WYSIWYG Color and Font CommonDialogs

using System;
using System.ComponentModel;
using System.Diagnostics;
using System.Drawing;
using System.Runtime.InteropServices;
using System.Windows.Forms;

// RightToCopy & PublishAndPerish: OrlandoCurioso 2005

// default template file, include file: Platform SDK/Include/Color.dlg, ColorDlg.h

namespace OC.Windows.Forms
{
	/// <summary>
	/// ColorDialog enhanced to provide current user choice, while running.
	/// Caveat: Needs FullOpen == true for WYSIWYG functionality.
	/// </summary>
	public partial class ocColorDialog : ColorDialog, IColorChangeNotify
	{
		/// <summary>
		/// Occurs when user chooses color in open ColorDialog.
		/// </summary>
		[DescriptionAttribute("Occurs when user chooses color in open ColorDialog.")]
		public event EventHandler<ColorChangedEventArgs> ColorChanged;

		public ocColorDialog() : base()
		{
			base.AllowFullOpen = true;
			base.FullOpen = true;
		}

		#region Interop

		#region Constants ColorDlg.h

		//private const int COLOR_HUE = 703;		// Edit
		//private const int COLOR_SAT = 704;		// Edit
		//private const int COLOR_LUM = 705;		// Edit
		private const int COLOR_RED = 706;		  // Edit
		private const int COLOR_GREEN = 707;		// Edit
		private const int COLOR_BLUE = 708;		 // Edit
		private const int COLOR_CURRENT = 709;
		//private const int COLOR_RAINBOW = 710;
		private const int COLOR_ADD = 712;		  // Button: "&Add Custom Colors"
		private const int COLOR_MIX = 719;		  // Button: "&Define Colors >>"
		//private const int COLOR_BOX1 = 720;	   // Static: basic colors
		//private const int COLOR_CUSTOM1 = 721;	// Static: custom colors

		//private const int COLOR_HUEACCEL = 723;   // Label Edit
		//private const int COLOR_SATACCEL = 724;   // Label Edit
		//private const int COLOR_LUMACCEL = 725;   // Label Edit
		//private const int COLOR_REDACCEL = 726;   // Label Edit
		//private const int COLOR_GREENACCEL = 727; // Label Edit
		//private const int COLOR_BLUEACCEL = 728;  // Label Edit

		#endregion

		#region Constants CommDlg.h

		//private const int CC_ENABLETEMPLATEHANDLE = 0x00000040;

		//private const int CDM_SETDEFAULTFOCUS = 0x451;

		//private const string COLOROKSTRINGW = "commdlg_ColorOK";
		//private const string SETRGBSTRINGW = "commdlg_SetRGBColor";

		#endregion

		[DllImport("user32.dll")]
		private static extern IntPtr GetDlgItem(IntPtr hDlg, int nIDDlgItem);

		[DllImport("user32.dll")]
		static extern uint GetDlgItemInt(IntPtr hDlg, int nIDDlgItem, IntPtr lpTranslated, bool bSigned);

		[DllImport("user32.dll")]
		private static extern bool ShowWindow(IntPtr hWnd, int nCmdShow);

		private const int WM_DESTROY = 0x0002;
		private const int WM_PAINT = 0x000F;
		private const int WM_INITDIALOG = 0x0110;
		private const int WM_COMMAND = 0x0111;

		private const int BN_CLICKED = 0;

		#endregion

		#region Fields

		private IntPtr hDlg;
		private ColorLabelWnd colorLabelWnd;
		private Color lastColor;
		private bool _UseCancelEvent;
		private bool _SerializeCustom;

		#endregion

		/// <summary>
		/// Gets or sets the set of custom colors shown in the dialog box. The default value is null.
		/// Base.CustomColors is an int array.
		/// </summary>
		[Browsable(false), DesignerSerializationVisibility(0)]
		public new Color[] CustomColors
		{
			get
			{
				if (base.CustomColors == null) return null;
				Converter<int, Color> conv = delegate(int clr) { return ColorTranslator.FromWin32(clr); };
				return Array.ConvertAll<int, System.Drawing.Color>(base.CustomColors, conv);
			}
			set
			{
				_SerializeCustom = false;
				Converter<Color, int> conv = delegate(Color clr) { return ColorTranslator.ToWin32(clr); };
				base.CustomColors = Array.ConvertAll<System.Drawing.Color, int>(value, conv);
			}
		}

