Programming Web Graphics with Perl and GNU Softwar

Presenting Images in HTML

As of the HTML 3.2 specification, there was only one way to include an image in an HTML document, and that was with the <IMG> tag. With the HTML 4.0 standard there are two equally supported means of including images—the <IMG> tag and the <OBJECT> tag. The <OBJECT> element is intended as a more open solution to the problem of inserting inline media into web documents. The examples in this book all use the <IMG> tag, because it is very likely that 3.2 will still be the most widely implemented standard for quite some time. However, we will look at both the <IMG> and <OBJECT> forms in this chapter.

The <IMG> element embeds an image in the body of a document (it cannot be used in the head section). The element consists of a start tag without an end tag, and does not include content as such. It is formed according to standard HTML syntax, which is to say it should look like this in its simplest form:

<IMG SRC="someimage.png" >  # include an inline png

In Perl, you may use the HTML::Element module to create image tags. This module is designed to let you build the nodes of an HTML syntax tree with method calls. It can be used as in the following example:

use HTML::Element;         # use this module

# Set attributes when creating the element...
my $img = new HTML::Element 'img', src => 'someimage.gif'; 

# ...or add them later with the attr() method
$img->attr('alt','This is Some Image!');           

# Use as_HTML() to print the element as an html tag
print $img->as_HTML;

The SRC Attribute ...