Visually Located


Managing Extents within the ArcGIS WPF/Silverlight/etc. APIs

Managing extents within the ArcGIS .Net client API’s is pretty simple. Esri has an example on the resources page. I implemented one for the ArcFM Silverlight SDK sample. Oddly enough, they are quite similar. I don’t remember copying theirs, but you never know. Like most things we as developers do, after a couple of years you look back and wonder “What was I thinking?” I look back at my original code and wonder why did I implement the Extents class the way that I did. I originally used one List to hold all of the Extents. This made some of the code pretty ugly. I’ve created a different implementation that utilizes two stacks. I have one class that manages all of the extents:

   1: public class Extents
   2: {
   3:     private readonly Stack<Envelope> _backStack = new Stack<Envelope>();
   4:     private readonly Stack<Envelope> _forwardStack = new Stack<Envelope>();
   6:     public bool HasPreviousExtent
   7:     {
   8:         get { return _backStack.Count > 0; }
   9:     }
  11:     public bool HasNextExtent
  12:     {
  13:         get { return _forwardStack.Count > 0; }
  14:     }
  16:     public Envelope CurrentExtent { get; set; }
  18:     public Envelope PreviousExtent
  19:     {
  20:         get
  21:         {
  22:             if (HasPreviousExtent)
  23:             {
  24:                 _forwardStack.Push(CurrentExtent);
  25:                 CurrentExtent = _backStack.Pop();
  26:                 return CurrentExtent;
  27:             }
  28:             return null;
  29:         }
  30:     }
  32:     public Envelope NextExtent
  33:     {
  34:         get
  35:         {
  36:             if (HasNextExtent)
  37:             {
  38:                 _backStack.Push(CurrentExtent);
  39:                 CurrentExtent = _forwardStack.Pop();
  40:                 return CurrentExtent;
  41:             }
  42:             return null;
  43:         }
  44:     }
  46:     public void Add(Envelope extent)
  47:     {
  48:         if (extent == null) return;
  50:         if (CurrentExtent != null)
  51:         {
  52:             _backStack.Push(CurrentExtent);
  53:         }
  54:         CurrentExtent = extent;
  56:         // If a new extent is added, then anything in our forward stack needs to be removed
  57:         _forwardStack.Clear();
  58:     }
  59: }

I’m a big fan of MVVM, so I’ll use a ViewModel to access the Extents. I’ll also be using the DelegateCommand from Microsoft.

   1: public class ViewModel
   2: {
   3:     public ViewModel()
   4:     {
   5:         Extents = new Extents();
   6:         PreviousExtent = new DelegateCommand(MovePreviousExtent, extent => Extents.HasPreviousExtent);
   7:         NextExtent = new DelegateCommand(MoveNextExtent, extent => Extents.HasNextExtent);
   8:         IsNewExtent = true;
   9:     }
  11:     private Map _map;
  13:     public Map Map
  14:     {
  15:         get { return _map; }
  16:         set
  17:         {
  18:             UnsubscribeMapEvents(_map);
  19:             SubscribeMapEvents(value);
  20:             _map = value; 
  21:         }
  22:     }
  24:     public DelegateCommand PreviousExtent { get; private set; }
  25:     public DelegateCommand NextExtent { get; private set; }
  27:     private bool IsNewExtent { get; set; }
  28:     private Extents Extents { get; set; }
  30:     private void MovePreviousExtent(object obj)
  31:     {
  32:         // This extent should not be put onto the Extents stack.
  33:         IsNewExtent = false;
  34:         Map.ZoomTo(Extents.PreviousExtent);
  35:     }
  37:     private void MoveNextExtent(object obj)
  38:     {
  39:         // This extent should not be put onto the Extents stack.
  40:         IsNewExtent = false;
  41:         Map.ZoomTo(Extents.NextExtent);
  42:     }
  44:     private void UnsubscribeMapEvents(Map map)
  45:     {
  46:         if (map == null) return;
  47:         map.ExtentChanged -= Map_ExtentChanged;
  48:     }
  50:     private void SubscribeMapEvents(Map map)
  51:     {
  52:         if (map == null) return;
  53:         map.ExtentChanged += Map_ExtentChanged;
  54:     }
  56:     private void Map_ExtentChanged(object sender, ExtentEventArgs e)
  57:     {
  58:         // Only add the extent if it is "new" ie: Not a Previous or Next extent
  59:         if (IsNewExtent)
  60:         {
  61:             Extents.Add(e.NewExtent);
  62:         }
  63:         IsNewExtent = true;
  64:         PreviousExtent.RaiseCanExecuteChanged();
  65:         NextExtent.RaiseCanExecuteChanged();
  66:     }
  67: }

