Silverlight 服务器端打印出现错误

class MapLayers : IEnumerable<Layer>

{

List<Layer> myList = new List<Layer>();



public void add(int index, Layer layer)

{

myList.Insert(index, layer);

}



public IEnumerator<Layer> GetEnumerator()

{

return myList.GetEnumerator();

}



System.Collections.IEnumerator System.Collections.IEnumerable.GetEnumerator()

{

return this.GetEnumerator();

}

using System;

using System.Collections.Generic;

using System.Linq;

using System.Net;

using System.Windows;

using System.Windows.Browser;

using System.Windows.Controls;

using System.Windows.Documents;

using System.Windows.Input;

using System.Windows.Media;

using System.Windows.Media.Animation;

using System.Windows.Markup;

using System.Windows.Shapes;

using System.ComponentModel;

using ESRI.ArcGIS.Client;

using ESRI.ArcGIS.Client.Printing;

using System.Windows.Controls.Primitives;



namespace PrintProblem

{

public partial class MainPage : UserControl

{

PrintTask printTask;

PrintParameters printParameters;

MapLayers mapLayers;

ArcGISDynamicMapServiceLayer Layer1;

FeatureLayer Layer2;

ArcGISTiledMapServiceLayer Layer3;



public MainPage()

{

InitializeComponent();

mapLayers = new MapLayers();

Layer1 = new ArcGISDynamicMapServiceLayer();

Layer1.Url = http://sampleserver3.arcgisonl ... er%3B



Layer2 = new FeatureLayer();

Layer2.Url = http://sampleserver3.arcgisonl ... er%3B



Layer3 = new ArcGISTiledMapServiceLayer();

Layer3.Url = http://services.arcgisonline.c ... er%3B



printTask = new PrintTask(http://sampleserver6.arcgisonl ... 20Task);

printTask.DisableClientCaching = true;

printTask.ExecuteCompleted += printTask_PrintCompleted;

printTask.GetServiceInfoCompleted += printTask_GetServiceInfoCompleted;

printTask.GetServiceInfoAsync();





}



private void printTask_GetServiceInfoCompleted(object sender, ServiceInfoEventArgs e)

{

LayoutTemplates.ItemsSource = e.ServiceInfo.LayoutTemplates;

Formats.ItemsSource = e.ServiceInfo.Formats;

}



private void printTask_PrintCompleted(object sender, PrintEventArgs e)

{

System.Windows.Browser.HtmlPage.Window.Navigate(e.PrintResult.Url, _blank);

}



private void ExportMap_Click(object sender, RoutedEventArgs e)

{

if (printTask == null || printTask.IsBusy) return;



mapLayers.add(0, Layer3);

mapLayers.add(1, Layer2);

mapLayers.add(2, Layer1);



PrintParameters printParameters = new PrintParameters(mapLayers, MyMap.Extent)

{

ExportOptions = new ExportOptions() { Dpi = 96, OutputSize = new Size(MyMap.ActualWidth, MyMap.ActualHeight) },

LayoutTemplate = (string)LayoutTemplates.SelectedItem ?? string.Empty,

Format = (string)Formats.SelectedItem

};



printTask.ExecuteAsync(printParameters);

}



}



class MapLayers : IEnumerable<Layer>

{

List<Layer> myList = new List<Layer>();



public void add(int index, Layer layer)

{

myList.Insert(index, layer);

}



public IEnumerator<Layer> GetEnumerator()

{

return myList.GetEnumerator();

}



System.Collections.IEnumerator System.Collections.IEnumerable.GetEnumerator()

{

return this.GetEnumerator();

}

}

}