Programming PHP

Images and Graphics

There’s more to documents than text. Most PDF files contain some type of logo, diagram, illustration, or picture. This section shows how to include image files, build your own line-art illustrations, and repeat elements on every page (for instance, a header with a logo).

Images

PDF supports many different embedded image formats: PNG, JPEG, GIF, TIFF, CCITT, and a raw image format that consists of a stream of the exact byte sequence of pixels. Not every feature of every format is supported, however.

For PNG images, the alpha channel is lost (however, the later versions of pdflib and Acrobat do support transparency, which means that you can indicate a color index to be the transparent color, but you cannot have partial transparency). For JPEG, you only need to watch out for progressive JPEGs; they are not supported prior to Acrobat 4, so it is a good idea to stick to nonprogressive JPEGs. For GIF images, avoid interlacing.

Adding an image to a PDF document is relatively simple. The first step is to call the appropriate open function for the type of image you are using. These functions all take the form pdf_open_ format ( ). For instance:

$image = pdf_open_jpeg(pdf, filename);

Once you have opened the image, use pdf_place_image( ) to indicate where in your document the image should be located. While you have an image open, you can place it multiple times throughout your document; your generated file will contain only one copy of the actual image data. ...