C#图片压缩处理

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
        /**/
        /// <summary>
        /// 生成缩略图
        /// </summary>
        /// <param name="sourceFile">原始图片文件</param>
        /// <param name="quality">质量压缩比</param>
        /// <param name="multiple">收缩倍数</param>
        /// <param name="outputFile">输出文件名称</param>
        /// <returns>成功返回true,失败则返回false</returns>
        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

        /**/
        /// <summary>
        /// 获取图片编码信息
        /// </summary>
        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。