Multiple Waveform Graphs

Multiple Waveform Graphs

Post by Jim Mcfadd » Wed, 12 May 2004 23:10:39

Dear group,

I have a user panel that contains three waveform graphs in which only one
graph is visible to the user. All three graphs plot the contents of the same
one dimensional array; although only one graph is being displayed all three
graphs contain a plot of the array. The user selects whether to display
graph 1,2 or 3 using a Dialog Ring.

This is the question I have: is it better to have all three charts plotted
simultaneously even though only one is being displayed or is it better to
only plot the chart that is being displayed on the screen?

In the case of the former do I use much more memory or slow down the
execution of my program more than in the case of the latter?

Thank you in advance,


Multiple Waveform Graphs

Post by Greg McKas » Wed, 12 May 2004 23:31:48

In part of your question you call the control a graph, and in other
parts a chart. The answer depends a bit on which you are showing and
hiding. Graphs only show the most recent data written to them, charts
retain and show history.

Neither the graph or chart will have much overhead receiving data while
hidden. On the otherhand, it isn't zero either since they will at least
be doing a data copy so they can draw with correct data when shown.

It will be easiest to send the data all the time since otherwise, you
will need to send fresh data when showing the graph. If dealing charts,
not only will you need to update the current data, but the history will
be old. You will need to clear or write the history.

If it doesn't cause a problem, write to them always, but if you can
measure a problem or have spare time on your hands, add code to make the
update conditional and deal with the data when being shown.

Greg McKaskle


Multiple Waveform Graphs

Post by Luca Notin » Wed, 12 May 2004 23:56:20

My apologies, it should say graph instead of chart.