/***************************************************************************/ | |
/* */ | |
/* 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 */ |