Drawing an image from a slow-scan transmission

[Neoklis <neok spidernet com cy>]

Hi All!

I am preparing to write my first app in GTK+ and while I read
the tutorial, I thought I should ask for help since the objective
is somewhat unusual and without any experience I am unlikely to
find the right solution:

I already have a console app (tool) written, that decodes weather
images from satellites transmitting in the APT format. At the
moment this app produces PGM image files after finishing with the
satellite pass. I intend to port this to GTK+ and arrange it to
display the incoming image line-by-line as it is decoded. So what
I need is a suitable way to plot the line of pixels on the screen
(in 8-bit gray levels) so that the image can be seen to form, one
line at a time. Pixel rate is quite slow (2 lines of 696 8-bit
pixels per second) with an average of about 800-900 lines per
image. So I think the recommendation of the FAQ not to use
gdk_draw_point() may not apply here.

If so, I would appreciate some general pointers on how to proceed
with this objective.

My thanks in advance!

--
Regards      My Ham Radio callsign: 5B4AZ  QTH Loc: KM64MR
            My website (with some Ham Radio/Linux software):
Neoklis      http://leonardo.spidernet.net/Copernicus/22420/