Format coordinates

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// Copyright 2022 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 Esri.ArcGISRuntime.Geometry;
using Esri.ArcGISRuntime.Mapping;
using Esri.ArcGISRuntime.Symbology;
using Esri.ArcGISRuntime.UI;

using Color = System.Drawing.Color;

namespace ArcGIS.Samples.FormatCoordinates
{
    [ArcGIS.Samples.Shared.Attributes.Sample(
        name: "Format coordinates",
        category: "Geometry",
        description: "Format coordinates in a variety of common notations.",
        instructions: "Tap on the map to see a callout with the tapped location's coordinate formatted in 4 different ways. You can also put a coordinate string in any of these formats in the text field. Hit Enter and the coordinate string will be parsed to a map location which the callout will move to.",
        tags: new[] { "USNG", "UTM", "convert", "coordinate", "decimal degrees", "degree minutes seconds", "format", "latitude", "longitude" })]
    public partial class FormatCoordinates : ContentPage
    {
        // Hold a reference to the most recently updated field.
        private Entry _selectedEntry;

        private List<Entry> _entries;

        public FormatCoordinates()
        {
            InitializeComponent();
            Initialize();
        }

        private void Initialize()
        {
            // Create a list of the entries.
            _entries = new List<Entry> { UtmTextField, DmsTextField, DecimalDegreesTextField, UsngTextField };

            // Create the map.
            MyMapView.Map = new Map(BasemapStyle.ArcGISNavigation);

            // Add the graphics overlay to the map.
            MyMapView.GraphicsOverlays.Add(new GraphicsOverlay());

            // Create the starting point.
            var startingPoint = new MapPoint(0, 0, SpatialReferences.WebMercator);

            // Update the UI with the initial point.
            UpdateUIFromMapPoint(startingPoint);

            // Subscribe to map tap events to enable tapping on map to update coordinates.
            MyMapView.GeoViewTapped += (s, e) => { UpdateUIFromMapPoint(e.Location); };
        }

        private void InputTextChanged(object sender, TextChangedEventArgs e)
        {
            // Keep track of the last edited field.
            _selectedEntry = (Entry)sender;
        }

        private void RecalculateFields(object sender, EventArgs e)
        {
            // Only update the point if the user has changed text.
            if (_selectedEntry == null) return;

            // Hold the entered point.
            MapPoint enteredPoint = null;

            // Update the point based on which text sent the event.
            try
            {
                switch (_selectedEntry.Placeholder)
                {
                    case "Decimal Degrees":
                    case "Degrees, Minutes, Seconds":
                        enteredPoint =
                            CoordinateFormatter.FromLatitudeLongitude(_selectedEntry.Text, MyMapView.SpatialReference);
                        break;

                    case "UTM":
                        enteredPoint =
                            CoordinateFormatter.FromUtm(_selectedEntry.Text, MyMapView.SpatialReference, UtmConversionMode.NorthSouthIndicators);
                        break;

                    case "USNG":
                        enteredPoint =
                            CoordinateFormatter.FromUsng(_selectedEntry.Text, MyMapView.SpatialReference);
                        break;
                }
            }
            catch (Exception ex)
            {
                // The coordinate is malformed, warn and return
                Application.Current.MainPage.DisplayAlert("Invalid Format", ex.Message, "OK");
                return;
            }

            // Update the UI from the MapPoint.
            UpdateUIFromMapPoint(enteredPoint);
        }

        private void UpdateUIFromMapPoint(MapPoint selectedPoint)
        {
            try
            {
                // Check if the selected point can be formatted into coordinates.
                CoordinateFormatter.ToLatitudeLongitude(selectedPoint, LatitudeLongitudeFormat.DecimalDegrees, 0);
            }
            catch (Exception ex)
            {
                Application.Current.MainPage.DisplayAlert("Error", ex.Message, "OK");
                return;
            }

            // "Deselect" any text box.
            _selectedEntry = null;

            // Disable event handlers while updating text in text boxes.
            _entries.ForEach(box => box.TextChanged -= InputTextChanged);

            // Update Entry values.
            DecimalDegreesTextField.Text = CoordinateFormatter.ToLatitudeLongitude(selectedPoint, LatitudeLongitudeFormat.DecimalDegrees, 4);
            DmsTextField.Text = CoordinateFormatter.ToLatitudeLongitude(selectedPoint, LatitudeLongitudeFormat.DegreesMinutesSeconds, 1);
            UtmTextField.Text = CoordinateFormatter.ToUtm(selectedPoint, UtmConversionMode.NorthSouthIndicators, true);
            UsngTextField.Text = CoordinateFormatter.ToUsng(selectedPoint, 4, true);

            // Enable event handlers for all of the text boxes.
            _entries.ForEach(box => box.TextChanged += InputTextChanged);

            // Clear existing graphics.
            MyMapView.GraphicsOverlays[0].Graphics.Clear();

            // Create a symbol to symbolize the point.
            var symbol = new SimpleMarkerSymbol(SimpleMarkerSymbolStyle.X, Color.Yellow, 20);

            // Create the graphic.
            var symbolGraphic = new Graphic(selectedPoint, symbol);

            // Add the graphic to the graphics overlay.
            MyMapView.GraphicsOverlays[0].Graphics.Add(symbolGraphic);
        }
    }
}