Symbol Dictionary Search

This sample illustrates how to search the Mil2525C symbol dictionary. The military symbols which are displayed using the MessageProcessor class are stored in a symbol dictionary and accessed vie the SymbolDictionary class. The symbols in the dictionary have metadata stored with them which can be used to perform searches to find the correct symbol. Each military symbol in the SymbolDictionary can be searched using Keywords and/or Filters. Every symbol has a number of keywords associated with it. These could be keywords such as "Trainer", "Volcanic Eruption", "Vip" etc. All possible keywords used in the symbol dictionary can be obtained from the SymbolDictionary. Each symbol also has 3 attributes ("StyleFile", "Category" and "Geometry Type"). These attributes will have a value assigned to them. All possible attribute value combinations (known as filters) can be obtained using the SymbolDictionary. The chosen symbol identifier (SIC) can then be used to construct a new message using the MessageHelper class to aid the construction of a Message which in turn can be processed by the MessageProcessor to display the symbol on the map. Typically the results from the Keywords and Filters methods will be used to populate user interface components which allow an application user to search for symbols to place the appropriate symbol on the map, for example when making a spot report.

XAML

<UserControl x:Class="ArcGISWPFSDK.SymbolDictionarySearch"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" 
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" 
    xmlns:esri="http://schemas.esri.com/arcgis/client/2009">
    <Grid x:Name="LayoutRoot" Background="White">
        <Grid.Resources>
            <LinearGradientBrush x:Key="PanelGradient" EndPoint="0.5,1" StartPoint="0.5,0">
                <LinearGradientBrush.RelativeTransform>
                    <TransformGroup>
                        <ScaleTransform CenterY="0.5" CenterX="0.5"/>
                        <SkewTransform CenterY="0.5" CenterX="0.5"/>
                        <RotateTransform Angle="176" CenterY="0.5" CenterX="0.5"/>
                        <TranslateTransform/>
                    </TransformGroup>
                </LinearGradientBrush.RelativeTransform>
                <GradientStop Color="#FF145787" Offset="0.16"/>
                <GradientStop Color="#FF3D7FAC" Offset="0.502"/>
                <GradientStop Color="#FF88C5EF" Offset="0.984"/>
            </LinearGradientBrush>
        </Grid.Resources>

        <esri:Map x:Name="_map" UseAcceleratedDisplay="True" MouseClick="_map_MouseClick">
            <esri:ArcGISTiledMapServiceLayer ID="MyLayer" 
                Url="http://services.arcgisonline.com/ArcGIS/rest/services/Canvas/World_Light_Gray_Base/MapServer" />
            <esri:MessageGroupLayer x:Name="_messageGroupLayer" SymbolDictionaryType="Mil2525C" />
        </esri:Map>
        <Border Background="{ StaticResource PanelGradient}" BorderThickness="1" CornerRadius="5"
                HorizontalAlignment="Left"  VerticalAlignment="Top"
                Margin="5" Padding="10" BorderBrush="Gray">
        <StackPanel>
                <TextBlock FontWeight="Bold" Foreground="White">
                    Search the symbol dictionary by <LineBreak/>
                    choosing a combination of one or <LineBreak/>       
                    more keywords or filters.<LineBreak/>
                    To view symbols on the map select <LineBreak/>
                    a symbol from the results list then <LineBreak/>
                    click on the map.<LineBreak/>
                </TextBlock>
            </StackPanel>
        </Border>
        <Grid HorizontalAlignment="Right" VerticalAlignment="Top" Margin="5,5,5,5" >
            <Rectangle Fill="{StaticResource PanelGradient}" Stroke="Gray" RadiusX="10" RadiusY="10"  Margin="0,0,0,5" >
            </Rectangle>
            <Grid Height="540" Width="400">
                <Grid.RowDefinitions>
                    <RowDefinition Height="auto" />
                    <RowDefinition Height="auto"></RowDefinition>
                    <RowDefinition Height="auto"></RowDefinition>
                    <RowDefinition Height="auto"></RowDefinition>
                    <RowDefinition Height="auto"></RowDefinition>
                    <RowDefinition Height="auto"></RowDefinition>
                    <RowDefinition Height="auto"></RowDefinition>
                    <RowDefinition Height="auto"></RowDefinition>
                    <RowDefinition Height="auto"></RowDefinition>
                    <RowDefinition Height="auto"></RowDefinition>
                    <RowDefinition Height="*"></RowDefinition>
                </Grid.RowDefinitions>
                <Grid.ColumnDefinitions>
                    <ColumnDefinition Width="auto"/>
                    <ColumnDefinition/>
                </Grid.ColumnDefinitions>

