本例效果图:

代码文件:

unit Unit1;interfaceuses  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,  Dialogs, StdCtrls, ExtCtrls;type  TMyShape = class(TShape)  protected    procedure CMMouseenter(var Message: TMessage); message CM_MOUSEENTER;    procedure CMMouseleave(var Message: TMessage); message CM_MOUSELEAVE;  end;  TForm1 = class(TForm)    Panel1: TPanel;    Button1: TButton;    Button2: TButton;    procedure Button1Click(Sender: TObject);    procedure Button2Click(Sender: TObject);  end;var  Form1: TForm1;implementation{$R *.dfm}procedure TForm1.Button1Click(Sender: TObject);const  W = 50;  H = 50;var  shape: TMyShape;begin  shape := TMyShape.Create(Self);  shape.Parent := Panel1;  shape.Width := W;  shape.Height := H;  Randomize;  shape.Left := Random(Panel1.ClientWidth - W);  shape.Top := Random(Panel1.ClientHeight - H);  shape.Brush.Color := Random($FFFFFF);end;procedure TForm1.Button2Click(Sender: TObject);var  i: Integer;begin  if Panel1.ControlCount = 0 then Exit;  Randomize;  i := Random(Panel1.ControlCount - 1);  Panel1.Controls[i].Free;end;{ TMyShape }procedure TMyShape.CMMouseenter(var Message: TMessage);const  s = ‘当前 %s 的颜色值是: %.6x‘;var  WCtrl: TWinControl;begin  WCtrl := Parent;  while WCtrl.HasParent do WCtrl := WCtrl.Parent;  if WCtrl is TForm then TForm(WCtrl).Caption := Format(s, [ClassName,Brush.Color]);  inherited;end;procedure TMyShape.CMMouseleave(var Message: TMessage);const  s = ‘Form1‘;var  WCtrl: TWinControl;begin  WCtrl := Parent;  while WCtrl.HasParent do WCtrl := WCtrl.Parent;  if WCtrl is TForm then TForm(WCtrl).Caption := s;  inherited;end;end.

http://www.cnblogs.com/del/archive/2008/10/23/1317926.html

Controls 属性与继承 TShape 类的小练习（使用TShape可以解决很多图形问题）