kc3-lang/freetype/src/shared/autohint.h
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Hash : 81d02dbc
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Date : 2000-05-05T01:37:32
finally a auto-hinter module interface I'm satisfied with, it's now time to change other font drivers to take advantage of it :-)
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src/shared/autohint.h
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/***************************************************************************/ /* */ /* autohint.h */ /* */ /* High-level `autohint" driver interface (specification) */ /* */ /* Copyright 1996-2000 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 */ /* when 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 * agressively 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 require a lot more horsepower. * * Because a sufficiently sophisticated font management system would * typically implement a 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 :o) * * I initially though that it'd be a good idea to cache the glyph hints too, * however, if my general idea now is that if you really need to cache these * too, you're 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 <freetype.h> typedef struct FT_AutoHinterRec_ *FT_AutoHinter; /*********************************************************************** * * <FuncType> * FT_AutoHinter_Get_Global_Func * * <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_Done_Global_Func. * * <Input> * hinter :: handle to source auto-hinter * face :: handle to source face object * * <Output> * global_hints :: typeless pointer to the global hints * global_len :: size in bytes of global hints * */ typedef void (*FT_AutoHinter_Get_Global_Func)( FT_AutoHinter hinter, FT_Face face, void* *global_hints, long *global_len ); /*********************************************************************** * * <FuncType> * FT_AutoHinter_Done_Global_Func * * <Description> * Discards the global hints retrieved through * FT_AutoHinter_Get_Global_Func. This is the only way these hints * are freed from memory. * * <Input> * hinter :: handle to auto-hinter module * global :: pointer to retrieved global hints to discard */ typedef void (*FT_AutoHinter_Done_Global_Func)( FT_AutoHinter hinter, void* global ); /*********************************************************************** * * <FuncType> * FT_AutoHinter_Init_Func * * <Description> * Compute or set the global hints for a given face object. * * <Input> * hinter :: handle to source auto-hinter module * face :: handle to target face object. * global_hints :: typeless pointer to global hints. If 0, the * hints are computed for the face * * <Note> * it is up to client applications to ensure that the global hints * were retrieved for the same face object. Strange results may occur * otherwise.. * */ typedef FT_Error (*FT_AutoHinter_Init_Func)( FT_AutoHinter hinter, FT_Face face, void* global_hints ); /*********************************************************************** * * <FuncType> * FT_AutoHinter_Done_Func * * <Description> * Discards the global hints for a given face.. * * <Input> * hinter :: handle to source auto-hinter module * face :: handle to target face object. * */ typedef FT_Error (*FT_AutoHinter_Done_Func)( FT_AutoHinter hinter, FT_Face face ); /*********************************************************************** * * <FuncType> * FT_AutoHinter_Load_Func * * <Description> * This function is used to load, scale and automatically hint a glyph * from a given face. * * <Input> * face :: handle to the face. * glyph_index :: glyph index * load_flags :: 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_Load_Func)( FT_Face face, FT_UInt glyph_index, FT_ULong load_flags ); /*********************************************************************** * * <Struct> * FT_AutoHinter_Interface * * <Description> * The auto-hinter module's interface. * */ typedef struct FT_AutoHinter_Interface { FT_AutoHinter_Init_Func init_autohinter; FT_AutoHinter_Done_Func done_autohinter; FT_AutoHinter_Load_Func load_glyph; FT_AutoHinter_Get_Global_Func get_global_hints; FT_AutoHinter_Done_Global_Func done_global_hints; } FT_AutoHinter_Interface; #endif /* AUTOHINT_H */