unit1.pas

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unit Unit1;

interface

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

type
  TForm1 = class(TForm)
    FontDialog1: TFontDialog;
    btnUndo: TButton;
    btnSet: TButton;
    Memo1: TMemo;
    procedure btnSetClick(Sender: TObject);
    procedure FormCreate(Sender: TObject);
    procedure btnUndoClick(Sender: TObject);
  private
    FOriginalFont:TFont;
  public
    { Public declarations }
  end;

var
  Form1: TForm1;

implementation

{$R *.dfm}

procedure TForm1.btnSetClick(Sender: TObject);
begin
  if  FontDialog1.Execute then
    Memo1.Font:=FontDialog1.Font;
end;

procedure TForm1.FormCreate(Sender: TObject);
begin
  Memo1.Lines.Add(
    '一个可以任意设置字体和复原字体的例子。') ;
  FOriginalFont:=TFont.create;
  FOriginalFont.assign(Memo1.Font);
end;

procedure TForm1.btnUndoClick(Sender: TObject);
begin
  Memo1.Font.Assign(FOriginalFont);
end;

end.