Project Structure

• QOdlist.dpr
• ODListF.pas
• ODListF.dfm

program QOdlist;

uses
  QForms,
  ODListF in 'ODListF.pas' {ODListForm};

{$R *.res}

begin
  Application.Initialize;
  Application.CreateForm(TODListForm, ODListForm);
  Application.Run;
end.

unit ODListF;

interface

uses
  Qt, SysUtils, Classes, QGraphics, QControls, QForms, QDialogs,
  QStdCtrls, Types;

type
  TODListForm = class(TForm)
    ListBox1: TListBox;
    ColorDialog1: TColorDialog;
    procedure FormCreate(Sender: TObject);
    procedure ListBox1DblClick(Sender: TObject);
    procedure ListBox1DrawItem(Sender: TObject; Index: Integer;
      Rect: TRect; State: TOwnerDrawState; var Handled: Boolean);
  private
    { Private declarations }
  public
    procedure AddColors (Colors: array of TColor);
  end;

var
  ODListForm: TODListForm;

implementation

{$R *.xfm}

procedure TODListForm.AddColors (Colors: array of TColor);
var
  I: Integer;
begin
  for I := Low (Colors) to High (Colors) do
    ListBox1.Items.AddObject (
      ColorToString (Colors[I]),
      TObject(Colors[I]));
end;

function RGB (red, green, blue: Byte): Cardinal;
begin
  Result := blue + green * 256 + red * 256 * 256;
end;

procedure TODListForm.FormCreate(Sender: TObject);
begin
  Canvas.Font := ListBox1.Font;
  ListBox1.ItemHeight := Canvas.TextHeight('0');
  AddColors ([clRed, clBlue, clYellow, clGreen, clFuchsia, clLime, clPurple,
    clGray, RGB (213, 23, 123), RGB (0, 0, 0), clAqua, clNavy, clOlive, clTeal]);
end;

procedure TODListForm.ListBox1DblClick(Sender: TObject);
begin
  if ColorDialog1.Execute then
    AddColors ([ColorDialog1.Color]);
end;

procedure TODListForm.ListBox1DrawItem(Sender: TObject; Index: Integer;
  Rect: TRect; State: TOwnerDrawState; var Handled: Boolean);
begin
  with Sender as TListbox do
  begin
    // erase
    Canvas.FillRect (Rect);
    // draw item
    Canvas.Font.Color := TColor (
      Items.Objects [Index]);
    Canvas.TextOut(Rect.Left, Rect.Top,
      Listbox1.Items[Index]);

//    InflateRect (Rect, -1, -1);
    if (odFocused in State) and (odSelected in State) then
      Canvas.DrawFocusRect (Rect);
   end;
end;

end.

object ODListForm: TODListForm
  Left = 242
  Top = 121
  Width = 423
  Height = 442
  ActiveControl = ListBox1
  Caption = 'Owner-draw Listbox'
  Color = clButton
  Font.Color = clText
  Font.Height = 11
  Font.Name = 'MS Sans Serif'
  Font.Pitch = fpVariable
  Font.Style = []
  Font.Weight = 40
  ParentFont = False
  OnCreate = FormCreate
  PixelsPerInch = 96
  TextHeight = 13
  TextWidth = 6
  object ListBox1: TListBox
    Left = 0
    Top = 0
    Width = 423
    Height = 442
    Style = lbOwnerDrawFixed
    Align = alClient
    Font.CharSet = fcsLatin1
    Font.Color = clBlack
    Font.Height = 32
    Font.Name = 'Arial'
    Font.Pitch = fpVariable
    Font.Style = [fsBold]
    ItemHeight = 37
    ParentFont = False
    TabOrder = 0
    OnDblClick = ListBox1DblClick
    OnDrawItem = ListBox1DrawItem
  end
  object ColorDialog1: TColorDialog
    Left = 72
    Top = 48
  end
end