DirectShow.NET中筛选器的QueryInterface

本文关键字：QueryInterface 筛选 NET DirectShow | 更新日期: 2023-09-27 18:00:03

我使用视频处理项目中的过滤器，并希望设置过滤器的设置。在c++中，它通过ISettingsInterface工作。

ISettingsInterface * pSettingsInterface = NULL;
pRotateFilter->QueryInterface ( IID_ISettingsInterface, ( void ** ) &pSettingsInterface );
hr = pSettingsInterface->SetParameter ( "rotationmode", "3" );
hr = g_pGraph->AddFilter ( pRotateFilter, L"RotateFilter" );

在DirectShowlib c#包装器中没有这样的接口？过滤器上也没有QueryInterface函数。

我通过声明接口解决了这个问题：

 [ComImport, System.Security.SuppressUnmanagedCodeSecurity,Guid("388EEF20-40CC-4752-A0FF-66AA5C4AF8FA"),InterfaceType(ComInterfaceType.InterfaceIsIUnknown)]
    public interface ISettingsInterface
    {
        [PreserveSig]
        int GetParameter(
            [MarshalAs(UnmanagedType.LPStr)] String type,
            [MarshalAs(UnmanagedType.I4)] int buffersize,
            [In, Out, MarshalAs(UnmanagedType.LPStr)] String value,
            [In, Out, MarshalAs(UnmanagedType.I4)] ref int length
            );
        [PreserveSig]
        int SetParameter(
            [MarshalAs(UnmanagedType.LPStr)] String type,
            [MarshalAs(UnmanagedType.LPStr)] String value
            );
        [PreserveSig]
        int GetParameterSettings(
            [MarshalAs(UnmanagedType.LPStr)] ref String szResult,
            [In] int nSize
            );
    }