Re: hi

john wrote:
(snip)
> make a gtk_window
> make new canvas and plot widgets, plot the data i have, and add it 
> to the window
> if the user requests new data to be graphed, i destroy the canvas and plot
> widget, make new canvas and plot widgets, plot the data i have, and add it 
> to the old window
> 
> this seems to work for the first few times, however, after a while, the 
> canvas and plot would no longer show up. when i click on the region, the 
> widgets seem to be there but hidden from view (all i can see is the window 
> widget and gray inside).
> 
> i was wondering if anyone has run into this problem before ...
> 

No, but I can tell you that you're working way harder than you need to 
to change the data.

I do:

       /* Now, update plot data (whew!) */
       gtk_plot_data_set_numpoints(pXYPState->apGtkPlotData[0], 
iPointsToPlot);
       gtk_plot_data_set_x(pXYPState->apGtkPlotData[0],
			  pXYPState->paAVPlotData[0].x_data);
       gtk_plot_data_set_y(pXYPState->apGtkPlotData[0],
			  pXYPState->paAVPlotData[0].y_data);

and the new data is applied.  The apGtkPlotData is the return from 
initialization time call:

pXYPState->apGtkPlotData[0] = GTK_PLOT_DATA(gtk_plot_data_new());

which I had previously added to the plot with:

   /* Add data to plot (dataset should be empty). Show plot layer */
   gtk_plot_add_data(GTK_PLOT(pPlotLayer),pXYPState->apGtkPlotData[0]);
   gtk_plot_autoscale(GTK_PLOT(pPlotLayer));
   gtk_widget_show(pPlotLayer);


So, when new data arrives I update my arrays of x_data and y_data, and 
then just tell gtk_plot_ routines how many points, and the x and y sets.

Then I cause repaint, refresh, etc.  The gdk_flush() call below should 
not be required, but I was getting errors with crappy Win32 X-servers 
until I added it.


       gtk_plot_canvas_paint(GTK_PLOT_CANVAS(pXYPState->pPlotCanvas));

       /* This flush has caught X errors */
       gdk_flush();

       gtk_plot_canvas_refresh(GTK_PLOT_CANVAS(pXYPState->pPlotCanvas));

       /* This flush commented out, as the prev. flush caught an error */
       /* gdk_flush(); */
	
#if 0
       g_message("XYPlot refreshed with %d points",iPointsToPlot);
#endif

       gtk_widget_show(pXYPState->pXYPWin);


I think that all of the above came out of the so-called 'realtime' demo 
in the gtkextra distribution.

HTH,

Eric



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