datatype image in $.ajax - asp.net

Question

in page cap.aspx
==========================================================================
string code = GetRandomText();
Bitmap bitmap = new Bitmap(160,50,System.Drawing.Imaging.PixelFormat.Format32bppArgb);
Graphics g = Graphics.FromImage(bitmap);
Pen pen = new Pen(Color.LavenderBlush);
Rectangle rect = new Rectangle(0,0,160,50);
SolidBrush b = new SolidBrush(Color.LightPink);
SolidBrush blue = new SolidBrush(Color.White);
int counter = 0;
g.DrawRectangle(pen, rect);
g.FillRectangle(b, rect);
for (int i = 0; i < code.Length; i++)
{
g.DrawString(code[i].ToString(), new Font("Tahoma", 10 + rand.Next(14, 18)), blue, new PointF(10 + counter, 10));
counter += 20;
}
DrawRandomLines(g);
bitmap.Save(Response.OutputStream,ImageFormat.Gif);
g.Dispose();
b.Dispose();
blue.Dispose();
bitmap.Dispose();
===================================================================================
<div id="DIVdialog" style="display:none">
<img src="cap.aspx"/>
</div>
===================================================================================
$("#DIVdialog").dialog();
==================================================================================
show dialog but does not show image? address cap.aspx is correct!
how get cap.aspx by $.ajax and datatype:image?

Answer 1

I think that the key here is to add the ContentType and the BufferOutput
context.Response.ContentType = "image/gif";
context.Response.BufferOutput = false;
Eg:
public void RenderIt(HttpContext context)
{
context.Response.ContentType = "image/gif";
context.Response.BufferOutput = false;
string code = GetRandomText();
using(Bitmap bitmap = new Bitmap(160,50,System.Drawing.Imaging.PixelFormat.Format32bppArgb))
{
using(Graphics g = Graphics.FromImage(bitmap))
{
using(Pen pen = new Pen(Color.LavenderBlush)
{
using(SolidBrush b = new SolidBrush(Color.LightPink))
{
using(SolidBrush blue = new SolidBrush(Color.White))
{
Rectangle rect = new Rectangle(0,0,160,50);
int counter = 0;
g.DrawRectangle(pen, rect);
g.FillRectangle(b, rect);
for (int i = 0; i < code.Length; i++)
{
g.DrawString(code[i].ToString(), new Font("Tahoma", 10 + rand.Next(14, 18)), blue, new PointF(10 + counter, 10));
counter += 20;
}
DrawRandomLines(g);
g.Dispose();
b.Dispose();
blue.Dispose();
// Return
bitmap.Save(context.Response.OutputStream, ImageFormat.Gif);
// Dispose
bitmap.Dispose();
}
}
}
}
}
context.Response.End();
}