path: root/Build/source/texk/seetexk/font.h

/*
 * Copyright (c) 1987, 1989 University of Maryland
 * Department of Computer Science.  All rights reserved.
 * Permission to copy for any purpose is hereby granted
 * so long as this copyright notice remains intact.
 */

#ifndef _MCTEX_FONT_
#define _MCTEX_FONT_

/*
 * Font file information, readers, etc.
 */

#ifndef _MCTEX_TYPES_
#include "types.h"
#endif

/*
 * First, font independent information: per glyph info, and per font
 * info.
 */
struct glyph {
	short	g_flags;	/* see below */
	/*
	 * The following cannot be used with GetRasterlessFont
	 */
	short	g_rotation;	/* see below */
	char	*g_raster;	/* raster, if known */
	/*
	 * These, however, do come with rasterless fonts,
	 * even though they relate only to the raster.
	 */
	i32	g_height;	/* height of bounding box */
	i32	g_width;	/* width of bounding box */
	i32	g_yorigin;	/* y origin (>= 0 -> within box) */
	i32	g_xorigin;	/* x origin (>= 0 -> within box) */
	/*
	 * These of course come with every font.
	 */
	i32	g_rawtfmwidth;	/* raw TFM width (in FIXes) */
	i32	g_tfmwidth;	/* TFM width in scaled points */
	/*
	 * The X and Y escapements come from PK and GF fonts.
	 * They are in scaled pixels (65536 scaled pixels = 1 pixel).
	 * If they are not defined by the font, these are set to
	 * NO_ESCAPEMENT.
	 */
	i32	g_xescapement;	/* x escapement (`chardx') */
	i32	g_yescapement;	/* y escapement (`chardy') */
#define	NO_ESCAPEMENT	((i32)0x89abcdef)
	/*
	 * This is provided purely for DVI to device conversion programs.
	 */
	int	g_pixwidth;	/* width in pixels */
	/*
	 * Mainly for internal use, index is the glyph index within the
	 * font.  That is, f->f_gly[i]->g_index == i.
	 */
	int	g_index;	/* character index */
	/*
	 * g_details and g_integer are purely for the font reading
	 * subroutines to use however they will.  g_next makes lists
	 * of glyphs while the glyphs are free.
	 */
	union {			/* various options */
		char	*g_details;	/* details: arbitrary */
		i32	g_integer;	/* 32 bit integer */
		struct	glyph *g_next;	/* linked list */
	} g_un;
};

/*
 * Glyph flags.
 */
#define	GF_VALID	0x0001	/* glyph is `real' */
#define	GF_SEEN		0x0002	/* glyph has been encountered/loaded */

#define	GF_USR0		0x0100	/* reserved to user code */
#define	GF_USR1		0x0200	/* reserved to user code */
#define	GF_USR2		0x0400	/* reserved to user code */
#define	GF_USR3		0x0800	/* reserved to user code */

/*
 * Rotations are in quarter-pi steps, counterclockwise of course.
 * This order must be maintained; see rotate.c.
 */
#define	ROT_NORM	0		/* no rotation: `normal' position */
#define	ROT_LEFT	1		/* 1/4 turn counterclockwise */
#define	ROT_DOWN	2		/* 1/2 turn, i.e., upside-down */
#define	ROT_RIGHT	3		/* 3/4 turn ccw, or 1/4 turn cw */

