c++builder自定义控件

void __fastcall SetFocusControl(TWinControl* Value);
    void __fastcall CMDialogChar(TWMKey& Message);
    void __fastcall CMTextChanged(TMessage& Message);
 
protected:
    virtual void __fastcall Notification(TComponent* AComponent, TOperation Operation);
    virtual void __fastcall Paint(void);
 
public:
    __fastcall virtual TDemoLabel(TComponent* AOwner);
 
__published:
    __property Caption ;
    __property Color ;
    __property TWinControl* FocusControl = {read=FFocusControl, write=SetFocusControl, nodefault};
    __property Font ;
    __property ParentColor ;
    __property ParentFont ;
public:
    __fastcall virtual ~TDemoLabel(void) { }
 
BEGIN_MESSAGE_MAP
  MESSAGE_HANDLER(CM_DIALOGCHAR, TWMKey, CMDialogChar);
  MESSAGE_HANDLER(CM_TEXTCHANGED, TMessage, CMTextChanged);
END_MESSAGE_MAP(TGraphicControl);
};


void __fastcall PACKAGE Register()
{
  TComponentClass classes[1] = {__classid(TDemoLabel)};
  RegisterComponents("Samples", classes, 0);
  RegisterComponents("MySystem", classes, 0);
}
 
__fastcall TDemoLabel::TDemoLabel(TComponent *AOwner):
    TGraphicControl(AOwner)
{
  FComponentStyle >> csInheritable;
  Width=64;
  Height=13;
}
 
void __fastcall    TDemoLabel::Notification(TComponent *AComponent, TOperation Operation)
{
  TGraphicControl::Notification(AComponent, Operation);
  if ((Operation == opRemove)  && (AComponent == FFocusControl))
    FFocusControl = 0;
}
 
void __fastcall    TDemoLabel::SetFocusControl(TWinControl *Value)
{
  FFocusControl = Value;
 
  // Calling FreeNotification ensures that this component 
  // will receive an opRemove when Value is either removed 
  // from its owner or destroyed.
 
  Value->FreeNotification(Value);
}
 
void __fastcall    TDemoLabel::Paint()
{
  TRect    Rect = ClientRect;
  Canvas->Font = Font;
  Canvas->Brush->Color = Color;
  Canvas->FillRect(Rect);
  DrawText(
    Canvas->Handle,
    Caption.t_str(),
    Caption.Length(),
    &Rect,
    DT_EXPANDTABS | DT_WORDBREAK | DT_LEFT);
}
 
void __fastcall    TDemoLabel::CMDialogChar(TCMDialogKey &Message)
{
  if (FFocusControl != NULL &&
      Enabled == true &&
      IsAccel(Message.CharCode, Caption))
      if (FFocusControl->CanFocus()){
        FFocusControl->SetFocus();
        Message.Result = 1;
      }
}
 
void __fastcall    TDemoLabel::CMTextChanged(TMessage &Message)
{
  Invalidate();
}