dik@comp.lancs.ac.uk (Mr R. M. Bentley) (10/31/90)
I am trying to implement a C-program which displays a colored raster
image on the screen as a Smalltalk method. The point to position the
image is passed to the C function as parameters to the primitive method.
I am having trouble mapping the local co-ordinates used in Smalltalk to
refer to the Smalltalk display within the Sunview window to absolute
display coordinates.
What I really want to be able to do is position a colored image within a
View. I can get the local origin of the View (using insetDisplayBox) but
I need to be able to translate this to global screen co-ordinates for the
primitive function.
As far as I can see, I have two options:
1. Modify the co-ordinates in Smalltalk before passing to the
primitive.
2. Use SunView to locate the Smalltalk window origin and add this
as a constant in the C function to the parameters passed from
Smalltalk.
Currently we're using pixrect onto the frame buffer, opening ("/dev/fb").
I'm told that this problem can be resolved if anyone knows if smalltalk
provides a handle to its pixrect. (I am using Smalltalk 2.5).
If anyone knows if either of the two approaches is feasible and how to go
about it, I would be very grateful for advice/assistance.laukee@canon.co.uk (David Lau-Kee) (11/02/90)
dik@comp.lancs.ac.uk (Mr R. M. Bentley) writes:
[ stuff about displaying colour images in PPS 2.5
Q. does one get st's pixrect or frig a window offset, and how? ]
Well, what you ought to do is grab Smalltalk's window offsets direct and use
those. You also need the colour map info to hand. When I did something
similar I couldn't figure out how do this properly, so I frigged it (your
option 1). Note that you'll also need to replicate the standard bitblt
(since Smalltalk will assume it can just toggle LSB for black/white), *and*
set up the colour map to have every other entry black (to get the cursor
functioning over the deep parts). I'm sure there's an easier way, still
this was just a "design as you type" exercise .
I'll mail you some code to get you started.
-------------
David Lau-Kee
Canon Research Centre Europe,
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