struct font {
	int	f_flags;	/* see below */
	struct	fontops *f_ops;	/* operations */
	/*
	 * f_un is provided for DVI drivers, which typically need
	 * some way to translate DVI font numbers into local values.
	 * Most seem to need integers.
	 */
	union {
		int	f_int;	/* value if int */
		i32	f_i32;	/* value if i32 */
		char	*f_ptr;	/* value if pointer */
	} f_un;
#ifdef notdef
	/* for LRU cacheing; not yet implemented */
	i32	f_lastuse;
#endif
	/*
	 * f_details is provided for font reading subroutines.
	 * It is intended to be cast to a pointer to a structure
	 * that is allocated by those routines, and used to keep
	 * track of whatever information those routines need to
	 * determine glyph boxes and (if asked for) rasters.
	 */
	char	*f_details;	/* type dependent stuff */
	/*
	 * f_path is the full pathname to the font file, filled in
	 * by GetFont and GetRasterlessFont.  Note that since we
	 * hold on to the path until the font is freed, it should be
	 * possible to cache glyph accesses on memory-poor machines.
	 */
	char	*f_path;	/* font file pathname */
	/*
	 * f_dvimag and f_dvidsz are the magnification and design size
	 * values from the DVI file.  f_font and f_scaled correspond to
	 * TeX's idea of the proper name for the font (e.g., `cmr10',
	 * `cmbx10 scaled 1440').  (Note that f_scaled is just the
	 * ratio of f_dvimag and f_dvidsz; you could save a bit of memory
	 * by eliminating it and altering the routine Font_TeXName()).
	 * f_design_size is the font's design size, or 0 for fake (TFM)
	 * fonts.  f_checksum should be set by the font reading routines
	 * to the font checksum.  If the value is nonzero, it will be
	 * compared to the checksum in the DVI file.
	 */
	i32	f_dvimag;	/* magnification from DVI file */
	i32	f_dvidsz;	/* design size from DVI file */
	char	*f_font;	/* TeX's name for the font */
	int	f_scaled;	/* the ratio of dvimag to dvidsz, x1000 */
	i32	f_design_size;	/* font design size */
	i32	f_checksum;	/* font checksum, or 0 */
	/*
	 * The three values f_pspace, f_nspace, and f_vspace correspond
	 * to the amount of positive, negative, and vertical space that
	 * limits `kerning' (if horizontal) or `in-line motion' (vertical).
	 * f_pspace is equal to 1/6 of f_dvimag, and f_nspace and f_vspace
	 * are -4 and 5 times this value respectively.  DVItype puts it
	 * this way (slightly edited):
	 *
	 *	Rounding to the nearest pixel is best done in [this]
	 *	manner ... so as to be inoffensive to the eye:  When [a]
	 *	horizontal motion is small, like a kern, [the device
	 *	position] changes by rounding the kern; but when the
	 *	motion is large, [the device position] changes by rounding
	 *	the [DVI position] so that accumulated rounding errors
	 *	disappear.  We allow a larger space in the negative
	 *	direction than in the positive one, because TeX makes
	 *	comparatively large backspaces when it positions accents.
	 *
	 *	Vertical motion is done similarly, but with the threshold
	 *	between ``small'' and ``large'' increased by a factor of
	 *	five. The idea is to make fractions like ``$1\over2$''
	 *	round consistently, but to absorb accumulated rounding
	 *	errors in the baseline-skip moves.
	 *
	 * There is, however, an exception:
	 *
	 *	A sequence of consecutive rules, or consecutive characters
	 *	in a fixed-width font whose width is not an integer number
	 *	of pixels, can cause [the device position] to drift far
	 *	away from a correctly rounded value.
	 *
	 * The drift correction is applied after every horizontal or
	 * vertical motion, including any resulting from printing a
	 * character.
	 */
	i32	f_pspace;	/* limit on positive kerns */
	i32	f_nspace;	/* limit on negative kerns */
	i32	f_vspace;	/* limit on vertical `kerns' */

	/*
	 * If set, f_hppp and f_vppp tell how many pixels there are
	 * per scaled point in the font.  For instance, a 300 dpi font
	 * has 300pixels/1inch * 1inch/72.27pt * 65536pt/1sp ~=
	 * 272046 pixels/sp.
	 *
	 * If they are zero, the font does not tell us.
	 */
	i32	f_hppp;		/* horizontal pixels per point */
	i32	f_vppp;		/* vertical pixels per point */
	/*
	 * f_lowch and f_highch bound the region in which f_gly
	 * indicies are valid.  Specificially, f_gly[i] may be
	 * read or written if and only if i is in the half-open
	 * interval [f_lowch..f_highch).  f_gly is an array of
	 * pointers to glyph structures.  The structures themselves
	 * are not allocated until requested.
	 *
	 * f_glybase is the actual return from malloc(), since it
	 * is theoretically possible for f_gly-f_lowch to become
	 * NULL.
	 */
	int	f_lowch;	/* first character */
	int	f_highch;	/* last character, plus 1 */
	struct	glyph **f_gly;	/* glyphs */
	struct	glyph **f_glybase;
};

