topic Zooming into an extent more than once causes features within it to shift in ArcGIS API for Silverlight Questions

Zooming into an extent more than once causes features within it to shift

HasheenDeBerry — Fri, 07 Oct 2011 14:34:53 GMT

Hello All,

I am using the Silverlight API v2.2 and I noticed a rather odd issue.

I have some code that will zoom into the extent of the features on the map (usually points and/or polygons). When the function is called again on the same extent, the features within the extent shift north and east a little. Below is the code for the function:

 private void ZoomIn(List<Graphic> lstGraphics)
        {
            if (lstGraphics.Count > 0)
            {
                Envelope zoomExtent = lstGraphics.First().Geometry.Extent;

                for (int i = 1, il = lstGraphics.Count; i < il; i++)
                {
                    try
                    {
                        zoomExtent = zoomExtent.Union(lstGraphics.Geometry.Extent);
                    }
                    catch { continue; }
                }

                Utils.ApplyWKID(zoomExtent, myCurrentMap.Layers[0].SpatialReference.WKID);

                double width = zoomExtent.XMax - zoomExtent.XMin;
                double height = zoomExtent.YMax - zoomExtent.YMin;

                if (width > 0 && height > 0)
                {
                    //expand by 10%

                    double newWidth = width + (width * 0.1);
                    double newHeight = height + (height * 0.1);

                    double dx = (newWidth - width) / 2;
                    double dy = (newHeight - height) / 2;

                    //update extent
                    zoomExtent.XMin -= dx;
                    zoomExtent.XMax += dx;
                    zoomExtent.YMin -= dy;
                    zoomExtent.YMax += dy;

                    myCurrentMap.ZoomTo(zoomExtent);
                }
                else
                {
                    //assume it is a single map point and zoom in
                    ZoomIn(new MapPoint(zoomExtent.XMin, zoomExtent.YMin, zoomExtent.SpatialReference), LinearUnit.Meter, 1610);
                }
            }
            else
            {
                ShowMessage("Unable to zoom to map featues. No map features found.");
            }
        }

I've been able to recreate the behaviour on different basemaps hosted in house and on ESRI's servers. Any help or insight that anyone can provide is greatly appreciated.

Thanks In Advance

Re: Zooming into an extent more than once causes features within it to shift

JenniferNery — Sat, 11 Dec 2021 12:54:15 GMT

I cannot repro with your code using sampleserver services although I had to skip the following lines (since there was no implementation provided):

 Utils.ApplyWKID(zoomExtent, myCurrentMap.Layers[0].SpatialReference.WKID);
  ZoomIn(new MapPoint(zoomExtent.XMin, zoomExtent.YMin, zoomExtent.SpatialReference), LinearUnit.Meter, 1610);

I called ZoomIn() method in a Button.Click event multiple times and I did not see a shift in the features using v2.2 assemblies.

Could you check if there was a mismatch between FeatureService.SpatialReference and Map.SpatialReference?

Re: Zooming into an extent more than once causes features within it to shift

HasheenDeBerry — Mon, 17 Oct 2011 17:12:29 GMT

@jenniferdnery

Thank you for your help. Upon further review this was an EBCAK error on my end and not an issue with the SDK. Is there a way to mark this thread as complete?

Re: Zooming into an extent more than once causes features within it to shift

JenniferNery — Wed, 19 Oct 2011 16:23:18 GMT

I'm not how forum threads can be marked resolved. But thanks for giving us a follow up. I think your last post is a good indicator that it has been resolved 🙂