[XFree86] XDrawLine problem encountered using 4.2.0

[ktang <keith.tang@xxxxxxxxxxxx>]

I just install Mandrake 8.2 on a system and ran an application which 
which is running on several Redhat 5.0 systems.  The application can 
acquired and plot waveforms much in the same manner as a digital oscope.
The new Mandrake system is using XFree86.4.2.0.  This system has a 
plotting problem.

The plots are generated using the XDrawLine such as:

   XDrawLine(DspAdr, mainform->window, gc, xo, yo, x, y);
   xo = x;
   yo = y;

This is called from another function for however many points have been 
recorded.  The xo and yo variables are static integers within the called 
function which used to keep the values of the last point, which is 
needed for the next line segment.

The problem on the Mandrake 8.2 system is the xo point is in the wrong 
location.  The result is discontinuous plot segments.  I have printed 
the points as they are being plotted and they are correct.  The exact 
same application works on the Redhat 5.0.  The points are correct.

It appears rather strange when the top 25% of a sine wave looks like a 
Christmas tree.

Has anyone else encountered anything like this?

Thanks,

Keith Tang
Marathon Electric
100 E Randolph St.
Wausau, WI. 54402-8002

715 675-3359


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