Sketch on map

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Use the Sketch Editor to edit or sketch a new point, line, or polygon geometry on to a map.

Image of sketch on map

Use case

A field worker could annotate features of interest on a map (via the GUI) such as location of dwellings (marked as points), geological features (polylines), or areas of glaciation (polygons).

How to use the sample

Choose which geometry type to sketch from one of the available buttons. Choose from points, multipoints, polylines, polygons, freehand polylines, and freehand polygons.

Use the control panel to cancel the sketch, undo or redo changes made to the sketch and to save the sketch to the graphics overlay. There is also the option to select a saved graphic and edit its geometry using the Sketch Editor. The graphics overlay can be cleared using the clear all button.

How it works

  1. Use SketchEditor.StartAsync() to start sketching. If editing an existing graphic's geometry, use SketchEditor.StartAsync(graphic.Geometry).
  2. Use the UndoCommand and RedoCommand to undo and redo edits in the sketch.
  3. Use a CompleteCommand to finish the sketch and get the Geometry result. Use the CancelCommand to cancel the sketch.
  4. Create a Graphic for the geometry and add it to the GraphicsOverlay in the map view.

Relevant API

  • Geometry
  • Graphic
  • GraphicsOverlay
  • MapView
  • SketchCreationMode
  • SketchEditor

Tags

draw, edit

Sample Code

SketchOnMap.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.Views;
using Android.Widget;
using Esri.ArcGISRuntime.Data;
using Esri.ArcGISRuntime.Geometry;
using Esri.ArcGISRuntime.Mapping;
using Esri.ArcGISRuntime.Symbology;
using Esri.ArcGISRuntime.UI;
using Esri.ArcGISRuntime.UI.Controls;
using System;
using System.Collections.Generic;
using System.Drawing;
using System.Linq;
using System.Threading.Tasks;
using System.Windows.Input;

namespace ArcGISRuntime.Samples.SketchOnMap
{
    [Activity (ConfigurationChanges=Android.Content.PM.ConfigChanges.Orientation | Android.Content.PM.ConfigChanges.ScreenSize)]
    [ArcGISRuntime.Samples.Shared.Attributes.Sample(
        name: "Sketch on map",
        category: "GraphicsOverlay",
        description: "Use the Sketch Editor to edit or sketch a new point, line, or polygon geometry on to a map.",
        instructions: "Choose which geometry type to sketch from one of the available buttons. Choose from points, multipoints, polylines, polygons, freehand polylines, and freehand polygons.",
        tags: new[] { "draw", "edit" })]
    public class SketchOnMap : Activity
    {
        // Hold a reference to the map view
        private MapView _myMapView;

        // Dictionary to hold sketch mode enum names and values
        private Dictionary<string, int> _sketchModeDictionary;

        // Graphics overlay to host sketch graphics
        private GraphicsOverlay _sketchOverlay;

        // Buttons for interacting with the SketchEditor
        private Button _editButton;

        private Button _undoButton;
        private Button _redoButton;
        private Button _doneButton;
        private Button _clearButton;

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

            Title = "Sketch on map";

            // Create the UI
            CreateLayout();

            // Initialize controls, set up event handlers, etc.
            Initialize();
        }

        private void Initialize()
        {
            // Create a light gray canvas map
            Map myMap = new Map(BasemapStyle.ArcGISLightGray);

            // Create graphics overlay to display sketch geometry
            _sketchOverlay = new GraphicsOverlay();
            _myMapView.GraphicsOverlays.Add(_sketchOverlay);

            // Assign the map to the MapView
            _myMapView.Map = myMap;

            // Listen to the sketch editor tools CanExecuteChange so controls can be enabled/disabled
            _myMapView.SketchEditor.UndoCommand.CanExecuteChanged += CanExecuteChanged;
            _myMapView.SketchEditor.RedoCommand.CanExecuteChanged += CanExecuteChanged;
            _myMapView.SketchEditor.CompleteCommand.CanExecuteChanged += CanExecuteChanged;