The joy of these classes is that they can be used within all of the .Net Client API’s! This can even be used within the new ArcGIS Runtime (currently in Beta). Using these within our application is now a breeze! Here is the xaml for a WPF Window

   1: <Window x:Class="ExtentNavigationApp.MainWindow"
   2:         xmlns=""
   3:         xmlns:x="" 
   4:         xmlns:esri=""
   5:         Title="MainWindow" Height="350" Width="525">
   6:     <Grid x:Name="LayoutRoot" Background="White">
   7:         <esri:Map x:Name="Map" >
   8:             <esri:ArcGISTiledMapServiceLayer Url=""/>
   9:             <esri:ArcGISTiledMapServiceLayer Url=""/>
  10:         </esri:Map>
  11:         <StackPanel Orientation="Horizontal" VerticalAlignment="Top">
  12:             <Button Content="Previous Extent" Command="{Binding PreviousExtent}" Height="25" Width="100"/>
  13:             <Button Content="Next Extent" Command="{Binding NextExtent}" Height="25" Width="100"/>
  14:         </StackPanel>
  15:     </Grid>
  16: </Window>

And the code behind:

   1: public partial class MainWindow : Window
   2: {
   3:     public MainWindow()
   4:     {
   5:         InitializeComponent();
   6:         DataContext = new ViewModel() { Map = Map };
   7:     }
   8: }

Creating a Custom MessageBox for Windows Phone Applications

UPDATE: See a new post to get the latest code for the custom MessageBox.

UPDATE: After posting this blog I found out about the message box within the XNA framework. This does allow for custom button text which is what I was trying to accomplish. However, the user experience is different than what you get from the message boxes within the native phone applications (eg: deleting a text). With the native message boxes, the application bar disappears, but with the XNA message box, it gets greyed out. It’s the little things that matter. Also within the XNA framework you cannot add additional components to the message box. For example, you might want to add a “Do not show me this again” option within the message box.

While using a Windows Phone you get prompted every once in awhile by a message box. Custom Applications have them, even apps native to the phone has them. When deleting a text message or a contact you get a nice prompt asking you if you want to delete it. But there is something unique about these message boxes that separates them from the one that you and I get to have. The standard message box only allows for an “OK” and a “Cancel” button. The message boxes that are native to the phone have custom text. When you delete a text, you are prompted with buttons “delete” and “cancel”. Seeing as there is not a way to do this, you need to create your own. I’ve created a very simple sample that can be used.

The CustomMessageBox sample is based on the assumption that message boxes are “binary”. What I mean is that you get binary options, Yes/No, OK/Cancel, etc. So I’ve limited what is allowed to be a valid result.

 1: public enum CustomMessageBoxResult
 2: {
 3:     Yes, 
 4:     No,
 5:     // Not using this yet, but you could wire up to the back button of the phone to be a cancel
 6:     Cancel
 7: }

I don’t have the ability to have a Show method return the CustomMessageBoxResult so I’ll need an EventArg that will be used within an event.

 1: public class MessageBoxEventArgs : EventArgs
 2: {
 3:     public CustomMessageBoxResult Result { get; set; }
 4: }

The xaml is pretty straight forward. We need to "”block” the page the CustomMessageBox is for. To do this I made the control a grid so it will fill up everything. Then give it a background with an opacity that will block all clicks.

