topic Re: How to get the scale control to dynamically display scale like 1:50000? in ArcGIS API for Silverlight Questions

How to get the scale control to dynamically display scale like 1:50000?

weiliang — Tue, 17 Aug 2010 20:19:55 GMT

Hi??

I want to add a control to show the current scale (e.g., 1:15,000) of the map. Is there any such control ready to be embedded?

Thanks,

Wei

Re: How to get the scale control to dynamically display scale like 1:50000?

weiliang — Thu, 19 Aug 2010 21:52:58 GMT

Can someone kindly help me to answer this?

Many thanks,

Wei

Re: How to get the scale control to dynamically display scale like 1:50000?

egismazeika — Fri, 20 Aug 2010 05:42:46 GMT

You can read the manual: http://help.arcgis.com/en/webapi/silverlight/apiref/ESRI.ArcGIS.Client~ESRI.ArcGIS.Client.Map.html
"Map Scale and Resolution" topic.

Then create a nice control and share it with us:)

Re: How to get the scale control to dynamically display scale like 1:50000?

dotMorten_esri — Fri, 20 Aug 2010 14:47:18 GMT

emazeika is correct. The topic linked to gives you the formula to convert to scale. Use the map's ExtentChanging event to recalculate the scale based on Map.Resolution.

Note: As hinted in the doc, its technically impossible to display the correct scale, since there's no way of knowing the size of the screen and it's pixel resolution. (in cases where you have the screen cloned on multiple screens - like with a projector connected - the scale is even different on each screen!).

Re: How to get the scale control to dynamically display scale like 1:50000?

weiliang — Sun, 22 Aug 2010 13:22:59 GMT

Many thanks, Egis and Morten. Your answers really help me a lot. So, even the scale in ArcMap desktop is inaccurate? And, since we use GCS as our web app's coordinate system, I assume that the scale in the direction of lon and lat should be different. Am I correct? Also, how can I know the accurate scale if I want to print to a paper, should I still use the same formula?

Best,

Wei