Class UndoNotify
See Also: Class TVNodeNotify.
class UndoNotify : public TVNodeNotify
Description:
This class is available in release 2.0 and later only.
This class can be used so an ImageFilter plug-in can get notified on a change to one of its Track View Nodes.
This class provides an implementation of the NotifyRefChanged() method of class TVNodeNotify. The constructor of this class stores a window handle. Usually this is the control dialog window handle of the ImageFilter plug-in using this class. Upon receipt of a message via TVNodeNotify::NotifyRefChanged() this implementation sends a FLT_UNDO message to the ImageFilter control dialog window proc and invalidates the window. Most filters will set a flag indicating that an undo has occurred when they get the FLT_UNDO message, and actually update the UI controls when they process the WM_PAINT message. This is because the FLT_UNDO message may be sent many time and the controls shouldn't be updated each time (as they might appear to 'flicker'). See the code for the Negative filter in \MAXSDK\SAMPLES\FILTERS\NEGATIVE\NEGATIVE.CPP for details.
All methods of this class are implemented by the system.
Methods:
Prototype:
UndoNotify(HWND hwnd);
Remarks:
Constructor.
Parameters:
HWND hwnd
The control dialog window handle where the FLT_UNDO message will be sent. This window handle is also passed to InvalidateRectangle() so a WM_PAINT message will be sent.