/**************************************************************************** * * autohint.h * * High-level `autohint' module-specific interface (specification). * * Copyright 1996-2018 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 #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; #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_ \ }; FT_END_HEADER #endif /* AUTOHINT_H_ */ /* END */