forked from minhngoc25a/freetype2
245 lines
14 KiB
C
245 lines
14 KiB
C
/***************************************************************************/
|
|
/* */
|
|
/* autohint.h */
|
|
/* */
|
|
/* High-level `autohint' module-specific interface (specification). */
|
|
/* */
|
|
/* Copyright 1996-2002, 2007, 2009, 2012 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 */
|