postbgi.c

这是一个同样来自贝尔实验室的和UNIX有着渊源的操作系统, 其简洁的设计和实现易于我们学习和理解

/*
 *
 * postbgi - BGI (Basic Graphical Instructions) to PostScript translator.
 *
 * A simple program that translates BGI files into PostScript. Probably only
 * useful in Computer Centers that support STARE or PRISM plotters. Most of the
 * code was borrowed from the corresponding program that was written for printers
 * that understand Impress.
 *
 * Extending the original program to handle PRISM jobs was not trivial. Graphics
 * packages that support PRISM occasionally use BGI commands that I ignored in the
 * STARE implementation. Subroutines, color requests, patterns (for filling), and
 * filled trapeziods were the most important omissions. All are now implemented,
 * and at present only repeats, filled slices, and raster rectangles are missing.
 *
 * Pattern filling results were not always predictable or even good, unless the
 * halftone screen definitions were changed and scaling was adjusted so one pixel
 * in user space mapped into an integral number of device space pixels. Doing that
 * makes the resulting PostScript output device dependent, but was often necessary.
 * I've added two booleans to the PostScript prologue (fixscreen and scaletodevice)
 * that control what's done. By default both are false (check postbgi.ps) but can
 * be set to true on the command line using the -P option or by hand by changing
 * the definitions in the prologue. A command line that would set fixscreen and
 * scaletodevice true would look like,
 *
 *	postbgi -P"/fixscreen true" -P"/scaletodevice true" file >file.ps
 *
 * Several other approaches are available if you want to have your spooler handle
 * STARE and PRISM jobs differently. A boolean called prism is defined in the
 * prologue (postbgi.ps) and if it's set to true PostScript procedure setup will
 * set fixscreen and scaletodevice to true before anything important is done. That
 * means the following command line,
 *
 *	postbgi -P"/prism true" file >file.ps
 *
 * accomplishes the same things as the last example. Two different prologue files,
 * one for STARE jobs and the other for PRISM, could be used and the spooler could
 * point postbgi to the appropriate one using the -L option. In that case the only
 * important difference in the two prologues would be the definition of prism. The
 * prologue used for PRISM jobs would have prism set to true, while the STARE
 * prologue would have it set to false.
 *
 * Also included is code that ties lines to device space coordinates. What you get
 * is a consistent line thickness, but placement of lines won't be exact. It's a
 * trade-off that should be right for most jobs. Everything is implemented in the
 * prologue (postbgi.ps) and nothing will be done if the linewidth is zero or if
 * the boolean fixlinewidth (again in postbgi.ps) is false. Once again the -P
 * option can be used to set fixlinewidth to whatever you choose.
 *
 * BGI supports color mixing but PostScript doesn't. BGI files that expect to mix
 * colors won't print properly. PostScript's fill operator overlays whatever has
 * already been put down. Implementing color mixing would have been a terribly
 * difficult job - not worth the effort!
 *
 * The PostScript prologue is copied from *prologue before any of the input files
 * are translated. The program expects that the following PostScript procedures
 * are defined in that file:
 *
 *	setup
 *
 *	  mark ... setup -
 *
 *	    Handles special initialization stuff that depends on how the program
 *	    was called. Expects to find a mark followed by key/value pairs on the
 *	    stack. The def operator is applied to each pair up to the mark, then
 *	    the default state is set up.
 *
 *	pagesetup
 *
 *	  page pagesetup -
 *
 *	    Does whatever is needed to set things up for the next page. Expects
 *	    to find the current page number on the stack.
 *
 *	v
 *
 *	  dx1 dy1 ... dxn dyn x y v -
 *
 *	    Draws the vector described by the numbers on the stack. The top two
 *	    numbers are the coordinates of the starting point. The rest of the
 *	    numbers are relative displacements from the preceeding point.
 *
 *	pp
 *
 *	  x1 y1 ... xn yn string pp -
 *
 *	    Prints string, which is always a single character, at the points
 *	    represented by the rest of the numbers on the stack.
 *
 *	R
 *
 *	  n deltax deltay x y R -
 *
 *	    Creates a rectangular path with its lower left corner at (x, y) and
 *	    sides of length deltax and deltay. The resulting path is stroked if
 *	    n is 0 and filled otherwise.
 *
 *	T
 *
 *	  dx3 dy3 dx2 dy2 dx1 dy1 x y T -
 *
 *	    Fills a trapezoid starting at (x, y) and having relative displacements
 *	    given by the (dx, dy) pairs.
 *
 *	t
 *
 *	  angle x y string t -
 *
 *	    Prints string starting at (x, y) using an orientation of angle degrees.
 *	    The PostScript procedure can handle any angle, but BGI files will only
 *	    request 0 or 90 degrees. Text printed at any other orientation will be
 *	    vector generated.
 *
 *	p
 *
 *	  x y p -
 *
 *	    Called to mark the point (x, y). It fills a small circle, that right
 *	    now has a constant radius. This stuff could probably be much more
 *	    efficient?
 *
 *	l
 *
 *	  array l -
 *
 *	    Sets the line drawing mode according to the description given in
 *	    array. The arrays that describe the different line styles are declared
 *	    in STYLES (file posttek.h), although it would be better to have them
 *	    defined in the prologue.
 *
 *	c
 *
 *	  red green blue c -
 *
 *	    Sets the current PostScript RGB color using setrgbcolor. Also used for
 *	    selecting appropriate patterns as colors.
 *
 *	f
 *
 *	  bgisize f -
 *
 *	    Changes the size of the font that's used to print text. bgisize is a
 *	    grid separation in a 5 by 7 array in which characters are assumed to
 *	    be built.
 *
 *	done
 *
 *	  done
 *
 *	    Makes sure the last page is printed. Only needed when we're printing
 *	    more than one page on each sheet of paper.
 *
 * The default line width is zero, which forces lines to be one pixel wide. That
 * works well for 'write to black' engines but won't be right for 'write to white'
 * engines. The line width can be changed using the -w option, or you can change
 * the initialization of linewidth in the prologue. Code in the prologue supports
 * the generation of uniform width lines when linewidth is non-zero and boolean
 * fixlinewidth is true.
 *
 * Many default values, like the magnification and orientation, are defined in 
 * the prologue, which is where they belong. If they're changed (by options), an
 * appropriate definition is made after the prologue is added to the output file.
 * The -P option passes arbitrary PostScript through to the output file. Among
 * other things it can be used to set (or change) values that can't be accessed by
 * other options.
 *
 */

