Program Description:

  This is an OS/2 2.x port of the GNU GhostScript 2.6.1 with a Presentation
Manager driver.  


To use the program:

        1.  Edit the file gs.cmd file.  Set the position of the drawing
            window with the environment variable gsos2_pos.  Syntax:

                gsos2_pos=X Y windowCX widowCY imageCX imageCY

            where (X,Y) is the lower left corner of the client window,
            windowCX and windowCY are the width and height of the client
            window, and imageCX, imageCY are the width and height of the
            document. If the document size is larger then the client window
	    size, scroll bars will be created automatically.  
	    You can use the arrow keys and the Page Up, Page Down keys to
	    move the scroll bars.
	    The values
			 352 4 442 572 442 572 
	    for gsos2_pos specified in gs.cmd are ok if you have a 
	    800 x 600 display.  Also, set the environment
            variable gs_lib to tell GhostScript were the initialization files
            (gs_init.ps, gs_fonts.ps, etc) are.

            In addition, set the environment variable gsos2_dpi.  Syntax:

                        gsos2_dpi=Xdpi Ydpi,

            where Xdpi = WIDTH / (paper width in inches), and Ydpi = HEIGHT /
            (paper height in inches).  For example, if you specify 442 as
            WIDTH and 572 as HEIGHT for gsos2_pos, and you want use the 
            drawing window to preview 8.5 inch X 11 inch documents, then
            Xdpi = 442 / 8.5 = 52 and Ydpi = 572 / 11 = 52.  GhostScript
            produce better results for halftone patterns (dithering) 
            if you make Xdpi = Ydpi.

            Set the environment variable gsos2_mode.  Syntax:

                        gsos2_mode=N

	    where 
			N = 8 for 256 color mode
			N = 4 for 16 gray scale mode
			N = 2 for 4 gray scale mode
			N = 1 for monochrome mode

	2.  Put gsos2a.exe and gsos2b.exe in you PATH and gspm.dll in
	    your LIBPATH.

        3.  Type 'gs' from a windowed os2 session.  For example, type

                gs "-sDEVICE=gif8"

            to select the gif8 device.  Note the quotes around 
            -sDEVICE=gif8.

To terminate the program: type 'quit' or double click on the ghost icon
on the upper left hand corner of the drawing window.

You can type commands when either the command window or the drawing window
has the input focus.  However, the drawing window accepts only simple
characters, including carriage return and backspace, but not characters
like tab.  The ability of the drawing window to take input is mainly
intended for passing carriage return to the GS interpreter in response to 
the "showpage, press <return> to continue" prompt, and for issusing simple
commands like "(tiger.ps) run".  Since the inputs to the command window and
inputs to the drawing window are maintained by differents threads with
different character buffers, you should finish typing a complete
line (punctuated by carriage return) before switching to the other window.
For example, you should not start typing a line into the command window, and
subsequently switch and type the rest of the line into the drawing window.


Optional:

        1.  Add a program object to one of your folders that points to the
            file 'gs.cmd', and then attach the gsos2b.ico icon (included
            with this archive) to the program object.  Then you can drag
            and drop a PostScript file over the ghost icon and GS will
            automatically display that file.

        2.  Edit the file "fontmap" so that GS uses the .pfb fonts in your
            \psfonts directory.  For example, append the line

                /Helvetica	(d:/psfonts/helv.pfb);

            to the end of the file fontmap, and GS will use d:/psfonts/helv.pfb
            whenever it needs the Helvetica font.  For your convience,
	    a file called fontmap.tail is included with this archive.  If
	    you append fontmap.tail to the end of fontmap, GS will use
	    all of the ATM fonts that came with OS/2 2.x.  Fontmap.tail
	    assumes that the ATM fonts are in the d:\psfonts directory.

Remember, use forward slashes to separated directories - ie, use 
"(/apps/gs/tiger.ps) run" to preview the file 'tiger.ps'.


Known Problems:

1.  When using the 256 color mode, some windows' colors are all wrong.  This
    is because these programs do not handle the WM_REALIZEPALETTE message
    correctly.  Solution: don't use these programs, or use the 16 gray scale
    mode of the gspm26.

2.  If you use the VGA display driver, you can only use the 
    4 gray scale mode; furthermore, screen redraw using the 
    VGA display driver is rather slow due to a bug in the 
    function GpiDrawBits.  If you use the 64k color driver
    from S3-64k, you cannot use the 256 color mode because
    the 64k color driver does not support the palette manager.
    (I should fix this problem but I don't have the time.)
    Finally, the 256 color driver from S3-16m does not redraw
    the image correctly (apparently a bug in GpiDrawBits)
    so use the 256 color driver from either S3-256 or S3-64k.

    This PM driver has been tested with the 256 color driver from
    IBM's S3-256 and S3-64k driver.



Jim Yang
jyang@daedalus.caltech.edu

