Building a Simple PDF - PDF Explained - page 16

• The page tree , which enumerates the pages in the document.
• At least one page . Each page must have:
—Its resources , which include, for example, fonts.
—Its page content , which contains the instructions for drawing text and graphics
on the page.
This arrangement is illustrated in Figure 2-1 .
Figure 2-1. Object graph for Hello, World! PDF, with object numbers in brackets from Example 2-1
Building the Elements
We'll type the PDF data into a text file. The line endings chosen by your text editor are
unimportant (<CR> [Unix and Mac OS X] and <CR><LF> [Microsoft Windows] are
both fine). We're going to skip some information (the data that is hard to work out
manually), relying on pdftk to fill it in afterward. We will:
• Use an abbreviated header.
• Miss out the length of the page content stream, so we don't have to manually count
the number of bytes.
• Omit almost all of the cross-reference table.
• Use 0 for the byte offset of the cross-reference table, again to avoid having to count
it manually.