                <Rectangle Fill="#FFFFFFFF" Stroke="DarkGray" RadiusX="5" RadiusY="5" Margin="5,25,5,0" 
                           Grid.ColumnSpan="2" Grid.RowSpan="3"/>

                <Rectangle Fill="#FFFFFFFF" Grid.Row="4" Stroke="DarkGray" RadiusX="5" RadiusY="5" Margin="5,0,5,0" 
                           Grid.ColumnSpan="2" Grid.RowSpan="3"/>

                <Rectangle Fill="#FFFFFFFF" Grid.Row="8" Stroke="DarkGray" RadiusX="5" RadiusY="5" Margin="5,0,5,10" 
                           Grid.ColumnSpan="2" Grid.RowSpan="3"/>

                <TextBlock Margin="5,5,10,5" Grid.ColumnSpan="2" FontWeight="Bold" HorizontalAlignment="Left" 
                           Foreground="White">Keywords:</TextBlock>

                <TextBlock Margin="10,5,10,5" HorizontalAlignment="Left" Grid.Row="1">Keyword(s):</TextBlock>
                <ComboBox Name="cmbKeyword" SelectionChanged="KeywordSelectionChanged" ItemsSource="{Binding Keywords}" 
                          Width="280" Margin="5,5,0,0" HorizontalAlignment="Left" Grid.Column="1" Grid.Row="1" />
                <ListBox Margin="10,5,10,5"  Grid.Row="2" Grid.ColumnSpan="2" Name="lstKeywords" ItemsSource="{Binding SelectedKeywords}"
                         BorderThickness="0">
                    <ListBox.ItemTemplate>
                        <DataTemplate>
                            <DockPanel LastChildFill="True">
                                <Button Height="16" Width="16" DockPanel.Dock="Right" Click="RemoveKeyword">
                                    <Image Source="/Assets/Images/remove.png"/>
                                </Button>
                                <TextBlock MinWidth="355" Margin="0,0,0,5" Text="{Binding}"></TextBlock>
                            </DockPanel>
                        </DataTemplate>
                    </ListBox.ItemTemplate>
                </ListBox>

                <TextBlock Margin="5,5,5,5" Grid.Row="3" Grid.ColumnSpan="2" FontWeight="Bold" HorizontalAlignment="Left" 
                           Foreground="White">Filters:</TextBlock>

                <TextBlock Margin="10,5,5,5"  HorizontalAlignment="Left" Grid.Row="4">StyleFile:</TextBlock>
                <ComboBox Grid.Row="4" Name="cmbStyleFile" SelectionChanged="SelectionChanged" Grid.Column="1" ItemsSource="{Binding StyleFiles}"
                          Width="280" Margin="5,5,5,5"  HorizontalAlignment="Left"/>

                <TextBlock Margin="10,0,5,5"  HorizontalAlignment="Left" Grid.Row="5">Category:</TextBlock>
                <ComboBox Name="cmbCategory" SelectionChanged="SelectionChanged"  Grid.Row="5" Grid.Column="1" ItemsSource="{Binding Categories}"
                          Width="280" Margin="5,0,5,5" HorizontalAlignment="Left"/>

                <TextBlock Margin="10,0,5,5" HorizontalAlignment="Left" Grid.Row="6">Geometry Type:</TextBlock>
                <ListBox Name="cmbGeometryType" SelectionChanged="SelectionChanged" ItemsSource="{Binding GeometryTypes}"
                          Width="280" Margin="5,0,5,5"  HorizontalAlignment="Left" Grid.Row="6" Grid.Column="1" SelectionMode="Extended" />

