ticks.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

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <math.h>
#include "grap.h"
#include "y.tab.h"

#define	MAXTICK	200
int	ntick	= 0;
double	tickval[MAXTICK];	/* tick values (one axis at a time */
char	*tickstr[MAXTICK];	/* and labels */

int	tside	= 0;
int	tlist	= 0;		/* 1 => explicit values given */
int	toffside = 0;		/* no ticks on these sides */
int	goffside = 0;		/* no ticks on grid on these sides */
int	tick_dir = OUT;
double	ticklen	= TICKLEN;	/* default tick length */
int	autoticks = LEFT|BOT;
int	autodir = 0;		/* set LEFT, etc. if automatic ticks go in */

void savetick(double f, char *s)	/* remember tick location and label */
{
	if (ntick >= MAXTICK)
		ERROR "too many ticks (%d)", MAXTICK FATAL;
	tickval[ntick] = f;
	tickstr[ntick] = s;
	ntick++;
}

void dflt_tick(double f)
{
	if (f >= 0.0)
		savetick(f, tostring("%g"));
	else
		savetick(f, tostring("\\%g"));
}

void tickside(int n)	/* remember which side these ticks/gridlines go on */
{
	tside |= n;
}

void tickoff(int side)	/* remember explicit sides */
{
	toffside |= side;
}

void gridtickoff(void)	/* turn grid ticks off on the side previously specified (ugh) */
{
	goffside = tside;
}

void setlist(void)	/* remember that there was an explicit list */
{
	tlist = 1;
}

void tickdir(int dir, double val, int explicit)	/* remember in/out [expr] */
{
	tick_dir = dir;
	if (explicit)
		ticklen = val;
}

void ticks(void)		/* set autoticks after ticks statement */
{
	/* was there an explicit "ticks [side] off"? */
	if (toffside)
		autoticks &= ~toffside;
	/* was there an explicit list? (eg "ticks at ..." or "ticks from ...") */
	if (tlist) {
		if (tside & (BOT|TOP))
			autoticks &= ~(BOT|TOP);
		if (tside & (LEFT|RIGHT))
			autoticks &= ~(LEFT|RIGHT);
	}
	/* was there a side without a list? (eg "ticks left in") */
	if (tside && !tlist) {
		if (tick_dir == IN)
			autodir |= tside;
		if (tside & (BOT|TOP))
			autoticks = (autoticks & ~(BOT|TOP)) | (tside & (BOT|TOP));
		if (tside & (LEFT|RIGHT))
			autoticks = (autoticks & ~(LEFT|RIGHT)) | (tside & (LEFT|RIGHT));
	}
	tlist = tside = toffside = goffside = 0;
	tick_dir = OUT;
}

double modfloor(double f, double t)
{
	t = fabs(t);
	return floor(f/t) * t;
}

double modceil(double f, double t)
{
	t = fabs(t);
	return ceil(f/t) * t;
}

double	xtmin, xtmax;	/* range of ticks */
double	ytmin, ytmax;
double	xquant, xmult;	/* quantization & scale for auto x ticks */
double	yquant, ymult;
double	lograt = 5;

void do_autoticks(Obj *p)	/* make set of ticks for default coord only */
{
	double x, xl, xu, q;

	if (p == NULL)
		return;
	fprintf(tfd, "Autoticks:\t# x %g..%g, y %g..%g",
		p->pt.x, p->pt1.x, p->pt.y, p->pt1.y);
	fprintf(tfd, ";   xt %g,%g, yt %g,%g, xq,xm = %g,%g, yq,ym = %g,%g\n",
		xtmin, xtmax, ytmin, ytmax, xquant, xmult, yquant, ymult);
	if ((autoticks & (BOT|TOP)) && p->pt1.x >= p->pt.x) {	/* make x ticks */
		q = xquant;
		xl = p->pt.x;
		xu = p->pt1.x;
		if (xl >= xu)
			dflt_tick(xl);
		else if ((p->log & XFLAG) && xu/xl >= lograt) {
			for (x = q; x < xu; x *= 10) {
				logtick(x, xl, xu);
				if (xu/xl <= 100) {
					logtick(2*x, xl, xu);
					logtick(5*x, xl, xu);
				}
			}
		} else {
			xl = modceil(xtmin - q/100, q);
			xu = modfloor(xtmax + q/100, q) + q/2;
			for (x = xl; x <= xu; x += q)
				dflt_tick(x);
		}
		tside = autoticks & (BOT|TOP);
		ticklist(p, 0);
	}
	if ((autoticks & (LEFT|RIGHT)) && p->pt1.y >= p->pt.y) {	/* make y ticks */
		q = yquant;
		xl = p->pt.y;
		xu = p->pt1.y;
		if (xl >= xu)
			dflt_tick(xl);
		else if ((p->log & YFLAG) && xu/xl >= lograt) {
			for (x = q; x < xu; x *= 10) {
				logtick(x, xl, xu);
				if (xu/xl <= 100) {
					logtick(2*x, xl, xu);
					logtick(5*x, xl, xu);
				}
			}
		} else {
			xl = modceil(ytmin - q/100, q);
			xu = modfloor(ytmax + q/100, q) + q/2;
			for (x = xl; x <= xu; x += q)
				dflt_tick(x);
		}
		tside = autoticks & (LEFT|RIGHT);
		ticklist(p, 0);
	}
}

