source: binary-improvements/MapRendering/Web/Handlers/ItemIconHandler.cs@ 270

using System;
using System.Collections.Generic;
using System.Net;
using System.Threading;

using UnityEngine;

namespace AllocsFixes.NetConnections.Servers.Web.Handlers
{
        public class ItemIconHandler : PathHandler {
                private static ItemIconHandler instance = null;
                public static ItemIconHandler Instance {
                        get { return instance; }
                }

                private string staticPart;
                private bool logMissingFiles;
                private Dictionary<string, byte[]> icons = new Dictionary<string, byte[]> ();
                private bool loaded = false;

                public ItemIconHandler (string staticPart, bool logMissingFiles, string moduleName = null) : base(moduleName) {
                        this.staticPart = staticPart;
                        this.logMissingFiles = logMissingFiles;
                        ItemIconHandler.instance = this;
                }

                public override void HandleRequest (HttpListenerRequest req, HttpListenerResponse resp, WebConnection user, int permissionLevel) {
                        if (!loaded) {
                                if (!LoadIcons ()) {
                                        resp.StatusCode = (int)HttpStatusCode.NotFound;
                                        Log.Out ("Web:IconHandler: Could not load icons");
                                        return;
                                }
                        }

                        string requestFileName = req.Url.AbsolutePath.Remove (0, staticPart.Length);
                        requestFileName = requestFileName.Remove (requestFileName.LastIndexOf ('.'));

                        if (icons.ContainsKey (requestFileName) && req.Url.AbsolutePath.ToLower ().EndsWith (".png")) {
                                resp.ContentType = MimeType.GetMimeType (".png");

                                byte[] itemIconData = icons [requestFileName];

                                resp.ContentLength64 = itemIconData.Length;
                                resp.OutputStream.Write (itemIconData, 0, itemIconData.Length);
                        } else {
                                resp.StatusCode = (int)HttpStatusCode.NotFound;
                                if (logMissingFiles) {
                                        Log.Out ("Web:IconHandler:FileNotFound: \"" + req.Url.AbsolutePath + "\" ");
                                }
                                return;
                        }
                }

                public bool LoadIcons () {
                        lock (icons) {
                                if (loaded) {
                                        return true;
                                }

                                MicroStopwatch microStopwatch = new MicroStopwatch ();

                                GameObject atlasObj = GameObject.Find ("/NGUI Root (2D)/ItemIconAtlas");
                                if (atlasObj == null) {
                                        Log.Error ("Web:IconHandler: Atlas object not found");
                                        loaded = true;
                                        return false;
                                }
                                DynamicUIAtlas atlas = atlasObj.GetComponent<DynamicUIAtlas> ();
                                if (atlas == null) {
                                        Log.Error ("Web:IconHandler: Atlas component not found");
                                        loaded = true;
                                        return false;
                                }

                                Dictionary<string, List<Color>> tintedIcons = new Dictionary<string, List<Color>> ();
                                foreach (ItemClass ic in ItemClass.list) {
                                        if (ic != null) {
                                                Color tintColor = ic.GetIconTint ();
                                                if (tintColor != Color.white) {
                                                        string name = ic.GetIconName ();
                                                        if (!tintedIcons.ContainsKey (name)) {
                                                                tintedIcons.Add (name, new List<Color> ());
                                                        }
                                                        List<Color> list = tintedIcons [name];
                                                        list.Add (tintColor);
                                                }
                                        }
                                }

                                Texture2D atlasTex = atlas.texture as Texture2D;

                                foreach (UISpriteData data in atlas.spriteList) {
                                        string name = data.name;
                                        Texture2D tex = new Texture2D (data.width, data.height, TextureFormat.ARGB32, false);
                                        tex.SetPixels (atlasTex.GetPixels (data.x, atlasTex.height - data.height - data.y, data.width, data.height));

                                        icons.Add (name + "__FFFFFF", tex.EncodeToPNG ());

                                        if (tintedIcons.ContainsKey (name)) {
                                                foreach (Color c in tintedIcons [name]) {
                                                        string tintedName = name + "__" + AllocsUtils.ColorToHex (c);
                                                        if (!icons.ContainsKey (tintedName)) {
                                                                Texture2D tintedTex = new Texture2D (data.width, data.height, TextureFormat.ARGB32, false);

                                                                for (int x = 0; x < data.width; x++) {
                                                                        for (int y = 0; y < data.height; y++) {
                                                                                tintedTex.SetPixel (x, y, tex.GetPixel (x, y) * c);
                                                                        }
                                                                }

                                                                icons.Add (tintedName, tintedTex.EncodeToPNG ());

                                                                UnityEngine.Object.Destroy (tintedTex);
                                                        }
                                                }
                                        }

                                        UnityEngine.Object.Destroy (tex);
                                }

                                loaded = true;
                                Log.Out ("Web:IconHandler: Icons loaded - {0} ms", microStopwatch.ElapsedMilliseconds);

                                return true;
                        }
                }
        }
}