RAD Studio VCL Reference
TControl.MouseWheelHandler Method

Dispatches messages received from a mouse wheel.

procedure MouseWheelHandler(var Message: TMessage); dynamic;
__fastcall MouseWheelHandler(TMessage Message);

The WndProc method calls MouseWheelHandler when it receives a mouse wheel message. MouseWheelHandler checks whether the windowed control is embedded in a form, and if so, calls the form's MouseWheelHandler method. This allows the form to respond to mouse wheel messages before they are handled by individual controls. If the windowed control is not in a form, MouseWheelHandler passes the mouse wheel message to the Perform method, which generates an OnMouseWheel event, followed (if necessary) by an OnMouseWheelUp or OnMouseWheelDown event. 


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