                <TextBlock Margin="5,5,10,5" Grid.Row="7" Grid.ColumnSpan="2" FontWeight="Bold" HorizontalAlignment="Left" 
                           Foreground="White">Symbol Results:</TextBlock>

                <TextBlock Margin="10,5,10,5"  HorizontalAlignment="Left" Grid.Row="8" Grid.Column="0">Symbols found:</TextBlock>
                <TextBlock Margin="15,5,10,5"  HorizontalAlignment="Left" Grid.Row="8" Grid.Column="1" Text="{Binding Symbols.Count}"></TextBlock>

                <ListBox x:Name="SymbolListBox" SelectionChanged="SymbolListBox_SelectionChanged" Grid.ColumnSpan="2" Margin="10,0,10,15"  Grid.Row="10" ItemsSource="{Binding Symbols}">
                    <ListBox.ItemTemplate>
                        <DataTemplate>
                            <StackPanel>
                                <TextBlock HorizontalAlignment="Left" Text="{Binding Name}"/>
                                <TextBlock HorizontalAlignment="Left" FontSize="10" Foreground="Gray" Text="{Binding Keywords}"/>
                                <Grid HorizontalAlignment="Left">
                                    <Grid.RowDefinitions>
                                        <RowDefinition Height="auto"/>
                                        <RowDefinition Height="200"/>
                                    </Grid.RowDefinitions>
                                    <Grid.ColumnDefinitions>
                                        <ColumnDefinition Width="auto"/>
                                        <ColumnDefinition Width="*"/>
                                    </Grid.ColumnDefinitions>
                                    <Image Width="{Binding ImageSize}" Height="{Binding ImageSize}" VerticalAlignment="Center" Grid.Row="1" Grid.Column="0" HorizontalAlignment="Left" Stretch="Uniform" Source="{Binding Thumbnail}"/>
                                    <Grid>
                                        <Grid.RowDefinitions>
                                            <RowDefinition Height="auto"></RowDefinition>
                                            <RowDefinition Height="auto"></RowDefinition>
                                            <RowDefinition Height="auto"></RowDefinition>
                                        </Grid.RowDefinitions>
                                        <Grid.ColumnDefinitions>
                                            <ColumnDefinition Width="auto"/>
                                            <ColumnDefinition Width="auto"/>
                                        </Grid.ColumnDefinitions>
                                        <TextBlock Grid.Row="0" Grid.Column="0" Width="100">Category:</TextBlock>
                                        <TextBlock Grid.Row="0" Grid.Column="1" Text="{Binding Category}"/>
                                        <TextBlock Grid.Row="1" Grid.Column="0">Symbol ID:</TextBlock>
                                        <TextBlock Grid.Row="1" Grid.Column="1" Text="{Binding SymbolID}"/>
                                        <TextBlock Grid.Row="2" Grid.Column="0">Stylefile:</TextBlock>
                                        <TextBlock Grid.Row="2" Grid.Column="1" Text="{Binding StyleFile}"/>
                                    </Grid>
                                </Grid>
                            </StackPanel>
                        </DataTemplate>
                    </ListBox.ItemTemplate>
                </ListBox>
            </Grid>
        </Grid>
    </Grid>
</UserControl>

C#

using System;
using System.Linq;
using System.Windows.Controls;
using System.Collections.Generic;
using System.Collections.ObjectModel;
using System.ComponentModel;
using System.Windows;
using System.Windows.Media;
using ESRI.ArcGIS.Client;
using ESRI.ArcGIS.Client.AdvancedSymbology;

namespace ArcGISWPFSDK
{
    public partial class SymbolDictionarySearch : UserControl, INotifyPropertyChanged
    {
         // The SymbolDictionary
        public static SymbolDictionary _symbolDictionary;

        // The symbol dictionary filters
        public IDictionary<string, IList<string>> Filters { get { return _symbolDictionary.Filters; } }

