不失真压缩图片

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.Drawing.Drawing2D;
using System.Drawing.Imaging;
using System.IO;
namespace Compositing
{
    public partial class Form1 : Form
    {
        public Form1（）
        {
            InitializeComponent（）;
        }
        public static bool GetPicThumbnail（string sFile string dFile int dHeight int dWidth）
        {
            Image iSource = Image.FromFile（sFile）;
            ImageFormat tFormat = iSource.RawFormat;
            int sW = 0 sH = 0;
            // 按比例缩放
            Size tem_size = new Size（iSource.Width iSource.Height）;
            if （tem_size.Height > dHeight || tem_size.Width > dWidth）
            {
                if （（tem_size.Width * dHeight） > （tem_size.Height * dWidth））
                {
                    sW = dWidth;
                

 属性            大小     日期    时间   名称
----------- ---------  ---------- -----  ----
     文件         923  2009-02-06 14:35  sj\01\Compositing\Compositing.sln
     文件       15360  2009-02-06 15:13  sj\01\Compositing\Compositing.suo
     文件        3768  2009-02-06 14:38  sj\01\Compositing\Compositing\Compositing.csproj
     文件        4601  2009-02-06 14:57  sj\01\Compositing\Compositing\Form1.cs
     文件        4006  2009-02-06 14:50  sj\01\Compositing\Compositing\Form1.Designer.cs
     文件        6017  2009-02-06 14:50  sj\01\Compositing\Compositing\Form1.resx
     文件         492  2009-02-06 14:35  sj\01\Compositing\Compositing\Program.cs
     文件       10752  2009-02-06 14:57  sj\01\Compositing\Compositing\bin\Debug\Compositing.exe
     文件       26112  2009-02-06 14:57  sj\01\Compositing\Compositing\bin\Debug\Compositing.pdb
     文件       14328  2009-02-06 15:12  sj\01\Compositing\Compositing\bin\Debug\Compositing.vshost.exe
     文件         490  2007-07-21 01:33  sj\01\Compositing\Compositing\bin\Debug\Compositing.vshost.exe.manifest
     文件         830  2009-02-06 15:12  sj\01\Compositing\Compositing\obj\Debug\Compositing.csproj.FileListAbsolute.txt
     文件         847  2009-02-06 14:50  sj\01\Compositing\Compositing\obj\Debug\Compositing.csproj.GenerateResource.Cache
     文件       10752  2009-02-06 14:57  sj\01\Compositing\Compositing\obj\Debug\Compositing.exe
     文件         180  2009-02-06 14:50  sj\01\Compositing\Compositing\obj\Debug\Compositing.Form1.resources
     文件       26112  2009-02-06 14:57  sj\01\Compositing\Compositing\obj\Debug\Compositing.pdb
     文件         180  2009-02-06 14:38  sj\01\Compositing\Compositing\obj\Debug\Compositing.Properties.Resources.resources
     文件        1354  2009-02-06 14:35  sj\01\Compositing\Compositing\Properties\AssemblyInfo.cs
     文件        2872  2009-02-06 14:35  sj\01\Compositing\Compositing\Properties\Resources.Designer.cs
     文件        5612  2009-02-06 14:35  sj\01\Compositing\Compositing\Properties\Resources.resx
     文件        1096  2009-02-06 14:35  sj\01\Compositing\Compositing\Properties\Settings.Designer.cs
     文件         249  2009-02-06 14:35  sj\01\Compositing\Compositing\Properties\Settings.settings
     文件         923  2008-10-13 08:28  sl\CompressImg.sln
     文件       13312  2009-02-06 14:53  sl\CompressImg.suo
     文件        3883  2008-10-13 09:16  sl\CompressImg\CompressImg.csproj
     文件        8859  2008-12-28 13:44  sl\CompressImg\Form1.cs
     文件       17659  2008-12-27 10:40  sl\CompressImg\Form1.Designer.cs
     文件        6231  2008-12-27 10:40  sl\CompressImg\Form1.resx
     文件         492  2008-10-13 08:28  sl\CompressImg\Program.cs
     文件        6144  2009-03-11 13:57  sl\CompressImg\Thumbs.db
     文件        3225  2008-10-13 09:16  sl\CompressImg\文件夹打开.png
............此处省略16个文件信息