Recognises Rainbow Six: Siege icons.

Recogniser.cs

using ImageMagick;
using Newtonsoft.Json.Linq;
using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.IO;
using System.Net.Http;
using System.Threading.Tasks;

namespace SiegeOpDetector
{
    class Program
    {
        static HttpClient http = new HttpClient();
        const string CacheFolder = "cache/";
        const string Source = @"D:\dok_crop.png";

        static void Main(string[] args)
        {
            //CacheOperators().Wait();
            var bmtask = BestMatch(Source);
            bmtask.Wait();
            Console.WriteLine("Done: " + bmtask.Result);
            Console.ReadKey();
        }

        /// <summary>
        /// Finds the file with the best match out of the .shrink.png images.
        /// </summary>
        /// <param name="source"></param>
        /// <returns></returns>
        static async Task<string> BestMatch(string source, double minMetric = 0.70)
        {
            return await Task.Run(() =>
            {
                double bestMatch = minMetric;
                string bestFile = "";

                using (var imgSource = new MagickImage(source))
                {
                    foreach (string file in Directory.EnumerateFiles(CacheFolder, "*.shrink.png"))
                    {
                        using (var imgShrink = new MagickImage(file))
                        {
                            double diff = imgSource.Compare(imgShrink, new ErrorMetric());
                            if (diff > bestMatch)
                            {
                                bestMatch = diff;
                                bestFile = file;
                            }
                        }
                    }
                }

                return bestFile;
            });
        }

        /// <summary>
        /// Downloads the icon for every operator, then shrinks them and stores both images into the file cache.
        /// </summary>
        /// <returns></returns>
        static async Task CacheOperators()
        {
            //Make sure cache exists
            if (!Directory.Exists(CacheFolder))
                Directory.CreateDirectory(CacheFolder);

            //Get all the operators
            JObject response = await GetOperators();            
            foreach (var x in response)
            {
                //Download their image and crop their images.
                string name         = x.Key;
                string url          = x.Value["img"].ToString();
                string path         = Path.Combine(CacheFolder, name + ".png");
                string pathShrink   = Path.Combine(CacheFolder, name + ".shrink.png");

                Console.WriteLine("Processing " + name);

                //Download file
                await DownloadFileAsync(new Uri(url), path);

                //Shrink the file
                using (var source = new MagickImage(path))
                {
                    source.Crop(new MagickGeometry(19, 21, 89, 89));
                    source.Scale(22, 22);
                    source.RePage();
                    source.Write(pathShrink);
                }
            }
        }

        /// <summary>
        /// Downloads a list of operators
        /// </summary>
        /// <returns></returns>
        static async Task<JObject> GetOperators()
        {
            HttpResponseMessage response = await http.GetAsync("https://d.lu.je/siege/operators.php?username=KommadantKlink");
            if (response.IsSuccessStatusCode)
            {
                string content = await response.Content.ReadAsStringAsync();
                return JObject.Parse(content);
            }

            return null;
        }

        /// <summary>
        /// Downloads a file
        /// </summary>
        /// <param name="requestUri"></param>
        /// <param name="filename"></param>
        /// <returns></returns>
        public static async Task DownloadFileAsync(Uri requestUri, string filename)
        {
            if (filename == null)
                throw new ArgumentNullException("filename");

            using (var request = new HttpRequestMessage(HttpMethod.Get, requestUri))
            {
                using (Stream contentStream = await (await http.SendAsync(request)).Content.ReadAsStreamAsync(), stream = new FileStream(filename, FileMode.Create, FileAccess.Write, FileShare.None))
                {
                    await contentStream.CopyToAsync(stream);
                }
            }
        }

    }
}