        // Public members for data binding
        public IEnumerable<string> Keywords { get { return new[] { "" }.Concat(_keywords.OrderBy(k => k)); } }
        public ObservableCollection<string> SelectedKeywords { get; private set; }
        public IEnumerable<string> StyleFiles { get { return new[] { "" }.Concat(_symbolDictionary.Filters["StyleFile"]); } }
        public IEnumerable<string> Categories { get { return new[] { "" }.Concat(_symbolDictionary.Filters["Category"]); } }
        public IEnumerable<string> GeometryTypes { get { return new[] { "" }.Concat(_symbolDictionary.Filters["GeometryType"]); } }
        public ObservableCollection<SymbolViewModel> Symbols { get; private set; }

        private IList<string> _keywords;

        public event PropertyChangedEventHandler PropertyChanged;

        private int _imageSize;

        // Currently selected symbol 
        SymbolViewModel _SelectedSymbol = null;

        public SymbolDictionarySearch()
        {
            // Check the ArcGIS Runtime is initialized
            if(!ArcGISRuntime.IsInitialized )
                ArcGISRuntime.Initialize();

            // Create a new SymbolDictionary instance 
            _symbolDictionary = new SymbolDictionary(SymbolDictionaryType.Mil2525C);

            // Collection of view models for the displayed list of symbols
            Symbols = new ObservableCollection<SymbolViewModel>();

            // Collection of strings to hold the selected symbol dictionary keywords
            SelectedKeywords = new ObservableCollection<string>();
            _keywords = _symbolDictionary.Keywords;

            // Set the DataContext for binding
            DataContext = this;
            
            InitializeComponent();

            // Set the image size
            _imageSize = 128;
            
            // Perform search to populate symbol browser dialog
            Search();
        }

        // Function to search the symbol dictionary based on the selected value in the style file, category and/or geometry type ListBoxes
        void Search()
        {
            Dictionary<string, string> filters = new Dictionary<string, string>();

            if (cmbStyleFile.SelectedValue != null && !cmbStyleFile.SelectedValue.Equals(""))
                filters["StyleFile"] = cmbStyleFile.SelectedValue.ToString();

            if (cmbCategory.SelectedValue != null && !cmbCategory.SelectedValue.Equals(""))
                filters["Category"] = cmbCategory.SelectedValue.ToString();

            foreach (var item in cmbGeometryType.SelectedItems)
            {
                if (item.ToString() != null && !item.ToString().Equals(""))
                    filters["GeometryType"] = item.ToString();
            }           

            // Clear the current Symbols collection
            Symbols.Clear();

            // Perform the search applying any selected keywords and filters 
            IEnumerable<SymbolProperties> symbols = _symbolDictionary.FindSymbols(SelectedKeywords, filters);
            var allSymbols = symbols.ToList();

            // Update the list of applicable keywords (excluding any keywords that are not on the current result set)
            if (SelectedKeywords == null || SelectedKeywords.Count == 0)
            {
                _keywords = _symbolDictionary.Keywords.Where(k => !IsSymbolId(k)).ToList();
            }
            else
            {
                IEnumerable<string> allSymbolKeywords = allSymbols.SelectMany(s => s.Keywords);
                _keywords = allSymbolKeywords.Distinct().Except(SelectedKeywords).Where(k => !IsSymbolId(k)).ToList();
            }
            FirePropertyChanged("Keywords");

            // Add symbols to UI collection
            foreach (var s in from symbol in allSymbols select new SymbolViewModel(symbol, _imageSize))
                Symbols.Add(s);
        }

