Moving Objects

This sample demonstrates an approach to displaying real time feeds of data on the map. The objects in this example are exposed as a Satellites class which implements IEnumerable<Graphic>. This means the class can act as the collection of Graphics contained by the GraphicsLayer via data binding. The Satellites class also exposes two properties: number of satellites; and update speed. These properties provide the items content for the two ComboBoxes on the UI again via data binding and propagate any changes on the UI down to the Satellites class.

XAML

<UserControl x:Class="ArcGISWPFSDK.MovingObjects"
             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"
             xmlns:local="clr-namespace:ArcGISWPFSDK">
    <Grid x:Name="LayoutRoot">
        <Grid.Resources>

            <local:Satellites x:Key="satellites" />

            <esri:PictureMarkerSymbol x:Key="SatellitePictureMarkerSymbol" Source="/Assets/Images/Satellite64.png" Width="24" Height="24"/>
            <esri:SimpleRenderer x:Key="SatelliteSimpleRenderer" Symbol="{StaticResource SatellitePictureMarkerSymbol}"/>

            <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>

            <Style x:Key="ComboStyle" TargetType="{x:Type ComboBox}">
                <Setter Property="HorizontalContentAlignment" Value="Right" />
                <Setter Property="VerticalContentAlignment" Value="Center"/>
            </Style>

        </Grid.Resources>
        <esri:Map x:Name="_map" UseAcceleratedDisplay="True" WrapAround="True">
            <!-- ArcGIS Online Tiled Basemap Layer -->
            <esri:ArcGISTiledMapServiceLayer ID="World Topo Map" 
                       Url="http://services.arcgisonline.com/ArcGIS/rest/services/World_Topo_Map/MapServer"/>

            <esri:GraphicsLayer ID="MyGraphicsLayer" 
                                GraphicsSource="{StaticResource satellites}" Renderer="{StaticResource SatelliteSimpleRenderer}"/>
        </esri:Map>

        <Grid HorizontalAlignment="Left" VerticalAlignment="Top" Margin="15,15,15,0" Width="275">
            <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="5,5,5,10" />
            <StackPanel Orientation="Vertical" Margin="10,10,10,10" HorizontalAlignment="Left" >
                <TextBlock Text="Use the options below to change the number of satellites and the update speed of the satellites." 
                           TextWrapping="Wrap" HorizontalAlignment="Center" Foreground="Black" Margin="5,0,5,0"/>
                <StackPanel Orientation="Horizontal" Margin="5,0,5,0" HorizontalAlignment="Left" >
                    <TextBlock Text="Number of Satellites:" Width="155" VerticalAlignment="Stretch" Foreground="Black" Margin="5,5,5,0"/>
                    <ComboBox x:Name="NumberOfSatellites" SelectedIndex="0" ItemsSource="{Binding Path=NumberOfObjectsValues,Mode=OneTime}" SelectedItem="{Binding NumberOfObjects}" 
                              Height="auto" Width="75" Style="{StaticResource ComboStyle}" Margin="0,5,5,5"/>
                </StackPanel>
                <StackPanel Orientation="Horizontal" Margin="5,0,5,0" HorizontalAlignment="Left" >
                    <TextBlock Text="Update speed (seconds):" Width="155" VerticalAlignment="Stretch" Foreground="Black" Margin="5,5,5,0"/>
                    <ComboBox x:Name="UpdateSpeed" SelectedIndex="0" ItemsSource="{Binding Path=UpdateSpeedValues,Mode=OneTime}" SelectedItem="{Binding UpdateSpeed}" 
                              Height="auto" Width="75" Style="{StaticResource ComboStyle}"  Margin="0,5,5,5"/>
                </StackPanel>

