Add graphics with symbols

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Use a symbol style to display a graphic on a graphics overlay.

Image of Add graphics with symbols

Use case

Allows you to customize a graphic by assigning a unique symbol. For example, you may wish to display individual graphics for different landmarks across a region, and to style each one with a unique symbol.

How to use the sample

Observe the graphics on the map.

How it works

  1. Create a GraphicsOverlay and add it to the MapView.
  2. Create a Symbol such as SimpleMarkerSymbol, SimpleLineSymbol or SimpleFillSymbol.
  3. Create a Graphic, specifying a Geometry and a Symbol.
  4. Add the Graphic to the GraphicsOverlay.

Relevant API

  • Geometry
  • Graphic
  • GraphicsOverlay
  • SimpleFillSymbol
  • SimpleLineSymbol
  • SimpleMarkerSymbol

Additional information

To set a symbol style across a number of graphics (e.g. showing trees as graphics sharing a symbol in a park), see the "Add graphics with renderer" sample.

Tags

SimpleFillSymbol, SimpleLineSymbol, SimpleMarkerSymbol

Sample Code

AddGraphicsWithSymbols.cs
                                                                                                                                                                                                            
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// Copyright 2018 Esri.
//
// Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License.
// You may obtain a copy of the License at: http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an
// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific
// language governing permissions and limitations under the License.

using Android.App;
using Android.OS;
using Android.Widget;
using Esri.ArcGISRuntime.Geometry;
using Esri.ArcGISRuntime.Mapping;
using Esri.ArcGISRuntime.Symbology;
using Esri.ArcGISRuntime.UI;
using Esri.ArcGISRuntime.UI.Controls;
using System.Drawing;

namespace ArcGISRuntime.Samples.AddGraphicsWithSymbols
{
    [Activity (ConfigurationChanges=Android.Content.PM.ConfigChanges.Orientation | Android.Content.PM.ConfigChanges.ScreenSize)]
    [ArcGISRuntime.Samples.Shared.Attributes.Sample(
        name: "Add graphics with symbols",
        category: "GraphicsOverlay",
        description: "Use a symbol style to display a graphic on a graphics overlay.",
        instructions: "Observe the graphics on the map.",
        tags: new[] { "SimpleFillSymbol", "SimpleLineSymbol", "SimpleMarkerSymbol" })]
    public class AddGraphicsWithSymbols : Activity
    {
        // Hold a reference to the map view
        private MapView _myMapView;

        // Create the graphics overlay
        private readonly GraphicsOverlay _overlay = new GraphicsOverlay();

        protected override void OnCreate(Bundle bundle)
        {
            base.OnCreate(bundle);

            Title = "Add graphics with symbols";

            // Create the UI, setup the control references and execute initialization
            CreateLayout();
            Initialize();
        }

        private void Initialize()
        {
            // Create the map
            Map myMap = new Map(BasemapType.Oceans, 56.075844, -2.681572, 13);

            // Add the map to the map view
            _myMapView.Map = myMap;

            // Add the graphics overlay to the map view
            _myMapView.GraphicsOverlays.Add(_overlay);

            // Call functions to create the graphics
            CreatePoints();
            CreatePolygon();
            CreatePolyline();
            CreateText();

            // Update the extent to encompass all of the symbols
            SetExtent();
        }

        private void CreatePoints()
        {
            // Create a red circle simple marker symbol
            SimpleMarkerSymbol redCircleSymbol = new SimpleMarkerSymbol(SimpleMarkerSymbolStyle.Circle, Color.Red, 10);

            // Create graphics and add them to graphics overlay
            Graphic graphic = new Graphic(new MapPoint(-2.72, 56.065, SpatialReferences.Wgs84), redCircleSymbol);
            _overlay.Graphics.Add(graphic);

            graphic = new Graphic(new MapPoint(-2.69, 56.065, SpatialReferences.Wgs84), redCircleSymbol);
            _overlay.Graphics.Add(graphic);

            graphic = new Graphic(new MapPoint(-2.66, 56.065, SpatialReferences.Wgs84), redCircleSymbol);
            _overlay.Graphics.Add(graphic);

            graphic = new Graphic(new MapPoint(-2.63, 56.065, SpatialReferences.Wgs84), redCircleSymbol);
            _overlay.Graphics.Add(graphic);
        }

        private void CreatePolyline()
        {
            // Create a purple simple line symbol
            SimpleLineSymbol lineSymbol = new SimpleLineSymbol(SimpleLineSymbolStyle.Dash, Color.Purple, 4);

