inno setup extract exe在安装前运行

Question

在我的设置中，我需要检查是否已安装程序，如果没有安装，我需要在安装应用程序之前先安装它。 我不知道如何在[文件]部分之前提取所需的文件 这是我的代码：

[Files]
Source: "..\PREREQUIREMENTS\DicomObjects\DicomObjectsSetup43.exe"; DestDir: "{src}\PreReq\DO\Setup\"; DestName: "DOSETUP.exe"; Flags: ignoreversion
Source: "..\PREREQUIREMENTS\DicomObjects\License\DicomObjects.lic"; DestDir: "{src}\PreReq\DO\Lic\"; Flags: ignoreversion

procedure CurStepChanged(CurStep: TSetupStep);

begin

  if CurStep = ssInstall then
  begin
    if not FileExists(ExpandConstant('"{pf}\Medical Connections\DicomObjects\DicomObjects.ocx"'))then if MsgBox ('installazione DO', mbInformation, mb_YesNo) = idYes then 
    begin
      Exec(ExpandConstant('{src}\PreReq\DO\Setup\DOSETUP.exe'), '', '', SW_SHOW,ewWaitUntilTerminated, ResultCode);
      Exec('cmd.exe','/c COPY "{src}\PreReq\DO\Lic\*.*" "{pf}\Medical Connections\DicomObjects\"', '', SW_HIDE, ewWaitUntilTerminated, ResultCode);
    end;
  end;

我也尝试了此代码，但没有用

function PrepareToInstall(var NeedsRestart: Boolean): String;

begin
    if not FileExists(ExpandConstant('"{pf}\Medical Connections\DicomObjects\DicomObjects.ocx"'))then  
    begin
        ExtractTemporaryFile('DOSETUP.exe');
        Exec(ExpandConstant('{src}\PreReq\DO\Setup\DOSETUP.exe'), '', '', SW_SHOW,ewWaitUntilTerminated, ResultCode);
        Exec('cmd.exe','/c COPY "{src}\PreReq\DO\Lic\*.*" "{pf}\Medical Connections\DicomObjects\"', '', SW_HIDE, ewWaitUntilTerminated, ResultCode);
    end;
end;