Start work on optimising /imgprint, start by creating faster pixel getter class.

Drawing/Image/PixelGetter.cs

@@ -0,0 +1,95 @@
+/*
+    Copyright 2015 MCGalaxy
+        
+    Dual-licensed under the Educational Community License, Version 2.0 and
+    the GNU General Public License, Version 3 (the "Licenses"); you may
+    not use this file except in compliance with the Licenses. You may
+    obtain a copy of the Licenses at
+    
+    http://www.opensource.org/licenses/ecl2.php
+    http://www.gnu.org/licenses/gpl-3.0.html
+    
+    Unless required by applicable law or agreed to in writing,
+    software distributed under the Licenses are distributed on an "AS IS"
+    BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
+    or implied. See the Licenses for the specific language governing
+    permissions and limitations under the Licenses.
+ */
+using System;
+using System.Drawing;
+using System.Drawing.Imaging;
+
+namespace MCGalaxy.Drawing {
+    
+    public sealed class PixelGetter : IDisposable {
+        
+        Bitmap bmp;
+        BitmapData data;
+        public PixelGetter(Bitmap bmp) {
+            this.bmp = bmp;
+        }
+        
+        public void Init() {
+            bool fastPath = bmp.PixelFormat == PixelFormat.Format32bppRgb
+                || bmp.PixelFormat == PixelFormat.Format32bppArgb;
+            if (!fastPath) return;
+            // We can only use the fast path for 32bpp bitmaps
+            
+            Rectangle r = new Rectangle(0, 0, bmp.Width, bmp.Height);
+            data = bmp.LockBits(r, ImageLockMode.ReadOnly, bmp.PixelFormat);
+        }
+        
+        public void Iterate(Action<Pixel> callback) {
+            if (data == null) IterateSlow(callback);
+            else IterateFast(callback);
+        }
+        
+        unsafe void IterateFast(Action<Pixel> callback) {
+            Pixel pixel;
+            int width = bmp.Width, height = bmp.Height;
+            byte* scan0 = (byte*)data.Scan0;
+                
+            for (int y = 0; y < height; y++) {
+                pixel.Y = (ushort)y;
+                int* row = (int*)(scan0 + y * data.Stride);
+                for (int x = 0; x < width; x++) {
+                    pixel.X = (ushort)x;
+                    int argb = row[x];
+                    
+                    pixel.R = (byte)(argb >> 16);
+                    pixel.G = (byte)(argb >> 8);
+                    pixel.B = (byte)(argb >> 8);
+                    callback(pixel);
+                }
+            }
+        }
+        
+        void IterateSlow(Action<Pixel> callback) {
+            Pixel pixel;
+            int width = bmp.Width, height = bmp.Height;
+            for (int y = 0; y < height; y++)
+                for (int x = 0; x < width; x++)
+            {
+                pixel.X = (ushort)x; pixel.Y = (ushort)y;
+                Color col = bmp.GetPixel(x, y);
+                int argb = col.ToArgb(); // R/G/B properties incur overhead
+                
+                pixel.R = (byte)(argb >> 16);
+                pixel.G = (byte)(argb >> 8);
+                pixel.B = (byte)(argb >> 8);
+                callback(pixel);
+            }
+        }
+        
+        public void Dispose() {
+            if (data != null) bmp.UnlockBits(data);
+            data = null;
+            bmp = null;
+        }
+    }
+    
+    public struct Pixel {
+        public ushort X, Y;
+        public byte R, G, B;
+    }
+}

MCGalaxy_.csproj

@@ -453,6 +453,7 @@
     <Compile Include="Drawing\Flip.cs" />
     <Compile Include="Drawing\Image\ImagePalette.cs" />
     <Compile Include="Drawing\Image\IPalette.cs" />
+    <Compile Include="Drawing\Image\PixelGetter.cs" />
     <Compile Include="Drawing\TransformFactories\SimpleTransforms.cs" />
     <Compile Include="Drawing\TransformFactories\TransformFactory.cs" />
     <Compile Include="Drawing\Transform\SimpleTransforms.cs" />