        // Do not add keywords which represent a single symbol to the Keywords list.
        private bool IsSymbolId(string keyword)
        {
            if (keyword.Length == 15)
            {
                keyword = keyword.ToUpperInvariant();

                if (!"SGWIOE".Contains(keyword[0]))
                    return false;

                if (!"PUAFNSHGWMDLJKO-".Contains(keyword[1]))
                    return false;

                if (!"PAGSUFXTMOEVLIRNZ-".Contains(keyword[2]))
                    return false;

                if (!"APCDXF-".Contains(keyword[3]))
                    return false;

                if (Enumerable.Range(4, 6).Any(i => !"ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789-".Contains(keyword[i])))
                    return false;

                if (Enumerable.Range(10, 2).Any(i => !"ABCDEFGHIJKLMNOPQRSTUVWXYZ-*".Contains(keyword[i])))
                    return false;

                if (Enumerable.Range(12, 2).Any(i => !"ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789-*".Contains(keyword[i])))
                    return false;

                if (!"AECGNSX-".Contains(keyword[14]))
                    return false;

                return true;
            }
            return false;
        }

        // SelectedChanged event handler for the ListBoxes
        private void SelectionChanged(object sender, SelectionChangedEventArgs e)
        {
            Search();
        }

        // Remove a keyword from the selected keywords collection and rerun the search
        private void RemoveKeyword(object sender, RoutedEventArgs e)
        {
            Button b = (Button)sender;
            string kw = (string)b.DataContext;
            SelectedKeywords.Remove(kw);
            Search();
        }

        // SelectionChanged event handler for the keywords ListBox
        private void KeywordSelectionChanged(object sender, SelectionChangedEventArgs e)
        {
            if (cmbKeyword.SelectedValue == null)
                return;

            string kw = cmbKeyword.SelectedValue.ToString();
            if (kw == "")
                return;
            if (null == SelectedKeywords.FirstOrDefault(s => s == kw))
                SelectedKeywords.Add(kw);
            Search();
        }

        // Raises the PropertyChanged event (e.g. when the list of selected keywords changes).
        private void FirePropertyChanged(string name)
        {
            if (PropertyChanged != null)
                PropertyChanged(this, new PropertyChangedEventArgs(name));
        }

        // Instructs the MessageProcessor to process a new message based on the selected symbol id and the mouse click location
        private void _map_MouseClick(object sender, ESRI.ArcGIS.Client.Map.MouseEventArgs e)
        {
            if (_SelectedSymbol == null)
                return;

            //create a new message
            Message msg = new Message();
            
            //set the ID and other parts of the message
            msg.Id = Guid.NewGuid().ToString();
            msg.Add("_type", "position_report");
            msg.Add("_action", "update");
            msg.Add("_control_points", e.MapPoint.X.ToString() + "," + e.MapPoint.Y.ToString());
            msg.Add("_wkid", "3857");
            msg.Add("sic", _SelectedSymbol.SymbolID);
            msg.Add("UniqueDesignation", "1");

            //Process the message using the MessageProcessor within the MessageGroupLayer
            _messageGroupLayer.MessageProcessor.ProcessMessage(msg);
        }
   
        // Sets the currently selected symbol
        private void SymbolListBox_SelectionChanged(object sender, SelectionChangedEventArgs e)
        {
            if (e.AddedItems.Count != 1)
                return;
            if (e.AddedItems[0].GetType() != typeof(SymbolViewModel))
                return;
            _SelectedSymbol = e.AddedItems[0] as SymbolViewModel;
        }      
    }

    // Symbol view model. Primary role is to expose an image property to be used in data binding.
    public class SymbolViewModel : INotifyPropertyChanged
    {
        public string Category
        {
            get { return _model.Values["Category"].ToString(); }
        }

        public string SymbolID
        {
            get { return _model.Values["SymbolID"].ToString(); }
        }

        public string StyleFile
        {
            get { return _model.Values["StyleFile"].ToString(); }
        }

        private ImageSource _image;

        private int _imageSize;

        private SymbolProperties _model;

        public SymbolViewModel(SymbolProperties model, int imageSize)
        {
            _model = model;
            _imageSize = imageSize;
        }

        public string Name { get { return _model.Name; } }

        public int ImageSize { get { return _imageSize; } }

        public string Keywords { get { return string.Join(", ", _model.Keywords); } }

        public ImageSource Thumbnail
        {
            get
            {
                if (_image == null)
                {
                    try
                    {
                        _image = _model.GetImage(_imageSize, _imageSize);
                    }
                    catch (Exception)
                    {
                        return null;
                    }
                }
                return _image;
            }
        }

