C#写的放大镜程序模拟真实放大镜的效果

C#写的放大镜程序,模拟真实放大镜的效果,能放大鼠标位置的区域并直接显示在鼠标的位置,不偏移显示,效果跟真实放大镜一样,鼠标滚轮可调节放大倍率,ESC键退出.只是代码雏形,没有完全完成,卡在实时更新的问题,希望网友们集思广益,一起实现.

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Text;
using System.Windows.Forms;
using System.Runtime.InteropServices;

namespace WindowsFormsApplication1
{
	public partial class Form1 : Form
	{
		const float zommDelta = 0.2f;
		private float zoom = 2;
		private float lastZoom = 2;
		private Point offset = new Point（0 0）;
		private Point lastMousePosition = new Point（0 0）;
		private Bitmap tempMap;

		public Form1（）
		{
			InitializeComponent（）;
			Setstyle（Controlstyles.UserPaint true）;
			Setstyle（Controlstyles.DoubleBuffer true）;
			Setstyle（Controlstyles.AllPaintingInWmPaint true）;
			Setstyle（Controlstyles.ResizeRedraw true）;

			this.MouseWheel += new System.Windows.Forms.MouseEventHandler（this.Form1_MouseWheel）;
		}

		private void Form1_PreviewKeyDown（object sender PreviewKeyDownEventArgs e）
		{
			if （e.KeyValue == 27）
			{
				Close（）;
			}
		}

		private void Form1_MouseWheel（object sender System.Windows.Forms.MouseEventArgs e）
		{
			if （e.Delta > 0）
			{
				zoom += zommDelta;
			}
			else
			{
				zoom -= zommDelta;
				if （zoom < 1） zoom = 1;
			}
			DoMove（）;
		}

		private void timer1_Tick（object sender EventArgs e）
		{
			DoMove（）;
		}

		private void DoMove（）
		{
			Point newMousePosition = MousePosition;
			if （lastMousePosition != newMousePosition || lastZoom != zoom）
			{
				lastZoom = zoom;
				offset = lastMousePosition - new Size（newMousePosition）;
				lastMousePosition = newMousePosition;

				Point mousePosition = MousePosition;
				mousePosition.Offset（-Width / 2 -Height / 2）;

				Bitmap newMap = GetScreen（new Rectangle（mousePosition Size））;
				if （tempMap != null）
				{
					Graphics g = Graphics.FromImage（newMap）;
					g.DrawImage（tempMap offset）;
				}
				tempMap = newMap;
				Location = mousePosition;
				Invalidate（）;
			}
		}

		private void Form1_Shown（object sender EventArgs e）
		{
			DoMove（）;
		}

		protected override void OnPaint（PaintEventArgs e）
		{
			e.Graphics.DrawImage（tempMap -Width * （zoom - 1） / 2 -Height * （zoom - 1） / 2 Width * zoom Height * zoom）;
		}


		[DllImportAttribute（“gdi32.dll“）]
		public static extern bool BitBlt（
		IntPtr hdcDest
		int nXDest
		int nYDest
		int nWidth
		int nHeight
		IntPtr hdcSrc
		int nXSrc
		int nYSrc
		System.Int32 dwRop
		）;

		private Bitmap GetScreen（Rectangle rect）
		{
			Graphics grpScreen = Graphics.FromHwnd（IntPtr.Zero）;
			Bitmap bitmap = new Bitmap（rect.Width rect.Height grpScreen）;
			Graphics grpBitmap = Graphics.FromImage（bitmap）;
			IntPtr hdcScreen = grpScreen.GetHdc（）;
			IntPtr hdcBitmap = grpBitmap.GetHdc（）;
			BitBlt（hdcBitmap 0 0 bitmap.Width bitmap.Height hdcScreen rect.X rect.Y 0x00CC0020）;
			grpBitmap.ReleaseHdc（hdcBitmap）;
			grpScreen.ReleaseHdc（hdcScreen）;
			grpBitmap.Dispose（）;
			grpScreen.Dispose（）;

 属性            大小     日期    时间   名称
----------- ---------  ---------- -----  ----

     文件      10240  2013-06-07 13:39  WindowsFormsApplication1\WindowsFormsApplication1\bin\Debug\WindowsFormsApplication1.exe

