翻译piDftDocServices->GetDrawing(IID_CATIDrawing, (void **)&piDrawing);

这段代码是获取一个绘图对象的指针，翻译如下：

`piDftDocServices->GetDrawing(IID_CATIDrawing, (void **)&piDrawing);`

通过调用`piDftDocServices`对象的`GetDrawing`方法，传入参数`IID_CATIDrawing`表示需要获取的绘图对象的接口标识符，将返回的指针强制转换为`void **`类型，再将其赋值给`piDrawing`指针变量。

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hr = pCaptureGraphBuilder2->FindInterface(&PIN_CATEGORY_CAPTURE, &MEDIATYPE_Video, NULL, IID_IBaseFilter, (void**)&pVideoCaptureFilter);

NULL, &MEDIATYPE_Video, pSourceFilter, IID_IBaseFilter, (void**)&pVideoFilter);

This code snippet uses the function FindInterface of the CaptureGraphBuilder2 interface to find the video filter interface of a source filter. The function takes in the following parameters:

- NULL: This is the filter category used to search for the interface. In this case, we are not specifying a filter category, so we pass NULL.
- &MEDIATYPE_Video: This specifies the media type of the interface we are searching for. In this case, we are looking for the video filter interface, so we pass MEDIATYPE_Video.
- pSourceFilter: This is a pointer to the source filter for which we want to find the video filter interface.
- IID_IBaseFilter: This is the interface identifier for the IBaseFilter interface, which is the base interface for all DirectShow filters.
- (void**)&pVideoFilter: This is a pointer to the video filter interface that will be returned by the function if it succeeds. The function uses the address of this pointer to return the interface.

void CSpinningCodeDlg::Connect() { HRESULT hRes = CoInitialize(NULL); // LPUNKNOWN lp = CreateObjectEx( _T("cnc8070.PparamTable"), _T("172.16.0.85"), 0 ); LPUNKNOWN lp = CreateObjectEx( _T("cnc8070.PparamTable"), _T(""), 0 ); SCODE sc; sc = OleRun(lp); if (FAILED(sc)) return; lp->QueryInterface(IID_IFCDualApiPParamTable, (void **)&m_pDualVar); lp->Release(); // lp = CreateObjectEx( _T("cnc8070.variables"), _T("172.16.0.85"), 0 ); lp = CreateObjectEx( _T("cnc8070.variables"), _T(""), 0 ); sc = OleRun(lp); if (FAILED(sc)) return; lp->QueryInterface(IID_IFCDualVar8070, (void **)&m_pDualVar1); lp->Release(); OpenVar(); } 什么意思解释一下

这段代码是一个 MFC 对话框类 CSpinningCodeDlg 的 Connect 成员函数。它的主要作用是连接到一个名为 cnc8070 的 ActiveX 控件，并获取该控件的 IFCDualApiPParamTable 和 IFCDualVar8070 接口，以便后续对该控件的参数和变量进行操作。

具体来说，这段代码会先调用 CoInitialize 函数初始化 COM 库，然后通过 CreateObjectEx 函数创建一个名为 "cnc8070.PparamTable" 的控件对象，并通过 OleRun 函数运行该控件对象。如果运行失败，函数返回。然后通过 QueryInterface 函数获取该控件对象的 IFCDualApiPParamTable 接口，并将其保存到成员变量 m_pDualVar 中，最后释放该控件对象的引用。

接下来，代码又创建了一个名为 "cnc8070.variables" 的控件对象，并通过与上述类似的过程获取该控件对象的 IFCDualVar8070 接口，并将其保存到成员变量 m_pDualVar1 中，最后调用 OpenVar 函数来打开变量。

总之，这段代码的作用是连接到一个名为 cnc8070 的 ActiveX 控件，并获取该控件的接口以便后续对其进行操作。