unit Unit1;

interface

uses
  Winapi.Windows, Winapi.Messages, System.SysUtils, System.Variants,
  System.Classes, Vcl.Graphics,
  Vcl.Controls, Vcl.Forms, Vcl.Dialogs, ovcbase, ovcviewr, Vcl.StdCtrls;

type
  TForm3 = class( TForm )
    ListBox1 : TListBox;
    Button1 : TButton;
    lblNumber : TLabel;
    lblColor : TLabel;
    Edit1 : TEdit;
    procedure FormCreate( Sender : TObject );
    procedure FormDestroy( Sender : TObject );
    procedure ListBox1Data( Control : TWinControl; Index : Integer;
      var Data : string );
    procedure ListBox1DataObject( Control : TWinControl; Index : Integer;
      var DataObject : TObject );
    function ListBox1DataFind( Control : TWinControl; FindString : string )
      : Integer;
    procedure Button1Click( Sender : TObject );
    procedure ListBox1Click( Sender : TObject );
  private
    { Private declarations }
  public
    { Public declarations }
    ObjList : TList;
  end;

  TMyObj = class
    fColor : string;
    fNumber : Integer;
    constructor create( const color : string; const Number : Integer );
  end;

var
  Form3 : TForm3;

implementation

{$R *.dfm}
{ TMyObj }

constructor TMyObj.create( const color : string; const Number : Integer );
begin
  fColor := color;
  fNumber := Number;
end;

procedure TForm3.Button1Click( Sender : TObject );
begin
  ListBox1.ItemIndex := ListBox1.Items.IndexOf( Edit1.Text );
  // I don't think this next should be necessary but..
  //ListBox1Click( Self );
end;

procedure TForm3.FormCreate( Sender : TObject );
begin
  // create a TList and add some data to it.
  ObjList := TList.create;
  ObjList.Add( TMyObj.create( 'Red', 1 ) );
  ObjList.Add( TMyObj.create( 'Yellow', 15 ) );
  ObjList.Add( TMyObj.create( 'Blue', 21 ) );
  ObjList.Add( TMyObj.create( 'Green', 37 ) );
  ObjList.Add( TMyObj.create( 'Brown', 16 ) );
  ObjList.Add( TMyObj.create( 'Black', 5135 ) );
  ObjList.Add( TMyObj.create( 'White', 4 ) );
  ObjList.Add( TMyObj.create( 'Orange', 333 ) );
  // ABSOLUTELY REQUIRED Set the count of the virtual listbox
  ListBox1.Count := ObjList.Count;
end;

procedure TForm3.FormDestroy( Sender : TObject );
var
  I : Integer;
begin
  for I := 0 to ObjList.Count - 1 do
    TMyObj( ObjList.Items[ I ] ).free;
  ObjList.free;
end;

procedure TForm3.ListBox1Click( Sender : TObject );
begin
  lblColor.Caption :=
    TMyObj( ListBox1.Items.objects[ ListBox1.ItemIndex ] ).fColor;
  lblNumber.Caption :=
    IntToStr( TMyObj( ListBox1.Items.objects[ ListBox1.ItemIndex ] ).fNumber );

end;

procedure TForm3.ListBox1Data( Control : TWinControl; Index : Integer;
  var Data : string );
begin
  Data := TMyObj( ObjList.Items[ index ] ).fColor;
end;

function TForm3.ListBox1DataFind( Control : TWinControl; FindString : string )
  : Integer;
var
  I : Integer;
begin
  // the simplest but most brain dead approach
  result := -1;
  for I := 0 to TListBox( Control ).Count - 1 do
    if TListBox( Control ).Items[ I ] = FindString then
      result := I;
end;

procedure TForm3.ListBox1DataObject( Control : TWinControl; Index : Integer;
  var DataObject : TObject );
begin
  DataObject := ObjList.Items[ index ];
end;

end.

object Form3: TForm3
  Left = 0
  Top = 0
  Caption = 'Form3'
  ClientHeight = 189
  ClientWidth = 780
  Color = clBtnFace
  Font.Charset = GB2312_CHARSET
  Font.Color = clWindowText
  Font.Height = -11
  Font.Name = 'Fixedsys'
  Font.Style = []
  OldCreateOrder = False
  OnCreate = FormCreate
  OnDestroy = FormDestroy
  PixelsPerInch = 96
  TextHeight = 16
  object lblNumber: TLabel
    Left = 16
    Top = 144
    Width = 72
    Height = 16
    Caption = 'lblNumber'
  end
  object lblColor: TLabel
    Left = 168
    Top = 144
    Width = 48
    Height = 16
    Caption = 'Label1'
  end
  object ListBox1: TListBox
    Left = 16
    Top = 24
    Width = 737
    Height = 89
    Style = lbVirtual
    TabOrder = 0
    OnClick = ListBox1Click
    OnData = ListBox1Data
    OnDataFind = ListBox1DataFind
    OnDataObject = ListBox1DataObject
  end
  object Button1: TButton
    Left = 678
    Top = 141
    Width = 75
    Height = 25
    Caption = 'Button1'
    TabOrder = 1
    OnClick = Button1Click
  end
  object Edit1: TEdit
    Left = 312
    Top = 141
    Width = 121

    Height = 24
    TabOrder = 2
    Text = 'Orange'
  end
end

TListBoxStyle = (
  lbStandard,
  lbOwnerDrawFixed,
  lbOwnerDrawVariable,
  lbVirtual,
  lbVirtualOwnerDraw
);