# To subscribers of the xforms list from Daniela Soares de Almeida <daniela.soares@openlink.com.br> :
Steve,
Thank you very much for your help (again!). I've not could try your code
but when i do i'll send the results. Best regards,
Daniela.
At 09:53 AM 05/06/00 -0700, you wrote:
># To subscribers of the xforms list from Steve Lamont <spl@blinky.ucsd.edu> :
>
>> Thank you very much for your help, with it i corrected my code. My
>> intention doing the while was try to make xyplot works like a stripchart. I
>> know that i would have to insert others pieces of code but you think it's
>> possible? (I need something like a stripchart with a fixed scale in the
>> both axis) Could i use a fifo to pass data to the xyplot? Thanks in
advance,
>
>It can be done, although it can be a bit tricky, since the XYPlot
>object is pretty thickheaded about how it wants to do scaling, etc.
>
>You'll have to keep an array of points to which you make your updates
>and then feed them to XYPlot, since there's no way to add a single
>point. For example, the following piece of code plots the most recent
>100 points:
>
> void add_point( float x, float y, FL_OBJECT *xyplot )
>
> {
>
> static int n = 0;
> static float X[1000];
> static float Y[1000];
>
> if ( n == 1000 ) {
>
> memcpy( &X[0], &X[901], sizeof( float ) * 99 );
> memcpy( &Y[0], &Y[901], sizeof( float ) * 99 );
>
> n = 99;
>
> }
> X[n] = x;
> Y[n] = y;
> n++;
>
> fl_set_xyplot_data( xyplot,
> &X[n - 100],
> &Y[n - 100],
> 100,
> ... );
>
> }
>
>Note that there is a bug in this code (what happens when n < 100?) and
>it's not intended to be used "straight out of the box." I leave it to
>the user to deal with the startup case.
>
>As for the mechanism for passing data from your monitoring code to the
>plot code, a FIFO, I suppose, is as good as anything. You may wish to
>refer to the manual's discussion of asynchronous I/O or check the
>archives of this mailing list -- there has been considerable
>discussion of this subject and numerous different solutions to the
>problem, including use of threads.
>
> spl
>
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