从实作标题栏按钮开始浅谈组件的制作

RegisterComponents(''''Liao'''', [TTitleBarButton]);

end;

{ TTitleBarButton }

constructor TTitleBarButton.Create(AOwner: TComponent);

var

ptr: Pointer;

begin

inherited;

FForm := GetParentForm(TControl(AOwner));

FGlyph := TBitmap.Create;

FColor := clBtnFace;

FVisible := False;

FRightMargin := 66;

FButtonDown := False;

FOldWndProc := Pointer(GetWindowLong(FForm.Handle,GWL_WNDPROC));

ptr := MakeObjectInstance(NewWndProc);

SetWindowLong(FForm.Handle, GWL_WNDPROC, Longint(ptr));

end;

destructor TTitleBarButton.Destroy;

begin

if not (csDestroying in FForm.ComponentState) then

begin

SetVisible(false);

SetWindowLong(FForm.Handle, GWL_WNDPROC, LongInt(FOldWndProc));

end;

FGlyph.Free;

inherited;

end;

procedure TTitleBarButton.NewWndProc(var message: TMessage);