Callback Function Trouble

09-04-2008 10:24 AM |

I have a function called from Page() in Page.xaml.cs which contains a foreach loop. 

The loop calls a web service and retrieves coordinate geometry from user specified polygons.  This is done through a callback function. 

MY PROBLEM:

The callback function successfully retrieves the coordinate geometry for the first polygon, however all subsequent loops through the callback function contain the same coordinate geometry.  So if I loop through the callback function four times, only the geometry from polygon 1 is correctly accessed.  The remaining three coordinate geometries are the same as the first geometry.  If I run the callback on each polygon separately, the corresponding geometry is correctly returned for each polygon.  NOTE: for my purposes, the program needs dynamic geometry retrieval.

Suggestions for solving this.......thanks.

Re: Callback Function Trouble

09-04-2008 10:30 AM |

Without some code it's hard to see your problem.

Can you post some please.

Re: Callback Function Trouble

09-04-2008 10:36 AM |

There are several possible problems, and I don't understand the problem.

Do you have problems with a xaml created polygons?

WCF provided polygons?

Code behind created polygons?

Maybe a Thread problem?

Can you explain a litle more?

Re: Callback Function Trouble

09-04-2008 10:57 AM |

From Page() in Page.xaml.cs, I call a web service to tell me the geometry type of a shapefile (ESRI format).  The geometry type is returned as a string.  Then I make a call to another web service to return coordinate geometry.  To get the coordinate geometry from the shapefile, I use FDO (Feature Data Object - OSGeo).  The coordinates are returned to the calling program in string[] format.  The geometries (polygons) are added to a virtual earth map.

pCoords (returned coordinate geometry) in CompletePoly always contains the first geometry.

CODE BELOW:

//*****************THIS FUNCTION IS CALLED FROM Page() in Page.xaml.cs 

//LOAD XML FILE CONTAINING LAYER INFORMATION

//CREATE SHAPELAYER FOR EACH GIS LAYER AND ADD TO MAP

//ADD FEATURES TO THE SHAPELAYERS

SessionManager.Session["MAPID"] = s.mapID;

//CALL ASP.NET WEB SERVICE TO READ SHAPEFILE COORDINATES

asmx.SHP_LayerGeometryTypeCompleted += new System.EventHandler<DeepEarthPrototype.GISFunctions.SHP_LayerGeometryTypeCompletedEventArgs>(returnGeometry);

asmx.SHP_LayerGeometryTypeAsync((string)SessionManager.Session["SHPFILEPATH"]);

//AN STRING ARRAY IS RETURNED; EACH RECORD CONTAINS THE X AND Y COORDINATES FOR FEATURE SEPARATED BY :

string geometryType = (string)e.Result;

//************THIS MAKES ANOTHER CALL TO ANOTHER WEB SERVICE TO GET COORDINATE GEOMETRY

{

//CALL ASP.NET WEB SERVICE TO READ SHAPEFILE COORDINATES

asmx.SHP_ReturnGeometryCompleted += new System.EventHandler<DeepEarthPrototype.GISFunctions.SHP_ReturnGeometryCompletedEventArgs>(CompletePoly);

//AN STRING ARRAY IS RETURNED; EACH RECORD CONTAINS THE X AND Y COORDINATES FOR FEATURE SEPARATED BY :

//pGeometryList.Add(pCoords);

//ADD THE POLYGON LAYER TO THE MAP

////HARDCODED A TEST POLYGON

//List<Point> points = new List<Point> { new Point(-114.1576, 45.0711), new Point(-116.1576, 44.0711), new Point(-113.1576, 43.0711), new Point(-114.1576, 45.0711) };

//PolygonShape polygon = new PolygonShape { Points = points };

//shapeLayer.List.Add(polygon);