C # precautions for custom events

The following events are defined in a class:

Public Delegate void afterdrawpointevent (Object sender, double X, Double Y );

<textarea readonly name="code" class="csharp">Private afterdrawpointevent pafterdrawpointevent; <br/> /// <summary> <br/> // insert element event <br/> /// </Summary> <br/> public event afterdrawpointevent afterdrawpoint <BR/>{< br/> Add <br/>{< br/> pafterdrawpointevent + = value; <br/>}< br/> remove <br/> {<br/> pafterdrawpointevent-= value; <br/>}< br/> private void raiseafterdrawpointevent (Object sender, double X, Double Y) <br/>{< br/> If (Pafterdrawpointevent! = NULL) <br/>{< br/> pafterdrawpointevent (sender, x, y); <br/>}</P> <p>}</textarea> Then define the implementation response method. Note that the old response method should be removed first. Otherwise, the status of some variables may not be updated.Code As follows:

M_pdrawcustompoint.afterdrawpoint-= new drawcustompoint. afterdrawpointevent (optional); <br/> m_pdrawcustompoint.afterdrawpoint + = new drawcustompoint. afterdrawpointevent (optional );