[comp.sys.apollo] blt problem: gpr display bitmap -> external file

tim@walt.cc.utexas.edu (Tim Eakin) (08/07/90)

Hi Apollo experts !

     I am having a bit of a problem getting a gpr graphics-generated bitmap
from a display pad to an external file that can then be piped into a laser
writer for producing a hard copy.  Maybe one of you can tell me what is
going on.

     I generate a display bitmap with gpr calls in SR10.2 using gpr_$direct
mode.  This works fine, but then when I try to blt the bitmap to an external
file with [ yes, I'm a Fortran neanderthal :-) ]:

 call gpr_$set_bitmap(external_file_pathname,status)
 call gpr_$pixel_blt(display_bitmap,source_window,destination_origin,status)

a strange thing happens.  The external file has been "created" with size 4,
only about 1% of what it should be.  Furthermore, if I try to ftp it or rm it,
I get the message that the file does not exist, and if I mv some other
random file of size x to the same name, the name appears twice with 'ls -s', 
once with size 4 and once with size x !!

     Que paso ??  I am using the exact inverse of an example in the gpr
programming reference manual that writes to an external file first and then
does a blt to the display, except that it generates the original bitmap in
the external file using gpr_$borrow mode.

     Anyway, if anyone has successfully developed a similar routine, or can
see what the problem is, I would sure appreciate getting some email details.
Thanks guys.

                  --  Tim               tim@walt.cc.utexas.edu