     文件      28160  2013-06-07 13:39  WindowsFormsApplication1\WindowsFormsApplication1\bin\Debug\WindowsFormsApplication1.pdb

     文件      11608  2013-06-07 13:40  WindowsFormsApplication1\WindowsFormsApplication1\bin\Debug\WindowsFormsApplication1.vshost.exe

     文件        490  2010-03-17 22:39  WindowsFormsApplication1\WindowsFormsApplication1\bin\Debug\WindowsFormsApplication1.vshost.exe.manifest

     文件       3035  2013-06-07 13:40  WindowsFormsApplication1\WindowsFormsApplication1\Form1.cs

     文件       1817  2013-06-06 17:56  WindowsFormsApplication1\WindowsFormsApplication1\Form1.Designer.cs

     文件       6011  2013-06-06 17:56  WindowsFormsApplication1\WindowsFormsApplication1\Form1.resx

     文件       5513  2013-06-07 13:39  WindowsFormsApplication1\WindowsFormsApplication1\obj\x86\Debug\DesignTimeResolveAssemblyReferencesInput.cache

     文件        516  2013-06-06 17:56  WindowsFormsApplication1\WindowsFormsApplication1\obj\x86\Debug\GenerateResource-ResGen.read.1.tlog

     文件       1198  2013-06-06 17:56  WindowsFormsApplication1\WindowsFormsApplication1\obj\x86\Debug\GenerateResource-ResGen.write.1.tlog

     文件       1416  2013-06-07 13:40  WindowsFormsApplication1\WindowsFormsApplication1\obj\x86\Debug\WindowsFormsApplication1.csproj.FileListAbsolute.txt

     文件      10240  2013-06-07 13:39  WindowsFormsApplication1\WindowsFormsApplication1\obj\x86\Debug\WindowsFormsApplication1.exe

     文件        180  2013-06-06 17:56  WindowsFormsApplication1\WindowsFormsApplication1\obj\x86\Debug\WindowsFormsApplication1.Form1.resources

     文件      28160  2013-06-07 13:39  WindowsFormsApplication1\WindowsFormsApplication1\obj\x86\Debug\WindowsFormsApplication1.pdb

     文件        180  2013-06-06 14:56  WindowsFormsApplication1\WindowsFormsApplication1\obj\x86\Debug\WindowsFormsApplication1.Properties.Resources.resources

     文件        418  2013-06-06 14:50  WindowsFormsApplication1\WindowsFormsApplication1\Program.cs

     文件       1460  2013-06-06 14:50  WindowsFormsApplication1\WindowsFormsApplication1\Properties\AssemblyInfo.cs

     文件       2528  2013-06-06 14:50  WindowsFormsApplication1\WindowsFormsApplication1\Properties\Resources.Designer.cs

     文件       5612  2013-06-06 14:50  WindowsFormsApplication1\WindowsFormsApplication1\Properties\Resources.resx

     文件       1031  2013-06-06 14:50  WindowsFormsApplication1\WindowsFormsApplication1\Properties\Settings.Designer.cs

     文件        249  2013-06-06 14:50  WindowsFormsApplication1\WindowsFormsApplication1\Properties\Settings.settings

     文件       3455  2013-06-06 14:56  WindowsFormsApplication1\WindowsFormsApplication1\WindowsFormsApplication1.csproj

     文件        914  2013-06-06 14:50  WindowsFormsApplication1\WindowsFormsApplication1.sln

    ..A..H.     17920  2013-06-07 13:40  WindowsFormsApplication1\WindowsFormsApplication1.suo

     目录          0  2013-06-06 14:50  WindowsFormsApplication1\WindowsFormsApplication1\obj\x86\Debug\TempPE

     目录          0  2013-06-07 13:39  WindowsFormsApplication1\WindowsFormsApplication1\obj\x86\Debug

     目录          0  2013-06-06 14:56  WindowsFormsApplication1\WindowsFormsApplication1\bin\Debug

     目录          0  2013-06-06 14:50  WindowsFormsApplication1\WindowsFormsApplication1\obj\x86

     目录          0  2013-06-06 14:50  WindowsFormsApplication1\WindowsFormsApplication1\bin

     目录          0  2013-06-06 14:50  WindowsFormsApplication1\WindowsFormsApplication1\obj

............此处省略6个文件信息