            // Listen to collection changed event on the graphics overlay to enable/disable controls that require a graphic
            _sketchOverlay.Graphics.CollectionChanged += GraphicsChanged;
        }

        private void CreateLayout()
        {
            // Create horizontal layouts for the buttons at the top
            LinearLayout buttonLayoutOne = new LinearLayout(this) { Orientation = Orientation.Horizontal };
            LinearLayout buttonLayoutTwo = new LinearLayout(this) { Orientation = Orientation.Horizontal };

            // Parameters for all of the buttons. Used to set buttons height and width.
            LinearLayout.LayoutParams param = new LinearLayout.LayoutParams(
                ViewGroup.LayoutParams.MatchParent,
                ViewGroup.LayoutParams.MatchParent,
                1.0f
            );

            // Button to sketch a selected geometry type on the map view
            Button sketchButton = new Button(this)
            {
                Text = "Sketch",
                LayoutParameters = param
            };
            sketchButton.Click += OnSketchClicked;

            // Button to edit an existing graphic's geometry
            _editButton = new Button(this)
            {
                Text = "Edit",
                LayoutParameters = param
            };
            _editButton.Click += OnEditClicked;
            _editButton.Enabled = false;

            // Buttons to Undo/Redo sketch and edit operations
            _undoButton = new Button(this)
            {
                Text = "Undo",
                LayoutParameters = param
            };
            _undoButton.Click += OnUndoClicked;
            _undoButton.Enabled = false;
            _redoButton = new Button(this)
            {
                Text = "Redo",
                LayoutParameters = param
            };
            _redoButton.Click += OnRedoClicked;
            _redoButton.Enabled = false;

            // Button to complete the sketch or edit
            _doneButton = new Button(this)
            {
                Text = "Done",
                LayoutParameters = param
            };
            _doneButton.Click += OnCompleteClicked;
            _doneButton.Enabled = false;

            // Button to clear all graphics and sketches
            _clearButton = new Button(this)
            {
                Text = "Clear",
                LayoutParameters = param
            };
            _clearButton.Click += OnClearClicked;
            _clearButton.Enabled = false;

            // Add all sketch controls (buttons) to the button bars
            buttonLayoutOne.AddView(sketchButton);
            buttonLayoutOne.AddView(_editButton);
            buttonLayoutOne.AddView(_clearButton);
            // Second button bar
            buttonLayoutTwo.AddView(_undoButton);
            buttonLayoutTwo.AddView(_redoButton);
            buttonLayoutTwo.AddView(_doneButton);

            // Create a new vertical layout for the app (buttons followed by map view)
            LinearLayout mainLayout = new LinearLayout(this) { Orientation = Orientation.Vertical };

            // Add the button layouts
            mainLayout.AddView(buttonLayoutOne);
            mainLayout.AddView(buttonLayoutTwo);

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

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

        private void OnSketchClicked(object sender, EventArgs e)
        {
            Button sketchButton = (Button)sender;

            // Create a dictionary of enum names and values
            IEnumerable<int> enumValues = Enum.GetValues(typeof(SketchCreationMode)).Cast<int>();
            _sketchModeDictionary = enumValues.ToDictionary(v => Enum.GetName(typeof(SketchCreationMode), v), v => v);

            // Create a menu to show sketch modes
            PopupMenu sketchModesMenu = new PopupMenu(sketchButton.Context, sketchButton);
            sketchModesMenu.MenuItemClick += OnSketchModeItemClicked;

            // Create a menu option for each basemap type
            foreach (string mode in _sketchModeDictionary.Keys)
            {
                sketchModesMenu.Menu.Add(mode);
            }

            // Show menu in the view
            sketchModesMenu.Show();
        }

        private async void OnSketchModeItemClicked(object sender, PopupMenu.MenuItemClickEventArgs e)
        {
            try
            {
                // Get the title of the selected menu item (sketch mode)
                string sketchModeName = e.Item.TitleCondensedFormatted.ToString();