<Grid x:Class="Visual.Controls.MessageBox"
        <SolidColorBrush Color="{StaticResource PhoneBackgroundColor}" Opacity=".5"/>
    <Grid x:Name="MessagePanel" Background="{StaticResource PhoneChromeBrush}"
          VerticalAlignment="Top" HorizontalAlignment="Stretch"
        <StackPanel Margin="12,12,12,18">
            <TextBlock x:Name="HeaderTextBlock" TextWrapping="Wrap"
                       Style="{StaticResource PhoneTextLargeStyle}"
                       FontFamily="{StaticResource PhoneFontFamilySemiBold}"
            <TextBlock x:Name="MessageTextBlock" TextWrapping="Wrap"
                       Style="{StaticResource PhoneTextNormalStyle}"
                       FontSize="{StaticResource PhoneFontSizeMedium}"
            <Grid HorizontalAlignment="Stretch" Margin="0,6,0,0">
                    <ColumnDefinition Width="*"/>
                    <ColumnDefinition Width="*"/>
                <Button x:Name="YesButton" Click="YesButton_Click"/>
                <Button x:Name="NoButton" Grid.Column="1" Click="NoButton_Click"/>

The message box has really one basic function, to ask the user a question. To accomplish that one function, we need to do three things.

  1. The message box must be put into the application. (Show method)
  2. When the user answers the question, the message box needs to be removed from the application. (Remove method)
  3. The message box needs to tell the application what the user picked. (Closed event)
using System;
using System.ComponentModel;
using System.Windows;
using System.Windows.Controls;
using Microsoft.Phone.Controls;
namespace Visual.Controls
    public partial class MessageBox : Grid
        private PhoneApplicationPage _page;
        private MessageBox()
        public event EventHandler<MessageBoxEventArgs> Closed;
        protected virtual void OnClosed(MessageBoxResult result)
            // need to unsubscribe from the backkeypress
            _page.BackKeyPress -= Page_BackKeyPress;
            var handler = this.Closed;
            if (handler != null)
                handler(this, new MessageBoxEventArgs { Result = result });
        public static MessageBox Show(string message, string caption, string yesButtonText, string noButtonText = null)
            MessageBox msgBox = new MessageBox();
            msgBox.HeaderTextBlock.Text = caption;
            msgBox.MessageTextBlock.Text = message;
            msgBox.YesButton.Content = yesButtonText;
            if (string.IsNullOrWhiteSpace(noButtonText))
                msgBox.NoButton.Visibility = Visibility.Collapsed;
                msgBox.NoButton.Content = noButtonText;
            return msgBox;
        private void Insert()
            // Make an assumption that this is within a phone application that is developed "normally"
            var frame = Application.Current.RootVisual as Microsoft.Phone.Controls.PhoneApplicationFrame;
            _page = frame.Content as PhoneApplicationPage;
            _page.BackKeyPress += Page_BackKeyPress;
            // assume the child is a Grid, span all of the rows
            var grid = System.Windows.Media.VisualTreeHelper.GetChild(_page, 0) as Grid;
            if (grid.RowDefinitions.Count > 0)
                Grid.SetRowSpan(this, grid.RowDefinitions.Count);
            // Create a transition like the regular MessageBox
            SwivelTransition transitionIn = new SwivelTransition();
            transitionIn.Mode = SwivelTransitionMode.BackwardIn;
            // Transition only the MessagePanel
            ITransition transition = transitionIn.GetTransition(MessagePanel);
            transition.Completed += (s, e) => transition.Stop();
            if (_page.ApplicationBar != null)
                // Hide the app bar so they cannot open more message boxes
                _page.ApplicationBar.IsVisible = false;
        private void Remove()
            var frame = Application.Current.RootVisual as Microsoft.Phone.Controls.PhoneApplicationFrame;
            var page = frame.Content as PhoneApplicationPage;
            var grid = System.Windows.Media.VisualTreeHelper.GetChild(page, 0) as Grid;
            // Create a transition like the regular MessageBox
            SwivelTransition transitionOut = new SwivelTransition();
            transitionOut.Mode = SwivelTransitionMode.BackwardOut;
            ITransition transition = transitionOut.GetTransition(MessagePanel);
            transition.Completed += (s, e) =>
                    if (page.ApplicationBar != null)
                        page.ApplicationBar.IsVisible = true;
        private void Page_BackKeyPress(object sender, CancelEventArgs e)
            e.Cancel = true;
        private void YesButton_Click(object sender, RoutedEventArgs e)
        private void NoButton_Click(object sender, RoutedEventArgs e)

