Page 295 - Open Soource Technologies 304.indd

Unit 12: Portable Document Format

12.2.1 Initializing the Document Notes
In above Example, we started by calling pdf_new( ), to create a new PDF data structure, followed
by pdf_open_file( ) , to open a new document. pdf_open_file( ) takes an optional second argument
that, when set, specifies the filename to which to write the PDF data:
pdf_open_file(pdf [, filename ]);
The output of pdf_open_file( ) is sent to stdout if the filename is “-”. If no filename argument
is provided, the PDF data is written to a memory buffer, which can later be fetched by calling
pdf_get_buffer( ). The latter approach is the one we used in above Example.
12.2.2 Setting Metadata

The pdf_set_info( ) function inserts information fields into the PDF file:
pdf_set_info(pdf, fieldname, value);
There are five standard field names: Subject, Author, Title, Creator, and Keywords. You can
also add arbitrary information fields.
In addition to informational fields, the pdflib library has various parameters that you can change
with pdf_get_parameter( ) and pdf_set_parameter( ):
$value = pdf_get_parameter(pdf, name); pdf_set_parameter(pdf, name, value);
A useful parameter to set is openaction, which lets you specify the zoom (magnification) of
the file when it’s opened. The values “fitpage”, “fitwidth”, and “fitheight” fit the file to the
complete page, the width of the page, and the height of the page, respectively. If you don’t set
open action, your document is displayed at whatever zoom the viewer had set at the time the
document was opened.
12.2.3 Creating a Page

A page starts with a call to pdf_begin_page ( ) and ends with a call to pdf_end_page ( ):
pdf_end_page(pdf);
You specify the paper size in points in the call to pdf_begin_page ( ). Table 12.1 shows some
typical sizes.

Table 12.1: Paper Sizes

Page format Width Height
US-Letter 612 792
US-Legal 612 1008
US-Ledger 1224 792
11 x 17 792 1224
A0 2380 3368
A1 1684 2380
A2 1190 1684
A3 842 1190
A4 595 842
A5 421 595
A6 297 421
B5 501 709

LOVELY PROFESSIONAL UNIVERSITY 289