want to select a non rectangular area in xy graph( ellipse, oval)

[Kubs23]

I have a xy graph that is the combination of 1 histogram in the x plane and a different histogram in the y plane.  I would like to be able to draw a shape  around the resulting smear to be able to see how many events occured in this area of interest.  I can get close with 2 cursors, but my application requires to be a tighter fit.

Thanks,

kubs23

[altenbach]

Here's an idea:

Draw the ellipse on top of the graph using the plot image feature. Here are some references.

How to draw on top of an xy graphs: http://forums.ni.com/ni/board/message?board.id=170&message.id=202702#M202702

(Instead of cursor positions, use mouse-down and mouse-move events.  Of course an ellipse has more degrees of freedom, so you need extra inputs to e.g. set the excentricity, or keep that fixed at e.g. 3:1.). Now just draw an ellipse between the mouse-down and mouse-move coordinates which has the major axis connecting the two points.

How to draw a rotated ellipse (see attached, modified from: http://forums.ni.com/ni/board/message?board.id=170&message.id=140604#M140604).