Now you can show your message box like such:

 1: var msgBox = CustomMessageBox.Show("Do you like Windows Phone.", "Custom Prompt", "I <3 WP", "No Thanks");

And you get the following:


Improving the User Experience (with Silverlight 5)

In case you were unable to see my lighting talk I gave at this years Esri Dev Meetup, here’s your chance!

It’s hard to see the slides in the video of my presentation, so you’ll have to sync up the video with my slides.

Devmeetup Colorado Shawn Kendrot from glenn letham on Vimeo.

The talk was a lot of fun and I look forward to doing another. Maybe at the next Ignite Spatial?

Using the Silverlight 5 PivotViewer with ArcGIS Silverlight

Pivot was originally released as a demonstration project that was a separate download from Silverlight itself. At version 5, Pivot becomes part of the Silverlight family. Pivot allows users the ability to visualize their data. Puts the power of filtering and grouping their data without the need to learn complex SQL statements. The original version of Pivot required you to have an XML representation of the data, and images that it would display. This required extra work for the developer, or web administrator to create this data from their data store. With Silverlight 5, you now have the ability to bind to any property that your class has. It also allows you the ability to create what’s known as trading cards with XAML. These cards replace the images you previously needed. You can even define at what stage you want a trading card to display. By defining different trading cards at different levels, you can give the user more information the more they filter down their data.

When I first started looking into whether I’d be able to get PivotViewer results from ArcGIS Server, I figured I would have to create a Silverlight class with properties for all of the fields that I wanted to use within Pivot. It turns out that Pivot works great with the data you get straight from the ArcGIS or ArcFM Silverlight SDK. It easily binds to the Attributes Dictionary that is on the Graphics objects.

To get started using Pivot, you need to download the latest Silverlight 5 Tools. Create a new Silverlight Application. Make sure to pick Silverlight 5 as the version


You’ll need to add a reference to ESRI.ArcGIS.Client and System.Windows.Controls.Pivot. To add the ArcGIS Silverlight SDK, open the Add Reference dialog, and click the Browse tab. Browse to the location of ESRI.ArcGIS.Client assembly. The default location is C:\Program Files (x86)\ESRI SDKs\Silverlight.

Open MainPage.xaml.cs. We’re going to need to create a query to the ArcGIS Server. For my example, I’m going to use the Telvent ArcGIS Server at First, we need to query for the electrical switches that we’ll use within Pivot

public MainPage()


private void QueryForSwitches()
    // Query for switches. Switches have LayerID of 3 
QueryTask task = new QueryTask(""); Query query = new Query(); // Return all of the fields, we want use them all, but good to have 'em anyways! query.OutFields.Add("*"); // Get as many of the switches as we can
query.Where = "ObjectID > 0"; task.ExecuteCompleted += QueryTask_ExecuteCompleted; task.ExecuteAsync(query); }

Add a call to this method within the constructor of the MainPage. When the task completes, all we need to do is set the DataContext to the Features that are returned.

void QueryTask_ExecuteCompleted(object sender, QueryEventArgs e)
    DataContext = e.FeatureSet.Features;

The XAML is where all of the magic happens. We are able to pick which fields the user will be able to filter/sort by, and define the trading cards. I want to give the user the ability to sort and filter switches by Installation Date, the Phase Designation, which Feeder it belongs to, and the Operating Voltage. So the fields I need from the Attributes dictionary are INSTALLATIONDATE, PHASEDESIGNATION, FEEDERID, and OPERATINGVOLTAGE. To do this, you add PivotViewerProperties.