            </StackPanel>
        </Grid>
    </Grid>
</UserControl>

C#

using System;
using System.Collections.Generic;
using System.Collections.ObjectModel;
using System.ComponentModel;
using System.Windows.Controls;
using System.Windows.Threading;
using ESRI.ArcGIS.Client;
using ESRI.ArcGIS.Client.Geometry;

namespace ArcGISWPFSDK
{
    public partial class MovingObjects : UserControl
    {
        public MovingObjects()
        {
            InitializeComponent();

            DataContext = LayoutRoot.Resources["satellites"] as Satellites;
        }
    }

    public class Satellites : ObservableCollection<Graphic>
    {

        // List of numeric values for the ComboBox
        private List<int> numberOfObjectsValues = new List<int> { 1000, 2000, 3000, 5000, 10000 };
        public List<int> NumberOfObjectsValues
        {
            get { return numberOfObjectsValues; }
        }

        // List of update speed values for the ComboBox
        private List<double> updateSpeedValues = new List<double> { 0.1, 0.2, 0.3, 0.5, 1 };
        public List<double> UpdateSpeedValues
        {
            get { return updateSpeedValues; }
        }

        private int numberOfObjects = 1000;
        public int NumberOfObjects
        {
            get { return numberOfObjects; }
            set
            {
                // Stop the timer and increase the number of features.
                _timer.Stop();
                numberOfObjects = value;
                UpdateSatellites();
                _timer.Start();
            }
        }

        private double updateSpeed = 0.1;
        public double UpdateSpeed
        {
            get { return updateSpeed; }
            set
            {
                // Stop the timer and change the interval.
                _timer.Stop();
                updateSpeed = value;
                _timer.Interval = TimeSpan.FromSeconds(updateSpeed);
                _timer.Start();
            }
        }

        DispatcherTimer _timer;

        public Satellites()
        {
            // Abort initialization if in design mode.
            if (LicenseManager.UsageMode == LicenseUsageMode.Designtime)
                return;

            // Create a large number of graphic objects with random coordinate pairs within the map extent (Web Mercator Auxiliary Sphere).
            UpdateSatellites();

            // Create a new DispatcherTimer which fires every 10th of a second to trigger the object coordinate updates.
            _timer = new DispatcherTimer() { Interval = TimeSpan.FromSeconds(updateSpeed) };
            _timer.Tick += new EventHandler(timer_Tick);
            _timer.Start();
        }

        private void UpdateSatellites()
        {
            // Clear the existing satellites.
            Clear();

            // The Random class is used to generate initial coordinate pairs and status attribute values.
            Random random = new Random();

            for (int i = 0; i < numberOfObjects; i++)
            {
                // Generate the coordinates.
                var x = (random.NextDouble() * 40000000) - 20000000;
                var y = (random.NextDouble() * 40000000) - 20000000;
                var graphic = new Graphic() { Geometry = new MapPoint(x, y) };

                Add(graphic);
            }
        }

        void timer_Tick(object sender, EventArgs e)
        {
            // Update the location of each graphic by a small distance using the MapPoint.MoveTo() method. This is a more efficient approach to updating the geometry 
            // than replacing one set of coordinates with another.
            var counter = 0;
            foreach (var g in this)
            {
                var p = g.Geometry as MapPoint;

                // Calculate new coordinates which have the effect of moving each object by the same amount each time.
                // The Y coordinate is shifted by a smaller amount to ensure the objects move generally across the map.
                var id = counter;
                var dx = Math.Cos(id * .1);
                var dy = Math.Sin(id * .1);
                p.MoveTo(p.X + (dx * 50000d), p.Y + (dy * 5000d));
                counter++;
            }
        }
    }
}

VB.NET

Imports System.Windows
Imports ESRI.ArcGIS.Client
Imports System.Collections.ObjectModel
Imports System
Imports System.Windows.Threading
Imports ESRI.ArcGIS.Client.Geometry
Imports System.Collections.Generic
Imports System.ComponentModel
Imports System.Windows.Controls

Namespace ArcGISWPFSDK
    ''' <summary>
    ''' Interaction logic for MovingObjects.xaml
    ''' </summary>
    Partial Public Class MovingObjects
        Inherits UserControl
        Public Sub New()
            InitializeComponent()

