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authorNikolas <nikolas@boutalas.com>2024-10-27 12:52:55 +0200
committerNikolas <nikolas@boutalas.com>2024-10-27 12:52:55 +0200
commit43394c8a8908442982e3a7e25975c31b3c952923 (patch)
tree2facd563e29f48fe3b0653ac5c113998940b4d5e /3rdparty/include/freetype/internal/autohint.h
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+/***************************************************************************/
+/* */
+/* 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 <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 */