Intermittent System.Drawing/GDI +「Generic」Error

Question

我有一個ASPX頁面，它將查詢字符串中的任何內容呈現爲垂直文本並返回一個PNG。它效果很好。

我剛好有一位遇到問題的客戶。每隔幾天，頁面停止工作，並引發可怕的GDI +「通用」錯誤。

Error: System.Runtime.InteropServices.ExternalException (0x80004005): A generic error occurred in GDI+. 
at System.Drawing.Image.Save(Stream stream, ImageCodecInfo encoder, EncoderParameters encoderParams) 
at System.Drawing.Image.Save(Stream stream, ImageFormat format) 
... 

我不知道爲什麼會出現錯誤，或者爲什麼最終會消失。我能夠將一個測試ASPX文件放入他們的安裝中，運行類似的代碼並進行了一些修改，以查看我是否可以找出問題所在。我發現如果我將ImageFormat從Png更改爲Jpeg，錯誤就消失了。

我可以想象將產品更改爲呈現JPEG而不是PNG。然而，我無法知道這是否最終會像現在一樣間歇性地引發錯誤。

有人知道什麼可能會導致這樣的問題？謝謝！代碼如下。

更新：客戶服務器是運行IIS 7.5的Windows Server 2008 R2框，我的應用程序在.NET 4.0上運行。

protected void Page_Load(object sender, EventArgs e) 
    { 
     byte[] image = GetImageBytes(this.Text); 
     if (image != null) 
     { 
      Response.ClearContent(); 
      Response.ClearHeaders(); 
      Response.ContentType = "image/png"; 
      Response.OutputStream.Write(image, 0, image.Length); 
     } 
    } 

    private byte[] GetImageBytes(string text) 
    { 
     var font = new Font("Tahoma", 11, FontStyle.Bold, GraphicsUnit.Pixel); 

     // Create an image the size of the text we are writing 
     Bitmap img = new Bitmap(1,1); 
     var graphics = Graphics.FromImage(img); 
     int width = (int)graphics.MeasureString(text, font).Width; 
     int height = (int)graphics.MeasureString(text, font).Height; 
     img = new Bitmap(img, new Size(width, height)); 

     // Draw the text onto the image 
     graphics = Graphics.FromImage(img); 
     graphics.Clear(Color.Transparent); 
     graphics.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.AntiAlias; 
     graphics.TextRenderingHint = System.Drawing.Text.TextRenderingHint.AntiAlias; 
     graphics.CompositingQuality = System.Drawing.Drawing2D.CompositingQuality.HighQuality; 
     graphics.DrawString(text, font, new SolidBrush(Color.Black), 0, 0); 
     graphics.Flush(); 

     // Rotate the image to be vertical 
     img.RotateFlip(RotateFlipType.Rotate270FlipNone); 

     var stream = new System.IO.MemoryStream(); 
     img.Save(stream, ImageFormat.Png); 
     stream.Position = 0; 
     return stream.ToArray(); 
    } 

Answer 1

I would say that the flush could be the issue

強制所有未決的圖形操作的執行，並立即返回，而無需等待操作完成。

此成員已被超載。有關此成員的完整信息（包括語法，用法和示例），請單擊重載列表中的名稱。

你可以試試看看你是否仍然有這個問題？

private byte[] GetImageBytes(string text) 
    { 
     using (var font = new Font("Tahoma", 20, FontStyle.Bold, GraphicsUnit.Pixel)) 
     using (var img = new Bitmap(1, 1)) 
     { 
      int width; 
      int height; 
      using (var graphics = Graphics.FromImage(img)) 
      { 
       width = (int)graphics.MeasureString(text, font).Width; 
       height = (int)graphics.MeasureString(text, font).Height; 
      } 
      using (var realImg = new Bitmap(img, new Size(width, height))) 
      { 
       using (var graphics = Graphics.FromImage(realImg)) 
       { 
        graphics.Clear(Color.Transparent); 
        graphics.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.AntiAlias; 
        graphics.TextRenderingHint = System.Drawing.Text.TextRenderingHint.AntiAlias; 
        graphics.CompositingQuality = System.Drawing.Drawing2D.CompositingQuality.HighQuality; 
        graphics.DrawString(text, font, new SolidBrush(Color.Black), 0, 0); 
       } 

       realImg.RotateFlip(RotateFlipType.Rotate270FlipNone); 

       using (var stream = new System.IO.MemoryStream()) 
       { 
        realImg.Save(stream, System.Drawing.Imaging.ImageFormat.Png); 
        stream.Position = 0; 
        return stream.ToArray(); 
       } 
      } 
     } 
    }