Adobe Color Picker Clone

using System;
using System.ComponentModel;
using System.Drawing;
using System.Drawing.Drawing2D;
using System.Windows.Forms;

namespace DrawingEx.ColorManagement.ColorModels.Selection
{
	/// <summary>
	/// Zusammenfassung f�r ColorSelectionPlane.
	/// </summary>
	public class ColorSelectionPlane:Control
	{
		#region variables
		private Bitmap _bmp=new Bitmap(1,1);
		private double _x=0.0, _y=0.0;
		#endregion
		/// <summary>
		/// ctor
		/// </summary>
		[ToolboxItem(false)]
		public ColorSelectionPlane()
		{
			this.SetStyle(ControlStyles.AllPaintingInWmPaint |
				ControlStyles.DoubleBuffer |
				ControlStyles.UserPaint |
				ControlStyles.ResizeRedraw, true);
			base.Cursor=Cursors.Cross;
//			try
//			{
//				base.Cursor=new Cursor(this.GetType(),"ColorPicker.cur");
//			}
//			catch{}
		}
		#region helpers
		private Rectangle GetCursorBounds(double x, double y)
		{
			return new Rectangle(
				(int)(x*(double)(this.Width-3))-4,
				(int)(y*(double)(this.Height-3))-4,
				10,10);
		}

		#endregion
		#region controller
		protected override void OnSizeChanged(EventArgs e)
		{
			base.OnSizeChanged (e);
			//construct new bitmap
			if(_bmp!=null)
				_bmp.Dispose();
			_bmp=new Bitmap(Math.Max(1,this.Width-2),Math.Max(1,this.Height-2),
				System.Drawing.Imaging.PixelFormat.Format32bppArgb);
		}
		protected override void OnPaint(PaintEventArgs e)
		{
			base.OnPaint (e);
			if(_bmp==null) return;
			e.Graphics.DrawImageUnscaled(_bmp,1,1);
			e.Graphics.SmoothingMode=
				System.Drawing.Drawing2D.SmoothingMode.AntiAlias;
			//draw cursor ring
			Rectangle crs=GetCursorBounds(_x,_y);
			if((crs.X+4)>=0 && (crs.X+4)<_bmp.Width &&
				(crs.Y+4)>=0 && (crs.Y+4)<_bmp.Height)
			{
				Color col=_bmp.GetPixel(crs.X+4,crs.Y+4);
				if(col.R+col.G+col.B>381)
					e.Graphics.DrawEllipse(Pens.Black,GetCursorBounds(_x,_y));
				else
					e.Graphics.DrawEllipse(Pens.White,GetCursorBounds(_x,_y));
			}
			if((Control.ModifierKeys&Keys.Shift)!=0)
			{
				float dx=(float)(this.Width-3)/8f,
					dy=(float)(this.Height-3)/8f,
					x=1f, y=1f;
				using(Pen pn=new Pen(new HatchBrush(HatchStyle.SmallCheckerBoard,
						  Color.FromArgb(80,255,255,255),
						  Color.FromArgb(0,0,0,0))))
				{
					for(int i=0;i<=8;i++,x+=dx,y+=dy)
					{
						e.Graphics.DrawLine(pn,0,(int)y,this.Width,(int)y);
						e.Graphics.DrawLine(pn,(int)x,0,(int)x,this.Height);
					}
				}
			}
			e.Graphics.DrawRectangle(Pens.Silver,0,0,this.Width-1,this.Height-1);
		}
		//mouse
		protected override void OnMouseDown(MouseEventArgs e)
		{
			base.OnMouseDown (e);
			if(SetPosition(
				(double)(e.X-0)/Math.Max(1.0,(double)(this.Width-2)),
				(double)(e.Y-0)/Math.Max(1.0,(double)(this.Height-2))))
				RaiseScroll();

		}
		protected override void OnMouseMove(MouseEventArgs e)
		{
			base.OnMouseMove (e);
			if(e.Button!=MouseButtons.None)
			if(SetPosition(
				(double)(e.X-0)/Math.Max(1.0,(double)(this.Width-2)),
				(double)(e.Y-0)/Math.Max(1.0,(double)(this.Height-2))))
				RaiseScroll();
		}
		#endregion
		#region members
		public bool SetPosition(double posx, double posy)
		{
			posx=XYZ.ClipValue(posx,0.0,1.0);
			posy=XYZ.ClipValue(posy,0.0,1.0);
			if((Control.ModifierKeys&Keys.Shift)!=0)
			{
				posx=Math.Round(posx*8.0,0)/8.0;
				posy=Math.Round(posy*8.0,0)/8.0;
			}
			if(posx==_x && posy==_y) return false;
			Invalidate(Rectangle.Inflate(GetCursorBounds(_x,_y),1,1));
			_x=posx; _y=posy;
			Invalidate(Rectangle.Inflate(GetCursorBounds(_x,_y),1,1));
			this.Update();
			return true;
		}
		#endregion
		#region properties
		[Browsable(false),
		DefaultValue(null),
		DesignerSerializationVisibility(DesignerSerializationVisibility.Hidden)]
		public override Cursor Cursor
		{
			get
			{
				return base.Cursor;
			}
			set
			{
				return;
			}
		}

		internal Bitmap Image
		{
			get{return _bmp;}
		}
		internal double PositionX
		{
			get{return _x;}
			set
			{
				SetPosition(value,_y);
			}
		}
		internal double PositionY
		{
			get{return _y;}
			set
			{
				SetPosition(_x,value);
			}
		}
		#endregion
		#region events
		private void RaiseScroll()
		{
			if(Scroll!=null)
				Scroll(this,EventArgs.Empty);
		}
		internal event EventHandler Scroll;
		#endregion
	}
}