C#图片处理工具类，可以压缩JPG图像，图片自动生成缩略图，为图片添加水印效果等，返回高清缩略图，得到最佳的图片比例缩放尺寸，并获取图片类型等，类代码如下：
view sourceprint?001using System;
002using System.Collections.Generic;
003using System.Linq;
004using System.Text;
005using System.IO;
006using System.Drawing;
007using System.Drawing.Drawing2D;
008using System.Drawing.Imaging;
009namespace CLB.Utility.Tools
010{
011 ///
012 /// 图片工具类
013 ///
014 public static class ImageHelper
015 {
016 ///
017 /// 压缩JPG图片
018 ///
019 /// 压缩后图片存放的地址
020 /// 需要压缩的图片地址
021 /// 压缩质量：如果为0则默认调整为80
022 public static void SetCompressImage(string NewfileName, string OldfileName, long quality)
023 {
024 if (quality == 0)
025 {
026 quality = 80;
027 }
028 using (Bitmap bitmp = new Bitmap(OldfileName))
029 {
030 EncoderParameters ep = new EncoderParameters(1);
031 ep.Param[0] = new EncoderParameter(System.Drawing.Imaging.Encoder.Quality, quality);
032 ImageCodecInfo myImageCodecInfo = GetEncoderInfo("image/jpeg");
033 bitmp.Save(NewfileName, myImageCodecInfo, ep);
034 bitmp.Dispose();
035 }
036 }
037 ///
038 /// 返回高清缩略图
039 ///
040 /// 原文件
041 /// 新文件
042 /// 最大高度
043 /// 最大宽度
044 /// 质量，如果为0，则设为80
045 public static void SetGoodImage(string fileName, string newFile, int maxHeight, int maxWidth,longqualitys)
046 {
047 if (qualitys == 0)
048 {
049 qualitys = 80;
050 }
051 using (System.Drawing.Image img = System.Drawing.Image.FromFile(fileName))
052 {
053 System.Drawing.Imaging.ImageFormat
054 thisFormat = img.RawFormat;
055 Size newSize = NewSize(maxWidth, maxHeight, img.Width, img.Height);
056 Bitmap outBmp = new Bitmap(newSize.Width, newSize.Height);
057 Graphics g = Graphics.FromImage(outBmp);
058 // 设置画布的描绘质量
059 g.CompositingQuality = CompositingQuality.HighQuality;
060 g.SmoothingMode = SmoothingMode.HighQuality;
061 g.InterpolationMode = InterpolationMode.HighQualityBicubic;
062 g.DrawImage(img, new Rectangle(0, 0, newSize.Width, newSize.Height),
063 0, 0, img.Width, img.Height, GraphicsUnit.Pixel);
064 g.Dispose();
065 // 以下代码为保存图片时,设置压缩质量
066 EncoderParameters encoderParams = new EncoderParameters();
067 long[] quality = new long[1];
068 quality[0] = qualitys;
069 EncoderParameter encoderParam = new EncoderParameter(System.Drawing.Imaging.Encoder.Quality, quality);
070 encoderParams.Param[0] = encoderParam;
071 //获得包含有关内置图像编码解码器的信息的ImageCodecInfo 对象.
072 ImageCodecInfo[] arrayICI = ImageCodecInfo.GetImageEncoders();
073 ImageCodecInfo jpegICI = null;
074 for (int x = 0;
075 x < arrayICI.Length;
076 x++)
077 {
078 if (arrayICI[x].FormatDescription.Equals("JPEG"))
079 {
080 jpegICI = arrayICI[x];
081 //设置JPEG编码
082 break;
083 }
084 }
085 if (jpegICI != null)
086 {
087 outBmp.Save(newFile, jpegICI, encoderParams);
088 }
089 else
090 {
091 outBmp.Save(newFile, thisFormat);
092 }
093 img.Dispose();
094 outBmp.Dispose();
095 }
096 }
097 // 得到到按比例最佳尺寸
098 private static Size NewSize(int maxWidth, int maxHeight, int width, int height)
099 {
100 double w = 0.0;
101 double h = 0.0;
102 double sw = Convert.ToDouble(width);
103 double sh = Convert.ToDouble(height);
104 double mw = Convert.ToDouble(maxWidth);
105 double mh = Convert.ToDouble(maxHeight);
106 if (sw < mw && sh < mh)
107 {
108 w = sw;
109 h = sh;
110 }
111 else if ((sw / sh) > (mw / mh))
112 {
113 w = maxWidth;
114 h = (w * sh) / sw;
115 }
116 else
117 {
118 h = maxHeight;
119 w = (h * sw) / sh;
120 }
121 return new Size(Convert.ToInt32(w), Convert.ToInt32(h));
122 }
123 ///
124 /// 得到图片类型
125 ///
126 ///
127 ///
128 private static ImageCodecInfo GetEncoderInfo(String mimeType)
129 {
130 int j;
131 ImageCodecInfo[] encoders;
132 encoders = ImageCodecInfo.GetImageEncoders();
133 for (j = 0; j < encoders.Length; ++j)
134 {
135 if (encoders[j].MimeType == mimeType)
136 return encoders[j];
137 }
138 return null;
139 }
140 ///
141 /// 添加水印效果
142 ///
143 /// 输入路径
144 /// 输出路径
145 /// 水印文件路径
146 /// 水印靠近图片右边的像素
147 /// 水印靠近底边的像素
148 /// 透明度
149 public static void SetWaterMark( string fileName, string newfileName,string WaterImg,int RightSpace,intBottomSpace,int LucencyPercent)
150 {
151 using (System.Drawing.Image image = System.Drawing.Image.FromFile(fileName))
152 {
153 ImageModification wm = new ImageModification();
154 wm.DrawedImagePath = WaterImg; //水印图片
155 wm.ModifyImagePath = fileName; //图片的路径
156 wm.RightSpace = RightSpace; //水印位置
157 wm.BottoamSpace = image.Height - BottomSpace; //水银位置
158 wm.LucencyPercent = LucencyPercent; //透明度
159 wm.OutPath = newfileName; //生成的文件名
160 wm.DrawImage();
161 image.Dispose();
162 }
163 }
164 }
165}