Asp. NET output PNG image with GDI + General error resolution

I used ASP to generate a code picture with the JPG format, today want to change it to PNG format, the results appear GDI + General error, check the n-Long data, only to find the solution, to share this solution of netizens deep gratitude

Response.Clear ();
Response.ContentType = "Image/png";
IMG. Save (Response.outputstream, chartformat.png); The
unexpectedly appears to be an exception, which is GDI + generic error. But if the format is Response.ContentType = "Image/jpeg"; The
will not error.


has been encountered before, changed to
Response.ContentType = "Image/png";
 using (MemoryStream ms = new MemoryStream ())
 {
         Img. Save (MS, Chartformat.png);
        response.outputstream.write (Ms. GetBuffer (), 0, (int) Ms. Length);
 }

To enter a PNG image.
This is due to the inability of the Response.outputstream stream to be read backwards, that is, its CanSeek property
is false. PNG image generation is not like JPEG, not streaming, has been written to no longer tube, but need to go back to
constantly write structure data. But response flow can't go back to seek, so the direct use is not. Change to a MemoryStream that can
seek, sir, into a good PNG image, and then output to the response stream.