Making a new driver is pretty easy.  If you can write a C program that
can draw a line on the given device, you can probably write a plplot
driver for it.

Overview
The best way to create a new driver is to start with one of the old ones.
At the minimum you will need to supply routines to (1) open/initialize the
device, (2) draw a line between two points on the device, and (3) close
the device.  These three routines are discussed further below.
After writing the routines you will need to update the dispatch table
(dispatch.c) in the drivers directory.

The initialization routine.
   This routine is of type void and takes no arguments. This routine
   sets up the resolution and page size for plplot. It accomplishes this
   by calling the following routines:

   (1) setpxl(float x, float y)  
       Set the resolution in dots per mm in the x and y directions.
       example -- setpxl(40.,40.)    40 dots/mm or 1016 dpi

   (2) setphy(int minx, int maxx, int miny, int maxy)
       Set the min and max page coordinates for the device.  The values
       passed to your line drawing routine will be within this range.
       example -- setphy(0,10299,0,7649)

   (3) scol(int color) 
       Set default pen color.
       example -- scol(1)
       
   (4) swid(int width)
       Set default pen width.
       example -- swid(1)

   (5) smod(int mode)
       Set/clear interactive device flag. If mode == 1 device is interactive
       i.e. a terminal (plplot will wait for user input before clearing
       the screen). If mode == 0 device is not interactive.
       example -- smod(0) 

    Portrait/landscape mode of plotting is set by the driver.  See the
    supplied drivers for one method of doing this.  If you are writing
    a new dirver you might want to ignore this for now (add it in later).

The line drawing routine
    This should be of type void. It should draw a line between two points
    It takes the following integer arguments
       x1 - x coord of first point
       y1 - y coord of first point
       x2 - x coord of second point
       y2 - y coord of second point
    These will all be within the range specified by setphy() in the
    initialization routine.

The close/tidy routine
    This is of type void. It takes no arguments.  Use it to cleanup
    and recover any allocated resources.


Updating the dispatch table
    You'll need to update the dispatch table in dispatch.c.
    Add the function declarations for your 3 driver routines to the
    others near the top of the file. Update the dispatch table.
    The first entry is a character string that is printed out in
    the device selection menu.  The 4th entry should be the name
    of your initialization routine. The 5th your line routine and the
    8th your close/tidy routine.  All the others can be set to NULL
    (You'll probably want to add these later).


Note: I've noticed that the pattern fill routines mess up on low
resolution devices. I got around this by faking plplot into thinking
that the device has high resolution by using setpxl() and setphy()
to make a high resolution virtual page.  I then scale down the values
I receive in the line drawing routine before passing them on to the
device. An example of this is in the iff driver.

Tony
resolution