ColorTranslator.cs

//
// System.Drawing.ColorTranslator.cs
//
// Authors:
//	Dennis Hayes (dennish@raytek.com)
//	Ravindra (rkumar@novell.com)
//	Sebastien Pouliot  <sebastien@ximian.com>
//
// Copyright (C) 2001 Ximian, Inc.  http://www.ximian.com
// Copyright (C) 2004,2006-2007 Novell, Inc (http://www.novell.com)
//
// Permission is hereby granted, free of charge, to any person obtaining
// a copy of this software and associated documentation files (the
// "Software"), to deal in the Software without restriction, including
// without limitation the rights to use, copy, modify, merge, publish,
// distribute, sublicense, and/or sell copies of the Software, and to
// permit persons to whom the Software is furnished to do so, subject to
// the following conditions:
// 
// The above copyright notice and this permission notice shall be
// included in all copies or substantial portions of the Software.
// 
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
// EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
// MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
// NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
// LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
// OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
// WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
//
 
using System.ComponentModel;
using System.Globalization;

namespace System.Drawing {

	public sealed class ColorTranslator {

		private ColorTranslator ()
		{
		}

		public static Color FromHtml (string htmlColor)
		{
			if ((htmlColor == null) || (htmlColor.Length == 0))
				return Color.Empty;

			switch (htmlColor.ToLowerInvariant ()) {
			case "buttonface":
			case "threedface":		
				return SystemColors.Control;
			case "buttonhighlight":
			case "threedlightshadow":
				return SystemColors.ControlLightLight;
			case "buttonshadow":
				return SystemColors.ControlDark;
			case "captiontext":
				return SystemColors.ActiveCaptionText;
			case "threeddarkshadow":
				return SystemColors.ControlDarkDark;
			case "threedhighlight":
				return SystemColors.ControlLight;
			case "background":
				return SystemColors.Desktop;
			case "buttontext":
				return SystemColors.ControlText;
			case "infobackground":
				return SystemColors.Info;
			// special case for Color.LightGray versus html's LightGrey (#340917)
			case "lightgrey":
				return Color.LightGray;
			}
			
			TypeConverter converter = TypeDescriptor.GetConverter (typeof (Color));
			return (Color) converter.ConvertFromString (htmlColor);
		}

		internal static Color FromBGR (int bgr)
		{
			Color result = Color.FromArgb (0xFF, (bgr & 0xFF), ((bgr >> 8) & 0xFF), ((bgr >> 16) & 0xFF));
			Color known = KnownColors.FindColorMatch (result);
			return (known.IsEmpty) ? result : known;
		}

		public static Color FromOle (int oleColor)
		{
			// OleColor format is BGR
			return FromBGR (oleColor);
		}

		public static Color FromWin32 (int win32Color)
		{
			// Win32Color format is BGR
			return FromBGR (win32Color);
		}

		public static string ToHtml (Color c)
		{
			if (c.IsEmpty)
				return String.Empty;

			if (c.IsSystemColor) {
				KnownColor kc = c.ToKnownColor ();
				switch (kc) {
				case KnownColor.ActiveBorder:
				case KnownColor.ActiveCaption:
				case KnownColor.AppWorkspace:
				case KnownColor.GrayText:
				case KnownColor.Highlight:
				case KnownColor.HighlightText:
				case KnownColor.InactiveBorder:
				case KnownColor.InactiveCaption:
				case KnownColor.InactiveCaptionText:
				case KnownColor.InfoText:
				case KnownColor.Menu:
				case KnownColor.MenuText:
				case KnownColor.ScrollBar:
				case KnownColor.Window:
				case KnownColor.WindowFrame:
				case KnownColor.WindowText:
					return KnownColors.GetName (kc).ToLower (CultureInfo.InvariantCulture);

				case KnownColor.ActiveCaptionText:
					return "captiontext";
				case KnownColor.Control:
					return "buttonface";
				case KnownColor.ControlDark:
					return "buttonshadow";
				case KnownColor.ControlDarkDark:
					return "threeddarkshadow";
				case KnownColor.ControlLight:
					return "buttonface";
				case KnownColor.ControlLightLight:
					return "buttonhighlight";
				case KnownColor.ControlText:
					return "buttontext";
				case KnownColor.Desktop:
					return "background";
				case KnownColor.HotTrack:
					return "highlight";
				case KnownColor.Info:
					return "infobackground";

				default:
					return String.Empty;
				}
			}

			if (c.IsNamedColor) {
				if (c == Color.LightGray)
					return "LightGrey";
				else
					return c.Name;
			}

			return FormatHtml (c.R, c.G, c.B);
		}

		static char GetHexNumber (int b)
		{
			return (char) (b > 9 ? 55 + b : 48 + b);
		}

		static string FormatHtml (int r, int g, int b)
		{
			char [] htmlColor = new char [7];
			htmlColor [0] = '#';
			htmlColor [1] = GetHexNumber ((r >> 4) & 15);
			htmlColor [2] = GetHexNumber (r & 15);
			htmlColor [3] = GetHexNumber ((g >> 4) & 15);
			htmlColor [4] = GetHexNumber (g & 15);
			htmlColor [5] = GetHexNumber ((b >> 4) & 15);
			htmlColor [6] = GetHexNumber (b & 15);

			return new string (htmlColor);
		}

		public static int ToOle (Color c)
		{
			// OleColor format is BGR, same as Win32
			return  ((c.B << 16) | (c.G << 8) | c.R);
		}

		public static int ToWin32 (Color c)
		{
			// Win32Color format is BGR, Same as OleColor
			return  ((c.B << 16) | (c.G << 8) | c.R);
		}
	}
}