Fooling around with TWebbrowser #4

TWebbrowser and the Enter key
For some reason the Enter key in TWebbrowser does not work. This is very annoying, because users can't use the enter key to submit a form or, even worse, can not go to the next line in a textarea.

Searching the Internet I found two solutions to this problem:

Solution1: Use your applications MessageHandler;
The best solution,imo, is this one provided by SwissDelphiCenter. This solution 'listens' through the application's messagehandler to handle the keystrokes of your webbrowser. (Webbrowser1 in this case).
In my multitab browser I had to tweak this a little bit to give the handler the active webbrowser. (Don't forget to nil the FOleInPlaceObject when you switch TWebbrowser objects).

if AWebbrowser <> ActiveWebbrowser then begin   
 FOleInPlaceActiveObject := nil; 
  Webbrowser1:= ActiveWebbrowser; 
end; 

This works just fine! Kind of magic to me, but it works.

How to handle popup browsers?
As told in a previous episode of this serie, it is sometimes necessary to invoke the NewWindow2 event to handle popup-browsers. This is typicaly necessary when you need to retain a browser session.

In the NewWindow2 event a new form of you application is popped up modeless to hold the webbrowsers popup. To get the active webbrowser for your messagehandler in this scenario gets a little complicated, because there could be more popups open at the same time, and a popup could have one or more popups. The next solution seems to be more appropiate for that.

Solution 2: Use the Keybd_Event message
Well the Enter key might not work in textarea's, CONTROL + M seems to be doing just what we need, inserting a new line in the textarea.

So we must send a CTRL + M to our webbrowser. Here a solution, as found on Delphi3000, using the Keybd_event function. This function can be used to synthesize keystrokes. So send the CONTROL + M when an enter key is hit and we are done. (Supposing there is only a webbrowser on your popup form).

However there is one side effect with this solution, if you have a textarea and a submit button on your popup webpage, the page will also be submitted if you enter a new line in the textarea. Simple solution for this is to send the CANCEL event after the handling, so this is the code with the extra line (looks a bit messy):

procedure TfrmPopUpBrowser.FormKeyPress(Sender: TObject; 
      var Key: Char);
begin 
  //Don't forget ot set the Keypreview property 
  //of the form to true!
  if (Key=#13) then begin 
    Key := #0; 
    Keybd_Event(VK_LCONTROL, 0, 0, 0); //Ctrl key down 
    Keybd_Event(Ord('M'), MapVirtualKey(Ord('M'), 0), 
        0, 0); // 'M' key down 
    Keybd_Event(Ord('M'), MapVirtualKey(Ord('M'), 0), 
        KEYEVENTF_KEYUP, 0); // 'M' Key up 
    Keybd_Event(VK_LCONTROL, 0, KEYEVENTF_KEYUP, 
        0); // Ctrl key up 
    Keybd_Event(VK_CANCEL, 0, 0, 0);
  end; 
end;

More info on how use Keybd_event function take a look at the msdn article.

Well in my case it was a little harder to tackle this problem, but it works now just fine. Hope this usefull for others as well.