Take a screenshot of a webpage with JavaScript?

Another possible solution that I've discovered is http://www.phantomjs.org/ which allows one to very easily take screenshots of pages and a whole lot more. Whilst my original requirements for this question aren't valid any more (different job), I will likely integrate PhantomJS into future projects.

I have done this for an HTA by using an ActiveX control. It was pretty easy to build the control in VB6 to take the screenshot. I had to use the keybd_event API call because SendKeys can't do PrintScreen. Here's the code for that:

Declare Sub keybd_event Lib "user32" _
(ByVal bVk As Byte, ByVal bScan As Byte, ByVal dwFlags As Long, ByVal dwExtraInfo As Long)

Public Const CaptWindow = 2

Public Sub ScreenGrab()
   keybd_event &H12, 0, 0, 0
   keybd_event &H2C, CaptWindow, 0, 0
   keybd_event &H2C, CaptWindow, &H2, 0
   keybd_event &H12, 0, &H2, 0
End Sub

That only gets you as far as getting the window to the clipboard.

Another option, if the window you want a screenshot of is an HTA would be to just use an XMLHTTPRequest to send the DOM nodes to the server, then create the screenshots server-side.

Google is doing this in Google+ and a talented developer reverse engineered it and produced http://html2canvas.hertzen.com/ . To work in IE you'll need a canvas support library such as http://excanvas.sourceforge.net/