Buffer

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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 Colors = System.Drawing.Color;

namespace ArcGISRuntime.Samples.Buffer
{
    [Activity (ConfigurationChanges=Android.Content.PM.ConfigChanges.Orientation | Android.Content.PM.ConfigChanges.ScreenSize)]
    [ArcGISRuntime.Samples.Shared.Attributes.Sample(
        name: "Buffer",
        category: "Geometry",
        description: "Create a buffer around a map point and display the results as a `Graphic`",
        instructions: "1. Tap on the map.",
        tags: new[] { "analysis", "buffer", "euclidean", "geodesic", "geometry", "planar" })]
    [ArcGISRuntime.Samples.Shared.Attributes.AndroidLayoutAttribute("Buffer.axml")]
    public class Buffer : Activity
    {
        // Hold a reference to the map view.
        private MapView _myMapView;

        // Create an EditText to enter a buffer value (in miles).
        private EditText _bufferDistanceMilesEditText;

        // Text view controls to show the buffer colors in the UI.
        private TextView _geodesicSwatch;
        private TextView _planarSwatch;

        protected override void OnCreate(Bundle bundle)
        {
            base.OnCreate(bundle);
            Title = "Buffer";

            // Create the UI.
            CreateLayout();

            // Initialize the map and graphics overlays.
            Initialize();
        }

        private void Initialize()
        {
            // Create a map with a topographic basemap and add it to the map view.
            _myMapView.Map = new Map(BasemapStyle.ArcGISTopographic);

            // Handle the MapView's GeoViewTapped event to create buffers.
            _myMapView.GeoViewTapped += MyMapView_GeoViewTapped;

            // Create a fill symbol for geodesic buffer polygons.
            Colors geodesicBufferColor = Colors.FromArgb(120, 255, 0, 0);
            SimpleLineSymbol geodesicOutlineSymbol = new SimpleLineSymbol(SimpleLineSymbolStyle.Solid, geodesicBufferColor, 2);
            SimpleFillSymbol geodesicBufferFillSymbol = new SimpleFillSymbol(SimpleFillSymbolStyle.Solid, geodesicBufferColor, geodesicOutlineSymbol);

            // Create a fill symbol for planar buffer polygons.
            Colors planarBufferColor = Colors.FromArgb(120, 0, 0, 255);
            SimpleLineSymbol planarOutlineSymbol = new SimpleLineSymbol(SimpleLineSymbolStyle.Solid, planarBufferColor, 2);
            SimpleFillSymbol planarBufferFillSymbol = new SimpleFillSymbol(SimpleFillSymbolStyle.Solid, planarBufferColor, planarOutlineSymbol);

            // Create a marker symbol for tap locations.
            SimpleMarkerSymbol tapSymbol = new SimpleMarkerSymbol(SimpleMarkerSymbolStyle.Cross, System.Drawing.Color.White, 14);

            // Create a graphics overlay to display geodesic polygons, set its renderer and add it to the map view.
            GraphicsOverlay geodesicPolysOverlay = new GraphicsOverlay
            {
                Id = "GeodesicPolys",
                Renderer = new SimpleRenderer(geodesicBufferFillSymbol)
            };
            _myMapView.GraphicsOverlays.Add(geodesicPolysOverlay);

            // Create a graphics overlay to display planar polygons, set its renderer and add it to the map view.
            GraphicsOverlay planarPolysOverlay = new GraphicsOverlay
            {
                Id = "PlanarPolys",
                Renderer = new SimpleRenderer(planarBufferFillSymbol)
            };
            _myMapView.GraphicsOverlays.Add(planarPolysOverlay);

            // Create a graphics overlay to display tap locations for buffers, set its renderer and add it to the map view.
            GraphicsOverlay tapLocationsOverlay = new GraphicsOverlay
            {
                Id = "TapPoints",
                Renderer = new SimpleRenderer(tapSymbol)
            };
            _myMapView.GraphicsOverlays.Add(tapLocationsOverlay);

            // Show the colors for each type of buffer in the UI.
            ShowBufferSwatches(planarBufferColor, geodesicBufferColor);
        }

        private void MyMapView_GeoViewTapped(object sender, GeoViewInputEventArgs e)
        {
            try
            {
                // Get the location tapped by the user (a map point in the WebMercator projected coordinate system).
                MapPoint userTapPoint = e.Location;