        public void InvalidateImage(int imageSize)
        {
            _imageSize = imageSize;
            if (_image != null)
            {
                _image = null;
                if (PropertyChanged != null)
                    PropertyChanged(this, new PropertyChangedEventArgs("Thumbnail"));
            }

            if (PropertyChanged != null)
                PropertyChanged(this, new PropertyChangedEventArgs("ImageSize"));
        }

        public event PropertyChangedEventHandler PropertyChanged;
    } 
}

VB.NET

Imports System.Windows.Controls
Imports System.Collections.Generic
Imports System.Linq
Imports System.Windows
Imports System.Windows.Media
Imports System.ComponentModel
Imports System.Collections.ObjectModel
Imports ESRI.ArcGIS.Client
Imports ESRI.ArcGIS.Client.AdvancedSymbology

Namespace ArcGISWPFSDK

	Partial Public Class SymbolDictionarySearch
		Inherits UserControl
		Implements INotifyPropertyChanged

		' The SymbolDictionary
		Public Shared _symbolDictionary As SymbolDictionary

		' The symbol dictionary filters
		Public ReadOnly Property Filters() As IDictionary(Of String, IList(Of String))
			Get
				Return _symbolDictionary.Filters
			End Get
		End Property

		' Public members for data binding
		Public ReadOnly Property Keywords() As IEnumerable(Of String)
			Get
				Return New String() {""}.Concat(_keywords.OrderBy(Function(k) k))
			End Get
		End Property
		Public Property SelectedKeywords() As ObservableCollection(Of String)
			Get
				Return m_SelectedKeywords
			End Get
			Private Set(value As ObservableCollection(Of String))
				m_SelectedKeywords = value
			End Set
		End Property
		Private m_SelectedKeywords As ObservableCollection(Of String)
		Public ReadOnly Property StyleFiles() As IEnumerable(Of String)
			Get
				Return New String() {""}.Concat(_symbolDictionary.Filters("StyleFile"))
			End Get
		End Property
		Public ReadOnly Property Categories() As IEnumerable(Of String)
			Get
				Return New String() {""}.Concat(_symbolDictionary.Filters("Category"))
			End Get
		End Property
		Public ReadOnly Property GeometryTypes() As IEnumerable(Of String)
			Get
				Return _symbolDictionary.Filters("GeometryType")
			End Get
		End Property
		Public Property Symbols() As ObservableCollection(Of SymbolViewModel)
			Get
				Return m_Symbols
			End Get
			Private Set(value As ObservableCollection(Of SymbolViewModel))
				m_Symbols = value
			End Set
		End Property
		Private m_Symbols As ObservableCollection(Of SymbolViewModel)

		Private _keywords As IList(Of String)

		'Public Event PropertyChanged As PropertyChangedEventHandler
		Public Event PropertyChanged(ByVal sender As Object, ByVal e As System.ComponentModel.PropertyChangedEventArgs) Implements System.ComponentModel.INotifyPropertyChanged.PropertyChanged

		Private _imageSize As Integer

		' Currently selected symbol 
		Private _SelectedSymbol As SymbolViewModel = Nothing

		Public Sub New()
			' Check the ArcGIS Runtime is initialized
			If Not ArcGISRuntime.IsInitialized Then
				ArcGISRuntime.Initialize()
			End If

			' Create a new SymbolDictionary instance 
			_symbolDictionary = New SymbolDictionary(SymbolDictionaryType.Mil2525C)

			' Collection of view models for the displayed list of symbols
			Symbols = New ObservableCollection(Of SymbolViewModel)()

			' Collection of strings to hold the selected symbol dictionary keywords
			SelectedKeywords = New ObservableCollection(Of String)()
			_keywords = _symbolDictionary.Keywords

			' Set the DataContext for binding
			DataContext = Me

			InitializeComponent()

