DeinitializeEngine 関数

IEngine* FineReaderEngine = 0;
HMODULE EngineLibraryHandle = 0;
static HRESULT deinitializeEngine()
{
 // Engine オブジェクト を解放する
 if( FineReaderEngine != 0 ) {
  FineReaderEngine->Release();
  FineReaderEngine = 0;
 }
 // DeinitializeEngine を呼び出す
 typedef HRESULT (STDAPICALLTYPE* DeinitializeEngineFunc)();
 DeinitializeEngineFunc pDeinitializeEngine =
  (DeinitializeEngineFunc)GetProcAddress( EngineLibraryHandle, "DeinitializeEngine" );
 if( pDeinitializeEngine == 0 || FAILED( pDeinitializeEngine() ) ) {
  setLastErrorInfo( L"FineReader Engine をアンロードできません。" );
  return E_UNEXPECTED;
 }
 return S_OK;
}

public class EngineLoader : IDisposable
{
    // FineReader Engine をアンロードする
    public void Dispose()
    {
        if (engine == null)
        {
            // Engine はロードされていない
            return;
        }
        engine = null;
        // FreeLibrary を呼び出す前にすべての object を削除する
        GC.Collect();
        GC.WaitForPendingFinalizers();
        GC.Collect();
        int hresult = deinitializeEngine();
 
        hresult = dllCanUnloadNow();
        if (hresult == 0)
        {
            FreeLibrary(dllHandle);
        }
        dllHandle = IntPtr.Zero;
        initializeEngine = null;
        deinitializeEngine = null;
        dllCanUnloadNow = null;
        // クリーンアップ後に例外をスローする
        Marshal.ThrowExceptionForHR(hresult);
    }
    // Kernel32.dll の関数
    [DllImport("kernel32.dll")]
    private static extern IntPtr LoadLibraryEx(string dllToLoad, IntPtr reserved, uint flags);
    private const uint LOAD_WITH_ALTERED_SEARCH_PATH = 0x00000008;
    [DllImport("kernel32.dll")]
    private static extern IntPtr GetProcAddress(IntPtr hModule, string procedureName);
    [DllImport("kernel32.dll")]
    private static extern bool FreeLibrary(IntPtr hModule);
    // FREngine.dll の関数
    [UnmanagedFunctionPointer(CallingConvention.StdCall, CharSet = CharSet.Unicode)]
    private delegate int InitializeEngine( string customerProjectId, string LicensePath, string LicensePassword, , , , ref FREngine.IEngine engine);
    [UnmanagedFunctionPointer(CallingConvention.StdCall)]
    private delegate int DeinitializeEngine();
    [UnmanagedFunctionPointer(CallingConvention.StdCall)]
    private delegate int DllCanUnloadNow();
    // private 変数
    private FREngine.IEngine engine = null;
    // FREngine.dll へのハンドル
    private IntPtr dllHandle = IntPtr.Zero;
    private InitializeEngine initializeEngine = null;
    private DeinitializeEngine deinitializeEngine = null;
    private DllCanUnloadNow dllCanUnloadNow = null;
}