C# 生成图片缩略图

using System.IO;  
using System.Drawing;  
using System.Drawing.Imaging;  
  
/// <summary>     
/// 图片处理类     
/// 1、生成缩略图片或按照比例改变图片的大小和画质     
/// 2、将生成的缩略图放到指定的目录下     
/// </summary>     
public class ImageClass  
{  
    public Image ResourceImage;  
    private int ImageWidth;  
    private int ImageHeight;  
  
    public string ErrMessage;  
  
    /// <summary>     
    /// 类的构造函数     
    /// </summary>     
    /// <param name="ImageFileName">图片文件的全路径名称</param>     
    public ImageClass(string ImageFileName)  
    {  
        ResourceImage = Image.FromFile(ImageFileName);  
        ErrMessage = "";  
    }  
  
    public bool ThumbnailCallback()  
    {  
        return false;  
    }  
  
    /// <summary>     
    /// 生成缩略图重载方法1，返回缩略图的Image对象     
    /// </summary>     
    /// <param name="Width">缩略图的宽度</param>     
    /// <param name="Height">缩略图的高度</param>     
    /// <returns>缩略图的Image对象</returns>     
    public Image GetReducedImage(int Width, int Height)  
    {  
        try  
        {  
            Image ReducedImage;  
  
            Image.GetThumbnailImageAbort callb = new Image.GetThumbnailImageAbort(ThumbnailCallback);  
  
            ReducedImage = ResourceImage.GetThumbnailImage(Width, Height, callb, IntPtr.Zero);  
  
            return ReducedImage;  
        }  
        catch (Exception e)  
        {  
            ErrMessage = e.Message;  
            return null;  
        }  
    }  
  
    /// <summary>     
    /// 生成缩略图重载方法2，将缩略图文件保存到指定的路径     
    /// </summary>     
    /// <param name="Width">缩略图的宽度</param>     
    /// <param name="Height">缩略图的高度</param>     
    /// <param name="targetFilePath">缩略图保存的全文件名，(带路径)，参数格式：D:Images ilename.jpg</param>     
    /// <returns>成功返回true，否则返回false</returns>     
    public bool GetReducedImage(int Width, int Height, string targetFilePath)  
    {  
        try  
        {  
            Image ReducedImage;  
  
            Image.GetThumbnailImageAbort callb = new Image.GetThumbnailImageAbort(ThumbnailCallback);  
  
            ReducedImage = ResourceImage.GetThumbnailImage(Width, Height, callb, IntPtr.Zero);  
            ReducedImage.Save(@targetFilePath, ImageFormat.Jpeg);  
  
            ReducedImage.Dispose();  
  
            return true;  
        }  
        catch (Exception e)  
        {  
            ErrMessage = e.Message;  
            return false;  
        }  
    }  
  
    /// <summary>     
    /// 生成缩略图重载方法3，返回缩略图的Image对象     
    /// </summary>     
    /// <param name="Percent">缩略图的宽度百分比 如：需要百分之80，就填0.8</param>       
    /// <returns>缩略图的Image对象</returns>     
    public Image GetReducedImage(double Percent)  
    {  
        try  
        {  
            Image ReducedImage;  
  
            Image.GetThumbnailImageAbort callb = new Image.GetThumbnailImageAbort(ThumbnailCallback);  
  
            ImageWidth = Convert.ToInt32(ResourceImage.Width * Percent);  
            ImageHeight = Convert.ToInt32(ResourceImage.Width * Percent);  
  
            ReducedImage = ResourceImage.GetThumbnailImage(ImageWidth, ImageHeight, callb, IntPtr.Zero);  
  
            return ReducedImage;  
        }  
        catch (Exception e)  
        {  
            ErrMessage = e.Message;  
            return null;  
        }  
    }  
  
    /// <summary>     
    /// 生成缩略图重载方法4，返回缩略图的Image对象     
    /// </summary>     
    /// <param name="Percent">缩略图的宽度百分比 如：需要百分之80，就填0.8</param>       
    /// <param name="targetFilePath">缩略图保存的全文件名，(带路径)，参数格式：D:Images ilename.jpg</param>     
    /// <returns>成功返回true,否则返回false</returns>     
    public bool GetReducedImage(double Percent, string targetFilePath)  
    {  
        try  
        {  
            Image ReducedImage;  
  
            Image.GetThumbnailImageAbort callb = new Image.GetThumbnailImageAbort(ThumbnailCallback);  
  
            ImageWidth = Convert.ToInt32(ResourceImage.Width * Percent);  
            ImageHeight = Convert.ToInt32(ResourceImage.Width * Percent);  
  
            ReducedImage = ResourceImage.GetThumbnailImage(ImageWidth, ImageHeight, callb, IntPtr.Zero);  
  
            ReducedImage.Save(@targetFilePath, ImageFormat.Jpeg);  
  
            ReducedImage.Dispose();  
  
            return true;  
        }  
        catch (Exception e)  
        {  
            ErrMessage = e.Message;  
            return false;  
        }  
    }  
  
}