#include <u.h>#include <libc.h>#include <bio.h>#include "../common/common.h"#include "tr2post.h" BOOLEAN drawflag = FALSE; voidcover(double x, double y) {} voiddrawspline(Biobufhdr *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];} voiddraw(Biobufhdr *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"); 		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"); 		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"); 		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"); 		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);		break;	}}