lampros21_7 has asked for the wisdom of the Perl Monks concerning the following question:

Hi monks I am trying to create an image map by using Perl and JavaScript. I have got many points to use in my image map so i thought an implementation in Perl could help as i couldn't really tihnk of any other solution. Anyway here is the code: 
## Previous code to find x coordinates, y coordinates
## and website names

my @x_points;
my @y_points;
my @websites;

my $secondcount;
 
 <IMG SRC="figure.gif" USEMAP="#mymap">
 <MAP NAME="mymap">
 
 for ($secondcount=0; $secondcount < $webpage_no; $secondcount++) {
     <AREA SHAPE=circle COORDS="'$x_points[$secondcount],$y_points[$se
+condcount],1" HREF="'$websites[$secondcount]">
 }
 </MAP>

[download]
The problem is that i get errors at the line where i have the for loop. The errors are:

syntax error near ++) and

Syntax error near "for"

Also, even if those two problems are solved do you reckon the code will do what i want? That is, for say $x_points[0], $y_points[0] and $websites[0] then the coordinates will be the first two variables and the website they link to will be the $websites[0] variable. Thanks for looking and your replies

Replies are listed 'Best First'.
Re: Creating an image map using Perl code
by rhesa (Vicar) on Apr 06, 2006 at 01:38 UTC
    You can't just mix code and data like that. Even PHP has markers to separate them :)

    Try printing your html: 

    ## Previous code to find x coordinates, y coordinates
## and website names

my @x_points;
my @y_points;
my @websites;

my $secondcount;

print q(
 <IMG SRC="figure.gif" USEMAP="#mymap">
 <MAP NAME="mymap">
);

 for ($secondcount=1; $secondcount <= $webpage_no; $secondcount++) {
     print qq( <AREA SHAPE=circle COORDS="'$x_points[$secondcount],$y_
+points[$secondcount],1" HREF="'$websites[$secondcount]"> );
 }

print q( </MAP> );

    [download]
    Accessing an array element still needs a sigil: x_points[$secondcount] doesn't work, you meant to say $x_points[$secondcount].

    Oh, and why do you start counting at 1?

[reply]
[d/l]
[select]
      Sorry those were silly mistakes. I still get the same errors now with the sigils though. And i ve started counting from 0 but have removed the = sign from the second argument in the for loop. Is there a way to mix the for loop and the JavaScript/HTML? I still can't run and print my algorithm as i still get the same two errors. Thanks
[reply]
        The problem must be somewhere else in your code, because the snippet that I posted works (even though it doesn't print any <area> tags).

        Try starting your script with this: 

        use strict;
use warnings;

        [download]
        Then try running your script through the perl compiler:  perl -c your_script.pl. That should give you a lot more information about possible causes for the errors.

        If that doesn't help you out, can you post a bit more code?

[reply]
[d/l]
[select]
        Did you notice he also added prints, not just sigils? I see you've (silently) updated your node to add the sigils and to fix the loop bounds, but the prints are still missing.
[reply]
[d/l]
[select]
Re: Creating an image map using Perl code
by Cody Pendant (Prior) on Apr 06, 2006 at 07:36 UTC
    This seems to work, although of course I have no idea what's in your data: 
    #!/usr/bin/perl
my @x_points = ( 100, 200 );
my @y_points = ( 100, 200 );
my @radiuses = ( 50, 50 );

my @websites = qw( http://www.yahoo.com http://www.google.com );

print q(
    <IMG SRC="figure.gif" USEMAP="#mymap" width="400" height="400">
    <MAP NAME="mymap">
);

  for ( my $i = 0 ; $i < @x_points ; $i++ )
{
   print
     qq(<AREA SHAPE="circle" 
         COORDS="$x_points[$i],$y_points[$i],$radiuses[$i]" 
         HREF="$websites[$i]">
        );
}
print q(</MAP>);

    [download]
    This produces two circular links, centres at 100,100 and 200,200, with radius 50. Very roughly, something like this: 
    ######################################################  
#                                                    #  
#                                                    #  
#       ######                                       #  
#     ##      ##                                     #  
#    #          #                                    #  
#    #          #  <-yahoo                           #  
#    #          #                                    #  
#     ##      ##                                     #  
#       ######                                       #  
#                   ######                           #  
#                 ##      ##                         #  
#                #          #                        #  
#                #          # <- google              #  
#                #          #                        #  
#                 ##      ##                         #  
#                   ######                           #  
#                                                    #  
#                                                    #  
#                                                    #  
#                                                    #  
#                                                    #  
#                                                    #  
#                                                    #  
#                                                    #  
#                                                    #  
#                                                    #  
######################################################

    [download]
    But what your code is crying out for is a nice little AoH containing all the data in a much better structure. Exercise for the reader etc.

    ($_='kkvvttuu bbooppuuiiffss qqffssmm iibbddllffss')
    =~y~b-v~a-z~s; print
[reply]
[d/l]
[select]
      Right, i have ran Cody Pendant's algorithm and it works. My algorithm has similar data but it gives the same errors: 
       #!/usr/bin/perl
 use warnings;
 use strict;
 
 use DBIx::Simple;
 
 my $db = DBIx::Simple->connect('dbi:SQLite:dbname=mydatabase.db')
        or die DBIx::Simple->error;
 
 open (X_POINTS,"x_points.txt") || die "couldn't open the file!";
 open (Y_POINTS,"y_points.txt") || die "couldn't open the file!";
  
 # Insert all the x points in an array
 my @x_points = <X_POINTS>;
    
 # Insert all the y points in an array
 my @y_points = <Y_POINTS>;
  
 close(X_POINTS);
 close(Y_POINTS);
   
 print @x_points;
 print @y_points;
 
   
 my @webpages;
 my $webpage_no = 500;
  
 for (my $count=0; $count <= $webpage_no; $count++) {
      $webpages[$count] = $db->query("SELECT webpage FROM webpages_dat
+a WHERE id = '$count'")->list;
 }
 
 print @webpages;
 
 print q(<IMG SRC="figure.gif" USEMAP="#mymap">
 <MAP NAME="mymap"> )
 
 for (my $secondcount=0; $secondcount <= $webpage_no; $secondcount++) 
+{
     print qq(<AREA SHAPE=circle COORDS="$x_points[$secondcount],$y_po
+ints[$secondcount],1" HREF="$webpages[$secondcount]">);
 }
 print q(</MAP>);
 
******************************************

      [download]
      This is the complete code. The print statements work for the coordinates and the webpages so that's fine. The errors are:

      syntax error at image_map_gui.pl line 49, near "0;"

      syntax error at image_map_gui.pl line 49, near "++) "

      Execution of image_map_gui.pl aborted due to compilation errors. Can't really understand what's the problem here. If i comment out the JavaScript and the for loop bit it works fine but if i add those it gives the errors. Any ideas? thanks for your help

[reply]
[d/l]
        You're missing a semicolon after your first print q(...) statement.
[reply]
[d/l]
Re: Creating an image map using Perl code
by Cody Pendant (Prior) on Apr 06, 2006 at 07:25 UTC
    Not strictly Perl related but you don't actually want X and Y coordinates if your AREA tag is a circle. You have X and Y coordinates for the centre of the circle, and a pixel number for the radius.

    ($_='kkvvttuu bbooppuuiiffss qqffssmm iibbddllffss')
    =~y~b-v~a-z~s; print
[reply]
Re: Creating an image map using Perl code
by TedPride (Priest) on Apr 06, 2006 at 03:29 UTC
    How are you getting the coordinates from Javascript to Perl? That's the part that always confused me.
[reply]

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