FRDocument 对象的 AddImageFile 方法

// 如果图像加载耗时过长，则启用超时控制
frDocumentCallback.SetShouldTrackTime( true );
frDocumentCallback.FlushTimer();
// 调用 AddImageFile 方法打开图像文件
CheckResult( frDocument->AddImageFile( imageFilePath, 0, pageIndices ) );
// 为后续处理关闭超时控制
frDocumentCallback.SetShouldTrackTime( false );
...
// 使用 IFRDocumentEvents 回调接口报告事件
class CFRDocumentCallback: public IFRDocumentEvents {
public:
    CFRDocumentCallback() : startTime( 0 ) {}
 
    // 实现 IUnknown 方法
    ULONG STDMETHODCALLTYPE AddRef() { return 1; }
    ULONG STDMETHODCALLTYPE Release() { return 1; }
    HRESULT STDMETHODCALLTYPE QueryInterface( REFIID riid, void** ppObject );
    HRESULT STDMETHODCALLTYPE OnProgress( IFRDocument* document, int percentage, VARIANT_BOOL* ShouldContinue );
    HRESULT STDMETHODCALLTYPE OnWarning( IFRDocument* frPage, int pageNumber, BSTR recognizerTip, 
        VARIANT_BOOL* ShouldContinue );
    HRESULT STDMETHODCALLTYPE OnPageProcessed( IFRDocument* document, int pageNumber, PageProcessingStageEnum stage );
    void FlushTimer();
    void SetShouldTrackTime( bool _shouldTrackTime );
private:
    time_t startTime;
    bool shouldTrackTime = true;
};
// 调用 FlushTimer 方法以重置 startTime
void CFRDocumentCallback::FlushTimer() {
    time( &startTime );
}
// 此回调也可用于其他方法，因此如果您不想再重置超时，请将 shouldTrackTime 设为 FALSE
void CFRDocumentCallback::SetShouldTrackTime( bool _shouldTrackTime ) {
    shouldTrackTime = _shouldTrackTime;
}
 
// 如果当前时间与“startTime”之间的差值超过某个阈值，进程将被中止。AddImageFile 方法向 OnProgress 方法传递的是 0，
而不是 percentage
HRESULT STDMETHODCALLTYPE CFRDocumentCallback::OnProgress( IFRDocument* frDocument, int percentage, 
    VARIANT_BOOL* shouldTerminate )
{
    if( shouldTrackTime ) {
        time_t currentTime;
        time( ¤tTime );
        double seconds = difftime( currentTime, startTime );
        printf( "%f\n", seconds );
        *shouldTerminate = ( seconds > 100 ? VARIANT_TRUE : VARIANT_FALSE );
    }
    return S_OK;
}