            DataContext = TryCast(LayoutRoot.Resources("satellites"), Satellites)
        End Sub
    End Class

    Public Class Satellites
        Inherits ObservableCollection(Of Graphic)

        ' List of numeric values for the ComboBox
		Private m_numberOfObjectsValues As New List(Of Integer)() With { _
			1000, _
			2000, _
			3000, _
			5000, _
			10000 _
		}
        Public ReadOnly Property NumberOfObjectsValues() As List(Of Integer)
            Get
                Return m_numberOfObjectsValues
            End Get
        End Property

        ' List of update speed values for the ComboBox
		Private m_updateSpeedValues As New List(Of Double)() With { _
			0.1, _
			0.2, _
			0.3, _
			0.5, _
			1 _
		}
        Public ReadOnly Property UpdateSpeedValues() As List(Of Double)
            Get
                Return m_updateSpeedValues
            End Get
        End Property

        Private m_numberOfObjects As Integer = 1000
        Public Property NumberOfObjects() As Integer
            Get
                Return m_numberOfObjects
            End Get
            Set(value As Integer)
                ' Stop the timer and increase the number of features.
                _timer.[Stop]()
                m_numberOfObjects = value
                UpdateSatellites()
                _timer.Start()
            End Set
        End Property

        Private m_updateSpeed As Double = 0.1
        Public Property UpdateSpeed() As Double
            Get
                Return m_updateSpeed
            End Get
            Set(value As Double)
                ' Stop the timer and change the interval.
                _timer.[Stop]()
                m_updateSpeed = value
                _timer.Interval = TimeSpan.FromSeconds(m_updateSpeed)
                _timer.Start()
            End Set
        End Property

        Private _timer As DispatcherTimer

        Public Sub New()
            ' Abort initialization if in design mode.
            If LicenseManager.UsageMode = LicenseUsageMode.Designtime Then
                Return
            End If

            ' Create a large number of graphic objects with random coordinate pairs within the map extent (Web Mercator Auxiliary Sphere).
            UpdateSatellites()

            ' Create a new DispatcherTimer which fires every 10th of a second to trigger the object coordinate updates.
            _timer = New DispatcherTimer() With { _
             .Interval = TimeSpan.FromSeconds(m_updateSpeed) _
            }
            AddHandler _timer.Tick, AddressOf timer_Tick
            _timer.Start()
        End Sub

        Private Sub UpdateSatellites()
            ' Clear the existing satellites.
            Clear()

            ' The Random class is used to generate initial coordinate pairs and status attribute values.
            Dim random As New Random()

            For i As Integer = 0 To m_numberOfObjects - 1
                ' Generate the coordinates.
                Dim x = (random.NextDouble() * 40000000) - 20000000
                Dim y = (random.NextDouble() * 40000000) - 20000000
                Dim graphic = New Graphic() With { _
                 .Geometry = New MapPoint(x, y) _
                }

                Add(graphic)
            Next
        End Sub

        Private Sub timer_Tick(sender As Object, e As EventArgs)
            ' Update the location of each graphic by a small distance using the MapPoint.MoveTo() method. This is a more efficient approach to updating the geometry 
            ' than replacing one set of coordinates with another.
            Dim counter As Int32 = 0
            For Each g As Graphic In Me
                Dim p = TryCast(g.Geometry, MapPoint)

                ' Calculate new coordinates which have the effect of moving each object by the same amount each time.
                ' The Y coordinate is shifted by a smaller amount to ensure the objects move generally across the map.
                Dim id = counter
                Dim dx As Double = Math.Cos((Double)id * 0.1)
                Dim dy As Double = Math.Sin((Double)id * 0.1)
                p.MoveTo(p.X + (dx * 50000.0), p.Y + (dy * 1000.0))
                counter += 1
            Next
        End Sub
    End Class
End Namespace