How to add a user-adjustable reference waveforms to a graph?

[OneOfTheDans]

I have an XY Graph in LabVIEW 2013 that displays two waveforms. I'm interested in visually comparing sections of those waveforms to an expected slope. Does anyone know a way to add a reference line/waveform to a graph, which can get manually dragged around the graph at run time?

[Ben · Accepted solution]

How about another plot generated from two cursors?

When the cursors move, update the "reference" and re-plot.

Ben

[OneOfTheDans]

Good suggestion, thank you! Since my reference line has a fixed slope, I only needed one cursor instead of two.

Now I have an event case for Cursor Move that calculates 2 (x,y) pairs at the edges of the graph, such that a line between the two passes through the Cursor's (x,y) location.

The code is getting a bit involved to prevent infinitely growing auto-scale, and the fact my chart is log-log. But this still feels like the best solution.