            // Create a new point collection for polyline
            PointCollection points = new PointCollection(SpatialReferences.Wgs84)
            {
                // Create and add points to the point collection
                new MapPoint(-2.715, 56.061),
                new MapPoint(-2.6438, 56.079),
                new MapPoint(-2.638, 56.079),
                new MapPoint(-2.636, 56.078),
                new MapPoint(-2.636, 56.077),
                new MapPoint(-2.637, 56.076),
                new MapPoint(-2.715, 56.061)
            };

            // Create the polyline from the point collection
            Polyline polyline = new Polyline(points);

            // Create the graphic with polyline and symbol
            Graphic graphic = new Graphic(polyline, lineSymbol);

            // Add graphic to the graphics overlay
            _overlay.Graphics.Add(graphic);
        }

        private void CreatePolygon()
        {
            // Create a green simple line symbol
            SimpleLineSymbol outlineSymbol = new SimpleLineSymbol(SimpleLineSymbolStyle.Dash, Color.Green, 1);

            // Create a green mesh simple fill symbol
            SimpleFillSymbol fillSymbol = new SimpleFillSymbol(SimpleFillSymbolStyle.DiagonalCross, Color.Green, outlineSymbol);

            // Create a new point collection for polygon
            PointCollection points = new PointCollection(SpatialReferences.Wgs84)
            {
                // Create and add points to the point collection
                new MapPoint(-2.6425, 56.0784),
                new MapPoint(-2.6430, 56.0763),
                new MapPoint(-2.6410, 56.0759),
                new MapPoint(-2.6380, 56.0765),
                new MapPoint(-2.6380, 56.0784),
                new MapPoint(-2.6410, 56.0786)
            };

            // Create the polyline from the point collection
            Polygon polygon = new Polygon(points);

            // Create the graphic with polyline and symbol
            Graphic graphic = new Graphic(polygon, fillSymbol);

            // Add graphic to the graphics overlay
            _overlay.Graphics.Add(graphic);
        }

        private void CreateText()
        {
            // Create two text symbols
            TextSymbol bassRockTextSymbol = new TextSymbol("Black Rock", Color.Blue, 10,
                HorizontalAlignment.Left, VerticalAlignment.Bottom);

            TextSymbol craigleithTextSymbol = new TextSymbol("Craigleith", Color.Blue, 10,
                HorizontalAlignment.Right, VerticalAlignment.Top);

            // Create two points
            MapPoint bassPoint = new MapPoint(-2.64, 56.079, SpatialReferences.Wgs84);
            MapPoint craigleithPoint = new MapPoint(-2.72, 56.076, SpatialReferences.Wgs84);

            // Create two graphics from the points and symbols
            Graphic bassRockGraphic = new Graphic(bassPoint, bassRockTextSymbol);
            Graphic craigleithGraphic = new Graphic(craigleithPoint, craigleithTextSymbol);

            // Add graphics to the graphics overlay
            _overlay.Graphics.Add(bassRockGraphic);
            _overlay.Graphics.Add(craigleithGraphic);
        }

        private void SetExtent()
        {
            // Get all of the graphics contained in the graphics overlay
            GraphicCollection myGraphicCollection = _overlay.Graphics;

            // Create a new envelope builder using the same spatial reference as the graphics
            EnvelopeBuilder myEnvelopeBuilder = new EnvelopeBuilder(SpatialReferences.Wgs84);

            // Loop through each graphic in the graphic collection
            foreach (Graphic oneGraphic in myGraphicCollection)
            {
                // Union the extent of each graphic in the envelope builder
                myEnvelopeBuilder.UnionOf(oneGraphic.Geometry.Extent);
            }

            // Expand the envelope builder by 30%
            myEnvelopeBuilder.Expand(1.3);

            // Adjust the viewable area of the map to encompass all of the graphics in the
            // graphics overlay plus an extra 30% margin for better viewing
            _myMapView.SetViewpointAsync(new Viewpoint(myEnvelopeBuilder.Extent));
        }

        private void CreateLayout()
        {
            // Create a new vertical layout for the app
            LinearLayout layout = new LinearLayout(this) { Orientation = Orientation.Vertical };

            // Add the map view to the layout
            _myMapView = new MapView(this);
            layout.AddView(_myMapView);

            // Show the layout in the app
            SetContentView(layout);
        }
    }
}

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