topic Re: Get the current zoom level and Lat/Long in ArcGIS API for Silverlight Questions

Get the current zoom level and Lat/Long

TylerRothermund — Wed, 04 Jan 2012 00:34:12 GMT

How can I get the current zoom level and center point Lat/Long of the map? I need to save these settings so I can restore them the next time the user hits the page.

Re: Get the current zoom level and Lat/Long

SanajyJadhav — Wed, 04 Jan 2012 04:17:10 GMT

Can you clarify "current zoom level"?

If you mean current extent, you can get it by Map.Extent and it's center as Map.Extent.GetCenter().

Re: Get the current zoom level and Lat/Long

TylerRothermund — Wed, 04 Jan 2012 15:29:54 GMT

Is MyMap.Extent.GetCenter().X , Y = Lat / Long or are those some kind of screen coordinate?

Is there a property that tells me how far the user has zoomed (level) into the map like a (1-9) or something?

Re: Get the current zoom level and Lat/Long

JenniferNery — Wed, 04 Jan 2012 16:46:12 GMT

You can look at the following SDK samples:
Map.Extent updates on pan/zoom
http://help.arcgis.com/en/webapi/silverlight/samples/start.htm#MapExtent
Screen point can be converted to map coordinates
http://help.arcgis.com/en/webapi/silverlight/samples/start.htm#MouseCoords
You can compare Map.Resolution property against ArcGISTiledMapServiceLayer.TileInfo.Lods.Resolution to know what level you are currently zoomed in.
http://help.arcgis.com/en/webapi/silverlight/samples/start.htm#ShowMapProperties

Re: Get the current zoom level and Lat/Long

TylerRothermund — Sat, 11 Dec 2021 15:20:20 GMT

Shouldn't Map.Resolution = one of the LODs ?

I'm using this map:
http://services.arcgisonline.com/ArcGIS/rest/services/ESRI_Imagery_World_2D/MapServer

But Map.Resolution doesn't match any of the LODs.

  private int GetZoomLevel()
        {
            double currentRes = MyMap.Resolution;
            var lods = ((ArcGISTiledMapServiceLayer)MyMap.Layers[0]).TileInfo.Lods.ToList();
            int level = lods.IndexOf(lods.Where(l => l.Resolution == currentRes).FirstOrDefault());

            return level;
        }

Re: Get the current zoom level and Lat/Long

dotMorten_esri — Thu, 05 Jan 2012 13:35:39 GMT

Unless you set SnapToLevels=true on the map, you can zoom between levels, so no there is no guarantee.
You can instead pick the closest one which should be the one currently rendering.
Scale and/or Resolution is the most precise way for determining the zoom since this is a fully linear range as opposed to zoom levels.