ref: 772a5e5ddd2861e9b27de745699670e746442e0e
dir: /include/internal/autohint.h/
/***************************************************************************/
/* */
/* autohint.h */
/* */
/* High-level `autohint' module-specific interface (specification). */
/* */
/* Copyright 1996-2015 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-hinter is used to load and automatically hint glyphs if a */
/* format-specific hinter isn't available. */
/* */
/*************************************************************************/
#ifndef __AUTOHINT_H__
#define __AUTOHINT_H__
/*************************************************************************/
/* */
/* A small technical note regarding automatic hinting in order to */
/* clarify this module interface. */
/* */
/* An automatic hinter might compute two kinds of data for a given face: */
/* */
/* - global hints: Usually some metrics that describe global properties */
/* of the face. It is computed by scanning more or less */
/* aggressively the glyphs in the face, and thus can be */
/* very slow to compute (even if the size of global */
/* hints is really small). */
/* */
/* - glyph hints: These describe some important features of the glyph */
/* outline, as well as how to align them. They are */
/* generally much faster to compute than global hints. */
/* */
/* The current FreeType auto-hinter does a pretty good job while */
/* performing fast computations for both global and glyph hints. */
/* However, we might be interested in introducing more complex and */
/* powerful algorithms in the future, like the one described in the John */
/* D. Hobby paper, which unfortunately requires a lot more horsepower. */
/* */
/* Because a sufficiently sophisticated font management system would */
/* typically implement an LRU cache of opened face objects to reduce */
/* memory usage, it is a good idea to be able to avoid recomputing */
/* global hints every time the same face is re-opened. */
/* */
/* We thus provide the ability to cache global hints outside of the face */
/* object, in order to speed up font re-opening time. Of course, this */
/* feature is purely optional, so most client programs won't even notice */
/* it. */
/* */
/* I initially thought that it would be a good idea to cache the glyph */
/* hints too. However, my general idea now is that if you really need */
/* to cache these too, you are simply in need of a new font format, */
/* where all this information could be stored within the font file and */
/* decoded on the fly. */
/* */
/*************************************************************************/
#include <ft2build.h>
#include FT_FREETYPE_H
FT_BEGIN_HEADER
typedef struct FT_AutoHinterRec_ *FT_AutoHinter;
/*************************************************************************/
/* */
/* <FuncType> */
/* FT_AutoHinter_GlobalGetFunc */
/* */
/* <Description> */
/* Retrieve the global hints computed for a given face object. The */
/* resulting data is dissociated from the face and will survive a */
/* call to FT_Done_Face(). It must be discarded through the API */
/* FT_AutoHinter_GlobalDoneFunc(). */
/* */
/* <Input> */
/* hinter :: A handle to the source auto-hinter. */
/* */
/* face :: A handle to the source face object. */
/* */
/* <Output> */
/* global_hints :: A typeless pointer to the global hints. */
/* */
/* global_len :: The size in bytes of the global hints. */
/* */
typedef void
(*FT_AutoHinter_GlobalGetFunc)( FT_AutoHinter hinter,
FT_Face face,
void** global_hints,
long* global_len );
/*************************************************************************/
/* */
/* <FuncType> */
/* FT_AutoHinter_GlobalDoneFunc */
/* */
/* <Description> */
/* Discard the global hints retrieved through */
/* FT_AutoHinter_GlobalGetFunc(). This is the only way these hints */
/* are freed from memory. */
/* */
/* <Input> */
/* hinter :: A handle to the auto-hinter module. */
/* */
/* global :: A pointer to retrieved global hints to discard. */
/* */
typedef void
(*FT_AutoHinter_GlobalDoneFunc)( FT_AutoHinter hinter,
void* global );
/*************************************************************************/
/* */
/* <FuncType> */
/* FT_AutoHinter_GlobalResetFunc */
/* */
/* <Description> */
/* This function is used to recompute the global metrics in a given */
/* font. This is useful when global font data changes (e.g. Multiple */
/* Masters fonts where blend coordinates change). */
/* */
/* <Input> */
/* hinter :: A handle to the source auto-hinter. */
/* */
/* face :: A handle to the face. */
/* */
typedef void
(*FT_AutoHinter_GlobalResetFunc)( FT_AutoHinter hinter,
FT_Face face );
/*************************************************************************/
/* */
/* <FuncType> */
/* FT_AutoHinter_GlyphLoadFunc */
/* */
/* <Description> */
/* This function is used to load, scale, and automatically hint a */
/* glyph from a given face. */
/* */
/* <Input> */
/* face :: A handle to the face. */
/* */
/* glyph_index :: The glyph index. */
/* */
/* load_flags :: The load flags. */
/* */
/* <Note> */
/* This function is capable of loading composite glyphs by hinting */
/* each sub-glyph independently (which improves quality). */
/* */
/* It will call the font driver with @FT_Load_Glyph, with */
/* @FT_LOAD_NO_SCALE set. */
/* */
typedef FT_Error
(*FT_AutoHinter_GlyphLoadFunc)( FT_AutoHinter hinter,
FT_GlyphSlot slot,
FT_Size size,
FT_UInt glyph_index,
FT_Int32 load_flags );
/*************************************************************************/
/* */
/* <Struct> */
/* FT_AutoHinter_InterfaceRec */
/* */
/* <Description> */
/* The auto-hinter module's interface. */
/* */
typedef struct FT_AutoHinter_InterfaceRec_
{
FT_AutoHinter_GlobalResetFunc reset_face;
FT_AutoHinter_GlobalGetFunc get_global_hints;
FT_AutoHinter_GlobalDoneFunc done_global_hints;
FT_AutoHinter_GlyphLoadFunc load_glyph;
} FT_AutoHinter_InterfaceRec, *FT_AutoHinter_Interface;
#ifndef FT_CONFIG_OPTION_PIC
#define FT_DEFINE_AUTOHINTER_INTERFACE( \
class_, \
reset_face_, \
get_global_hints_, \
done_global_hints_, \
load_glyph_ ) \
FT_CALLBACK_TABLE_DEF \
const FT_AutoHinter_InterfaceRec class_ = \
{ \
reset_face_, \
get_global_hints_, \
done_global_hints_, \
load_glyph_ \
};
#else /* FT_CONFIG_OPTION_PIC */
#define FT_DEFINE_AUTOHINTER_INTERFACE( \
class_, \
reset_face_, \
get_global_hints_, \
done_global_hints_, \
load_glyph_ ) \
void \
FT_Init_Class_ ## class_( FT_Library library, \
FT_AutoHinter_InterfaceRec* clazz ) \
{ \
FT_UNUSED( library ); \
\
clazz->reset_face = reset_face_; \
clazz->get_global_hints = get_global_hints_; \
clazz->done_global_hints = done_global_hints_; \
clazz->load_glyph = load_glyph_; \
}
#endif /* FT_CONFIG_OPTION_PIC */
FT_END_HEADER
#endif /* __AUTOHINT_H__ */
/* END */