Perl Graphics Programming

Presenting Images in HTML

As of the Version 3.2 HTML specification, the only way to include an image in an HTML document was with the IMG tag. The 4.0 HTML standard introduced another means of including images: the OBJECT tag. The OBJECT element is intended as a more open solution to the problem of inserting inline media into web documents.

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, without any “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

The SRC attribute indicates the Uniform Resource Locator (URL) of the image. This can be an absolute or relative address, and it may refer to a file to be read as data or to a script to be run to create the proper image output. The syntax in either case is the same:

<IMG SRC = "images/staticfile.gif"> ...