/*
 * Macros for rounding DVI and device motions per DVItype rules.
 */
#define	F_SMALLH(f, m) ((m) < (f)->f_pspace && (m) > (f)->f_nspace)
#define	F_SMALLV(f, m) ((m) < (f)->f_vspace && -(m) < (f)->f_vspace)

/*
 * Font flags.
 */
#define	FF_RASTERS	0x0001	/* font has rasters */
#define	FF_USR0		0x0100	/* reserved to user code */
#define	FF_USR1		0x0200	/* reserved to user code */
#define	FF_USR2		0x0400	/* reserved to user code */
#define	FF_USR3		0x0800	/* reserved to user code */

/*
 * Operations on fonts.
 *
 * The `fo_dpitomag' field is used as a multiplier for a desired
 * resolution in dots per inch.  The result of the multiplication
 * is converted to a font name by multipying by 1000.0 and rounding.
 * The idea is that PXL files will have a multiplier of 5.0, and
 * others will have a multiplier of 1.0.  This suffices for the
 * present, at any rate; in the future, this field may be replaced
 * with something more general.
 *
 * N.B.: more operations may be added as they are discovered to be
 * useful.
 */
struct	fontops {
	char	*fo_name;		/* name, e.g., "gf" */
	int	fo_fakefont;		/* 1="box", 2="blank"; else 0 */
	double	fo_dpitomag;		/* multiplier */
	int	(*fo_read)();		/* open and read the font itself */
	int	(*fo_getgly)();		/* obtain specified glyphs (range) */
#ifdef notdef
	void	(*fo_freegly)();	/* release specified glyphs */
#endif
	int	(*fo_rasterise)();	/* rasterise specified glyphs */
	void	(*fo_freefont)();	/* discard font (free details) */
	struct	fontops *fo_next;	/* purely for font.c */
};

/*
 * Return a pointer to the glyph information for character `c' in
 * font `f'.
 */
#define	GLYPH(f, c) \
	((c) < (f)->f_lowch || (c) >= (f)->f_highch ? (struct glyph *)0 : \
	 ((f)->f_gly[c] ? (f)->f_gly[c] : GetGlyph(f, (int)(c))))

/*
 * True iff glyph `g' is valid.  Useful for checking return values
 * from GLYPH().
 */
#define	GVALID(g)	((g) && ((g)->g_flags & GF_VALID))

/*
 * True iff glyph g has a raster.
 */
#define	HASRASTER(g)	((g)->g_height && (g)->g_width)

/*
 * Return a pointer to the raster information for glyph `g' in font
 * `f' at rotation `r'.
 */
#define	RASTER(g, f, r)	((g)->g_rotation == (r) && (g)->g_raster ? \
			 (g)->g_raster : GetRaster(g, f, r))

/*
 * Function types.
 */
struct	font *GetFont(char *nm, i32 dvimag, i32 dvidsz, char *dev, char **fname);
struct	font *GetRasterlessFont(char *nm, i32 dvimag, i32 dvidsz, char *dev, char **fname);
struct	glyph *GetGlyph();
char	*GetRaster();
void	FreeFont();
void	FreeGlyph();
void	FreeRaster();
char	*Font_TeXName();
void	fontinit(char *file);

/*
 * Normally from stdio.h
 */
#ifndef NULL
#define	NULL	0
#endif

/*
 * The following environment variable overrides the default font
 * configuration file.  That default is used when fontinit() is not
 * called, or is passed a null pointer.
 */
#define	CONFENV	"TEXFONTDESC"

#endif /* _MCTEX_FONT_ */