C#圖片按比例縮放

昵稱10504424 2014-01-08

展開全文

 1       // 按比例縮放圖片
 2         public Image ZoomPicture(Image SourceImage, int TargetWidth, int TargetHeight)
 3         {
 4             int IntWidth; //新的圖片寬
 5             int IntHeight; //新的圖片高
 6             try
 7             {
 8                 System.Drawing.Imaging.ImageFormat format = SourceImage.RawFormat;
 9                 System.Drawing.Bitmap SaveImage = new System.Drawing.Bitmap(TargetWidth, TargetHeight);
10                 Graphics g = Graphics.FromImage(SaveImage);
11                 g.Clear(Color.White);
12 
13                 //計算縮放圖片的大小 http://www.cnblogs.com/roucheng/
14 
15                 if (SourceImage.Width > TargetWidth && SourceImage.Height <= TargetHeight)//寬度比目的圖片寬度大，長度比目的圖片長度小
16                 {
17                     IntWidth = TargetWidth;
18                     IntHeight = (IntWidth * SourceImage.Height) / SourceImage.Width;
19                 }
20                 else if (SourceImage.Width <= TargetWidth && SourceImage.Height > TargetHeight)//寬度比目的圖片寬度小，長度比目的圖片長度大
21                 {
22                     IntHeight = TargetHeight;
23                     IntWidth = (IntHeight * SourceImage.Width) / SourceImage.Height;
24                 }
25                 else if (SourceImage.Width <= TargetWidth && SourceImage.Height <= TargetHeight) //長寬比目的圖片長寬都小
26                 {
27                     IntHeight = SourceImage.Width;
28                     IntWidth = SourceImage.Height;
29                 }
30                 else//長寬比目的圖片的長寬都大
31                 {
32                     IntWidth = TargetWidth;
33                     IntHeight = (IntWidth * SourceImage.Height) / SourceImage.Width;
34                     if (IntHeight > TargetHeight)//重新計算
35                     {
36                         IntHeight = TargetHeight;
37                         IntWidth = (IntHeight * SourceImage.Width) / SourceImage.Height;
38                     }
39                 }
40 
41                 g.DrawImage(SourceImage, (TargetWidth - IntWidth) / 2, (TargetHeight - IntHeight) / 2, IntWidth, IntHeight);
42                 SourceImage.Dispose();
43 
44                 return SaveImage;
45             }
46             catch (Exception ex)
47             {
48               
49             }
50 
51             return null;
52         }