Label Points

This sample demonstrates using the ArcGIS Runtime SDK for WPF to perform a geometry operation to calculate the location of label points. To use the sample, click the Add New Polygon button, then click subsequent points on the map to draw a polygon. Double-click to complete the polygon. When a polygon is completed, a label point for the polygon will be calculated and shown on the map.

In the code-behind, a LocalGeometryService created and the url is passed into a GeometryService which is used to first simplify the polygon and then get a label point. When the label point is returned, it is added to the map.

XAML

<UserControl x:Class="ArcGISWPFSDK.LocalLabelPoints"
    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>
            <esri:SimpleFillSymbol x:Key="DefaultPolygonSymbol" Fill="#7F0000FF" BorderBrush="Blue" BorderThickness="2" />
            <esri:PictureMarkerSymbol x:Key="DefaultRasterSymbol" OffsetX="12" OffsetY="12" Source="/Assets/Images/x-24x24.png" />
            <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" Extent="-15000000,2000000,-7000000,8000000" Background="#FFE3E3E3" >
            <esri:ArcGISLocalTiledLayer ID="BaseMap" Path="..\\Data\\TPKs\\Topographic.tpk"/>
            <esri:GraphicsLayer ID="labelGraphicsLayer" x:Name="_labelGraphicsLayer">
                <esri:GraphicsLayer.MapTip>
                    <Grid Background="LightYellow">
                        <StackPanel Orientation="Vertical" Margin="5">
                            <TextBlock Text="{Binding [X]}" HorizontalAlignment="Left" Foreground="Black" />
                            <TextBlock Text="{Binding [Y]}" HorizontalAlignment="Left" Foreground="Black"/>
                        </StackPanel>
                        <Border BorderBrush="Black" BorderThickness="1" />
                    </Grid>
                </esri:GraphicsLayer.MapTip>
            </esri:GraphicsLayer>
        </esri:Map>

        <Grid HorizontalAlignment="Right" VerticalAlignment="Top" Margin="0,10,10,0" >
            <Rectangle Fill="{StaticResource PanelGradient}" Stroke="Gray"  RadiusX="10" RadiusY="10" Margin="0,0,0,5" >
                <Rectangle.Effect>
                    <DropShadowEffect/>
                </Rectangle.Effect>
            </Rectangle>
            <Rectangle Fill="#FFFFFFFF" Stroke="DarkGray" RadiusX="5" RadiusY="5" Margin="10,10,10,15" />
            <StackPanel Orientation="Vertical" Margin="30,25,25,30" >
                <TextBlock x:Name="ResponseText" Text="Create a polygon by clicking on map. The calculated position of a Label Point will be displayed." 
                    Width="250" TextAlignment="Left" TextWrapping="Wrap" Foreground="Black" />
                <Button x:Name="ClearGraphicsButton" Content="Clear Polygons" 
                        Click="ClearGraphicsButton_Click" />
            </StackPanel>
        </Grid>

    </Grid>
</UserControl>

C#

using System.Collections.Generic;
using System.Windows;
using System.Windows.Controls;
using ESRI.ArcGIS.Client;
using ESRI.ArcGIS.Client.Geometry;
using ESRI.ArcGIS.Client.Tasks;
using ESRI.ArcGIS.Client.Local;

namespace ArcGISWPFSDK
{
    public partial class LocalLabelPoints : UserControl
    {
        private Draw _drawObject;
        GeometryService _geometryTask;

        public LocalLabelPoints()
        {
            InitializeComponent();

            LocalGeometryService.GetServiceAsync(lgs =>
            {                
                _geometryTask = new GeometryService();
                _geometryTask.Url = lgs.UrlGeometryService;
                _geometryTask.SimplifyCompleted += GeometryService_SimplifyCompleted;
                _geometryTask.LabelPointsCompleted += GeometryService_LabelPointsCompleted;
                _geometryTask.Failed += GeometryService_Failed;
            });

            MyMap.Layers.LayersInitialized += (s, e) =>
            {
                _drawObject = new Draw(MyMap)
                {
                    FillSymbol = LayoutRoot.Resources["DefaultPolygonSymbol"] as ESRI.ArcGIS.Client.Symbols.FillSymbol,
                    DrawMode = DrawMode.Polygon,
                    IsEnabled = true
                };

                _drawObject.DrawComplete += DrawObject_DrawComplete;
            };
        }

        private void ClearGraphicsButton_Click(object sender, RoutedEventArgs e)
        {
            _labelGraphicsLayer.ClearGraphics();
        }

        private void AddPolygonButton_Click(object sender, RoutedEventArgs e)
        {
            _drawObject.IsEnabled = true; ;
        }

        private void DrawObject_DrawComplete(object sender, ESRI.ArcGIS.Client.DrawEventArgs args)
        {
            _drawObject.IsEnabled = false;

            ESRI.ArcGIS.Client.Geometry.Polygon polygon = args.Geometry as ESRI.ArcGIS.Client.Geometry.Polygon;

            Graphic graphic = new Graphic()
            {
                Symbol = LayoutRoot.Resources["DefaultPolygonSymbol"] as ESRI.ArcGIS.Client.Symbols.Symbol,
                Geometry = polygon
            };
            graphic.Attributes.Add("X", "Label Point Polygon");
            _labelGraphicsLayer.Graphics.Add(graphic);

