topic Re: Problem zooming in initially in ArcGIS API for Silverlight Questions

Problem zooming in initially

TylerRothermund — Thu, 05 Jan 2012 20:57:01 GMT

I'm having a problem zooming in on a point when my page first loads. I tried waiting for the intialize event of both my layers before calling ZoomTo() but nothing happens. After everything has loaded I can call ZoomTo from a button click and it works fine.

private void ZoomTo(double lat, double lng, int level)
        {
            var newResolution = GetResolution(level);
            double halfWidth = newResolution * MyMap.ActualWidth / 2;
            double halfHeight = newResolution * MyMap.ActualHeight / 2;
            var point = new MapPoint(lat, lng, MyMap.SpatialReference);

            Envelope newExtent = new Envelope(point.X - halfWidth, point.Y - halfHeight, point.X + halfWidth, point.Y + halfHeight);

            MyMap.ZoomTo(newExtent);
        }

        <esri:Map WrapAround="True" x:Name="MyMap" Grid.Row="1"  Grid.ColumnSpan="2">
            <esri:ArcGISTiledMapServiceLayer Initialized="MyMapLayer_Initialized" 
                                             Url="{StaticResource MapUrl}"/>
            <esri:GraphicsLayer Initialized="MyMapLayer_Initialized">
            </esri:GraphicsLayer>
            <i:Interaction.Behaviors>
                <esri:MaintainExtentBehavior />
            </i:Interaction.Behaviors>
        </esri:Map>

Re: Problem zooming in initially

JenniferNery — Fri, 06 Jan 2012 02:34:33 GMT

This is related thread. Kindly see post# 3forums.arcgis.com/threads/21946-Zoom-To-Point

Re: Problem zooming in initially

TylerRothermund — Thu, 12 Jan 2012 15:51:44 GMT

This is related thread. Kindly see post# 3forums.arcgis.com/threads/21946-Zoom-To-Point

I don't see how that post helps. the ZoomTo() will work if called from a button click but just not when the page first loads. There must be some sort of state that the control has to be in before i can call ZoomTo() ???

Re: Problem zooming in initially

ChristopherHill — Thu, 12 Jan 2012 16:35:59 GMT

Try using Map.Layers.LayersInitialized event. It fires when all layers have been initialized in the layers collection, which should occur later than the two initialize events you have set on the individual layers.

Re: Problem zooming in initially

dotMorten_esri — Sat, 11 Dec 2021 07:10:14 GMT

Instead of calling ZoomTo, try this:

if(Map.Extent == null) //Map not ready yet - set the startup extent
        Map.Extent = newExtent;
else
       Map.ZoomTo(newExtent);

Re: Problem zooming in initially

TylerRothermund — Thu, 12 Jan 2012 19:37:47 GMT

Try using Map.Layers.LayersInitialized event. It fires when all layers have been initialized in the layers collection, which should occur later than the two initialize events you have set on the individual layers.

Thanks, but it didn't fix the problem.

Re: Problem zooming in initially

TylerRothermund — Sat, 11 Dec 2021 07:10:16 GMT

Instead of calling ZoomTo, try this:

if(Map.Extent == null) //Map not ready yet - set the startup extent
        Map.Extent = newExtent;
else
       Map.ZoomTo(newExtent);

Removing the ZoomTo() and setting the Extent everytime seems to fix it. Will there be any side effects from doing this?

 Envelope newExtent = new Envelope(point.X - halfWidth, point.Y - halfHeight, point.X + halfWidth, point.Y + halfHeight);

            //if (MyMap.Extent == null)
                MyMap.Extent = newExtent;
            //else 
            //    MyMap.ZoomTo(newExtent);

Ok, so after a little bit of testing I've run into an issue when I use a different map
Setting MyMap.Extent = newExtent works great on this map
- http://services.arcgisonline.com/ArcGIS/rest/services/ESRI_Imagery_World_2D/MapServer
but has no effect on this one
- http://services.arcgisonline.com/ArcGIS/rest/services/World_Imagery/MapServer

Re: Problem zooming in initially

DominiqueBroux — Fri, 13 Jan 2012 05:33:24 GMT

Likely a spatial reference issue. Your seconnd map is not using Geographical coordinates.
See related answer : http://forums.arcgis.com/threads/47094-Invalid-spatial-reference?p=163076&posted=1#post163076

Re: Problem zooming in initially

TylerRothermund — Wed, 18 Jan 2012 16:48:52 GMT

Likely a spatial reference issue. Your seconnd map is not using Geographical coordinates.
See related answer : http://forums.arcgis.com/threads/47094-Invalid-spatial-reference?p=163076&posted=1#post163076

Thanks for your help Dominique

Re: Problem zooming in initially

RiverTaig1 — Thu, 23 Feb 2012 01:47:02 GMT

I noticed that you are passing the lat in for the X and a variable lng for Y. Assuming those are latitude and longitude, shouldn't it be the other way around?