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Home: Code Repository: Mastering Delphi 6

Chapter 05 - Project ChangeOwner

Project Structure

ChangeOwner.dpr
program ChangeOwner;

uses
  Forms,
  ChOwn1 in 'ChOwn1.pas' {Form1},
  ChOwn2 in 'ChOwn2.pas' {Form2};

{$R *.RES}

begin
  Application.Initialize;
  Application.CreateForm(TForm1, Form1);
  Application.CreateForm(TForm2, Form2);
  Application.Run;
end.
ChOwn1.pas
unit ChOwn1;

interface

uses
  Windows, Messages, SysUtils, Classes, Graphics, Controls, Forms, Dialogs,
  StdCtrls;

type
  TForm1 = class(TForm)
    Button1: TButton;
    ButtonChange: TButton;
    ButtonList: TButton;
    ListBox1: TListBox;
    procedure ButtonChangeClick(Sender: TObject);
    procedure ButtonListClick(Sender: TObject);
    procedure Button1Click(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;

var
  Form1: TForm1;

implementation

uses ChOwn2;

{$R *.DFM}

procedure ChangeOwner (Component, NewOwner: TComponent);
begin
  Component.Owner.RemoveComponent (Component);
  NewOwner.InsertComponent (Component);
end;

procedure TForm1.ButtonChangeClick(Sender: TObject);
begin
  if Assigned (Button1) then
  begin
    // change parent
    Button1.Parent := Form2;
    // change owner
    ChangeOwner (Button1, Form2);
  end;
end;

procedure TForm1.ButtonListClick(Sender: TObject);
var
 I: Integer;
begin
  ListBox1.Items.Clear;
  for I := 0 to ComponentCount - 1 do
    ListBox1.Items.Add (Components[I].Name);
end;

procedure TForm1.Button1Click(Sender: TObject);
begin
  ShowMessage ('My owner is ' +
    ((Sender as TButton).Owner as TForm).Caption);
end;

end.
ChOwn2.pas
unit ChOwn2;

interface

uses
  Windows, Messages, SysUtils, Classes, Graphics, Controls, Forms, Dialogs,
  StdCtrls;

type
  TForm2 = class(TForm)
    ButtonList: TButton;
    ListBox1: TListBox;
    procedure ButtonListClick(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;

var
  Form2: TForm2;

implementation

{$R *.DFM}


procedure TForm2.ButtonListClick(Sender: TObject);
var
 I: Integer;
begin
  ListBox1.Items.Clear;
  for I := 0 to ComponentCount - 1 do
    ListBox1.Items.Add (Components[I].Name);
end;

end.
ChOwn1.dfm
object Form1: TForm1
  Left = 194
  Top = 201
  Width = 482
  Height = 176
  Caption = 'Form1'
  Color = clBtnFace
  Font.Charset = DEFAULT_CHARSET
  Font.Color = clWindowText
  Font.Height = -11
  Font.Name = 'MS Sans Serif'
  Font.Style = []
  OldCreateOrder = True
  PixelsPerInch = 96
  TextHeight = 13
  object Button1: TButton
    Left = 152
    Top = 56
    Width = 75
    Height = 25
    Caption = 'Button1'
    TabOrder = 0
    OnClick = Button1Click
  end
  object ButtonChange: TButton
    Left = 56
    Top = 56
    Width = 75
    Height = 25
    Caption = 'Change'
    TabOrder = 1
    OnClick = ButtonChangeClick
  end
  object ButtonList: TButton
    Left = 312
    Top = 16
    Width = 75
    Height = 25
    Caption = 'List'
    TabOrder = 2
    OnClick = ButtonListClick
  end
  object ListBox1: TListBox
    Left = 280
    Top = 48
    Width = 145
    Height = 89
    ItemHeight = 13
    TabOrder = 3
  end
end
ChOwn2.dfm
object Form2: TForm2
  Left = 205
  Top = 284
  Width = 483
  Height = 176
  Caption = 'Form2'
  Font.Charset = DEFAULT_CHARSET
  Font.Color = clWindowText
  Font.Height = -11
  Font.Name = 'MS Sans Serif'
  Font.Style = []
  Visible = True
  PixelsPerInch = 96
  TextHeight = 13
  object ButtonList: TButton
    Left = 320
    Top = 16
    Width = 75
    Height = 25
    Caption = 'List'
    TabOrder = 0
    OnClick = ButtonListClick
  end
  object ListBox1: TListBox
    Left = 280
    Top = 48
    Width = 145
    Height = 89
    ItemHeight = 13
    TabOrder = 1
  end
end