Show Map Extent Online

This sample includes a Map and a ArcGISTiledMapServiceLayer and demonstrates how to handle extent changing and changed events on the map. Both events share the same event handler in code behind. The extent parameters of the map are displayed in a textblock as they change at runtime. Since the Map is in wrap-around mode, absolute values represent the map extent on an infinite continuous grid where values on the X axis increase or decrease as you pan. Normalized values represent the map extent in the real-world and take the dateline (or current central meridian) into account.

XAML

<UserControl x:Class="ArcGISWPFSDK.MapExtent"
    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">
        <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="MyMap" WrapAround="True" ExtentChanged="MyMap_ExtentChanged" ExtentChanging="MyMap_ExtentChanged">
            <esri:ArcGISTiledMapServiceLayer ID="StreetMapLayer" 
                Url="http://services.arcgisonline.com/ArcGIS/rest/services/World_Street_Map/MapServer" />
        </esri:Map>

        <Grid  HorizontalAlignment="Right" VerticalAlignment="Top" Margin="0,15,15,0" >

            <Rectangle Fill="{StaticResource PanelGradient}" Stroke="Gray"  RadiusX="10" RadiusY="10" Margin="0,0,0,5">
                <Rectangle.Effect>
                    <DropShadowEffect/>
                </Rectangle.Effect>
            </Rectangle>
            <Rectangle Fill="#DDFFFFFF" Stroke="DarkGray" RadiusX="5" RadiusY="5" Margin="10,10,10,15" />
            <StackPanel Orientation="Vertical" Margin="25">
                <StackPanel.Resources>
                    <Style TargetType="TextBlock">
                        <Setter Property="FontWeight" Value="Bold"/>
                        <Setter Property="FontSize" Value="11" />
                    </Style>
                </StackPanel.Resources>
                <TextBlock Foreground="Black">
          <Run FontStyle="Italic">Absolute</Run>
          <LineBreak />
          <Run>MinX: </Run>
          <Run Text="{Binding ElementName=MyMap, Path=Extent.XMin, StringFormat=\{0:F3\}}" />
          <LineBreak />

          <Run>MinY: </Run>
          <Run Text="{Binding ElementName=MyMap, Path=Extent.YMin, StringFormat=\{0:F3\}}" />
          <LineBreak />

          <Run>MaxX: </Run>
          <Run Text="{Binding ElementName=MyMap, Path=Extent.XMax, StringFormat=\{0:F3\}}" />
          <LineBreak />

          <Run>MaxY: </Run>
          <Run Text="{Binding ElementName=MyMap, Path=Extent.YMax, StringFormat=\{0:F3\}}" />
               
          <LineBreak />
          <LineBreak />
          <Run FontStyle="Italic">Normalized</Run>
          <LineBreak />
          <Run>Left X: </Run>
          <Run x:Name="MinXNormalized" />
          <LineBreak />
          <Run>Bottom Y: </Run>
          <Run x:Name="MinYNormalized"/>
          <LineBreak />
          <Run>Right X: </Run>
          <Run x:Name="MaxXNormalized"/>
          <LineBreak />
          <Run>Top Y: </Run>
          <Run x:Name="MaxYNormalized"/>
                </TextBlock>
            </StackPanel>
        </Grid>

    </Grid>
</UserControl>

C#

using System.Windows.Controls;
using ESRI.ArcGIS.Client.Geometry;

namespace ArcGISWPFSDK
{
    public partial class MapExtent : UserControl
    {
        public MapExtent()
        {
            InitializeComponent();
        }
        private void MyMap_ExtentChanged(object sender, ESRI.ArcGIS.Client.ExtentEventArgs e)
        {
            Envelope newExtent = null;

            if (MyMap.WrapAroundIsActive)
            {
                Geometry normalizedExtent = Geometry.NormalizeCentralMeridian(e.NewExtent);
                if (normalizedExtent is Polygon)
                {
                    newExtent = new Envelope();

                    foreach (MapPoint p in (normalizedExtent as Polygon).Rings[0])
                    {
                        if (p.X < newExtent.XMin || double.IsNaN(newExtent.XMin))
                            newExtent.XMin = p.X;
                        if (p.Y < newExtent.YMin || double.IsNaN(newExtent.YMin))
                            newExtent.YMin = p.Y;
                    }

                    foreach (MapPoint p in (normalizedExtent as Polygon).Rings[1])
                    {
                        if (p.X > newExtent.XMax || double.IsNaN(newExtent.XMax))
                            newExtent.XMax = p.X;
                        if (p.Y > newExtent.YMax || double.IsNaN(newExtent.YMax))
                            newExtent.YMax = p.Y;
                    }
                }
                else if (normalizedExtent is Envelope)
                    newExtent = normalizedExtent as Envelope;
            }
            else
                newExtent = e.NewExtent;

            MinXNormalized.Text = newExtent.XMin.ToString("0.000");
            MinYNormalized.Text = newExtent.YMin.ToString("0.000");
            MaxXNormalized.Text = newExtent.XMax.ToString("0.000");
            MaxYNormalized.Text = newExtent.YMax.ToString("0.000");
        }
    }
}

VB.NET

Imports System.Windows.Controls
Imports ESRI.ArcGIS.Client.Geometry

Namespace ArcGISWPFSDK
    Partial Public Class MapExtent
        Inherits UserControl
        Public Sub New()
            InitializeComponent()
        End Sub
        Private Sub MyMap_ExtentChanged(sender As Object, e As ESRI.ArcGIS.Client.ExtentEventArgs)
            Dim newExtent As Envelope = Nothing

            If MyMap.WrapAroundIsActive Then
                Dim normalizedExtent As Geometry = Geometry.NormalizeCentralMeridian(e.NewExtent)
                If TypeOf normalizedExtent Is Polygon Then
                    newExtent = New Envelope()

                    For Each p As MapPoint In TryCast(normalizedExtent, Polygon).Rings(0)
                        If p.X < newExtent.XMin OrElse Double.IsNaN(newExtent.XMin) Then
                            newExtent.XMin = p.X
                        End If
                        If p.Y < newExtent.YMin OrElse Double.IsNaN(newExtent.YMin) Then
                            newExtent.YMin = p.Y
                        End If
                    Next

                    For Each p As MapPoint In TryCast(normalizedExtent, Polygon).Rings(1)
                        If p.X > newExtent.XMax OrElse Double.IsNaN(newExtent.XMax) Then
                            newExtent.XMax = p.X
                        End If
                        If p.Y > newExtent.YMax OrElse Double.IsNaN(newExtent.YMax) Then
                            newExtent.YMax = p.Y
                        End If
                    Next
                ElseIf TypeOf normalizedExtent Is Envelope Then
                    newExtent = TryCast(normalizedExtent, Envelope)
                End If
            Else
                newExtent = e.NewExtent
            End If

            MinXNormalized.Text = newExtent.XMin.ToString("0.000")
            MinYNormalized.Text = newExtent.YMin.ToString("0.000")
            MaxXNormalized.Text = newExtent.XMax.ToString("0.000")
            MaxYNormalized.Text = newExtent.YMax.ToString("0.000")
        End Sub
    End Class
End Namespace