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I have an axMapControl in a WinForms application. According to the ArcGIS documentation,

[The]OnExtentUpdated [event] is triggered whenever the IMapControl2::Extent property is changed. Setting the extent explicitly, zooming, panning or using the IMapControl2::CenterAt method will change the extent.

But how can I know (programmatically) inside the event handler that it was zooming or panning that caused the extent to change? I am looking for some C# code which would enable me to know that the extent change was caused by one of those two things.

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1 Answer 1

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The second argument of this event handler (sizeChanged) checks whether the size of the extent is changed.

IMapControlEvents2.OnExtentUpdated (
  IDisplayTransformation displayTransformation,
  bool sizeChanged,
  IEnvelope newEnvelope
);

if the sizeChanged is true, then a zoom is happened, else its a pan!

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  • Thank you! Is there a way to know in the event handler that the extent change was caused by neither the zoom nor the pan? For example if the extent was explicitly set in code?
    – EleventhDoctor
    Commented May 14, 2015 at 9:35
  • I don't think that is possible with this event listener. In fact, when a zoom/pan happens, in the code behind the extent is changed. So either ways the extent is changed within the code.
    – Farid Cheraghi
    Commented May 14, 2015 at 10:29
  • To distinct between users zoom/pan and extent change using coding, you should check for the active tool in the event listener. If the active tool is pan/zoom then it is a pan and zoom.
    – Farid Cheraghi
    Commented May 14, 2015 at 10:33
  • Sounds good - do you think you could provide a code example in your answer to make it really clear?
    – EleventhDoctor
    Commented May 18, 2015 at 11:39

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