Improved Imagemap

Craig Milo Rogers (Rogers@ISI.EDU)
Mon, 11 Jul 94 22:29:11 PDT


As I had several requests for my imagemap changes, I decided
to send them to the list at large. After all, it's far smaller than
the average message about whether <p> is a separator or a container.
Oops, that's on another list now! :-)

The diffs were nearly as large as the whole file, so I'm
sending the file.

Craig Milo Rogers

/*
** mapper 1.2
** 7/26/93 Kevin Hughes, kevinh@pulua.hcc.hawaii.edu
** "macmartinized" polygon code copyright 1992 by Eric Haines, erich@eye.com
** All suggestions, help, etc. gratefully accepted!
**
** 1.1 : Better formatting, added better polygon code.
** 1.2 : Changed isname(), added config file specification.
**
** 11/13/93: Rob McCool, robm@ncsa.uiuc.edu
**
** Rewrote configuration stuff for NCSA /htbin script
**
** 12/05/93: Rob McCool, robm@ncsa.uiuc.edu
**
** Made CGI/1.0 compliant.
**
** 07/11/94: Craig Milo Rogers, Rogers@ISI.Edu
**
** Added the "point" datatype. The nearest point wins. Overrides "default".
** Added "-f" to act as a filter. Great for debugging, special uses.
*/

#include <stdio.h>
#include <string.h>
#include <stdlib.h>

#define CONF_FILE "/usr/local/etc/httpd/conf/imagemap.conf"

#define MAXLINE 500
#define MAXVERTS 100
#define X 0
#define Y 1

int isname(char);

int main(int argc, char **argv)
{
char input[MAXLINE], *mapname, def[MAXLINE], conf[MAXLINE];
double testpoint[2], pointarray[MAXVERTS][2];
int i, j, k;
FILE *fp;
char *t;
int filtermode = 0;
double dist, mindist;
int sawpoint = 0;

if (argc) {
argc--; /* Skip command name. */
argv++;
}

if (argc && !strcmp(*argv, "-f")) {
filtermode++; /* Get map info from stdin */
argc--;
argv++;
}

if (argc != 1)
servererr("Wrong number of arguments, client may not support ISMAP.");
if(!(t = strchr(*argv,',')))
servererr("Your client doesn't support image mapping properly.");
*t++ = '\0';
testpoint[X] = (double) atoi(*argv);
testpoint[Y] = (double) atoi(t);

if (filtermode) {
fp = stdin;
} else {
mapname=getenv("PATH_INFO");
if((!mapname) || (!mapname[0]))
servererr("No map name given. Please read the <A HREF=\"http://hoohoo.ncsa.uiuc.edu/docs/setup/admin/Imagemap.html\">instructions</A>.<P>");
mapname++;

if ((fp = fopen(CONF_FILE, "r")) == NULL)
servererr("Couldn't open configuration file.");

while(!(getline(input,MAXLINE,fp))) {
char confname[MAXLINE];
if((input[0] == '#') || (!input[0]))
continue;
for(i=0;isname(input[i]) && (input[i] != ':');i++)
confname[i] = input[i];
confname[i] = '\0';
if(!strcmp(confname,mapname))
goto found;
}
if(feof(fp))
servererr("Map not found in configuration file.");
found:
fclose(fp);
while(isspace(input[i]) || input[i] == ':') ++i;

for(j=0;input[i] && isname(input[i]);++i,++j)
conf[j] = input[i];
conf[j] = '\0';

if(!(fp=fopen(conf,"r")))
servererr("Couldn't open map file.");
}

while(!(getline(input,MAXLINE,fp))) {
char type[MAXLINE];
char url[MAXLINE];
char num[10];

if((input[0] == '#') || (!input[0]))
continue;

type[0] = '\0';url[0] = '\0';

for(i=0;isname(input[i]) && (input[i]);i++)
type[i] = input[i];
type[i] = '\0';

while(isspace(input[i])) ++i;
for(j=0;input[i] && isname(input[i]);++i,++j)
url[j] = input[i];
url[j] = '\0';