			' Set the image size 
			_imageSize = 128

			' Perform search to populate symbol browser dialog
			Search()
		End Sub

		' Function to search the symbol dictionary based on the selected value in the style file, category and/or geometry type ListBoxes
		Private Sub Search()
			Dim filters As New Dictionary(Of String, String)()

			If cmbStyleFile.SelectedValue IsNot Nothing AndAlso Not cmbStyleFile.SelectedValue.Equals("") Then
				filters("StyleFile") = cmbStyleFile.SelectedValue.ToString()
			End If

			If cmbCategory.SelectedValue IsNot Nothing AndAlso Not cmbCategory.SelectedValue.Equals("") Then
				filters("Category") = cmbCategory.SelectedValue.ToString()
			End If

			For Each item As String In cmbGeometryType.SelectedItems
				If item.ToString() IsNot Nothing AndAlso Not item.ToString().Equals("") Then
					filters("GeometryType") = item.ToString()
				End If
			Next

			' Clear the current Symbols collection
			Symbols.Clear()

			' Perform the search applying any selected keywords and filters 
			Dim symbolResults As IEnumerable(Of SymbolProperties) = _symbolDictionary.FindSymbols(SelectedKeywords, filters)
			Dim allSymbols As New List(Of SymbolProperties)
			allSymbols = symbolResults.ToList()

			' Update the list of applicable keywords (excluding any keywords that are not on the current result set)
			If SelectedKeywords Is Nothing OrElse SelectedKeywords.Count = 0 Then
				_keywords = _symbolDictionary.Keywords.Where(Function(k) Not IsSymbolId(k)).ToList()
			Else
				Dim allSymbolKeywords As IEnumerable(Of String) = allSymbols.SelectMany(Function(s) s.Keywords)
				_keywords = allSymbolKeywords.Distinct().Except(SelectedKeywords).Where(Function(k) Not IsSymbolId(k)).ToList()
			End If
			FirePropertyChanged("Keywords")

			' Add symbols to UI collection
			For Each s As SymbolViewModel In From symbol In allSymbols Select New SymbolViewModel(symbol, _imageSize)
				Symbols.Add(s)
			Next
		End Sub

		' Do not add keywords which represent a single symbol to the Keywords list.
		Private Function IsSymbolId(keyword As String) As Boolean
			If keyword.Length = 15 Then
				keyword = keyword.ToUpperInvariant()

				If Not "SGWIOE".Contains(keyword(0)) Then
					Return False
				End If

				If Not "PUAFNSHGWMDLJKO-".Contains(keyword(1)) Then
					Return False
				End If

				If Not "PAGSUFXTMOEVLIRNZ-".Contains(keyword(2)) Then
					Return False
				End If

				If Not "APCDXF-".Contains(keyword(3)) Then
					Return False
				End If

				If Enumerable.Range(4, 6).Any(Function(i) Not "ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789-".Contains(keyword(i))) Then
					Return False
				End If

				If Enumerable.Range(10, 2).Any(Function(i) Not "ABCDEFGHIJKLMNOPQRSTUVWXYZ-*".Contains(keyword(i))) Then
					Return False
				End If

				If Enumerable.Range(12, 2).Any(Function(i) Not "ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789-*".Contains(keyword(i))) Then
					Return False
				End If

				If Not "AECGNSX-".Contains(keyword(14)) Then
					Return False
				End If

				Return True
			End If
			Return False
		End Function

		' SelectedChanged event handler for the ListBoxes
		Private Sub SelectionChanged(sender As Object, e As SelectionChangedEventArgs)
			Search()
		End Sub

		' Remove a keyword from the selected keywords collection and rerun the search
		Private Sub RemoveKeyword(sender As Object, e As RoutedEventArgs)
			Dim b As Button = DirectCast(sender, Button)
			Dim kw As String = DirectCast(b.DataContext, String)
			SelectedKeywords.Remove(kw)
			Search()
		End Sub

		' SelectionChanged event handler for the keywords ListBox
		Private Sub KeywordSelectionChanged(sender As Object, e As SelectionChangedEventArgs)
			If cmbKeyword.SelectedValue Is Nothing Then
				Return
			End If

