Delphi中动态控件的创建、销毁和计数

unit MainForm;

interface

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

type
  TMainForm = class(TForm)
    btnCreate: TButton;
    btnDestroy: TButton;
    lblCount: TLabel;
    procedure btnCreateClick(Sender: TObject);
    procedure btnDestroyClick(Sender: TObject);
  private
    FDynamicControls: TList;
    FControlCount: Integer;
    procedure CreateDynamicControl;
    procedure DestroyDynamicControl;
    procedure UpdateControlCountLabel;
  public
    constructor Create(AOwner: TComponent); override;
    destructor Destroy; override;
  end;

var
  MainForm: TMainForm;

implementation

{$R *.dfm}

constructor TMainForm.Create(AOwner: TComponent);
begin
  inherited;
  FDynamicControls := TList.Create;
  FControlCount := 0;
end;

destructor TMainForm.Destroy;
begin
  FDynamicControls.Free;
  inherited;
end;

procedure TMainForm.CreateDynamicControl;
var
  NewButton: TButton;
begin
  NewButton := TButton.Create(Self);
  NewButton.Parent := Self;
  NewButton.Left := Random(Width - NewButton.Width);
  NewButton.Top := Random(Height - NewButton.Height);
  NewButton.Caption := 'Dynamic Button ' + IntToStr(FControlCount);
  FDynamicControls.Add(NewButton);
  Inc(FControlCount);
  UpdateControlCountLabel;
end;

procedure TMainForm.DestroyDynamicControl;
var
  LastButton: TButton;
begin
  if FDynamicControls.Count > 0 then
  begin
    LastButton := TButton(FDynamicControls.Last);
    FDynamicControls.Remove(LastButton);
    LastButton.Free;
    Dec(FControlCount);
    UpdateControlCountLabel;
  end;
end;

procedure TMainForm.UpdateControlCountLabel;
begin
  lblCount.Caption := 'Control Count: ' + IntToStr(FControlCount);
end;

procedure TMainForm.btnCreateClick(Sender: TObject);
begin
  CreateDynamicControl;
end;

procedure TMainForm.btnDestroyClick(Sender: TObject);
begin
  DestroyDynamicControl;
end;

end.