Controls attributes and small exercises inheriting the tshape class

In this example:

Code file:

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 = 'the current % s color value is: %. 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.
 

Form file:

object Form1: TForm1  Left = 0  Top = 0  Caption = 'Form1'  ClientHeight = 212  ClientWidth = 395  Color = clBtnFace  Font.Charset = DEFAULT_CHARSET  Font.Color = clWindowText  Font.Height = -11  Font.Name = 'Tahoma'  Font.Style = []  OldCreateOrder = False  PixelsPerInch = 96  TextHeight = 13  object Panel1: TPanel    Left = 8    Top = 8    Width = 297    Height = 193    Caption = 'Panel1'    TabOrder = 0  end  object Button1: TButton    Left = 311    Top = 40    Width = 75    Height = 25    Caption = #28155#21152    TabOrder = 1    OnClick = Button1Click  end  object Button2: TButton    Left = 311    Top = 85    Width = 75    Height = 25    Caption = #38543#26426#21024#38500    TabOrder = 2    OnClick = Button2Click  endend