		[Browsable(false), DefaultValue(false)]
		public bool ShouldSerializeCustomColors
		{
			get { return _SerializeCustom; }
			set { _SerializeCustom = value; }
		}

		/// <summary>
		/// If user cancels, reset client to initial color by single ColorChanged event.
		/// </summary>
		[DefaultValue(false), DescriptionAttribute("If user cancels, reset client to initial color by single ColorChanged event.")]
		public bool UseCancelEvent
		{
			get { return _UseCancelEvent; }
			set { _UseCancelEvent = value; }
		}

		public override bool AllowFullOpen
		{
			set
			{
				Debug.Assert(value == true, "WYSIWYG functionality only with FullOpen set");
				base.AllowFullOpen = value;
			}
		}

		public override bool FullOpen
		{
			set
			{
				Debug.Assert(value == true, "WYSIWYG functionality only with FullOpen set");
				base.FullOpen = value;
			}
		}

		protected override bool RunDialog(IntPtr hwndOwner)
		{
			_SerializeCustom = false;

			lastColor = base.Color;

			bool result = base.RunDialog(hwndOwner);

			if (_UseCancelEvent && !result && ColorChanged != null)
			{
				// user cancelled, reset client
				ColorChanged(this, new ColorChangedEventArgs(base.Color));
			}

			return result;
		}

		protected override IntPtr HookProc(IntPtr hWnd, int msg, IntPtr wparam, IntPtr lparam)
		{
			switch (msg)
			{
				case WM_INITDIALOG:

					this.hDlg = hWnd;

					// get handle of Color Label
					IntPtr hChild = GetDlgItem(hWnd, COLOR_CURRENT);

					// start subclassing child
					colorLabelWnd = new ColorLabelWnd(this);
					colorLabelWnd.AssignHandle(hChild);

					// hide useless button (always disabled for FullOpen)
					ShowWindow(GetDlgItem(hWnd, COLOR_MIX), 0);	// SW_HIDE == 0
					break;

				case WM_COMMAND:
					// wParam: The low-order word contains the button's control identifier. The high-order word specifies the notification message.

					int wp = wparam.ToInt32();

					if (LOWORD(wp) == COLOR_ADD && HIWORD(wp) == BN_CLICKED)
					{
						_SerializeCustom = true;
					}

					break;

				case WM_DESTROY:

					// stop subclassing child
					colorLabelWnd.ReleaseHandle();
					this.hDlg = IntPtr.Zero;
					break;
			}

			return base.HookProc(hWnd, msg, wparam, lparam);
		}

		protected static int LOWORD(int dword)
		{
			return (dword & 0xffff);
		}

		protected static int HIWORD(int dword)
		{
			return ((dword >> 16) & 0xffff);
		}

		protected Color getColor()
		{
			// color from RGB editboxes
			int r = (int)GetDlgItemInt(this.hDlg, COLOR_RED, IntPtr.Zero, false);
			int g = (int)GetDlgItemInt(this.hDlg, COLOR_GREEN, IntPtr.Zero, false);
			int b = (int)GetDlgItemInt(this.hDlg, COLOR_BLUE, IntPtr.Zero, false);

			return Color.FromArgb(r, g, b);
		}

		#region IColorChangeNotify Members

		void IColorChangeNotify.ColorChangeNotify()
		{
			Color newColor = getColor();

			// Filter out unwanted events by comparing with stored color
			if (newColor != lastColor)
			{
				if (ColorChanged != null)
				{
					ColorChanged(this, new ColorChangedEventArgs(newColor));
				}
				lastColor = newColor;
			}
		}

		#endregion

		// Intercepts the WM_PAINT window message of the Color label.
		private class ColorLabelWnd : NativeWindow
		{
			public ColorLabelWnd(IColorChangeNotify dialog)
				: base()
			{
				this.dialog = dialog;
			}

			private IColorChangeNotify dialog;

			protected override void WndProc(ref Message m)
			{
				base.WndProc(ref m);

				// label has repainted, may indicate that user chose new color
				if (m.Msg == WM_PAINT)
				{
					dialog.ColorChangeNotify();
				}
			}
		}
	}

	public interface IColorChangeNotify
	{
		void ColorChangeNotify();
	}

	public class ColorChangedEventArgs : EventArgs
	{
		public ColorChangedEventArgs(Color currentColor)
		{
			_CurrentColor = currentColor;
		}
		private Color _CurrentColor;

		public Color CurrentColor
		{
			get { return _CurrentColor; }
		}
	}

}