c#.net 生成清晰缩略图

 1  public void imgsize()
 2         {
 3             //本例中假定了两个变量：
 4 
 5             String src = "c:/myImages/a.jpg";   //源图像文件的绝对路径
 6             String dest = "c:/myImages/a_th.jpg";    //生成的缩略图图像文件的绝对路径
 7 
 8             int thumbWidth = 132;    //要生成的缩略图的宽度
 9             int thumbHeight = 100;   //要生成的缩略图的高度
10             System.Drawing.Image image = System.Drawing.Image.FromFile(src); //利用Image对象装载源图像
11 
12             //接着创建一个System.Drawing.Bitmap对象，并设置你希望的缩略图的宽度和高度。
13             int srcWidth = image.Width;
14             int srcHeight = image.Height;
15             Bitmap bmp = new Bitmap(thumbWidth, thumbHeight);
16 
17             //从Bitmap创建一个System.Drawing.Graphics对象，用来绘制高质量的缩小图。
18             System.Drawing.Graphics gr = System.Drawing.Graphics.FromImage(bmp);
19 
20             //设置 System.Drawing.Graphics对象的SmoothingMode属性为HighQuality
21             gr.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality;
22 
23             //下面这个也设成高质量
24             gr.CompositingQuality = System.Drawing.Drawing2D.CompositingQuality.HighQuality;
25 
26             //下面这个设成High
27             gr.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.High;
28 
29             //把原始图像绘制成上面所设置宽高的缩小图
30             System.Drawing.Rectangle rectDestination = new System.Drawing.Rectangle(0, 0, thumbWidth, thumbHeight);
31             gr.DrawImage(image, rectDestination, 0, 0, srcWidth, srcHeight, GraphicsUnit.Pixel);
32 
33             //保存图像，大功告成！
34             bmp.Save(dest);
35 
36             //最后别忘了释放资源
37             bmp.Dispose();
38             image.Dispose();
39         }