<UserControl x:Class="PivotViewer.MainPage"
    <Grid x:Name="LayoutRoot" Background="White">
            <ViewModels:PhaseDesignationValueConverter x:Key="PhaseConverter"/>
            <ViewModels:VoltageToStringValueConverter x:Key="VoltageConverter"/>            
        <sdk:PivotViewer x:Name="MyPivot" ItemsSource="{Binding}">
            <!-- Setting PivotProperties -->
                <sdk:PivotViewerDateTimeProperty Id="InstallDate" Options="CanFilter" DisplayName="Date Installed" 
Binding="{Binding Attributes[INSTALLATIONDATE], StringFormat=\{0:MM/dd/yyyy\}}" /> <sdk:PivotViewerStringProperty Id="Phase" Options="CanFilter" DisplayName="Phase"
Binding="{Binding Attributes[PHASEDESIGNATION], Converter={StaticResource PhaseConverter}}" /> <sdk:PivotViewerStringProperty Id="Feeder" Options="CanFilter" DisplayName="Feeder"
Binding="{Binding Attributes[FEEDERID]}" /> <sdk:PivotViewerStringProperty Id="OpVoltage" Options="CanFilter" DisplayName="Operating Voltage"
Binding="{Binding Attributes[OPERATINGVOLTAGE], Converter={StaticResource VoltageConverter}}" /> </sdk:PivotViewer.PivotProperties> </sdk:PivotViewer> </Grid> </UserControl>

I’m using fields that have domain values, so I need a few value converters, I won’t bore you with the conversion of the domains here. If you need to sort/filter by date values, like the Installation Date, use a PivotViewerDateTimeProperty This gives you cool date filtering capabilities. I don’t have any integer values that I’m sorting by, but if I did I would use the PivotViewerNumericProperty. To create a trading card, add a PivotViewerItemTemplate to the ItemTemplates collection.

        <Border Width="200" Height="200" Background="Gray" BorderBrush="Black" BorderThickness="1">
            <StackPanel Orientation="Vertical">
                <TextBlock Text="{Binding Attributes[FACILITYID]}" FontSize="24" Foreground="White" />
                <StackPanel Margin="10,0">
                    <TextBlock Text="Feeder" Foreground="White" FontSize="18" Margin="0,10,0,0"/>
                    <TextBlock Text="{Binding Attributes[FEEDERID]}" FontSize="14" Foreground="White" />

                    <TextBlock Text="Voltage" Foreground="White" FontSize="18" Margin="0,10,0,0"/>
                    <TextBlock Text="{Binding Attributes[OPERATINGVOLTAGE], 
Converter={StaticResource VoltageConverter}}"
FontSize="14" Foreground="White" /> <TextBlock Text="Installed" Foreground="White" FontSize="18" Margin="0,10,0,0"/> <TextBlock Text="{Binding Attributes[INSTALLATIONDATE], StringFormat=\{0:MM/dd/yyyy\}}"
FontSize="14" Foreground="White" /> </StackPanel> </StackPanel> </Border> </sdk:PivotViewerItemTemplate> </sdk:PivotViewer.ItemTemplates>

This gives our trading card a Metro feel. But there isn’t much data here, as the user drills further into their data, I want to show them more. We can add more trading cards if we want to add more detail when users start filtering their data, or using the zoom capability of Pivot. To do this you set the MaxWidth property of the PivotViewerItemTemplate, and add another template.

<sdk:PivotViewerItemTemplate MaxWidth="250">

To see more, download the complete sample here. Give your users the power to SEE their data.