                // Let the user draw on the map view using the chosen sketch mode
                SketchCreationMode creationMode = (SketchCreationMode)_sketchModeDictionary[sketchModeName];
                Geometry geometry = await _myMapView.SketchEditor.StartAsync(creationMode, true);

                // Create and add a graphic from the geometry the user drew
                Graphic graphic = CreateGraphic(geometry);
                _sketchOverlay.Graphics.Add(graphic);
            }
            catch (TaskCanceledException)
            {
                // Ignore ... let the user cancel drawing
            }
            catch (Exception ex)
            {
                // Report exceptions
                AlertDialog.Builder alertBuilder = new AlertDialog.Builder(this);
                alertBuilder.SetTitle("Error drawing graphic shape");
                alertBuilder.SetMessage(ex.Message);
                alertBuilder.Show();
            }
        }

        private async void OnEditClicked(object sender, EventArgs e)
        {
            try
            {
                // Allow the user to select a graphic
                Graphic editGraphic = await GetGraphicAsync();
                if (editGraphic == null) { return; }

                // Let the user make changes to the graphic's geometry, await the result (updated geometry)
                Geometry newGeometry = await _myMapView.SketchEditor.StartAsync(editGraphic.Geometry);

                // Display the updated geometry in the graphic
                editGraphic.Geometry = newGeometry;
            }
            catch (TaskCanceledException)
            {
                // Ignore ... let the user cancel editing
            }
            catch (Exception ex)
            {
                // Report exceptions
                AlertDialog.Builder alertBuilder = new AlertDialog.Builder(this);
                alertBuilder.SetTitle("Error editing shape");
                alertBuilder.SetMessage(ex.Message);
                alertBuilder.Show();
            }
        }

        private void OnClearClicked(object sender, EventArgs e)
        {
            // Remove all graphics from the graphics overlay
            _sketchOverlay.Graphics.Clear();

            // Cancel any uncompleted sketch
            if (_myMapView.SketchEditor.CancelCommand.CanExecute(null))
            {
                _myMapView.SketchEditor.CancelCommand.Execute(null);
            }
        }

        private void OnCompleteClicked(object sender, EventArgs e)
        {
            // Execute the CompleteCommand on the sketch editor
            if (_myMapView.SketchEditor.CompleteCommand.CanExecute(null))
            {
                _myMapView.SketchEditor.CompleteCommand.Execute(null);
            }
        }

        private void OnRedoClicked(object sender, EventArgs e)
        {
            // Execute the RedoCommand on the sketch editor
            if (_myMapView.SketchEditor.RedoCommand.CanExecute(null))
            {
                _myMapView.SketchEditor.RedoCommand.Execute(null);
            }
        }

        private void OnUndoClicked(object sender, EventArgs e)
        {
            // Execute the UndoCommand on the sketch editor
            if (_myMapView.SketchEditor.UndoCommand.CanExecute(null))
            {
                _myMapView.SketchEditor.UndoCommand.Execute(null);
            }
        }

        private void GraphicsChanged(object sender, System.Collections.Specialized.NotifyCollectionChangedEventArgs e)
        {
            // Enable or disable the clear and edit buttons depending on whether or not graphics exist
            bool haveGraphics = _sketchOverlay.Graphics.Count > 0;
            _editButton.Enabled = haveGraphics;
            _clearButton.Enabled = haveGraphics;
        }

        private void CanExecuteChanged(object sender, EventArgs e)
        {
            // Enable or disable the corresponding command for the sketch editor
            ICommand command = (ICommand)sender;
            if (command == _myMapView.SketchEditor.UndoCommand)
            {
                _undoButton.Enabled = command.CanExecute(null);
            }
            else if (command == _myMapView.SketchEditor.RedoCommand)
            {
                _redoButton.Enabled = command.CanExecute(null);
            }
            else if (command == _myMapView.SketchEditor.CompleteCommand)
            {
                _doneButton.Enabled = command.CanExecute(null);
            }
        }

