using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Text;
using System.Windows.Forms;
using System.Drawing.Drawing2D;
	
namespace SelectionRectTest {
	public class Form1 : Form {
		public Form1( ) {
			InitializeComponent( );
			BackColor = Color.White;
		}
	
		protected override void OnPaint(PaintEventArgs e) {
			if (selectionPanel == null) {
				e.Graphics.SmoothingMode = SmoothingMode.AntiAlias;
	
				// Draw some stuff so the transparent selection becomes visible
				int height = ClientRectangle.Height;
				int heightTenth = height / 10;
				int width = ClientRectangle.Width;
				int widthTenth = width / 10;
	
				e.Graphics.DrawLines(Pens.Red, new Point[] {
					new Point(widthTenth, heightTenth * 3),
					new Point(widthTenth * 5, heightTenth),
					new Point(widthTenth * 8, heightTenth * 9),
					new Point(widthTenth, heightTenth * 3)
				});
				e.Graphics.DrawEllipse(Pens.Blue, widthTenth * 4, heightTenth * 3, widthTenth * 5, heightTenth * 4);
			}
		}
	
		protected override void OnResize(EventArgs e) {
			base.OnResize(e);
			Invalidate( );
		}
	
		Point mouseDownPos = Point.Empty;
	
		protected override void OnMouseDown(MouseEventArgs e) {
			base.OnMouseDown(e);
	
			if (e.Button == MouseButtons.Left)
				mouseDownPos = e.Location;
	
			Bitmap contentBitmap = new Bitmap(Bounds.Width, Bounds.Height);
			Rectangle targetRect = Bounds;
			targetRect.X = 0 ;
			targetRect.Y = 0;
			DrawToBitmap(contentBitmap, targetRect);
	
			Point originScreen = PointToScreen(new Point(0, 0));
			Rectangle usableRect = new Rectangle(new Point(originScreen.X - Bounds.X, originScreen.Y - Bounds.Y), ClientRectangle.Size);
	
			selectionPanel = new SelectionPanel(contentBitmap, usableRect, mouseDownPos);
			Controls.Add(selectionPanel);
			selectionPanel.BringToFront( );
		}
	
		SelectionPanel selectionPanel;
	
		protected override void OnMouseMove(MouseEventArgs e) {
			base.OnMouseMove(e);
			if (e.Button == MouseButtons.Left && mouseDownPos != Point.Empty && selectionPanel != null)
				selectionPanel.Invalidate( );
		}
	
		protected override void OnMouseUp(MouseEventArgs e) {
			base.OnMouseUp(e);
			mouseDownPos = Point.Empty;
			Controls.Remove(selectionPanel);
			selectionPanel = null;
		}
	
		private Button button1;
	
		private void InitializeComponent( ) {
			this.button1 = new System.Windows.Forms.Button( );
			this.SuspendLayout( );
			//
			// button1
			//
			this.button1.Location = new System.Drawing.Point(114, 108);
			this.button1.Name = "button1";
			this.button1.Size = new System.Drawing.Size(75, 33);
			this.button1.TabIndex = 0;
			this.button1.Text = "button1";
			//
			// Form1
			//
			this.ClientSize = new System.Drawing.Size(292, 266);
			this.Controls.Add(this.button1);
			this.Name = "Form1";
			this.ResumeLayout(false);
	
		}
	}
	
	public class SelectionPanel : Panel {
		public SelectionPanel(Bitmap backgroundBitmap, Rectangle usableRect, Point mouseDownPos) {
			DoubleBuffered = true;
	
			this.backgroundBitmap = backgroundBitmap;
			this.mouseDownPos = mouseDownPos;
			this.usableRect = usableRect;
	
			this.Size = usableRect.Size;
			this.Location = new Point(0, 0);
	
			selectionColor = Color.FromArgb(200, 0xE8, 0xED, 0xF5);
			selectionBrush = new SolidBrush(selectionColor);
			frameColor = Color.FromArgb(0x33, 0x5E, 0xA8);
			framePen = new Pen(frameColor);
		}
	
		Bitmap backgroundBitmap;
		Point mouseDownPos;
		Color selectionColor;
		Brush selectionBrush;
		Color frameColor;
		Pen framePen;
		Rectangle usableRect;
	
		protected override void OnPaint(PaintEventArgs e) {
			// copy the backgroundImage
			e.Graphics.DrawImage(backgroundBitmap, ClientRectangle, usableRect, GraphicsUnit.Pixel);
	
			// Now, if needed, draw the selection rectangle
			if (mouseDownPos != Point.Empty) {
				Point mousePos = PointToClient(MousePosition);
				Rectangle selectedRect = new Rectangle(
					Math.Min(mouseDownPos.X, mousePos.X),
					Math.Min(mouseDownPos.Y, mousePos.Y),
					Math.Abs(mousePos.X - mouseDownPos.X),
					Math.Abs(mousePos.Y - mouseDownPos.Y));
				e.Graphics.FillRectangle(selectionBrush, selectedRect);
				e.Graphics.DrawRectangle(framePen, selectedRect);
			}
		}
	}
}