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Unit 12: Portable Document Format

Notes
Figure 12.14: Thumbnails

12.5.2 Links

pdflib supports functions that specify a region on a page that, when clicked on, takes the reader
somewhere else. The destination can be either another part of the same document, another PDF
document, some other application, or a web site.

The pdf_add_locallink( ) function adds a local link to another place within the current PDF file:
pdf_add_locallink(pdf, llx, lly, urx, ury, page, zoom);
All links in PDF files are rectangular. The lower-left coordinate is (urx,ury) and the upper-right
coordinate is (urx,ury). Valid zoom values are “retain”, “fitpage”, “fitwidth”, “fitheight”, and
“fitbbox”.
The following call defines a 50 x 50 area that, if clicked, takes the reader to page 3 and retains
the current zoom level:
pdf_add_locallink($p, 50, 700, 100, 750, 3, “retain”);
The pdf_add_pdflink( ) function adds a link to another PDF file. It takes the same parameters as
the pdf_add_locallink( ) function, with the addition of a new parameter containing the filename
to link to:
pdf_add_pdflink(pdf, llx, lly, urx, ury, filename, page, zoom);

pdf_add_pdflink($p, 50, 700, 100, 750, “another.pdf”, 3, “retain”);
The pdf_add_launchlink( ) function adds a link to another file, whose MIME type causes the
appropriate program to be launched to view the file:
pdf_add_launchlink($p, 50, 700, 100, 750, “/path/document.doc”);

The pdf_add_weblink( ) function creates a link whose destination is a URL:
pdf_add_weblink(pdf, llx, lly, urx, ury, url);

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