继承控件并增加属性问题 (50分)

继承控件并增加属性问题

1、 从Image继承一个新控件，要在新控件上增加（即TFont）一个设置画字体的各种属性
我写了如下，使用时点选Font属性时提示：Can not assign a nil to Tfont.
请各位修改一下：
unit image1;

interface

uses
Windows, Messages, SysUtils, Classes, Controls, ExtCtrls,Graphics;

type
timage1 = class(timage)
private
ffont:tfont;
{ Private declarations }
protected
procedure setFont(value:tfont);
{ Protected declarations }
public
{ Public declarations }
published
property Font:tfont read ffont write setfont;
{ Published declarations }
end;

procedure Register;

implementation

procedure timage1.setFont(value:tfont);
begin
ffont:=value;
invaldate;
end;

procedure Register;
begin
RegisterComponents('Samples', [timage1]);
end;

end.
-----------------------------
2、 另外，我想在该新控件上编写上一个控件如Tedit,Tmemo等，应如何编写？

我没试过，好像font 要先create
使用ccpack可以把几个控件组合一起

public
constructor create; override;
destructor destroy; override;
published

constructor timage1.create;
begin
inherited;
ffont:=tfont.create;
end;
destructor timage1.destroy;
begin
ffont.free;
inherited;
end;
procedure timage1.setFont(value:tfont);
begin
assert(assigned(value));
if value <> ffont then
begin
ffont.assign(value);
invaldate;
end;
end;

多人接受答案了。