压缩图片C#算法

转载自 http://www.open-open.com/lib/view/open1391348644910.html

using System.IO;  

using System.Drawing;  

using System.Drawing.Imaging;  

using System;  

namespace Bll  

{  

    /// <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 ImageHepler  

    {  

        public Image ResourceImage, ReducedImage;  

        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 ImageHepler(string ImageFileName)  

        {  

            ResourceImage = Image.FromFile(ImageFileName);  

            ErrMessage = "";  

        }  

  

        public bool ThumbnailCallback()  

        {  

            return false;  

        }  

  

        /// <summary>  

        /// 生成缩略图，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)  

        {  

            double LengthLong;          //存储（长和宽中）较短的长度  

            int widthOK, heightOK;      //存储实际要生成的图片的长宽  

            if (Width < Height)         //判断输入的长和宽那个较短  

            {  

                LengthLong = Width;     //把较短的存储在 LengthLonh 用于计算  

            }  

            else  

            {  

                LengthLong = Height;  

            }  

            try  

            {  

                //判断原图片 长和宽   

                //原图比较长的一个边要和缩略图的边相等  

                if (ResourceImage.Width > ResourceImage.Height)  

                {  

                    widthOK = (int)LengthLong;  

                    heightOK = (int)(LengthLong / ResourceImage.Width * ResourceImage.Height);  

                }  

                else  

                {  

                    heightOK = (int)LengthLong;  

                    widthOK = (int)LengthLong / ResourceImage.Height * ResourceImage.Width;  

  

                }  

                Image ReducedImage;  

                Image.GetThumbnailImageAbort callb = new Image.GetThumbnailImageAbort(ThumbnailCallback);  

                ReducedImage = ResourceImage.GetThumbnailImage(widthOK, heightOK, callb, IntPtr.Zero);  

                return ReducedImage;  

            }  

            catch (Exception e)  

            {  

                ErrMessage = e.Message;  

                return null;  

            }  

        }  

  

        /// <summary>  

        /// 生成缩略图，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)  

        {  

            double LengthLong;          //存储（长和宽中）较短的长度  

            int widthOK, heightOK;      //存储实际要生成的图片的长宽  

            if (Width < Height)         //判断输入的长和宽那个较短  

            {  

                LengthLong = Width;     //把较短的存储在 LengthLonh 用于计算  

            }  

            else  

            {  

                LengthLong = Height;  

            }  

            try  

            {  

                //判断原图片 长和宽   

                //原图比较长的一个边要和缩略图的边相等  

                if (ResourceImage.Width > ResourceImage.Height)  

                {  

                    widthOK = (int)LengthLong;  

                    heightOK = (int)(LengthLong / ResourceImage.Width * ResourceImage.Height);  

                }  

                else  

                {  

                    heightOK = (int)LengthLong;  

                    widthOK = (int)LengthLong / ResourceImage.Height * ResourceImage.Width;  

                }  

                Image.GetThumbnailImageAbort callb = new Image.GetThumbnailImageAbort(ThumbnailCallback);  

                ReducedImage = ResourceImage.GetThumbnailImage(widthOK, heightOK, 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，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，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.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;  

            }  

        }  

    }  

}