        #region Graphic and symbol helpers

        private Graphic CreateGraphic(Geometry geometry)
        {
            // Create a graphic to display the specified geometry
            Symbol symbol = null;
            switch (geometry.GeometryType)
            {
                // Symbolize with a fill symbol
                case GeometryType.Envelope:
                case GeometryType.Polygon:
                    {
                        symbol = new SimpleFillSymbol()
                        {
                            Color = Color.Red,
                            Style = SimpleFillSymbolStyle.Solid
                        };
                        break;
                    }
                // Symbolize with a line symbol
                case GeometryType.Polyline:
                    {
                        symbol = new SimpleLineSymbol()
                        {
                            Color = Color.Red,
                            Style = SimpleLineSymbolStyle.Solid,
                            Width = 5d
                        };
                        break;
                    }
                // Symbolize with a marker symbol
                case GeometryType.Point:
                case GeometryType.Multipoint:
                    {
                        symbol = new SimpleMarkerSymbol()
                        {
                            Color = Color.Red,
                            Style = SimpleMarkerSymbolStyle.Circle,
                            Size = 15d
                        };
                        break;
                    }
            }

            // pass back a new graphic with the appropriate symbol
            return new Graphic(geometry, symbol);
        }

        private async Task<Graphic> GetGraphicAsync()
        {
            // Wait for the user to click a location on the map
            Geometry mapPoint = await _myMapView.SketchEditor.StartAsync(SketchCreationMode.Point, false);

            // Convert the map point to a screen point
            Android.Graphics.PointF screenCoordinate = _myMapView.LocationToScreen((MapPoint)mapPoint);

            // Identify graphics in the graphics overlay using the point
            IReadOnlyList<IdentifyGraphicsOverlayResult> results = await _myMapView.IdentifyGraphicsOverlaysAsync(screenCoordinate, 2, false);

            // If results were found, get the first graphic
            Graphic graphic = null;
            IdentifyGraphicsOverlayResult idResult = results.FirstOrDefault();
            if (idResult != null && idResult.Graphics.Count > 0)
            {
                graphic = idResult.Graphics.FirstOrDefault();
            }

            // Return the graphic (or null if none were found)
            return graphic;
        }

        #endregion Graphic and symbol helpers

        private async void SketchGeometry(string sketchModeName)
        {
            try
            {
                // Let the user draw on the map view using the chosen sketch mode
                SketchCreationMode creationMode = (SketchCreationMode)_sketchModeDictionary[sketchModeName];
                Geometry geometry = await _myMapView.SketchEditor.StartAsync(creationMode, true);

                // Create and add a graphic from the geometry the user drew
                Graphic graphic = CreateGraphic(geometry);
                _sketchOverlay.Graphics.Add(graphic);
            }
            catch (TaskCanceledException)
            {
                // Ignore ... let the user cancel drawing
            }
            catch (Exception ex)
            {
                // Report exceptions
                AlertDialog.Builder alertBuilder = new AlertDialog.Builder(this);
                alertBuilder.SetTitle("Error drawing graphic shape");
                alertBuilder.SetMessage(ex.Message);
                alertBuilder.Show();
            }
        }

        private async void EditGraphic()
        {
            try
            {
                // Allow the user to select a graphic
                Graphic editGraphic = await GetGraphicAsync();
                if (editGraphic == null) { return; }

                // Let the user make changes to the graphic's geometry, await the result (updated geometry)
                Geometry newGeometry = await _myMapView.SketchEditor.StartAsync(editGraphic.Geometry);

                // Display the updated geometry in the graphic
                editGraphic.Geometry = newGeometry;
            }
            catch (TaskCanceledException)
            {
                // Ignore ... let the user cancel editing
            }
            catch (Exception ex)
            {
                // Report exceptions
                AlertDialog.Builder alertBuilder = new AlertDialog.Builder(this);
                alertBuilder.SetTitle("Error editing shape");
                alertBuilder.SetMessage(ex.Message);
                alertBuilder.Show();
            }
        }
    }
}

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