source: binary-improvements/MapRendering/Web/Handlers/ItemIconHandler.cs@ 251

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 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;
                }

                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;
                                }
                        }

            // BEGIN CHANGED BY PSOUZA4
                        string requestFileName = req.Url.AbsolutePath.Remove (0, staticPart.Length);
                        requestFileName = requestFileName.Remove (requestFileName.LastIndexOf ('.'));

            string requestColorTintHex = string.Empty;
            
            // Chose a split instead of using a querystring variable in the URI, but that may arguably be cleaner
            if (requestFileName.Contains("@@")) {
                try {
                    string[] tempTintingOptions = requestFileName.Split (new string[] { "@@" }, StringSplitOptions.RemoveEmptyEntries);
                    requestFileName = tempTintingOptions [0];
                    requestColorTintHex = tempTintingOptions [1].Trim ().ToUpper ();
                }
                catch { }
            }

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

                byte[] itemIconData = icons [requestFileName];

                // Note: optionally split this code into a ImageMultiplyBlend method
                if (!string.IsNullOrEmpty (requestColorTintHex) && (requestColorTintHex != "FFFFFF")) {
                    try {
                        System.Drawing.Color colorTint = System.Drawing.ColorTranslator.FromHtml ("#" + requestColorTintHex);
                        System.Drawing.Bitmap image = (System.Drawing.Bitmap)PetesUtils.GetImageFromBytes (itemIconData);

                        for (var x = 0; x < image.Width; x++) {
                            for (int y = 0; y < image.Height; y++) {
                                System.Drawing.Color originalColor = image.GetPixel (x, y);
                                System.Drawing.Color changedColor = originalColor;

                                // Only change the icon tinting if the alpha channel is fully opaque
                                if (originalColor.A == 255) {
                                    // based on http://stackoverflow.com/questions/3837757/multiply-two-images-in-c-sharp-as-multiply-two-layers-in-photoshop

                                    double component_R = (((double)originalColor.R) * ((double)colorTint.R)) / 255.0;
                                    double component_G = (((double)originalColor.G) * ((double)colorTint.G)) / 255.0;
                                    double component_B = (((double)originalColor.B) * ((double)colorTint.B)) / 255.0;

                                    if (component_R > 255.0) component_R = 255.0;
                                    if (component_G > 255.0) component_G = 255.0;
                                    if (component_B > 255.0) component_B = 255.0;

                                    // multiply blend shouldn't ever calculate below 0, but for completeness let's leave in this logic
                                    if (component_R < 0.0) component_R = 0.0;
                                    if (component_G < 0.0) component_G = 0.0;
                                    if (component_B < 0.0) component_B = 0.0;

                                    changedColor = System.Drawing.Color.FromArgb (originalColor.A, (int)component_R, (int)component_G, (int)component_B);
                                }                                

                                image.SetPixel (x, y, changedColor);
                            }
                        }

                        itemIconData = PetesUtils.SaveImage_ToBytes (image, true);
                    }
                    catch { }
                }

                                resp.ContentLength64 = itemIconData.Length;
                                resp.OutputStream.Write (itemIconData, 0, itemIconData.Length);
                // END CHANGED BY PSOUZA4
                        } else {
                                resp.StatusCode = (int)HttpStatusCode.NotFound;
                                if (logMissingFiles)
                                        Log.Out ("Web:IconHandler:FileNotFound: \"" + req.Url.AbsolutePath + "\" ");
                                return;
                        }
                }

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

                                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;
                                }

                                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));
                                        byte[] pixData = tex.EncodeToPNG ();

                                        icons.Add (name, pixData);
                                        UnityEngine.Object.Destroy (tex);
                                }

                                loaded = true;
                                Log.Out ("Web:IconHandler: Icons loaded");

                                return true;
                        }
                }
        }
}