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Diffstat (limited to 'src/include/font.h')
| -rw-r--r-- | src/include/font.h | 343 |
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diff --git a/src/include/font.h b/src/include/font.h new file mode 100644 index 0000000..68a82fa --- /dev/null +++ b/src/include/font.h @@ -0,0 +1,343 @@ +// -*- C++ -*- +/* Copyright (C) 1989-2020 Free Software Foundation, Inc. + Written by James Clark (jjc@jclark.com) + +This file is part of groff. + +groff is free software; you can redistribute it and/or modify it under +the terms of the GNU General Public License as published by the Free +Software Foundation, either version 3 of the License, or +(at your option) any later version. + +groff is distributed in the hope that it will be useful, but WITHOUT ANY +WARRANTY; without even the implied warranty of MERCHANTABILITY or +FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License +for more details. + +You should have received a copy of the GNU General Public License +along with this program. If not, see <http://www.gnu.org/licenses/>. */ + +// A function of this type can be registered to define the semantics of +// arbitrary commands in a font DESC file. +typedef void (*FONT_COMMAND_HANDLER)(const char *, // command + const char *, // arg + const char *, // file + int); // lineno + +// A glyph is represented by a font-independent 'glyph *' pointer. The +// functions name_to_glyph and number_to_glyph return such a pointer. +// +// There are two types of glyphs: +// +// - those with a name, and among these in particular: +// 'charNNN' denoting a single 'char' in the input character set, +// 'uXXXX' denoting a Unicode character, +// +// - those with a number, referring to the font-dependent glyph with +// the given number. + +// The statically allocated information about a glyph. +// +// This is an abstract class; only its subclass 'charinfo' is +// instantiated. 'charinfo' exists in two versions: one in +// roff/troff/input.cpp for troff, and one in +// libs/libgroff/nametoindex.cpp for the preprocessors and the +// postprocessors. +struct glyph { + int index; // A font-independent integer value. + int number; // Glyph number or -1. + friend class character_indexer; +}; + +#define UNDEFINED_GLYPH ((glyph *) 0) + +// The next three functions exist in two versions: one in +// roff/troff/input.cpp for troff, and one in +// libs/libgroff/nametoindex.cpp for the preprocessors and the +// postprocessors. +extern glyph *name_to_glyph(const char *); // Convert the glyph with + // the given name (arg1) to a 'glyph' object. This + // has the same semantics as the groff escape sequence + // \C'name'. If such a 'glyph' object does not yet + // exist, a new one is allocated. +extern glyph *number_to_glyph(int); // Convert the font-dependent glyph + // with the given number (in the font) to a 'glyph' + // object. This has the same semantics as the groff + // escape sequence \N'number'. If such a 'glyph' + // object does not yet exist, a new one is allocated. +extern const char *glyph_to_name(glyph *); // Convert the given + // glyph back to its name. Return null pointer + // if the glyph doesn't have a name. +inline int glyph_to_number(glyph *); // Convert the given glyph back to + // its number. Return -1 if it does not designate + // a numbered character. +inline int glyph_to_index(glyph *); // Return the unique index that is + // associated with the given glyph. It is >= 0. +extern int glyph_to_unicode(glyph *); // Convert the given glyph to its + // Unicode codepoint. Return -1 if it does not + // designate a Unicode character. + +inline int glyph_to_number(glyph *g) +{ + return g->number; +} + +inline int glyph_to_index(glyph *g) +{ + return g->index; +} + +// Types used in non-public members of 'class font'. +struct font_kern_list; +struct font_char_metric; +struct font_widths_cache; + +// A 'class font' instance represents the relevant information of a font of +// the given device. This includes the set of glyphs represented by the +// font, and metrics for each glyph. +class font { +public: + enum { // The valid argument values of 'has_ligature'. + LIG_ff = 1, + LIG_fi = 2, + LIG_fl = 4, + LIG_ffi = 8, + LIG_ffl = 16 + }; + + virtual ~font(); // Destructor. + bool contains(glyph *); // This font contains the given glyph. + bool is_special(); // This font is searched for glyphs not defined + // in the current font. See section 'Special + // Fonts' in the groff Texinfo manual. Used by + // make_glyph_node(). + int get_width(glyph *, int); // A rectangle represents the shape of the + // given glyph (arg1) at the given point size + // (arg2). Return the horizontal dimension of this + // rectangle. + int get_height(glyph *, int); // A rectangle represents the shape of the + // given glyph (arg1) at the given point size + // (arg2). Return the distance between the base + // line and the top of this rectangle. + // This is often also called the 'ascent' of the + // glyph. If the top is above the baseline, this + // value is positive. + int