ref: c3e9f026058981ee7ef6bf0b15601e11e994b1d9
dir: /include/internal/autohint.h/
/***************************************************************************/ /* */ /* 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 */