[转]c#生成图片缩略图的类

里面有4个重载方法,有直接返回Image对象的,有生成缩略图,并且保存到指定目录的!

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\filename.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\filename.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;
     }
    }

}