This causes IDL to use a printer driver to produce graphical output. By default, the default system printer is used for output. Use the DIALOG_PRINTERSETUP function to define the printing parameters for the printer device. Use the DIALOG_PRINTJOB function to control the print job itself.
Note that the printer device is an IDL Direct Graphics device. Like other Direct Graphics devices, you must change to the new device and then issue the IDL commands that send output to that device. With the printer device, you must use the CLOSE_DOCUMENT keyword to the DEVICE routine to actually initiate the print job and make something come out of your printer.