Analyze hotspots

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// Copyright 2016 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.Mapping;
using Esri.ArcGISRuntime.Tasks;
using Esri.ArcGISRuntime.Tasks.Geoprocessing;
using System;
using System.Threading.Tasks;
using System.Windows;

namespace ArcGIS.WPF.Samples.AnalyzeHotspots
{
    [ArcGIS.Samples.Shared.Attributes.Sample(
        name: "Analyze hotspots",
        category: "Geoprocessing",
        description: "Use a geoprocessing service and a set of features to identify statistically significant hot spots and cold spots.",
        instructions: "Select a date range (between 1998-01-01 and 1998-05-31) from the dialog and tap on Analyze. The results will be shown on the map upon successful completion of the `GeoprocessingJob`.",
        tags: new[] { "analysis", "density", "geoprocessing", "hot spots", "hotspots" })]
    public partial class AnalyzeHotspots
    {
        // URL for the geoprocessing service
        private const string _hotspotUrl =
            "https://sampleserver6.arcgisonline.com/arcgis/rest/services/911CallsHotspot/GPServer/911%20Calls%20Hotspot";

        // The geoprocessing task for hot spot analysis
        private GeoprocessingTask _hotspotTask;

        // The job that handles the communication between the application and the geoprocessing task
        private GeoprocessingJob _hotspotJob;

        public AnalyzeHotspots()
        {
            InitializeComponent();

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

        private async Task Initialize()
        {
            // Create a map with a topographic basemap
            MyMapView.Map = new Map(BasemapStyle.ArcGISTopographic);

            try
            {
                // Create a new geoprocessing task
                _hotspotTask = await GeoprocessingTask.CreateAsync(new Uri(_hotspotUrl));
            }
            catch (Exception e)
            {
                MessageBox.Show(e.ToString(), "Error");
            }
        }

        private async void OnAnalyzeHotspotsClicked(object sender, RoutedEventArgs e)
        {
            // Clear any existing results
            MyMapView.Map.OperationalLayers.Clear();

            // Show the waiting indication
            ShowBusyOverlay();

            // Get the 'from' and 'to' dates from the date pickers for the geoprocessing analysis
            DateTime myFromDate = FromDate.SelectedDate.Value;
            DateTime myToDate = ToDate.SelectedDate.Value;

            // The end date must be at least one day after the start date
            if (myToDate <= myFromDate.AddDays(1))
            {
                // Show error message
                MessageBox.Show(
                    "Please select valid time range. There has to be at least one day in between To and From dates.",
                    "Invalid date range");

                // Remove the waiting
                ShowBusyOverlay(false);
                return;
            }

            // Create the parameters that are passed to the used geoprocessing task
            GeoprocessingParameters myHotspotParameters = new GeoprocessingParameters(GeoprocessingExecutionType.AsynchronousSubmit);

            // Construct the date query
            string myQueryString = string.Format("(\"DATE\" > date '{0:yyyy-MM-dd} 00:00:00' AND \"DATE\" < date '{1:yyyy-MM-dd} 00:00:00')", myFromDate, myToDate);

            // Add the query that contains the date range used in the analysis
            myHotspotParameters.Inputs.Add("Query", new GeoprocessingString(myQueryString));

            // Create job that handles the communication between the application and the geoprocessing task
            _hotspotJob = _hotspotTask.CreateJob(myHotspotParameters);
            try
            {
                // Execute the geoprocessing analysis and wait for the results
                GeoprocessingResult myAnalysisResult = await _hotspotJob.GetResultAsync();

                // Add results to a map using map server from a geoprocessing task
                // Load to get access to full extent
                await myAnalysisResult.MapImageLayer.LoadAsync();

                // Add the analysis layer to the map view
                MyMapView.Map.OperationalLayers.Add(myAnalysisResult.MapImageLayer);

                // Zoom to the results
                await MyMapView.SetViewpointAsync(new Viewpoint(myAnalysisResult.MapImageLayer.FullExtent));
            }
            catch (TaskCanceledException)
            {
                // This is thrown if the task is canceled. Ignore.
            }
            catch (Exception ex)
            {
                // Display error messages if the geoprocessing task fails
                if (_hotspotJob.Status == JobStatus.Failed && _hotspotJob.Error != null)
                    MessageBox.Show("Executing geoprocessing failed. " + _hotspotJob.Error.Message, "Geoprocessing error");
                else
                    MessageBox.Show("An error occurred. " + ex, "Sample error");
            }
            finally
            {
                // Remove the waiting
                ShowBusyOverlay(false);
            }
        }

        private void OnCancelTaskClicked(object sender, RoutedEventArgs e)
        {
            // Cancel current geoprocessing job
            if (_hotspotJob.Status == JobStatus.Started)
                _hotspotJob.CancelAsync();

            // Hide the waiting indication
            ShowBusyOverlay(false);
        }

        private void ShowBusyOverlay(bool visibility = true)
        {
            // Function to toggle the visibility of interaction with the GUI for the user to
            // specify dates for the hot spot analysis. When the analysis is running, the GUI
            // for changing the dates is 'grayed-out' and the progress bar with a cancel
            // button (aka. waiting object) becomes active.

            if (visibility)
            {
                // The geoprocessing task is processing. The busyOverly is present.
                BusyOverlay.Visibility = Visibility.Visible;
                Progress.IsIndeterminate = true;
            }
            else
            {
                // The user can interact with the date pickers. The waiting is invisible.
                BusyOverlay.Visibility = Visibility.Collapsed;
                Progress.IsIndeterminate = false;
            }
        }
    }
}