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CurrentScale - error "Cannot evaluate expression because the current thread is in a stack overflow state"

#1

Hi,

We use ThinkGeo.MapSuite.DesktopEdition and

MapControl Settings:

MapControl.MinimumScale = 600; // default 200
MapControl.MaximumScale = 1156000; // default 80000000000000
MapControl.ZoomLevelSnapping = ZoomLevelSnappingMode.None;

Event handler

MapControl_CurrentScaleChanged(object sender, CurrentScaleChangedWinformsMapEventArgs e)
{
double current_scale = MapControl.CurrentScale;
}

It looks MinimumScale does not restrict zoom-in to lower scale and we got error in Event handler MapControl_CurrentScaleChanged(). The error cannot be controlled by try-catch blocks. The error says “Cannot evaluate expression because the current thread is in a stack overflow state”.

Any idea that we did wrong in calling MapControl.CurrentScale property?

Please help and thanks in advance,

Mengbo

#2

Hi Mengbo,

Please try the following code to get the current scale:

 private void WinformsMap1_CurrentScaleChanged(object sender, CurrentScaleChangedWinformsMapEventArgs e)
 {
     double current_scale = e.CurrentScale;
 }

The MapControl.CurrentScale calls the set_CurrentExtent internally, and then the set_CurrentExtent raises the CurrentScaleChangedEvent, in this case it creates a endless loop.

Thanks,
Peter

#3

Hi Peter,

Yes, your code works and stops the overflow caused the endless loop.

You are great and thank you so much!

Mengbo

#4

Hi Mengbo,

You’re welcome, very glad to hear it works for you.

Thanks,
Peter