#include <stdio.h>
#include <sys/types.h>
#include <fcntl.h>
#include <signal.h>
#include <math.h>
#include <ctype.h>
#ifdef plan9
#define	isascii(c)	((unsigned char)(c)<=0177)
#endif

#include "comments.h"			/* PostScript file structuring comments */
#include "gen.h"			/* general purpose definitions */
#include "path.h"			/* for the prologue */
#include "ext.h"			/* external variable declarations */
#include "postbgi.h"			/* a few definitions just used here */

char	*optnames = "a:c:f:m:n:o:p:w:x:y:A:C:E:J:L:P:R:DI";

char	*prologue = POSTBGI;		/* default PostScript prologue */
char	*formfile = FORMFILE;		/* stuff for multiple pages per sheet */

int	formsperpage = 1;		/* page images on each piece of paper */
int	copies = 1;			/* and this many copies of each sheet */

char	*styles[] = STYLES;		/* descriptions of line styles */

int	hpos = 0;			/* current horizontal */
int	vpos = 0;			/* and vertical position */

int	bgisize = BGISIZE;		/* just the character grid spacing */
int	linespace;			/* distance between lines of text */

int	bgimode;			/* character or graph mode */

int	in_subr = FALSE;		/* currently defining a subroutine */
int	in_global = FALSE;		/* to save space with subroutine defs */
int	subr_id = 0;			/* defining this subroutine */
int	shpos = 0;			/* starting horizontal */
int	svpos = 0;			/* and vertical positions - subroutines */
Disp	displacement[64];		/* dx and dy after a subroutine call */

