圖像調整大小，而不保存在磁盤上

Question

在asp.net我想調整圖像大小並顯示在一些控制，但沒有保存在磁盤上。 是否有像clasic asp一樣的免費工具？

http://www.aspjpeg.com/livedemo.html

Answer 1

這可能是你所需要的：

http://imageresizing.net/

Answer 2

這個縮略圖類將做的工作。

public class Thumbnail 
{ 
    private string _filePath; 
    private int _maxWidth = 120; 
    private int _maxHeight = 120; 

    public string MimeType; 
    public System.Drawing.Imaging.ImageFormat ImageFormat; 
    public byte[] ImageBytes; 

    public Thumbnail(string filePath, int maxWidth, int maxHeight) 
    { 
     _filePath = filePath; 
     _maxWidth = maxWidth; 
     _maxHeight = maxHeight; 

     MakeThumbnail(); 
    } 

    private void MakeThumbnail() 
    { 
     using (Image img = new Bitmap(_filePath)) 
     { 
      Size newSize = GenerateImageDimensions(img.Width, img.Height, _maxWidth, _maxHeight); 
      int imgWidth = newSize.Width; 
      int imgHeight = newSize.Height; 

      // create the thumbnail image 
      using (Image img2 = 
         img.GetThumbnailImage(imgWidth, imgHeight, 
         new Image.GetThumbnailImageAbort(Abort), 
         IntPtr.Zero)) 
      { 

       using (Graphics g = Graphics.FromImage(img2)) // Create Graphics object from original Image 
       { 
        g.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality; 
        g.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.High; 
        g.CompositingQuality = System.Drawing.Drawing2D.CompositingQuality.HighQuality; 

        //BMP 0, JPEG 1 , GIF 2 , TIFF 3, PNG 4 
        System.Drawing.Imaging.ImageCodecInfo codec; 

        switch (Path.GetExtension(_filePath)) 
        { 
         case ".gif": 
          codec = System.Drawing.Imaging.ImageCodecInfo.GetImageEncoders()[2]; 
          ImageFormat = System.Drawing.Imaging.ImageFormat.Gif; 
          MimeType = "image/gif"; 
          break; 

         case ".png": 
          codec = System.Drawing.Imaging.ImageCodecInfo.GetImageEncoders()[4]; 
          ImageFormat = System.Drawing.Imaging.ImageFormat.Png; 
          MimeType = "image/png"; 
          break; 

         default: //jpg 
          codec = System.Drawing.Imaging.ImageCodecInfo.GetImageEncoders()[1]; 
          ImageFormat = System.Drawing.Imaging.ImageFormat.Jpeg; 
          MimeType = "image/jpg"; 
          break; 
        } 

        //Set the parameters for defining the quality of the thumbnail... here it is set to 100% 
        System.Drawing.Imaging.EncoderParameters eParams = new System.Drawing.Imaging.EncoderParameters(1); 
        eParams.Param[0] = new System.Drawing.Imaging.EncoderParameter(System.Drawing.Imaging.Encoder.Quality, 90L); 

        //Now draw the image on the instance of thumbnail Bitmap object 
        g.DrawImage(img, new Rectangle(0, 0, img2.Width, img2.Height)); 

        MemoryStream ms = new MemoryStream(); 
        img2.Save(ms, codec, eParams); 
        ImageBytes = new byte[ms.Length]; 
        ImageBytes = ms.ToArray(); 

        ms.Close(); 
        ms.Dispose(); 
       } 
      } 
     } 
    } 

    public static Size GenerateImageDimensions(int currW, int currH, int destW, int destH) 
    { 
     int imgWidth = currW; 
     int imgHeight = currH; 

     if (imgWidth > destW) 
     { 
      double rate = (double)imgWidth/(double)destW; 
      imgWidth = destW; 
      imgHeight = (int)(imgHeight/rate); 
     } 

     if (imgHeight > destH) 
     { 
      double rate = (double)imgHeight/(double)destH; 
      imgHeight = destH; 
      imgWidth = (int)(imgWidth/rate); 
     } 

     return new Size(imgWidth, imgHeight); 
    } 

    private bool Abort() 
    { 
     return false; 
    } 
} 

使用很簡單，只是把這個放在你的頁面codebehind上。瀏覽器輸出將被調整大小的圖像。

Thumbnail thm = new Thumbnail("c:\some_image.jpg", 300, 300); 
Response.ContentType = thm.MimeType; 
Response.BinaryWrite(thm.ImageBytes);