topic ScreenToMap() retuning wrong values in ArcGIS API for Silverlight Questions

ScreenToMap() retuning wrong values

JaskiratAnand — Tue, 31 Aug 2010 16:45:19 GMT

Hi,
I am facing a issue with the ScreenToMap() method of the API. Whenever a user clicks on the map I'm capturing that event and performing a ScreeToMap() conversion on that point. Most of the time the conversion is correct, however, sometimes the returned value is wrong. I have confirmed the wrong values by running a mouse hover event on the map which gives me the current x,y co-ordinates corresponding to the current mouse location on the map. The map is in WGS1984.
If anybody else has ever faced the same issue or a relative issue please share your experience.

thanks
Jaskirat

Re: ScreenToMap() retuning wrong values

dotMorten_esri — Tue, 31 Aug 2010 18:42:15 GMT

Make sure you give it coordinates that are relative to the upper left corner of the map.
You can transform them using the TransformToVisual command. Ex:
Point relativeToMap = uiElementThatInputPointAreRelativeTo.TransformToVisual(MyMap).Transform(inputPoint);

Re: ScreenToMap() retuning wrong values

LakshmananVenkatesan — Mon, 06 Sep 2010 09:32:50 GMT

Make sure you give it coordinates that are relative to the upper left corner of the map.
You can transform them using the TransformToVisual command. Ex:
Point relativeToMap = uiElementThatInputPointAreRelativeTo.TransformToVisual(MyMap).Transform(inputPoint);

Hello

I have tried TransformToVisualMethod but still values are wrong. How to give relative to upper left corner of the Map?. I am using ESRI SL 1.2 API. Can you please elobrate on this issue.

Re: ScreenToMap() retuning wrong values

ShenglinXu — Fri, 24 Jun 2011 20:07:06 GMT

I have tested the following code, works fine. Basically, I added a polygon drawing points to a point collection and draw them again. If I use a UI element, a textbox for example, the polygon will shift to right to some extent. However, I found this works great.

var ps = e.GetPosition(null);
Point aPnt = this.TransformToVisual(Map).Transform(ps);
ESRI.ArcGIS.Client.Geometry.MapPoint mapPoint = Map.ScreenToMap(aPnt);
_measurPntCol.Add(mapPoint);