从网络中获取图片显示到Image控件并保存到磁盘

一、从网络中获取图片信息：

 1   /// <summary>
 2         /// 获取图片
 3         /// </summary>
 4         /// <param name="url">Url</param>
 5         /// <returns>BitmapImage</returns>
 6         public BitmapImage GetImage(string url)
 7         {
 8             BitmapImage image=null;
 9             try
10             {
11                 image = new BitmapImage();
12                 long fileLength = 0;
13                 //从url指定的网络地址获取图片信息
14                 WebRequest webReq = WebRequest.Create(url);
15                 WebResponse webRes = webReq.GetResponse();
16                 fileLength = webRes.ContentLength;
17                 Stream srm = webRes.GetResponseStream();
18                 byte[] bufferbyte = new byte[fileLength];
19                 int allByte = (int) bufferbyte.Length;
20                 int startByte = 0;
21                 while (fileLength > 0)
22                 {
23                     int downByte = srm.Read(bufferbyte, startByte, allByte);
24                     if (downByte == 0)
25                     {
26                         break;
27                     }
28                     startByte += downByte;
29                     allByte -= downByte;
30                 }
31                 //以流的形式初始化图片                                                                                                 
32                 image.BeginInit();
33                 image.StreamSource = new MemoryStream(bufferbyte);
34                 image.EndInit();
35                 srm.Close();
36                 webRes.Close();
37             }
38             catch (Exception)
39             {
40                 Console.WriteLine("获取图片信息失败");
41             }
42             return image;
43         }

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二、在Image控件中显示获取到的图片

1   public void ShowImage(BitmapImage img)
2         {
3             image.Source = img;
4             image.Width = img.PixelWidth;
5             image.Height = img.PixelHeight;
6         }

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image是Image控件

三、保存Image到磁盘

 1  /// <summary>
 2         /// 保存图片到磁盘
 3         /// </summary>
 4         /// <param name="img"></param>
 5         public void SaveImage(Image img)
 6         {
 7             //img为Image控件
 8             BitmapSource bsrc = (BitmapSource)img.Source;
 9             //保存文件对话框
10             SaveFileDialog sf = new SaveFileDialog();
11             //设定默认保存类型为Png
12             sf.DefaultExt = ".png";
13             //指定用户只能下载jpg和png格式的图片
14             sf.Filter = "JPG 图片 (*.jpg)|*.jpg|PNG 图片 (*.png)|*.png";
15             if (sf.ShowDialog() == true)
16             {
17                 PngBitmapEncoder pngE = new PngBitmapEncoder();
18                 pngE.Frames.Add(BitmapFrame.Create(bsrc));
19                 using (Stream stream = File.Create(sf.FileName))
20                 {
21                     pngE.Save(stream);
22                 }
23             }
24         }

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