Fix for bug 1444, the WuQuantizer doesn't work if the colors are already less than 256 so we just create a 8bpp image from the source.

git-svn-id: http://svn.code.sf.net/p/greenshot/code/trunk@2451 7dccd23d-a4a3-4e1f-8c07-b4c1b4018ab4

Greenshot/Drawing/Surface.cs

@@ -533,7 +533,7 @@ namespace Greenshot.Drawing {
 		/// <param name="memento">The memento implementing the undo</param>
 		public void MakeUndoable(IMemento memento, bool allowMerge) {
 			if (inUndoRedo) {
-				throw new InvalidOperationException("Involking do within an undo/redo action.");
+				throw new InvalidOperationException("Invoking do within an undo/redo action.");
 			}
 			if (memento != null) {
 				bool allowPush = true;

GreenshotPlugin/Core/ImageHelper.cs

@@ -1199,20 +1199,21 @@ namespace GreenshotPlugin.Core {
 		/// <param name="backgroundColor">The color to fill with, or Color.Empty to take the default depending on the pixel format</param>
 		/// <param name="horizontalResolution"></param>
 		/// <param name="verticalResolution"></param>
-		/// <returns></returns>
+		/// <returns>Bitmap</returns>
 		public static Bitmap CreateEmpty(int width, int height, PixelFormat format, Color backgroundColor, float horizontalResolution, float verticalResolution) {
 			// Create a new "clean" image
 			Bitmap newImage = new Bitmap(width, height, format);
 			newImage.SetResolution(horizontalResolution, verticalResolution);
-
-			using (Graphics graphics = Graphics.FromImage(newImage)) {
-				// Make sure the background color is what we want (transparent or white, depending on the pixel format)
-				if (!Color.Empty.Equals(backgroundColor)) {
-					graphics.Clear(backgroundColor);
-				} else if (Image.IsAlphaPixelFormat(format)) {
-					graphics.Clear(Color.Transparent);
-				} else {
-					graphics.Clear(Color.White);
+			if (format != PixelFormat.Format8bppIndexed) {
+				using (Graphics graphics = Graphics.FromImage(newImage)) {
+					// Make sure the background color is what we want (transparent or white, depending on the pixel format)
+					if (!Color.Empty.Equals(backgroundColor)) {
+						graphics.Clear(backgroundColor);
+					} else if (Image.IsAlphaPixelFormat(format)) {
+						graphics.Clear(Color.Transparent);
+					} else {
+						graphics.Clear(Color.White);
+					}
 				}
 			}
 			return newImage;

GreenshotPlugin/Core/ImageOutput.cs

@@ -264,8 +264,8 @@ namespace GreenshotPlugin.Core {
 					LOG.InfoFormat("Image with format {0} has {1} colors", imageToSave.PixelFormat, colorCount);
 					if (outputSettings.ReduceColors || colorCount < 256) {
 						try {
-							LOG.Info("Reducing colors on bitmap to 255.");
-							tmpImage = quantizer.GetQuantizedImage(255);
+							LOG.Info("Reducing colors on bitmap to 256.");
+							tmpImage = quantizer.GetQuantizedImage(256);
 							if (disposeImage) {
 								imageToSave.Dispose();
 							}

GreenshotPlugin/Core/QuantizerHelper.cs

@@ -184,10 +184,52 @@ namespace GreenshotPlugin.Core {
 			return colorCount;
 		}
 
+		/// <summary>
+		/// Reindex the 24/32 BPP (A)RGB image to a 8BPP
+		/// </summary>
+		/// <returns>Bitmap</returns>
+		public Bitmap SimpleReindex() {
+			List<Color> colors = new List<Color>();
+			Dictionary<Color, byte> lookup = new Dictionary<Color, byte>();
+			using (BitmapBuffer bbbDest = new BitmapBuffer(resultBitmap, false)) {
+				bbbDest.Lock();
+				using (BitmapBuffer bbbSrc = new BitmapBuffer(sourceBitmap, false)) {
+					bbbSrc.Lock();
+					byte index;
+					for (int y = 0; y < bbbSrc.Height; y++) {
+						for (int x = 0; x < bbbSrc.Width; x++) {
+							Color color = bbbSrc.GetColorAt(x, y);
+							if (lookup.ContainsKey(color)) {
+								index = lookup[color];
+							} else {
+								colors.Add(color);
+								index = (byte)(colors.Count - 1);
+								lookup.Add(color, index);
+							}
+							bbbDest.SetColorIndexAt(x, y, index);
+						}
+					}
+				}
+			}
+
+			// generates palette
+			ColorPalette imagePalette = resultBitmap.Palette;
+			for (Int32 paletteIndex = 0; paletteIndex < colorCount; paletteIndex++) {
+				imagePalette.Entries[paletteIndex] = colors[paletteIndex];
+			}
+			resultBitmap.Palette = imagePalette;
+			return resultBitmap;
+		}
+
 		/// <summary>
 		/// Get the image
 		/// </summary>
 		public Bitmap GetQuantizedImage(int allowedColorCount) {
+			if (colorCount < 256) {
+				// Simple logic to reduce to 8 bit
+				LOG.Info("Using simple copy, no quantizing needed!");
+				return SimpleReindex();
+			}
 			// preprocess the colors
 			CalculateMoments();
 			LOG.Info("Calculated the moments...");
@@ -302,9 +344,9 @@ namespace GreenshotPlugin.Core {
 				}
 			}
 
-			ColorPalette imagePalette = resultBitmap.Palette;
 
 			// generates palette
+			ColorPalette imagePalette = resultBitmap.Palette;
 			for (Int32 paletteIndex = 0; paletteIndex < allowedColorCount; paletteIndex++) {
 				if (sums[paletteIndex] > 0) {
 					reds[paletteIndex] /= sums[paletteIndex];