使用InnoSetup备份文件并在卸载时恢复它们？

[Setup]
AppName=MyApp
AppVersion=1.0
DefaultDirName={pf}\MyApp

[Files]
Source: "MyFile.txt"; DestDir: "{app}"

[Code]
var
  BackupDir: string;

procedure BackupFile(FilePath: string);
begin
  FileCopy(FilePath, BackupDir + '\' + ExtractFileName(FilePath), False);
end;

procedure RestoreFile(FilePath: string);
begin
  FileCopy(BackupDir + '\' + ExtractFileName(FilePath), FilePath, False);
  FileDelete(BackupDir + '\' + ExtractFileName(FilePath));
end;

procedure InitializeBackupDir;
begin
  BackupDir := ExpandConstant('{app}\Backup');
  if not DirExists(BackupDir) then
    CreateDir(BackupDir);
end;

procedure InitializeWizard;
begin
  InitializeBackupDir;
end;

procedure CurStepChanged(CurStep: TSetupStep);
begin
  if CurStep = ssInstall then
  begin
    // 备份文件
    BackupFile(ExpandConstant('{app}\MyFile.txt'));
  end
  else if CurStep = ssUninstall then
  begin
    // 恢复文件
    RestoreFile(ExpandConstant('{app}\MyFile.txt'));
  end;
end;