generation of PNG in asp.net failed

[angus]

<%@ Page Language = "VB" ContentType="image/Png" %>
<%@ Import Namespace = "System.Drawing"%>
<%@ Import Namespace = "System.Drawing.Imaging"%>
<%@ Import Namespace = "System.Drawing.Drawing2D"%>

<%
Response.Clear()
Dim height As integer = 100
Dim width As integer = 200

Dim bmp As New Bitmap(width, height, PixelFormat.Format24bppRgb)
Dim g As Graphics = Graphics.FromImage(bmp)

g.SmoothingMode = SmoothingMode.AntiAlias
g.Clear(Color.White)
g.FillRectangle(New SolidBrush(Color.LightGray), 1, 1, 150, 50)
g.DrawString("Zone", New Font("Verdana", 10), SystemBrushes.WindowText, New
PointF(10, 15))

bmp.Save(Response.OutputStream, ImageFormat.Png)
g.Dispose()
bmp.Dispose()
Response.End()

%>

Error Msg
Exception Details: System.Runtime.InteropServices.ExternalException: A
generic error occurred in GDI+.

I wonder if i could generate png in asp.net by using "Dim bmp As New
Bitmap(width, height, PixelFormat.Format24bppRgb)" that?

If not so, what i should use?

Thank you.

Regards,
Angus

 

[Patrice]

What if you "g.dispose" before saving ?

Patrice

 

[angus]

the same error happened also.

by the way, if i changed

to

bmp.Save(Response.OutputStream, ImageFormat.Jpeg)
as well as change the contenttype to "contenttype='image/jpeg'

every thing works fine.

 

[Patrice]

I made a search about this weird issue and found that according to
http://www.c-sharpcorner.com/Code/2002/Dec/WorkWithPNG.asp the PNG file
format requires a seekable stream...

 

[Hans Kesting]

MemoryStream io = new MemoryStream();
bmp.Save(io, ImageFormat.Png);
Response.BinaryWrite( io.GetBuffer() );