it exactly covers the glyphs
* addressable by the character map.
*
*/
#undef COVERAGE
#define COVERAGE( name, NAME, description, \
tag1, tag2, tag3, tag4 ) \
AF_COVERAGE_ ## NAME,
typedef enum AF_Coverage_
{
#include "afcover.h"
AF_COVERAGE_DEFAULT
} AF_Coverage;
/*************************************************************************/
/*************************************************************************/
/***** *****/
/***** S T Y L E S *****/
/***** *****/
/*************************************************************************/
/*************************************************************************/
/*
* The topmost structure for modelling the auto-hinter glyph input data
* is a `style class', grouping everything together.
*/
#undef STYLE
#define STYLE( s, S, d, ws, sc, ss, c ) \
AF_STYLE_ ## S,
/* The list of known styles. */
typedef enum AF_Style_
{
#include "afstyles.h"
AF_STYLE_MAX /* do not remove */
} AF_Style;
typedef struct AF_StyleClassRec_
{
AF_Style style;
AF_WritingSystem writing_system;
AF_Script script;
AF_Blue_Stringset blue_stringset;
AF_Coverage coverage;
} AF_StyleClassRec;
typedef const AF_StyleClassRec* AF_StyleClass;
/*************************************************************************/
/*************************************************************************/
/***** *****/
/***** S T Y L E M E T R I C S *****/
/***** *****/
/*************************************************************************/
/*************************************************************************/
typedef struct AF_FaceGlobalsRec_* AF_FaceGlobals;
/* This is the main structure that combines everything. Autofit modules */
/* specific to writing systems derive their structures from it, for */
/* example `AF_LatinMetrics'. */
typedef struct AF_StyleMetricsRec_
{
AF_StyleClass style_class;
AF_ScalerRec scaler;
FT_Bool digits_have_same_width;
AF_FaceGlobals globals; /* to access properties */
} AF_StyleMetricsRec;
#define AF_HINTING_BOTTOM_TO_TOP 0
#define AF_HINTING_TOP_TO_BOTTOM 1
/* Declare and define vtables for classes */
#define AF_DECLARE_WRITING_SYSTEM_CLASS( writing_system_class ) \
FT_CALLBACK_TABLE const AF_WritingSystemClassRec \
writing_system_class;
#define AF_DEFINE_WRITING_SYSTEM_CLASS( \
writing_system_class, \
system, \
m_size, \
m_init, \
m_scale, \
m_done, \
m_stdw, \
h_init, \
h_apply ) \
FT_CALLBACK_TABLE_DEF \
const AF_WritingSystemClassRec writing_system_class = \
{ \
system, \
\
m_size, \
\
m_init, \
m_scale, \
m_done, \
m_stdw, \
\
h_init, \
h_apply \
};
#define AF_DECLARE_SCRIPT_CLASS( script_class ) \
FT_CALLBACK_TABLE const AF_ScriptClassRec \
script_class;
#define AF_DEFINE_SCRIPT_CLASS( \
script_class, \
script, \
ranges, \
nonbase_ranges, \
top_to_bottom, \
std_charstring ) \
FT_CALLBACK_TABLE_DEF \
const AF_ScriptClassRec script_class = \
{ \
script, \
ranges, \
nonbase_ranges, \
top_to_bottom, \
std_charstring, \
};
#define AF_DECLARE_STYLE_CLASS( style_class ) \
FT_CALLBACK_TABLE const AF_StyleClassRec \
style_class;
#define AF_DEFINE_STYLE_CLASS( \
style_class, \
style, \
writing_system, \
script, \
blue_stringset, \
coverage ) \
FT_CALLBACK_TABLE_DEF \
const AF_StyleClassRec style_class = \
{ \
style, \
writing_system, \
script, \
blue_stringset, \
coverage \
};
/* */
FT_END_HEADER
#endif /* AFTYPES_H_ */
/* END */