Tutorial 1:

How to generate a simple SVG document using SVG.pm perl module.

We are going to first create a new instance of the SVG object. next, first, as in all good programs, we invoke perl witn -w to warn about dangerous coding. We also use strict to force us to declare our variables. Not using strict is a Big Mistake, so we always use strict

#!/usr/bin/perl -w
use strict;
use SVG;

Next, we create an SVG object and define its height and width.

# create an SVG object
my $svg= SVG->new(width=>200,height=>200); 

Notice that the constructor [SVG->new()] is called a constructor does not take a list of values but a hash .

# create an SVG object
my %hash;
$hash{width} = 200;
$hash{height} = 200;
my $svg= SVG->new(%hash); 

We could even have done this:

# create an SVG object
my $svg= SVG->new('width',200,'height',200); 

Remember that '=>' means assign value to. In the SVG module, we are constantly passing a hash as the input to tag-generation methods (A method is a command to the object that owns the method, or in plain English, an action that the SVG module performs). Now that we've invoked the object through it's constructor, let's build a drawing object. We're first going to draw a circle in the center of the object. most of the drawing objects in SVG such as circle, ellipe, rectangle, line, polyline, etc. are called using a method with the same name.

# draw a circle at position (100,100) with ID 'this_circle'
$svg->circle(id=>'this_circle',cx=>100,cy=>100,r=>50); 

Then we execute the xmlify method (command) which returns the XML text that we just generated.

my $out = $svg->xmlify;
print $out

Here is what this program returns:

<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<!DOCTYPE svg PUBLIC "-//W3C//DTD SVG 1.0//EN"
"http://www.w3.org/TR/2001/REC-SVG-20010904/DTD/svg10.dtd">
<svg height="200" width="200">
    <circle id="this_circle" cx="100" cy="100" r="50" />
</svg>