Hillshade renderer

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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 ArcGIS.Samples.Managers;
using Esri.ArcGISRuntime.Mapping;
using Esri.ArcGISRuntime.Rasters;

namespace ArcGIS.Samples.RasterHillshade
{
    [ArcGIS.Samples.Shared.Attributes.Sample(
        name: "Hillshade renderer",
        category: "Layers",
        description: "Apply a hillshade renderer to a raster.",
        instructions: "Choose and adjust the settings to update the hillshade renderer on the raster layer. The sample allows you to change the Altitude, Azimuth, and Slope Type.",
        tags: new[] { "altitude", "angle", "azimuth", "raster", "slope", "visualization" })]
    [ArcGIS.Samples.Shared.Attributes.OfflineData("134d60f50e184e8fa56365f44e5ce3fb")]
    public partial class RasterHillshade : ContentPage
    {
        // Constant to store a z-factor (conversion constant) applied to the hillshade.
        // If needed, this can be used to convert z-values to the same unit as the x/y coordinates or to apply a vertical exaggeration.
        private const double ZFactor = 1.0;

        // Constants to store the Pixel Size Power and Pixel Size Factor values.
        // Use these to account for altitude changes (scale) as the viewer zooms in and out (recommended when using worldwide datasets).
        private const double PixelSizePower = 1.0;
        private const double PixelSizeFactor = 1.0;

        // Constant to store the bit depth (pixel depth), which determines the range of values that the hillshade raster can store.
        private const int PixelBitDepth = 8;

        // Store a reference to the layer
        private RasterLayer _rasterLayer;

        // Store a dictionary of slope types
        private Dictionary<string, SlopeType> _slopeTypeValues = new Dictionary<string, SlopeType>();

        public RasterHillshade()
        {
            InitializeComponent();

            // Call a function to set up the map
            _ = Initialize();
        }

        private async Task Initialize()
        {
            // Create a map with a streets basemap
            Map map = new Map(BasemapStyle.ArcGISStreets);

            // Get the file name for the local raster dataset
            string filepath = GetRasterPath();

            // Load the raster file
            Raster rasterFile = new Raster(filepath);

            try
            {
                // Create and load a new raster layer to show the image
                _rasterLayer = new RasterLayer(rasterFile);
                await _rasterLayer.LoadAsync();

                // Enable the apply renderer button when the layer loads.
                ApplyHillshadeButton.IsEnabled = true;

                // Create a viewpoint with the raster's full extent
                Viewpoint fullRasterExtent = new Viewpoint(_rasterLayer.FullExtent);

                // Set the initial viewpoint for the map
                map.InitialViewpoint = fullRasterExtent;

                // Add the layer to the map
                map.OperationalLayers.Add(_rasterLayer);

                // Add the map to the map view
                MyMapView.Map = map;

                // Add slope type values to the dictionary and picker
                foreach (object slope in Enum.GetValues(typeof(SlopeType)))
                {
                    _slopeTypeValues.Add(Enum.GetName((SlopeType)slope), (SlopeType)slope);
                }
                SlopeTypePicker.ItemsSource = Enum.GetNames(typeof(SlopeType));

                // Select the "Scaled" slope type enum
                SlopeTypePicker.SelectedIndex = 2;
            }
            catch (Exception e)
            {
                await Application.Current.MainPage.DisplayAlert("Error", e.ToString(), "OK");
            }
        }

        private void ApplyHillshadeButton_Click(object sender, EventArgs e)
        {
            // Get the current parameter values
            double altitude = AltitudeSlider.Value;
            double azimuth = AzimuthSlider.Value;
            SlopeType typeOfSlope = _slopeTypeValues[SlopeTypePicker.SelectedItem.ToString()];

            // Create a hillshade renderer that uses the values selected by the user
            HillshadeRenderer hillshadeRenderer = new HillshadeRenderer(altitude, azimuth, ZFactor, typeOfSlope, PixelSizeFactor, PixelSizePower, PixelBitDepth);

            // Apply the new renderer to the raster layer
            _rasterLayer.Renderer = hillshadeRenderer;
        }

        private static string GetRasterPath()
        {
            return DataManager.GetDataFolder("134d60f50e184e8fa56365f44e5ce3fb", "srtm-hillshade", "srtm.tiff");
        }
    }
}