void logtick(double v, double lb, double ub)
{
	float slop = 1.0;	/* was 1.001 */

	if (slop * lb <= v && ub >= slop * v)
		dflt_tick(v);
}

Obj *setauto(void)	/* compute new min,max, and quant & mult */
{
	Obj *p, *q;

	if ((q = lookup("lograt",0)) != NULL)
		lograt = q->fval;
	for (p = objlist; p; p = p->next)
		if (p->type == NAME && strcmp(p->name,dflt_coord) == 0)
			break;
	if (p) {
		if ((p->log & XFLAG) && p->pt1.x/p->pt.x >= lograt)
			autolog(p, 'x');
		else
			autoside(p, 'x');
		if ((p->log & YFLAG) && p->pt1.y/p->pt.y >= lograt)
			autolog(p, 'y');
		else
			autoside(p, 'y');
	}
	return p;
}

void autoside(Obj *p, int side)
{
	double r, s, d, ub, lb;

	if (side == 'x') {
		xtmin = lb = p->pt.x;
		xtmax = ub = p->pt1.x;
	} else {
		ytmin = lb = p->pt.y;
		ytmax = ub = p->pt1.y;
	}
	if (ub <= lb)
		return;	/* cop out on little ranges */
	d = ub - lb;
	r = s = 1;
	while (d * s < 10)
		s *= 10;
	d *= s;
	while (10 * r < d)
		r *= 10;
	if (r > d/3)
		r /= 2;
	else if (r <= d/6)
		r *= 2;
	if (side == 'x') {
		xquant = r / s;
	} else {
		yquant = r / s;
	}
}

void autolog(Obj *p, int side)
{
	double r, s, t, ub, lb;
	int flg;

	if (side == 'x') {
		xtmin = lb = p->pt.x;
		xtmax = ub = p->pt1.x;
		flg = p->coord & XFLAG;
	} else {
		ytmin = lb = p->pt.y;
		ytmax = ub = p->pt1.y;
		flg = p->coord & YFLAG;
	}
	for (s = 1; lb * s < 1; s *= 10)
		;
	lb *= s;
	ub *= s;
	for (r = 1; 10 * r < lb; r *= 10)
		;
	for (t = 1; t < ub; t *= 10)
		;
	if (side == 'x')
		xquant = r / s;
	else
		yquant = r / s;
	if (flg)
		return;
	if (ub / lb < 100) {
		if (lb >= 5 * r)
			r *= 5;
		else if (lb >= 2 * r)
			r *= 2;
		if (ub * 5 <= t)
			t /= 5;
		else if (ub * 2 <= t)
			t /= 2;
		if (side == 'x') {
			xtmin = r / s;
			xtmax = t / s;
		} else {
			ytmin = r / s;
			ytmax = t / s;
		}
	}
}

void iterator(double from, double to, int op, double by, char *fmt)	/* create an iterator */
{
	double x;

	/* should validate limits, etc. */
	/* punt for now */

	dprintf("iterate from %g to %g by %g, op = %c, fmt=%s\n",
		from, to, by, op, fmt ? fmt : "");
	switch (op) {
	case '+':
	case ' ':
		for (x = from; x <= to + (SLOP-1) * by; x += by)
			if (fmt)
				savetick(x, tostring(fmt));
			else
				dflt_tick(x);
		break;
	case '-':
		for (x = from; x >= to; x -= by)
			if (fmt)
				savetick(x, tostring(fmt));
			else
				dflt_tick(x);
		break;
	case '*':
		for (x = from; x <= SLOP * to; x *= by)
			if (fmt)
				savetick(x, tostring(fmt));
			else
				dflt_tick(x);
		break;
	case '/':
		for (x = from; x >= to; x /= by)
			if (fmt)
				savetick(x, tostring(fmt));
			else
				dflt_tick(x);
		break;
	}
	if (fmt)
		free(fmt);
}

void ticklist(Obj *p, int explicit)	/* fire out the accumulated ticks */
					/* 1 => list, 0 => auto */
{
	if (p == NULL)
		return;
	fprintf(tfd, "Ticks_%s:\n\tticklen = %g\n", p->name, ticklen);
	print_ticks(TICKS, explicit, p, "ticklen", "");
}

void print_ticks(int type, int explicit, Obj *p, char *lenstr, char *descstr)
{
	int i, logflag, inside;
	char buf[100];
	double tv;

	for (i = 0; i < ntick; i++)	/* any ticks given explicitly? */
		if (tickstr[i] != NULL)
			break;
	if (i >= ntick && type == TICKS)	/* no, so use values */
		for (i = 0; i < ntick; i++) {
			if (tickval[i] >= 0.0)
				sprintf(buf, "%g", tickval[i]);
			else
				sprintf(buf, "\\-%g", -tickval[i]);
			tickstr[i] = tostring(buf);
		}
	else
		for (i = 0; i < ntick; i++) {
			if (tickstr[i] != NULL) {
				sprintf(buf, tickstr[i], tickval[i]);
				free(tickstr[i]);
				tickstr[i] = tostring(buf);
			}
		}
	logflag = sidelog(p->log, tside);
	for (i = 0; i < ntick; i++) {
		tv = tickval[i];
		halfrange(p, tside, tv);
		if (logflag) {
			if (tv <= 0.0)
				ERROR "can't take log of tick value %g", tv FATAL;
			logit(tv);
		}
		if (type == GRID)
			inside = LEFT|RIGHT|TOP|BOT;
		else if (explicit)
			inside = (tick_dir == IN) ? tside : 0;
		else
			inside = autodir;
		if (tside & BOT)
			maketick(type, p->name, BOT, inside, tv, tickstr[i], lenstr, descstr);
		if (tside & TOP)
			maketick(type, p->name, TOP, inside, tv, tickstr[i], lenstr, descstr);
		if (tside & LEFT)
			maketick(type, p->name, LEFT, inside, tv, tickstr[i], lenstr, descstr);
		if (tside & RIGHT)
			maketick(type, p->name, RIGHT, inside, tv, tickstr[i], lenstr, descstr);
		if (tickstr[i]) {
			free(tickstr[i]);
			tickstr[i] = NULL;
		}
	}
	ntick = 0;
}

void maketick(int type, char *name, int side, int inflag, double val, char *lab, char *lenstr, char *descstr)
{
	char *sidestr, *td;

	fprintf(tfd, "\tline %s ", descstr);
	inflag &= side;
	switch (side) {
	case BOT:
	case 0:
		td = inflag ? "up" : "down";
		fprintf(tfd, "%s %s from (x_%s(%g),0)", td, lenstr, name, val);
		break;
	case TOP:
		td = inflag ? "down" : "up";
		fprintf(tfd, "%s %s from (x_%s(%g),frameht)", td, lenstr, name, val);
		break;
	case LEFT:
		td = inflag ? "right" : "left";
		fprintf(tfd, "%s %s from (0,y_%s(%g))", td, lenstr, name, val);
		break;
	case RIGHT:
		td = inflag ? "left" : "right";
		fprintf(tfd, "%s %s from (framewid,y_%s(%g))", td, lenstr, name, val);
		break;
	}
	fprintf(tfd, "\n");
	if (type == GRID && (side & goffside))	/* wanted no ticks on grid */
		return;
	sidestr = tick_dir == IN ? "start" : "end";
	if (lab != NULL) {
		/* BUG: should fix size of lab here */
		double wid = strlen(lab)/7.5 + (tick_dir == IN ? 0 : 0.1);	/* estimate width at 15 chars/inch */
		switch (side) {
		case BOT: case 0:
			/* can drop "box invis" with new pic */
			fprintf(tfd, "\tbox invis \"%s\" ht .25 wid 0 with .n at last line.%s",
				lab, sidestr);
			break;
		case TOP:
			fprintf(tfd, "\tbox invis \"%s\" ht .2 wid 0 with .s at last line.%s",
				lab, sidestr);
			break;
		case LEFT:
			fprintf(tfd, "\t\"%s \" wid %.2f rjust at last line.%s",
				lab, wid, sidestr);
			break;
		case RIGHT:
			fprintf(tfd, "\t\" %s\" wid %.2f ljust at last line.%s",
				lab, wid, sidestr);
			break;
		}
		/* BUG: works only if "down x" comes before "at wherever" */
		lab_adjust();
		fprintf(tfd, "\n");
	}
}

Attr	*grid_desc	= 0;

void griddesc(Attr *a)
{
	grid_desc = a;
}

void gridlist(Obj *p)
{
	char *framestr;

	if ((tside & (BOT|TOP)) || tside == 0)
		framestr = "frameht";
	else
		framestr = "framewid";
	fprintf(tfd, "Grid_%s:\n", p->name);
	tick_dir = IN;
	print_ticks(GRID, 0, p, framestr, desc_str(grid_desc));
	if (grid_desc) {
		freeattr(grid_desc);
		grid_desc = 0;
	}
}

char *desc_str(Attr *a)	/* convert DOT to "dotted", etc. */
{
	static char buf[50], *p;

	if (a == NULL)
		return p = "";
	switch (a->type) {
	case DOT:	p = "dotted"; break;
	case DASH:	p = "dashed"; break;
	case INVIS:	p = "invis"; break;
	default:	p = "";
	}
	if (a->fval != 0.0) {
		sprintf(buf, "%s %g", p, a->fval);
		return buf;
	} else
		return p;
}

sidelog(int logflag, int side)	/* figure out whether to scale a side */
{
	if ((logflag & XFLAG) && ((side & (BOT|TOP)) || side == 0))
		return 1;
	else if ((logflag & YFLAG) && (side & (LEFT|RIGHT)))
		return 1;
	else
		return 0;
}