Zoom out on one axis only

[Adam P.]

In LabView 8.20, my waveform chart's graph palette has 6 zoom functions.  Only one is 'zoom out', as all the others are some type of 'zoom in.'  What if I want to zoom out in only one axis - just like I can zoom in on the X or Y axes separately?  For example, imagine plotting data acquired over time.  You have your Y-scale set how you would like based on what you know about data that may be arriving in the future (i.e. you do not want to use autoscale).  But data points are just streaming in too quickly and you miss them as they go by!  The only way to correct this is to zoom OUT from a point and THEN recorrect your Y axes back to how they were before.

I've seen some mention of 'locking' the Y scale programatically but it seems to be a function of CVI, Measurement Studio, or something I just don't feel the need to use (correct me if I am wrong!)  Does anyone EVER notice the issue I am having and can think of a way to solve it so I don't have to click around a zillion times just to "ZOOM OUT IN X" ?

Thanks in advance!
Adam

[Spex]

I see two possible solutions for changing the X axis without affecting the Y axis.  First, you could programatically lock the Y axis to a set range using property nodes.  If the user tried to change the Y axis (using zoom all, or zoom out), the X range would change, while the Y range would be coerced back to its original specification.  I have attached a small example that utilizes the Y Scale properties to implement this feature.

Secondly, you could create an event driven program that used front panel buttons to implement your own custom zoom functions.  For example, you could create a state machine that upon clicking on "Zoom Out X", the displayed X range would be doubled.  This method would also use property nodes to manipulate the "X Scale" properties of the waveform chart.

Hope this helps.