			Dim kw As String = cmbKeyword.SelectedValue.ToString()
			If kw = "" Then
				Return
			End If
			If SelectedKeywords.FirstOrDefault(Function(s) s = kw) Is Nothing Then
				SelectedKeywords.Add(kw)
			End If
			Search()
		End Sub

		' Raises the PropertyChanged event (e.g. when the list of selected keywords changes).
		Private Sub FirePropertyChanged(name As String)
			RaiseEvent PropertyChanged(Me, New PropertyChangedEventArgs(name))
		End Sub

		' Instructs the MessageProcessor to process a new message based on the selected symbol id and the mouse click location
		Private Sub _map_MouseClick(sender As Object, e As ESRI.ArcGIS.Client.Map.MouseEventArgs)
			If _SelectedSymbol Is Nothing Then
				Return
			End If

			'create a new message
			Dim msg As New Message()

			'set the ID and other parts of the message
			msg.Id = Guid.NewGuid().ToString()
			msg.Add("_type", "position_report")
			msg.Add("_action", "update")
			msg.Add("_control_points", e.MapPoint.X.ToString() & "," & e.MapPoint.Y.ToString())
			msg.Add("_wkid", "3857")
			msg.Add("sic", _SelectedSymbol.SymbolID)
			msg.Add("UniqueDesignation", "1")

			'Process the message using the MessageProcessor within the MessageGroupLayer
			_messageGroupLayer.MessageProcessor.ProcessMessage(msg)
		End Sub

		' Sets the currently selected symbol
		Private Sub SymbolListBox_SelectionChanged(sender As Object, e As SelectionChangedEventArgs)
			If e.AddedItems.Count <> 1 Then
				Return
			End If
			If e.AddedItems(0).[GetType]() IsNot GetType(SymbolViewModel) Then
				Return
			End If
			_SelectedSymbol = TryCast(e.AddedItems(0), SymbolViewModel)
		End Sub

	End Class

	' Symbol view model. Primary role is to expose an image property to be used in data binding.
	Public Class SymbolViewModel

		Implements INotifyPropertyChanged

		Public ReadOnly Property Category() As String
			Get
				Return _model.Values("Category").ToString()
			End Get
		End Property

		Public ReadOnly Property SymbolID() As String
			Get
				Return _model.Values("SymbolID").ToString()
			End Get
		End Property

		Public ReadOnly Property StyleFile() As String
			Get
				Return _model.Values("StyleFile").ToString()
			End Get
		End Property

		Private _image As ImageSource

		Private _imageSize As Integer

		Private _model As SymbolProperties

		Public Sub New(model As SymbolProperties, imageSize As Integer)
			_model = model
			_imageSize = imageSize
		End Sub

		Public ReadOnly Property Name() As String
			Get
				Return _model.Name
			End Get
		End Property

		Public ReadOnly Property ImageSize() As Integer
			Get
				Return _imageSize
			End Get
		End Property

		Public ReadOnly Property Keywords() As String
			Get
				Return String.Join(", ", _model.Keywords)
			End Get
		End Property

		Public ReadOnly Property Thumbnail() As ImageSource
			Get
				If _image Is Nothing Then
					Try
						_image = _model.GetImage(_imageSize, _imageSize)
					Catch generatedExceptionName As Exception
						Return Nothing
					End Try
				End If
				Return _image
			End Get
		End Property

		Public Sub InvalidateImage(imageSize As Integer)
			_imageSize = imageSize
			If _image IsNot Nothing Then
				_image = Nothing
				FirePropertyChanged("Thumbnail")
			End If
			FirePropertyChanged("ImageSize")
		End Sub

		Private Sub FirePropertyChanged(name As String)
			RaiseEvent PropertyChanged(Me, New PropertyChangedEventArgs(name))
		End Sub

		Public Event PropertyChanged(ByVal sender As Object, ByVal e As System.ComponentModel.PropertyChangedEventArgs) Implements System.ComponentModel.INotifyPropertyChanged.PropertyChanged

	End Class

End Namespace