CanAutoSize is called automatically when the AutoSize property is true and an attempt is made to resize the control. It allows controls to implement the AutoSize property before the resize sequence that begins with the OnCanResize and OnConstrainedResize events and ends with the OnResize event. 

When CanAutoSize is called, the NewWidth and NewHeight parameters indicate the proposed new dimensions of the control. CanAutoSize adjusts these values so that the control's size adjusts to its contents. If the adjustment results in values of NewWidth and NewHeight that differ from the control's current width and height, CanAutoSize returns true, indicating that the resize sequence should proceed. If, after adjustment, NewWidth and NewHeight equal Width and Height, CanAutoSize returns true, and the resize sequence is aborted. 

As implemented in TControl, CanAutoSize always returns true without changing NewWidth or NewHeight. Override CanAutoSize to implement the AutoSize property for a particular control class's contents. 

AutoSize 

OnResize 

OnCanResize 

OnConstrainedResize 

Width 

Height