get_depth(glyph *, int); // A rectangle represents the shape of the + // given glyph (arg1) at the given point size + // (arg2). Return the distance between the base + // line and the bottom of this rectangle. + // This is often also called the 'descent' of the + // glyph. If the bottom is below the baseline, + // this value is positive. + int get_space_width(int); // Return the normal width of a space at the + // given point size. + int get_character_type(glyph *); // Return a bit mask describing the + // shape of the given glyph. Bit 0 is set if the + // character has a descender. Bit 1 is set if the + // character has a tall glyph. See groff manual, + // description of \w and the 'ct' register. + int get_kern(glyph *, glyph *, int); // Return the kerning between the + // given glyphs (arg1 and arg2), both at the given + // point size (arg3). + int get_skew(glyph *, int, int); // A rectangle represents the shape + // of the given glyph (arg1) at the given point size + // (arg2). For slanted fonts like Times-Italic, the + // optical vertical axis is naturally slanted. The + // natural slant value (measured in degrees; + // positive values mean aslant to the right) is + // specified in the font's description file (see + // member variable SLANT below). In addition to + // this, any font can be artificially slanted. This + // artificial slant value (arg3, measured in + // degrees; positive values mean a slant to the + // right) is specified with the \S escape. + // + // Return the skew value which is the horizontal + // distance between the upper left corner of the + // glyph box and the upper left corner of the glyph + // box thought to be slanted by the sum of the + // natural and artificial slant. It basically means + // how much an accent must be shifted horizontally + // to put it on the optical axis of the glyph. + bool has_ligature(int); // This font has the given ligature type + // (one of LIG_ff, LIG_fi, ...). + int get_italic_correction(glyph *, int); // If the given glyph (arg1) + // at the given point size (arg2) is followed by an + // unslanted glyph, some horizontal white space may + // need to be inserted in between. See the groff + // manual, description of \/. Return the amount + // (width) of this white space. + int get_left_italic_correction(glyph *, int); // If the given glyph (arg1) + // at the given point size (arg2) is preceded by an + // unslanted roman glyph, some horizontal white + // space may need to be inserted in between. See + // the groff manual, description of \,. Return the + // amount (width) of this white space. + int get_subscript_correction(glyph *, int); // If the given glyph (arg1) + // at the given point size (arg2)is followed by a + // subscript glyph, the horizontal position may need + // to be advanced by some (possibly negative) + // amount. See groff manual, description of \w and + // the 'ssc' register. Return this amount. + void set_zoom(int); // Set the font's zoom factor * 1000. Must be a + // non-negative value. + int get_zoom(); // Return the font's zoom factor * 1000. + int get_code(glyph *); // Return the code point in the physical + // font of the given glyph. + const char *get_special_device_encoding(glyph *); // Return + // special device-dependent information about + // the given glyph. Return null pointer if + // there is no special information. + const char *get_name(); // Return the name of this font. + const char *get_internal_name(); // Return the 'internalname' + // attribute of this font or null pointer if it + // has none. + const char *get_image_generator(); // Return the 'image_generator' + // attribute of this font or null pointer if it + // has none. + static bool scan_papersize(const char *, const char **, + double *, double *); // Parse the + // 'papersize' directive in the DESC file name + // given in arg1. Update arg2 with the name + // of the paper format and arg3 and arg4 with + // its length and width, respectively. Return + // whether paper size was successfully set. + static font *load_font(const char *, bool = false); // Load the font + // description file with the given name (arg1) + // and return a pointer to a 'font' object. If + // arg2 is true, only the part of the font + // description file before the 'charset' and + // 'kernpairs' sections is loaded. Return null + // pointer in case of failure. + static void command_line_font_dir(const char *); // Prepend given + // path (arg1) to the list of directories in which + // to look up fonts. + static FILE *open_file(const char *, char **); // Open + // a font file with the given name (arg1), + // searching along the current font path. If + // arg2 points to a string pointer, set it to + // the found file name (this depends on the + // device also). Return the opened file. If + // not found, arg2 is unchanged, and a null + // pointer is returned. + + // Open the DESC file (depending on the device) and initialize some + // static variables with info from there. + static const char *load_desc(); + static FONT_COMMAND_HANDLER + set_unknown_desc_command_handler(FONT_COMMAND_HANDLER); // Register + // a function which defines the semantics of + // arbitrary commands in the font DESC file. + // Now the variables from the DESC file, shared by all fonts. + static int res; // The 'res' attribute given in the DESC file. + static int hor; // The 'hor' attribute given in the DESC file. + static int vert; // The 'vert' attribute given in the DESC file. + static int unitwidth; // The 'unitwidth' attribute given in the DESC file. + static int paperwidth; // The 'paperwidth' attribute given in the + // DESC file, or derived from the 'papersize' + // attribute given in the DESC file. + static int paperlength; // The 'paperlength' attribute given in the + // DESC file, or derived from the 'papersize' + // attribute given in the DESC file. + static const char *papersize; + static int biggestfont; // The 'biggestfont' attribute given in the + // DESC file. + static int spare2; + static int sizescale; // The 'sizescale' attribute given in the DESC file. + static bool has_tcommand; // DESC file has 'tcommand' directive. + static bool use_unscaled_charwidths; // DESC file has + // 'unscaled_charwidths' directive. + static bool pass_filenames; // DESC file has 'pass_filenames' + // directive. + static bool use_charnames_in_special; // DESC file has + // 'use_charnames_in_special' directive. + static bool is_unicode; // DESC file has the 'unicode' directive. + static const char *image_generator; // The 'image_generator' attribute + // given in the DESC file. + static const char **font_name_table; // The 'fonts' attribute given + // in the DESC file, as a null + // pointer-terminated array of strings. + static const char **style_table; // The 'styles' attribute given + // in the DESC file, as a null + // pointer-terminated array of strings. + static const char *family; // The 'family' attribute given in the DESC + // file. + static int *sizes; // The 'sizes' attribute given in the DESC file, as + // an array of intervals of the form { lower1, + // upper1, ... lowerN, upperN, 0 }. + +private: + unsigned ligatures; // Bit mask of available ligatures. Used by + // has_ligature(). + font_kern_list **kern_hash_table; // Hash table of kerning pairs. + // Used by get_kern(). + int space_width; // The normal width of a space. Used by + // get_space_width(). + bool special; // See public is_special() above. + char *name; // The name of this font. Used by get_name(). + char *internalname; // The 'internalname' attribute of this font, or + // a null pointer. Used by get_internal_name(). + double slant; // The natural slant angle (in degrees) of this font. + int zoom; // The font's magnification, multiplied by 1000. + // Used by scale(). A zero value means 'no zoom'. + int *ch_index; // Conversion table from font-independent character + // indices to indices for this particular font. + int nindices; + font_char_metric *ch; // Metrics information for every character in this + // font (if !is_unicode) or for just some characters + // (if is_unicode). The indices of this array are + // font-specific, found as values in ch_index[]. + int ch_used; + int ch_size; + font_widths_cache *widths_cache; // A cache of scaled character + // widths. Used by the get_width() function. + + static FONT_COMMAND_HANDLER unknown_desc_command_handler; // A + // function defining the semantics of arbitrary + // commands in the DESC file. + enum { KERN_HASH_TABLE_SIZE = 503 }; // Size of the hash table of kerning + // pairs. + + // These methods add new characters to the ch_index[] and ch[] arrays. + void add_entry(glyph *, // glyph + const font_char_metric &); // metric + void copy_entry(glyph *, // new_glyph + glyph *); // old_glyph + void alloc_ch_index(int); // index + void extend_ch(); + void compact(); + + void add_kern(glyph *, glyph *, int); // Add to the kerning table a + // kerning amount (arg3) between two given glyphs + // (arg1 and arg2). + static int hash_kern(glyph *, glyph *); // Return a hash code for + // the pair of glyphs (arg1 and arg2). + + /* Returns w * pointsize / unitwidth, rounded to the nearest integer. */ + int scale(int w, int pointsize); + static bool unit_scale(double *, char); // Convert value in arg1 from + // the given unit (arg2; possible values are + // 'i', 'c', 'p', and 'P' as documented in the + // info file of groff, section 'Measurements') + // to inches. Store result in arg1 and return + // whether conversion was successful. + virtual void handle_unknown_font_command(const char *, // command + const char *, // arg + const char *, // file + int); // lineno + +protected: + font(const char *); // Initialize a font with the given name. + + // Load the font description file with the name in member variable + // `name` into this object. If arg1 is true, only the part of the + // font description file before the 'charset' and 'kernpairs' sections + // is loaded. Return success/failure status of load. + bool load(bool = false); +}; + +// Local Variables: +// fill-column: 72 +// mode: C++ +// End: +// vim: set cindent noexpandtab shiftwidth=2 textwidth=72: |