在Aspx中上傳和調整圖像大小

Question

我有一個頁面，允許用戶上傳圖片。問題是我的舊用戶無法自己調整圖像大小。我想允許他們上傳任意大小的圖像，然後當服務器獲取它時，它會創建這張圖片的一個小副本。

Answer 1

有來調整圖像，所以很多的方法，但是我喜歡這個

System.Drawing.Image image = System.Drawing.Image.FromFile("FilePath");    
int newwidthimg = 160;     
float AspectRatio = (float)image.Size.Width/(float)image.Size.Height; 
int newHeight = Convert.ToInt32(newwidthimg/AspectRatio); 
Bitmap thumbnailBitmap = new Bitmap(newwidthimg, newHeight); 
Graphics thumbnailGraph = Graphics.FromImage(thumbnailBitmap); 
thumbnailGraph.CompositingQuality = CompositingQuality.HighQuality; 
thumbnailGraph.SmoothingMode = SmoothingMode.HighQuality; 
thumbnailGraph.InterpolationMode = InterpolationMode.HighQualityBicubic; 
var imageRectangle = new Rectangle(0, 0, newwidthimg, newHeight); 
thumbnailGraph.DrawImage(image, imageRectangle); 
thumbnailBitmap.Save("FilePath", ImageFormat.Jpeg); 
thumbnailGraph.Dispose(); 
thumbnailBitmap.Dispose(); 
image.Dispose();   

我有固定的寬度，因爲我想有寬度160我的所有圖片和高度根據長寬比

Answer 2

您可以使用某種調整大小方法。

protected void Button1_Click(object sender, EventArgs e) 
{ 
    HttpPostedFile pf = FileUpload1.PostedFile; 
    System.Drawing.Image bm = System.Drawing.Image.FromStream(pf.InputStream); 
    bm = ResizeBitmap((Bitmap) bm, 100, 100); /// new width, height 
    bm.Save(Path.Combine(YOURUPLOADPATH, pf.FileName); 
} 

private Bitmap ResizeBitmap(Bitmap b, int nWidth, int nHeight) 
{ 
    Bitmap result = new Bitmap(nWidth, nHeight); 
    using (Graphics g = Graphics.FromImage((System.Drawing.Image)result)) 
     g.DrawImage(b, 0, 0, nWidth, nHeight); 
    return result; 
} 

在另一方面，上傳一個如3 MB的文件和事後 * 調整 *到一個20KB PIC - 不不聲音很好給我。也許你可以考慮限制上傳文件的大小。

Answer 3

這是一個相當新的解決方案。希望它可以幫助

http://forums.asp.net/t/1657138.aspx/1?C+Resize+Profile+Image

protected void UploadButton_Click(object sender, EventArgs e) 
    { 
     if (File1.HasFile) 
     { 
      string fileName = Server.HtmlEncode(File1.FileName); 
      string extension = System.IO.Path.GetExtension(fileName); 
      System.Drawing.Image image_file = System.Drawing.Image.FromStream(File1.PostedFile.InputStream); 
      int image_height = image_file.Height; 
      int image_width = image_file.Width; 
      int max_height = 100; 
      int max_width = 100; 

      image_height = (image_height * max_width)/image_width; 
      image_width = max_width; 

      if (image_height > max_height) 
      { 
       image_width = (image_width * max_height)/image_height; 
       image_height = max_height; 
      } 

      Bitmap bitmap_file = new Bitmap(image_file, image_width, image_height); 
      System.IO.MemoryStream stream = new System.IO.MemoryStream(); 

      bitmap_file.Save(stream, System.Drawing.Imaging.ImageFormat.Png); 
      stream.Position = 0; 

      byte[] data = new byte[stream.Length + 1]; 
      stream.Read(data, 0, data.Length); 

      Profile.Picture = data; 
      Profile.PictureType = "image/png"; 
     } 
}