plan9port

draw.c (10800B)

---

 #include <u.h>
 #include <libc.h>
 #include <bio.h>
 #include <ctype.h>
 #include "../common/common.h"
 #include "tr2post.h"
 
 BOOLEAN drawflag = FALSE;
 BOOLEAN	inpath = FALSE;			/* TRUE if we're putting pieces together */
 
 void
 cover(double x, double y) {
 }
 
 void
 drawspline(Biobuf *Bp, int flag) {	/* flag!=1 connect end points */
 	int x[100], y[100];
 	int i, N;
 /*
  *
  * Spline drawing routine for Postscript printers. The complicated stuff is
  * handled by procedure Ds, which should be defined in the library file. I've
  * seen wrong implementations of troff's spline drawing, so fo the record I'll
  * write down the parametric equations and the necessary conversions to Bezier
  * cubic splines (as used in Postscript).
  *
  *
  * Parametric equation (x coordinate only):
  *
  *
  *	    (x2 - 2 * x1 + x0)    2                    (x0 + x1)
  *	x = ------------------ * t   + (x1 - x0) * t + ---------
  *		    2					   2
  *
  *
  * The coefficients in the Bezier cubic are,
  *
  *
  *	A = 0
  *	B = (x2 - 2 * x1 + x0) / 2
  *	C = x1 - x0
  *
  *
  * while the current point is,
  *
  *	current-point = (x0 + x1) / 2
  *
  * Using the relationships given in the Postscript manual (page 121) it's easy to
  * see that the control points are given by,
  *
  *
  *	x0' = (x0 + 5 * x1) / 6
  *	x1' = (x2 + 5 * x1) / 6
  *	x2' = (x1 + x2) / 2
  *
  *
  * where the primed variables are the ones used by curveto. The calculations
  * shown above are done in procedure Ds using the coordinates set up in both
  * the x[] and y[] arrays.
  *
  * A simple test of whether your spline drawing is correct would be to use cip
  * to draw a spline and some tangent lines at appropriate points and then print
  * the file.
  *
  */
 
 	for (N=2; N<sizeof(x)/sizeof(x[0]); N++)
 		if (Bgetfield(Bp, 'd', &x[N], 0)<=0 || Bgetfield(Bp, 'd', &y[N], 0)<=0)
 			break;
 
 	x[0] = x[1] = hpos;
 	y[0] = y[1] = vpos;
 
 	for (i = 1; i < N; i++) {
 		x[i+1] += x[i];
 		y[i+1] += y[i];
 	}
 
 	x[N] = x[N-1];
 	y[N] = y[N-1];
 
 	for (i = ((flag!=1)?0:1); i < ((flag!=1)?N-1:N-2); i++) {
 		endstring();
 		if (pageon())
 			Bprint(Bstdout, "%d %d %d %d %d %d Ds\n", x[i], y[i], x[i+1], y[i+1], x[i+2], y[i+2]);
 /*		if (dobbox == TRUE) {		/* could be better */
 /*	    		cover((double)(x[i] + x[i+1])/2,(double)-(y[i] + y[i+1])/2);
 /*	    		cover((double)x[i+1], (double)-y[i+1]);
 /*	    		cover((double)(x[i+1] + x[i+2])/2, (double)-(y[i+1] + y[i+2])/2);
 /*		}
  */
 	}
 
 	hpos = x[N];			/* where troff expects to be */
 	vpos = y[N];
 }
 
 void
 draw(Biobuf *Bp) {
 
 	int r, x1, y1, x2, y2, i;
 	int d1, d2;
 
 	drawflag = TRUE;
 	r = Bgetrune(Bp);
 	switch(r) {
 	case 'l':
 		if (Bgetfield(Bp, 'd', &x1, 0)<=0 || Bgetfield(Bp, 'd', &y1, 0)<=0 || Bgetfield(Bp, 'r', &i, 0)<=0) {
 			error(FATAL, "draw line function, destination coordinates not found.\n");
 			return;
 		}
 
 		endstring();
 		if (pageon())
 			Bprint(Bstdout, "%d %d %d %d Dl\n", hpos, vpos, hpos+x1, vpos+y1);
 		hpos += x1;
 		vpos += y1;
 		break;
 	case 'c':
 		if (Bgetfield(Bp, 'd', &d1, 0)<=0) {
 			error(FATAL, "draw circle function, diameter coordinates not found.\n");
 			return;
 		}
 
 		endstring();
 		if (pageon())
 			Bprint(Bstdout, "%d %d %d %d De\n", hpos, vpos, d1, d1);
 		hpos += d1;
 		break;
 	case 'e':
 		if (Bgetfield(Bp, 'd', &d1, 0)<=0 || Bgetfield(Bp, 'd', &d2, 0)<=0) {
 			error(FATAL, "draw ellipse function, diameter coordinates not found.\n");
 			return;
 		}
 
 		endstring();
 		if (pageon())
 			Bprint(Bstdout, "%d %d %d %d De\n", hpos, vpos, d1, d2);
 		hpos += d1;
 		break;
 	case 'a':
 		if (Bgetfield(Bp, 'd', &x1, 0)<=0 || Bgetfield(Bp, 'd', &y1, 0)<=0 || Bgetfield(Bp, 'd', &x2, 0)<=0 || Bgetfield(Bp, 'd', &y2, 0)<=0) {
 			error(FATAL, "draw arc function, coordinates not found.\n");
 			return;
 		}
 
 		endstring();
 		if (pageon())
 			Bprint(Bstdout, "%d %d %d %d %d %d Da\n", hpos, vpos, x1, y1, x2, y2);
 		hpos += x1 + x2;
 		vpos += y1 + y2;
 		break;
 	case 'q':
 		drawspline(Bp, 1);
 		break;
 	case '~':
 		drawspline(Bp, 2);
 		break;
 	default:
 		error(FATAL, "unknown draw function <%c>\n", r);
 		return;
 	}
 }
 
 void
 beginpath(char *buf, int copy) {
 
 /*
  * Called from devcntrl() whenever an "x X BeginPath" command is read. It's used
  * to mark the start of a sequence of drawing commands that should be grouped
  * together and treated as a single path. By default the drawing procedures in
  * *drawfile treat each drawing command as a separate object, and usually start
  * with a newpath (just as a precaution) and end with a stroke. The newpath and
  * stroke isolate individual drawing commands and make it impossible to deal with
  * composite objects. "x X BeginPath" can be used to mark the start of drawing
  * commands that should be grouped together and treated as a single object, and
  * part of what's done here ensures that the PostScript drawing commands defined
  * in *drawfile skip the newpath and stroke, until after the next "x X DrawPath"
  * command. At that point the path that's been built up can be manipulated in
  * various ways (eg. filled and/or stroked with a different line width).
  *
  * Color selection is one of the options that's available in parsebuf(),
  * so if we get here we add *colorfile to the output file before doing
  * anything important.
  *
  */
 	if (inpath == FALSE) {
 		endstring();
 	/*	getdraw();	*/
 	/*	getcolor(); */
 		Bprint(Bstdout, "gsave\n");
 		Bprint(Bstdout, "newpath\n");
 		Bprint(Bstdout, "%d %d m\n", hpos, vpos);
 		Bprint(Bstdout, "/inpath true def\n");
 		if ( copy == TRUE )
 			Bprint(Bstdout, "%s\n", buf);
 		inpath = TRUE;
 	}
 }
 
 static void parsebuf(char*);
 
 void
 drawpath(char *buf, int copy) {
 
 /*
  *
  * Called from devcntrl() whenever an "x X DrawPath" command is read. It marks the
  * end of the path started by the last "x X BeginPath" command and uses whatever
  * has been passed along in *buf to manipulate the path (eg. fill and/or stroke
  * the path). Once that's been done the drawing procedures are restored to their
  * default behavior in which each drawing command is treated as an isolated path.
  * The new version (called after "x X DrawPath") has copy set to FALSE, and calls
  * parsebuf() to figure out what goes in the output file. It's a feeble attempt
  * to free users and preprocessors (like pic) from having to know PostScript. The
  * comments in parsebuf() describe what's handled.
  *
  * In the early version a path was started with "x X BeginObject" and ended with
  * "x X EndObject". In both cases *buf was just copied to the output file, and
  * was expected to be legitimate PostScript that manipulated the current path.
  * The old escape sequence will be supported for a while (for Ravi), and always
  * call this routine with copy set to TRUE.
  *
  *
  */
 
 	if ( inpath == TRUE ) {
 		if ( copy == TRUE )
 			Bprint(Bstdout, "%s\n", buf);
 		else
 			parsebuf(buf);
 		Bprint(Bstdout, "grestore\n");
 		Bprint(Bstdout, "/inpath false def\n");
 /*		reset();		*/
 		inpath = FALSE;
 	}
 }
 
 
 /*****************************************************************************/
 
 static void
 parsebuf(char *buf)
 {
 	char	*p = (char*)0;			/* usually the next token */
 	char *q;
 	int		gsavelevel = 0;		/* non-zero if we've done a gsave */
 