            List<Graphic> graphicsList = new List<Graphic>();
            graphicsList.Add(graphic);

            _geometryTask.SimplifyAsync(graphicsList);

        }

        void GeometryService_SimplifyCompleted(object sender, GraphicsEventArgs e)
        {
            _geometryTask.LabelPointsAsync(e.Results);
        }

        private void GeometryService_LabelPointsCompleted(object sender, GraphicsEventArgs args)
        {
            foreach (Graphic graphic in args.Results)
            {
                graphic.Symbol = LayoutRoot.Resources["DefaultRasterSymbol"] as ESRI.ArcGIS.Client.Symbols.Symbol;
                MapPoint mapPoint = graphic.Geometry as MapPoint;
                graphic.Attributes.Add("X", mapPoint.X);
                graphic.Attributes.Add("Y", mapPoint.Y);
                _labelGraphicsLayer.Graphics.Add(graphic);
            }
            _drawObject.IsEnabled = true;
        }

        private void GeometryService_Failed(object sender, TaskFailedEventArgs e)
        {
            MessageBox.Show("Geometry Service error: " + e.Error);
            _drawObject.IsEnabled = true;
        }
    }
}

VB.NET

Imports System.Collections.Generic
Imports System.Windows
Imports System.Windows.Controls
Imports ESRI.ArcGIS.Client
Imports ESRI.ArcGIS.Client.Geometry
Imports ESRI.ArcGIS.Client.Tasks
Imports ESRI.ArcGIS.Client.Local

Namespace ArcGISWPFSDK
    Partial Public Class LocalLabelPoints
        Inherits UserControl
        Private MyDrawObject As Draw
        Private graphicsLayer As GraphicsLayer
        Private _geometryService As GeometryService

        Public Sub New()
            InitializeComponent()

            Dim localGeometryService As New LocalGeometryService()
            AddHandler localGeometryService.StartCompleted, Function(sender, eventargs)
                                                                Dim lgs As LocalGeometryService = TryCast(sender, LocalGeometryService)
                                                                _geometryService = New GeometryService()
                                                                _geometryService.Url = lgs.UrlGeometryService
                                                                AddHandler _geometryService.SimplifyCompleted, AddressOf GeometryService_SimplifyCompleted
                                                                AddHandler _geometryService.LabelPointsCompleted, AddressOf GeometryService_LabelPointsCompleted
                                                                AddHandler _geometryService.Failed, AddressOf GeometryService_Failed

                                                                MyDrawObject = New Draw(MyMap) With { _
                                                                 .FillSymbol = TryCast(LayoutRoot.Resources("DefaultPolygonSymbol"), ESRI.ArcGIS.Client.Symbols.FillSymbol), _
                                                                 .DrawMode = DrawMode.Polygon, _
                                                                 .IsEnabled = True _
                                                                }


                                                                AddHandler MyDrawObject.DrawComplete, AddressOf MyDrawObject_DrawComplete

                                                            End Function
            localGeometryService.StartAsync()

            graphicsLayer = TryCast(MyMap.Layers("MyGraphicsLayer"), GraphicsLayer)
        End Sub

        Private Sub ClearGraphicsButton_Click(sender As Object, e As RoutedEventArgs)
            graphicsLayer.ClearGraphics()
        End Sub

        Private Sub AddPolygonButton_Click(sender As Object, e As RoutedEventArgs)
            MyDrawObject.IsEnabled = True


        End Sub

        Private Sub MyDrawObject_DrawComplete(sender As Object, args As ESRI.ArcGIS.Client.DrawEventArgs)
            MyDrawObject.IsEnabled = False

            Dim polygon As ESRI.ArcGIS.Client.Geometry.Polygon = TryCast(args.Geometry, ESRI.ArcGIS.Client.Geometry.Polygon)

            Dim graphic As New Graphic() With { _
             .Symbol = TryCast(LayoutRoot.Resources("DefaultPolygonSymbol"), ESRI.ArcGIS.Client.Symbols.Symbol), _
             .Geometry = polygon _
            }
            graphic.Attributes.Add("X", "Label Point Polygon")
            graphicsLayer.Graphics.Add(graphic)

            Dim graphicsList As New List(Of Graphic)()
            graphicsList.Add(graphic)

            _geometryService.SimplifyAsync(graphicsList)

        End Sub

        Private Sub GeometryService_SimplifyCompleted(sender As Object, e As GraphicsEventArgs)
            _geometryService.LabelPointsAsync(e.Results)
        End Sub

        Private Sub GeometryService_LabelPointsCompleted(sender As Object, args As GraphicsEventArgs)
            For Each graphic As Graphic In args.Results
                graphic.Symbol = TryCast(LayoutRoot.Resources("DefaultRasterSymbol"), ESRI.ArcGIS.Client.Symbols.Symbol)
                Dim mapPoint As MapPoint = TryCast(graphic.Geometry, MapPoint)
                graphic.Attributes.Add("X", mapPoint.X)
                graphic.Attributes.Add("Y", mapPoint.Y)
                graphicsLayer.Graphics.Add(graphic)
            Next
            MyDrawObject.IsEnabled = True
        End Sub

        Private Sub GeometryService_Failed(sender As Object, e As TaskFailedEventArgs)
            MessageBox.Show("Geometry Service error: " & Convert.ToString(e.[Error]))
            MyDrawObject.IsEnabled = True
        End Sub
    End Class
End Namespace