private void HookWindowProc(IntPtr hwnd, NativeStructs.WndProc newWndProc, IntPtr oldWndProc)
{
_hwndAttached = hwnd;
_hwndHandleRef = new HandleRef(null, _hwndAttached);
_bond = Bond.Attached;
_attachedWndProc = newWndProc;
_oldWndProc = oldWndProc;
IntPtr oldWndProc2 = NativeMethods.SetWindowLong(_hwndAttached, NativeConstants.GWL_WNDPROC, _attachedWndProc);
// Track this window so that we can rip out the managed window proc
// when the CLR shuts down.
ManagedWndProcTracker.TrackHwnd(_hwndAttached);
}
// This method should only be called from Dispose. Otherwise
// assumptions about the disposing/finalize state could be violated.
private void UnhookWindowProc()
{
if (_bond == Bond.Attached || _bond == Bond.Orphaned)
{
ManagedWndProcTracker.UnhookHwnd(_hwndAttached, false /* don't hook up defWindowProc */);
try
{
NativeMethods.SetWindowLong(_hwndHandleRef.Handle, NativeConstants.GWL_WNDPROC, _oldWndProc);
}
catch (System.ComponentModel.Win32Exception e)
{
if (e.NativeErrorCode != 1400) // ERROR_INVALID_WINDOW_HANDLE
{
throw;
}
}
}
_bond = Bond.Detached;
_oldWndProc = IntPtr.Zero;
_attachedWndProc = null;
_hwndAttached = IntPtr.Zero;
_hwndHandleRef = new HandleRef(null, IntPtr.Zero);
// un-Pin this object.
// Note: the GC is free to collect this object at anytime
// after we have freed this handle - that is, once all
// other managed references go away.
//AvDebug.Assert(_gcHandle.IsAllocated, "External GC handle has not been allocated.");
if (_gcHandle.IsAllocated)
{
_gcHandle.Free();
}
}