                // Get the buffer distance (miles) entered in the text box.
                double bufferInMiles = System.Convert.ToDouble(_bufferDistanceMilesEditText.Text);

                // Call a helper method to convert the input distance to meters.
                double bufferInMeters = LinearUnits.Miles.ToMeters(bufferInMiles);

                // Create a planar buffer graphic around the input location at the specified distance.
                Geometry bufferGeometryPlanar = GeometryEngine.Buffer(userTapPoint, bufferInMeters);
                Graphic planarBufferGraphic = new Graphic(bufferGeometryPlanar);

                // Create a geodesic buffer graphic using the same location and distance.
                Geometry bufferGeometryGeodesic = GeometryEngine.BufferGeodetic(userTapPoint, bufferInMeters, LinearUnits.Meters, double.NaN, GeodeticCurveType.Geodesic);
                Graphic geodesicBufferGraphic = new Graphic(bufferGeometryGeodesic);

                // Create a graphic for the user tap location.
                Graphic locationGraphic = new Graphic(userTapPoint);

                // Get the graphics overlays.
                GraphicsOverlay planarBufferGraphicsOverlay = _myMapView.GraphicsOverlays["PlanarPolys"];
                GraphicsOverlay geodesicBufferGraphicsOverlay = _myMapView.GraphicsOverlays["GeodesicPolys"];
                GraphicsOverlay tapPointGraphicsOverlay = _myMapView.GraphicsOverlays["TapPoints"];

                // Add the buffer polygons and tap location graphics to the appropriate graphic overlays.
                planarBufferGraphicsOverlay.Graphics.Add(planarBufferGraphic);
                geodesicBufferGraphicsOverlay.Graphics.Add(geodesicBufferGraphic);
                tapPointGraphicsOverlay.Graphics.Add(locationGraphic);
            }
            catch (System.Exception ex)
            {
                // Display an error message if there is a problem generating the buffer polygon.
                AlertDialog.Builder alertBuilder = new AlertDialog.Builder(this);
                alertBuilder.SetTitle("There was a problem generating buffers.");
                alertBuilder.SetMessage(ex.ToString());
                alertBuilder.Show();
            }
        }

        private void ShowBufferSwatches(Colors planarBufferColor, Colors geodesicBufferColor)
        {
            // Create Android.Graphics.Colors to represent the System.Drawing.Colors used for the buffers.
            Android.Graphics.Color planarLabelColor = Android.Graphics.Color.Argb(planarBufferColor.A,
                planarBufferColor.R,
                planarBufferColor.G,
                planarBufferColor.B);
            Android.Graphics.Color geodesicLabelColor = Android.Graphics.Color.Argb(geodesicBufferColor.A,
                geodesicBufferColor.R,
                geodesicBufferColor.G,
                geodesicBufferColor.B);

            // Show buffer symbol colors in the UI by setting the appropriate text view fill color.
            _planarSwatch.SetBackgroundColor(planarLabelColor);
            _geodesicSwatch.SetBackgroundColor(geodesicLabelColor);
        }

        private void ClearBuffersButton_Click(object sender, System.EventArgs e)
        {
            // Clear the buffer and point graphics.
            foreach (GraphicsOverlay ov in _myMapView.GraphicsOverlays)
            {
                ov.Graphics.Clear();
            }
        }

        private void CreateLayout()
        {
            // Load the layout for the sample from the .axml file.
            SetContentView(Resource.Layout.Buffer);

            // Reference controls that will be needed to create the buffers.
            _myMapView = FindViewById<MapView>(Resource.Id.buffer_mapView);
            _bufferDistanceMilesEditText = FindViewById<EditText>(Resource.Id.buffer_distanceText);

            // Add a click event handler for the clear button.
            Button clearBuffersButton = FindViewById<Button>(Resource.Id.buffer_clearButton);
            clearBuffersButton.Click += ClearBuffersButton_Click;

            // Get the text views used to show the buffer colors.
            _geodesicSwatch = FindViewById<TextView>(Resource.Id.buffer_geodesicSwatchLabel);
            _planarSwatch = FindViewById<TextView>(Resource.Id.buffer_planarSwatchLabel);
        }
    }
}