Perl Graphics Programming

Introduction to PDF::API2

The top-level PDF::API2 object maintains an internal data structure that loosely resembles the PDF document structure. The top-level object knows how to construct the header, body, and cross-reference sections of the final PDF document. You then construct the document by creating objects and adding them to the top-level document. Three types of objects are defined: structural objects, content stream objects, and resource objects.

Structural objects are used to define the page, outline, and annotation trees of the document. A Page object describes a single page. The current version of PDF::API2 uses only a single-page hierarchy (see Chapter 10 for more about the page hierarchy). You can’t create multiple page trees with shared resources. The Outlines object defines the root of a tree of outline entries. An Outline object is used to define a single outline entry. The Annotation object is used to add floating notes to a page.

To draw graphics or text on a page, use one of the content stream objects. Example 12-1 shows how to use the Text object to draw a simple “Hello World” string on a page. First, create a new page and set its dimensions. Add a Text object, which is a repositionable block of text. A Font object is assigned to the Text object; in this case, the core Helvetica font is used. After that, the string is drawn, and the PDF is created with the stringify( ) method.

Example 12-1. Hello World with the Text object

#!/usr/bin/perl -w # # Example 12-1. Hello ...