Re: Notification when a window is subclassed

Thanks for your responses. For starters, all of this subclassing
activity is happening within the *same* application. Secondly, am
constrained to using the raw Win32 API.

Before I provide code details, here's rougly what am trying to
achieve. I have a Java UI application that hosts a few third-party COM/
ActiveX controls in it. One of the challenges of this integration is
Focus Management. Java's focus manager is unaware of these COM objects
sitting on it's canvas and hence doesn't account for them in it's
implementation of focus management. This results in two problems:

1. An ActiveX control that currently has the focus (by clicking on it)
does not get it back when the application regains focus, say when the
user switches away and then switches back on to app.
2. Focus does not cycle (using the Tab and Shift-tab keys) seamlessly
between Java UI elements and the ActiveX controls.

To fix these focus related problems am writing some bridging code that
works with Java's focus manager to make it aware of the ActiveX
controls hosted on it's canvas. For the implementation to work I need
to know when the ActiveX control gained focus (WM_SETFOCUS) and when
it receives the Tab and Shift-Tab key events (WM_KEYDOWN).

So when the application is being realized I create the control and
then subclass it by supplying my own window procedure. For events that
don't interest me I forward them to the OriginalWndProc.

/* Subclassing code */

  // Get the Hwnd of the control from the Control host.
HWND controlWindow = GetWindow(atlAxWin, GW_CHILD);
  // Subclass the Window
WNDPROC controlWndProc = (WNDPROC)SetWindowLong(controlWindow,
GWL_WNDPROC, (LONG)SubclassProc);
  // Remember the original WndProc
BOOL res = SetProp(controlWindow,
_T("OcxFocusMgr_ControlOrigWndProc"), (HANDLE)controlWndProc);

/* My WndProc */

LRESULT CALLBACK SubclassProc(HWND hwnd, UINT message, WPARAM wparam,
LPARAM lparam)
{
  HANDLE origWndProc = GetProp(hwnd,
L"OcxFocusMgr_ControlOrigWndProc");

  switch(message)
  {
  case WM_SETFOCUS:
    {
      LRESULT result = CallWindowProc((WNDPROC)origWndProc, hwnd,
message, wparam, lparam);
            // Do something.
      return result;
    }
    break;
  case WM_KEYDOWN:
    if(wparam == VK_TAB)
    {
      LRESULT result = CallWindowProc((WNDPROC)origWndProc, hwnd,
message, wparam, lparam);

      if(GetKeyState(VK_SHIFT) < 0) // Shift-Tab
        // Do something
      else
        // Do something else
      return result;
    }
    break;
  }
  return CallWindowProc((WNDPROC)origWndProc, hwnd, message, wparam,
lparam);
}

This works fine until the time that the control tries to internally
load a particular file at which time it again subclasses this very
window that I originally subclassed. The sad part is I can't know when
it does that - it could be a result of an explicit UI operation or a
side-effect of something else. As a result I stop receiving the events
that am interested in which causes my focus mgt solution to stop
working.

I hope I was able to clearly explain what am trying to get at. Based
on this I would appreciate any suggestions you may have.

Ranjit
P.S - I will research PreSubClassWindow in the meanwhile.

On Apr 8, 10:23 am, Joseph M. Newcomer <newco...@flounder.com> wrote: