December 2011
Beginner
140 pages
2h 59m
English
Content preview from PDF ExplainedBecome an O’Reilly member and get unlimited access to this title plus top books and audiobooks from O’Reilly and nearly 200 top publishers, thousands of courses curated by job role, 150+ live events each month,
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Chapter 5. Graphics
In this chapter, we’ll run through the main ways to build graphics in the content stream of a PDF page. All of the examples are based on the same PDF we created manually in Chapter 2 and processed into valid PDF documents with pdftk in the same fashion. All the examples are included in the online resources.
Looking at Content Streams
A PDF page is made up of one or more content
streams, defined by the /Contents entry in the page object, together
with a shared set of resources, defined by the /Resources entry. In all our examples, there
will only be a single content stream. Multiple content streams are
equivalent to a single stream containing their concatenated
content.
Here’s an example page, with no resources and a single content stream:
3 0 obj << /Type /Page /Parent 1 0 R /Resources << >> /MediaBox [ 0 0 792 612 ] /Rotate 0 /Contents [ 2 0 R ] >> endobj
Here’s the associated content stream, consisting of the stream dictionary and the stream data.
2 0 obj << /Length 18 >> Stream dictionary stream 200 150 m 600 450 l S Stream data endstream endobj
We’ll discover what the m,
l and S operators do in a moment. The numbers are
measurements in points—a point (or pt) is 1/72 inch.
The result of loading this document into a PDF viewer (after processing
with pdftk as per Chapter 2) is shown in Figure 5-1.
The full manually created file (before processing with pdftk) is shown in Example 5-1. We’re going to be using variations on this file for the rest of this chapter. For the ...
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O’Reilly covers everything we've got, with content to help us build a world-class technology community, upgrade the capabilities and competencies of our teams, and improve overall team performance as well as their engagement.Julian F.
I wanted to learn C and C++, but it didn't click for me until I picked up an O'Reilly book. When I went on the O’Reilly platform, I was astonished to find all the books there, plus live events and sandboxes so you could play around with the technology.Addison B.
I’ve been on the O’Reilly platform for more than eight years. I use a couple of learning platforms, but I'm on O'Reilly more than anybody else. When you're there, you start learning. I'm never disappointed.Amir M.
I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.