生成缩略图方法

using System;



using System.Collections.Generic;



using System.Text;



namespace DataInput



{



    using System.IO;



    using System.Drawing;



    using System.Drawing.Imaging;



    using System.Windows.Forms;



    /// <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)



        {



            try



            {



                ResourceImage = Image.FromFile(ImageFileName);



                ErrMessage = "";



            }



            catch



            {



                ResourceImage = Image.FromFile(Application.StartupPath + "\\null.jpg");



            }



        }



        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);



                ResourceImage.Dispose();



                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;



            }



        }



    }



}