Fontmap	fontmap[] = FONTMAP;		/* for translating font names */
char	*fontname = "Courier";		/* use this PostScript font */

int	page = 0;			/* page we're working on */
int	printed = 0;			/* printed this many pages */

FILE	*fp_in = stdin;			/* read from this file */
FILE	*fp_out = NULL;			/* and write stuff here */
FILE	*fp_acct = NULL;		/* for accounting data */

/*****************************************************************************/

main(agc, agv)

    int		agc;
    char	*agv[];

{

/*
 *
 * A program that converts BGI (Basic Graphical Instructions) files generated by
 * packages like GRAFPAC and DISSPLA into PostScript. It does an adequate job but
 * is far from perfect. A few things still haven't been implemented (eg. repeats
 * and raster rectangles), but what's here should be good enough for most of our
 * STARE and PRISM jobs. Color mixing (in PRISM jobs) won't work on PostScript
 * printers, and there's no chance I'll implement it!
 *
 */

    argc = agc;				/* global so everyone can use them */
    argv = agv;

    prog_name = argv[0];		/* just for error messages */

    init_signals();			/* set up interrupt handling */
    header();				/* PostScript header comments */
    options();				/* command line options */
    setup();				/* for PostScript */
    arguments();			/* followed by each input file */
    done();				/* print the last page etc. */
    account();				/* job accounting data */

    exit(x_stat);			/* everything probably went OK */

}   /* End of main */

/*****************************************************************************/

init_signals()

{

/*
 *
 * Make sure we handle interrupts.
 *
 */

    if ( signal(SIGINT, interrupt) == SIG_IGN )  {
	signal(SIGINT, SIG_IGN);
	signal(SIGQUIT, SIG_IGN);
	signal(SIGHUP, SIG_IGN);
    } else {
	signal(SIGHUP, interrupt);
	signal(SIGQUIT, interrupt);
    }   /* End else */

    signal(SIGTERM, interrupt);

}   /* End of init_signals */

/*****************************************************************************/

header()

{

    int		ch;			/* return value from getopt() */
    int		old_optind = optind;	/* for restoring optind - should be 1 */

/*
 *
 * Scans the option list looking for things, like the prologue file, that we need
 * right away but could be changed from the default. Doing things this way is an
 * attempt to conform to Adobe's latest file structuring conventions. In particular
 * they now say there should be nothing executed in the prologue, and they have
 * added two new comments that delimit global initialization calls. Once we know
 * where things really are we write out the job header, follow it by the prologue,
 * and then add the ENDPROLOG and BEGINSETUP comments.
 *
 */

    while ( (ch = getopt(argc, argv, optnames)) != EOF )
	if ( ch == 'L' )
	    prologue = optarg;
	else if ( ch == '?' )
	    error(FATAL, "");

    optind = old_optind;		/* get ready for option scanning */

    fprintf(stdout, "%s", CONFORMING);
    fprintf(stdout, "%s %s\n", VERSION, PROGRAMVERSION);
    fprintf(stdout, "%s %s\n", DOCUMENTFONTS, ATEND);
    fprintf(stdout, "%s %s\n", PAGES, ATEND);
    fprintf(stdout, "%s", ENDCOMMENTS);

    if ( cat(prologue) == FALSE )
	error(FATAL, "can't read %s", prologue);

    fprintf(stdout, "%s", ENDPROLOG);
    fprintf(stdout, "%s", BEGINSETUP);
    fprintf(stdout, "mark\n");

}   /* End of header */

/*****************************************************************************/

options()

