IMessageFilter and WM_DRAWCLIPBOARD

Question

I have a component that should be notified when the WM_DRAWCLIPBOARD event is sent, that indicates the the clipboard's content has changed. When i implement IMessageFilter for the component it gets all kind of messages, but not that event. Overriding a form's WndProc method makes it receive the message, but i want my component to work without having to override the form. Is there any way to make a IMessageFilter implementing component receive the WM_DRAWCLIPBOARD event?

Alan · Answer

If the component doesn't have any visual interface then I don't think it can capture the WM_DRAWCLIPBOARD message. As I understand it the message only goes to windows which have been added to the ClipboardViewer chain. Please see this MSDN link for confirmation of this: http://msdn.microsoft.com/en-us/library/ms649025(VS.85).aspx The only possible workaround I can think of would be to attach a hidden form to the component.

Justus · Answer

I would do this if i knew the form from the component. A component does not feature a property like Parent or Form that's the problem.

Alan · Answer

I've been trying to figure out why the WM_DRAWCLIPBOARD message wouldn't be captured when you implement IMessageFilter. Did you call the SetClipboardViewer() API function on your component's window handle to insert it in the ClipBoardViewer chain?