if(!strcmp(type,"default") && !sawpoint) {
strcpy(def,url);
continue;
}

k=0;
while (input[i]) {
while (isspace(input[i]) || input[i] == ',')
i++;
j = 0;
while (isdigit(input[i]))
num[j++] = input[i++];
num[j] = '\0';
if (num[0] != '\0')
pointarray[k][X] = (double) atoi(num);
else
break;
while (isspace(input[i]) || input[i] == ',')
i++;
j = 0;
while (isdigit(input[i]))
num[j++] = input[i++];
num[j] = '\0';
if (num[0] != '\0')
pointarray[k++][Y] = (double) atoi(num);
else {
fclose(fp);
servererr("Missing y value.");
}
}
pointarray[k][X] = -1;
if(!strcmp(type,"poly"))
if(pointinpoly(testpoint,pointarray))
sendmesg(url);
if(!strcmp(type,"circle"))
if(pointincircle(testpoint,pointarray))
sendmesg(url);
if(!strcmp(type,"rect"))
if(pointinrect(testpoint,pointarray))
sendmesg(url);
if(!strcmp(type,"point")) {
/* Don't need to take square root. */
dist = ((testpoint[X] - pointarray[0][X])
* (testpoint[X] - pointarray[0][X]))
+ ((testpoint[Y] - pointarray[0][Y])
* (testpoint[Y] - pointarray[0][Y]));
/* If this is the first point, or the nearest, set the default. */
if ((! sawpoint) || (dist < mindist)) {
mindist = dist;
strcpy(def,url);
}
sawpoint++;
}
}
if(def[0])
sendmesg(def);
servererr("No default specified.");
}

sendmesg(char *url)
{
printf("Location: %s%c%c",url,10,10);
printf("This document has moved <A HREF=\"%s\">here</A>%c",url,10);
exit(1);
}

int pointinrect(double point[2], double coords[MAXVERTS][2])
{
return ((point[X] >= coords[0][X] && point[X] <= coords[1][X]) &&
(point[Y] >= coords[0][Y] && point[Y] <= coords[1][Y]));
}

int pointincircle(double point[2], double coords[MAXVERTS][2])
{
int radius1, radius2;

radius1 = ((coords[0][Y] - coords[1][Y]) * (coords[0][Y] -
coords[1][Y])) + ((coords[0][X] - coords[1][X]) * (coords[0][X] -
coords[1][X]));
radius2 = ((coords[0][Y] - point[Y]) * (coords[0][Y] - point[Y])) +
((coords[0][X] - point[X]) * (coords[0][X] - point[X]));
return (radius2 <= radius1);
}

int pointinpoly(double point[2], double pgon[MAXVERTS][2])
{
int i, numverts, inside_flag, xflag0;
int crossings;
double *p, *stop;
double tx, ty, y;

for (i = 0; pgon[i][X] != -1 && i < MAXVERTS; i++)
;
numverts = i;
crossings = 0;

tx = point[X];
ty = point[Y];
y = pgon[numverts - 1][Y];

p = (double *) pgon + 1;
if ((y >= ty) != (*p >= ty)) {
if ((xflag0 = (pgon[numverts - 1][X] >= tx)) ==
(*(double *) pgon >= tx)) {
if (xflag0)
crossings++;
}
else {
crossings += (pgon[numverts - 1][X] - (y - ty) *
(*(double *) pgon - pgon[numverts - 1][X]) /
(*p - y)) >= tx;
}
}

stop = pgon[numverts];

for (y = *p, p += 2; p < stop; y = *p, p += 2) {
if (y >= ty) {
while ((p < stop) && (*p >= ty))
p += 2;
if (p >= stop)
break;
if ((xflag0 = (*(p - 3) >= tx)) == (*(p - 1) >= tx)) {
if (xflag0)
crossings++;
}
else {
crossings += (*(p - 3) - (*(p - 2) - ty) *
(*(p - 1) - *(p - 3)) / (*p - *(p - 2))) >= tx;
}
}
else {
while ((p < stop) && (*p < ty))
p += 2;
if (p >= stop)
break;
if ((xflag0 = (*(p - 3) >= tx)) == (*(p - 1) >= tx)) {
if (xflag0)
crossings++;
}
else {
crossings += (*(p - 3) - (*(p - 2) - ty) *
(*(p - 1) - *(p - 3)) / (*p - *(p - 2))) >= tx;
}
}
}
inside_flag = crossings & 0x01;
return (inside_flag);
}

servererr(char *msg)
{
printf("Content-type: text/html%c%c",10,10);
printf("<title>Mapping Server Error</title>");
printf("<h1>Mapping Server Error</h1>");
printf("This server encountered an error:<p>");
printf("%s", msg);
exit(-1);
}

int isname(char c)
{
return (!isspace(c));
}