{

    int		ch;			/* option name - from getopt() */

/*
 *
 * Reads and processes the command line options.
 *
 */

    while ( (ch = getopt(argc, argv, optnames)) != EOF )  {
	switch ( ch )  {
	    case 'a':			/* aspect ratio */
		    fprintf(stdout, "/aspectratio %s def\n", optarg);
		    break;

	    case 'c':			/* copies */
		    copies = atoi(optarg);
		    fprintf(stdout, "/#copies %s def\n", optarg);
		    break;

	    case 'f':			/* new font */
		    fontname = get_font(optarg);
		    fprintf(stdout, "/font /%s def\n", fontname);
		    break;

	    case 'm':			/* magnification */
		    fprintf(stdout, "/magnification %s def\n", optarg);
		    break;

	    case 'n':			/* forms per page */
		    formsperpage = atoi(optarg);
		    fprintf(stdout, "%s %s\n", FORMSPERPAGE, optarg);
		    fprintf(stdout, "/formsperpage %s def\n", optarg);
		    break;

	    case 'o':			/* output page list */
		    out_list(optarg);
		    break;

	    case 'p':			/* landscape or portrait mode */
		    if ( *optarg == 'l' )
			fprintf(stdout, "/landscape true def\n");
		    else fprintf(stdout, "/landscape false def\n");
		    break;

	    case 'w':			/* line width */
		    fprintf(stdout, "/linewidth %s def\n", optarg);
		    break;

	    case 'x':			/* shift horizontally */
		    fprintf(stdout, "/xoffset %s def\n", optarg);
		    break;

	    case 'y':			/* and vertically on the page */
		    fprintf(stdout, "/yoffset %s def\n", optarg);
		    break;

	    case 'A':			/* force job accounting */
	    case 'J':
		    if ( (fp_acct = fopen(optarg, "a")) == NULL )
		    	error(FATAL, "can't open accounting file %s", optarg);
		    break;

	    case 'C':			/* copy file straight to output */
		    if ( cat(optarg) == FALSE )
			error(FATAL, "can't read %s", optarg);
		    break;

	    case 'E':			/* text font encoding */
		    fontencoding = optarg;
		    break;

	    case 'L':			/* Postscript prologue file */
		    prologue = optarg;
		    break;

	    case 'P':			/* PostScript pass through */
		    fprintf(stdout, "%s\n", optarg);
		    break;

	    case 'R':			/* special global or page level request */
		    saverequest(optarg);
		    break;

	    case 'D':			/* debug flag */
		    debug = ON;
		    break;

	    case 'I':			/* ignore FATAL errors */
		    ignore = ON;
		    break;

	    case '?':			/* don't know the option */
		    error(FATAL, "");
		    break;

	    default:			/* don't know what to do for ch */
		    error(FATAL, "missing case for option %c", ch);
		    break;
	}   /* End switch */
    }	/* End while */

    argc -= optind;			/* get ready for non-option args */
    argv += optind;

}   /* End of options */

/*****************************************************************************/

char *get_font(name)

    char	*name;			/* name the user asked for */

{

    int		i;			/* for looking through fontmap[] */

/*
 *
 * Called from options() to map a user's font name into a legal PostScript name.
 * If the lookup fails *name is returned to the caller. That should let you choose
 * any PostScript font.
 *
 */

    for ( i = 0; fontmap[i].name != NULL; i++ )
	if ( strcmp(name, fontmap[i].name) == 0 )
	    return(fontmap[i].val);

    return(name);

}   /* End of get_font */

/*****************************************************************************/

setup()

{

/*
 *
 * Handles things that must be done after the options are read but before the
 * input files are processed.
 *
 */

    writerequest(0, stdout);		/* global requests eg. manual feed */
    setencoding(fontencoding);
    fprintf(stdout, "setup\n");

    if ( formsperpage > 1 )  {
	if ( cat(formfile) == FALSE )
	    error(FATAL, "can't read %s", formfile);
	fprintf(stdout, "%d setupforms\n", formsperpage);
    }	/* End if */

    fprintf(stdout, "%s", ENDSETUP);

}   /* End of setup */

/*****************************************************************************/

arguments()

{

/*
 *
 * Makes sure all the non-option command line options are processed. If we get
 * here and there aren't any arguments left, or if '-' is one of the input files
 * we'll process stdin.
 *
 */

    if ( argc < 1 )
	conv();
    else
	while ( argc > 0 )  {