近期在做相冊功能遇到一个问题，就是载入图片的时候然后放大，感觉有点卡。图片可能有点大，所以考虑用缩略图来实现。

也就是在查询出来一个相冊图片  ，一页显示几十张，这几十张用缩略图来显示，看相信情况的时候想QQ相冊样载入原图放大拉取图片相关信息。所用到的技术就是图片压缩功能。如今功能已经实现看代码。

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.Imaging;using System.IO;namespace WindowsFormsApplication1{    public partial class Form1 : Form    {        public Form1()        {            InitializeComponent();        }        private void button1_Click(object sender, EventArgs e)        {            string pathPerc = @"D:\0046620140807150650cin.jpg";            string source = @"G:\0046620140807150650cin.jpg";            if (!File.Exists(pathPerc))            {                File.Create(pathPerc).Close();            }            else            {                File.Delete(pathPerc);                File.Create(pathPerc).Close();            }            getThumImage(source, 18, 3, pathPerc);        }        #region getThumImage        /**/        /// 
        /// 生成缩略图        /// 
        /// 原始图片文件        /// 质量压缩比        /// 收缩倍数        /// 输出文件名称        /// 
     
      成功返回true,失败则返回false
             public static bool getThumImage(String sourceFile, long quality, int multiple, String outputFile)        {            try            {                long imageQuality = quality;                Bitmap sourceImage = new Bitmap(sourceFile);                ImageCodecInfo myImageCodecInfo = GetEncoderInfo("image/jpeg");                System.Drawing.Imaging.Encoder myEncoder = System.Drawing.Imaging.Encoder.Quality;                EncoderParameters myEncoderParameters = new EncoderParameters(1);                EncoderParameter myEncoderParameter = new EncoderParameter(myEncoder, imageQuality);                myEncoderParameters.Param[0] = myEncoderParameter;                float xWidth = sourceImage.Width;                float yWidth = sourceImage.Height;                Bitmap newImage = new Bitmap((int)(xWidth / multiple), (int)(yWidth / multiple));                Graphics g = Graphics.FromImage(newImage);                g.DrawImage(sourceImage, 0, 0, xWidth / multiple, yWidth / multiple);                g.Dispose();                newImage.Save(outputFile, myImageCodecInfo, myEncoderParameters);                return true;            }            catch            {                return false;            }        }        #endregion getThumImage        /**/        /// 
        /// 获取图片编码信息        /// 
        private static ImageCodecInfo GetEncoderInfo(String mimeType)        {            int j;            ImageCodecInfo[] encoders;            encoders = ImageCodecInfo.GetImageEncoders();            for (j = 0; j < encoders.Length; ++j)            {                if (encoders[j].MimeType == mimeType)                    return encoders[j];            }            return null;        }    }}

看下压缩后的图片例如以下

11KB

压缩前的图片

这样缩略图就成功了。