 /*
  *
  * Simple minded attempt at parsing the string that followed an "x X DrawPath"
  * command. Everything not recognized here is simply ignored - there's absolutely
  * no error checking and what was originally in buf is clobbered by strtok().
  * A typical *buf might look like,
  *
  *	gray .9 fill stroke
  *
  * to fill the current path with a gray level of .9 and follow that by stroking the
  * outline of the path. Since unrecognized tokens are ignored the last example
  * could also be written as,
  *
  *	with gray .9 fill then stroke
  *
  * The "with" and "then" strings aren't recognized tokens and are simply discarded.
  * The "stroke", "fill", and "wfill" force out appropriate PostScript code and are
  * followed by a grestore. In otherwords changes to the grahics state (eg. a gray
  * level or color) are reset to default values immediately after the stroke, fill,
  * or wfill tokens. For now "fill" gets invokes PostScript's eofill operator and
  * "wfill" calls fill (ie. the operator that uses the non-zero winding rule).
  *
  * The tokens that cause temporary changes to the graphics state are "gray" (for
  * setting the gray level), "color" (for selecting a known color from the colordict
  * dictionary defined in *colorfile), and "line" (for setting the line width). All
  * three tokens can be extended since strncmp() makes the comparison. For example
  * the strings "line" and "linewidth" accomplish the same thing. Colors are named
  * (eg. "red"), but must be appropriately defined in *colorfile. For now all three
  * tokens must be followed immediately by their single argument. The gray level
  * (ie. the argument that follows "gray") should be a number between 0 and 1, with
  * 0 for black and 1 for white.
  *
  * To pass straight PostScript through enclose the appropriate commands in double
  * quotes. Straight PostScript is only bracketed by the outermost gsave/grestore
  * pair (ie. the one from the initial "x X BeginPath") although that's probably
  * a mistake. Suspect I may have to change the double quote delimiters.
  *
  */
 
 	for( ; p != nil ; p = q ) {
 		if( q = strchr(p, ' ') ) {
 			*q++ = '\0';
 		}
 
 		if ( gsavelevel == 0 ) {
 			Bprint(Bstdout, "gsave\n");
 			gsavelevel++;
 		}
 		if ( strcmp(p, "stroke") == 0 ) {
 			Bprint(Bstdout, "closepath stroke\ngrestore\n");
 			gsavelevel--;
 		} else if ( strcmp(p, "openstroke") == 0 ) {
 			Bprint(Bstdout, "stroke\ngrestore\n");
 			gsavelevel--;
 		} else if ( strcmp(p, "fill") == 0 ) {
 			Bprint(Bstdout, "eofill\ngrestore\n");
 			gsavelevel--;
 		} else if ( strcmp(p, "wfill") == 0 ) {
 			Bprint(Bstdout, "fill\ngrestore\n");
 			gsavelevel--;
 		} else if ( strcmp(p, "sfill") == 0 ) {
 			Bprint(Bstdout, "eofill\ngrestore\ngsave\nstroke\ngrestore\n");
 			gsavelevel--;
 		} else if ( strncmp(p, "gray", strlen("gray")) == 0 ) {
 			if( q ) {
 				p = q;
 				if ( q = strchr(p, ' ') )
 					*q++ = '\0';
 				Bprint(Bstdout, "%s setgray\n", p);
 			}
 		} else if ( strncmp(p, "color", strlen("color")) == 0 ) {
 			if( q ) {
 				p = q;
 				if ( q = strchr(p, ' ') )
 					*q++ = '\0';
 				Bprint(Bstdout, "/%s setcolor\n", p);
 			}
 		} else if ( strncmp(p, "line", strlen("line")) == 0 ) {
 			if( q ) {
 				p = q;
 				if ( q = strchr(p, ' ') )
 					*q++ = '\0';
 				Bprint(Bstdout, "%s resolution mul 2 div setlinewidth\n", p);
 			}
 		} else if ( strncmp(p, "reverse", strlen("reverse")) == 0 )
 			Bprint(Bstdout, "reversepath\n");
 		else if ( *p == '"' ) {
 			for ( ; gsavelevel > 0; gsavelevel-- )
 				Bprint(Bstdout, "grestore\n");
 			if ( q != nil )
 				*--q = ' ';
 			if ( (q = strchr(p, '"')) != nil ) {
 				*q++ = '\0';
 				Bprint(Bstdout, "%s\n", p);
 			}
 		}
 	}
 
 	for ( ; gsavelevel > 0; gsavelevel-- )
 		Bprint(Bstdout, "grestore\n");
 
 }