The printer special flags (io_Flags) of the iodrpreq provide a high degree
of control over the printing of a rastport.

   SPECIAL_ASPECT       Allows one of the dimensions to be
                        reduced/expanded to preserve the correct
                        aspect ratio of the printout.

   SPECIAL_CENTER       Centers the image between the left and right
                        edge of the paper.

   SPECIAL_NOFORMFEED   Prevents the page from being ejected after
                        a graphics dump.  Usually used to mix graphics and
                        text or multiple graphics dump on a page oriented
                        printer (normally a laser printer).

   SPECIAL_NOPRINT      The print size will be computed, and set
                        in io_DestCols and io_DestRows, but won't print.
                        This way the application can see what the actual
                        printsize in printerpixels would be.

   SPECIAL_TRUSTME      Instructs the printer not to send a reset
                        before and after the dump.  This flag is obsolete
                        for V1.3 (and higher) drivers.

   SPECIAL_DENSITY1-7   This flag bit is set by the user in Preferences.
                        Refer to "Reading and Changing the Printer
                        preferences settings" if you want to change to
                        density of the printout. (Or any other setting for
                        that matter.)

   SPECIAL_FULLCOLS     The width is set to the maximum possible,
                        as determined by the printer or the configuration
                        limits.

   SPECIAL_FULLROWS     The height is set to the maximum possible, as
                        determined by the printer or the configuration
                        limits.

   SPECIAL_FRACCOLS     Informs the printer device that the value in
                        io_DestCols is to be taken as a longword binary
                        fraction of the maximum for the dimension.  For
                        example, if io_DestCols is 0x8000, the width
                        would be 1/2 (0x8000 / 0xffff) of the width of
                        the paper.

   SPECIAL_FRACROWS     Informs the printer device that the value in
                        io_DestRows is to be taken as a longword binary
                        fraction for the dimension.

   SPECIAL_MILCOLS      Informs the printer device that the value in
                        io_DestCols is specified in thousandths of an inch.
                        For example, if io_DestCols is 8000, the width of
                        the printout would be 8.000 inches.

   SPECIAL_MILROWS      Informs the printer device that the value in
                        io_DestRows is specified in thousandths of an inch.

The flags are defined in the include file devices/printer.h.