環境:win7 64位,vs2008,wps2013
錯誤代碼:
BOOL CWPSOper::ConvertToPdf(IDispatch* lpDoc,_bstr_t sTargetPath)
{
CComVariant varParams[15];
varParams[1].vt = VT_I4;
varParams[1].iVal = 1;
varParams[0].vt = VT_BYREF|*/VT_VARIANT;
varParams[0].pvarVal = &(varParams[1]);
CComVariant varRet, varRet2, varRet3;
HRESULT hr1 = GetProperty(lpDoc, L"Application", &varRet);
HRESULT hr2 = GetProperty(varRet.pdispVal, L"Documents", &varRet2);
hr1 = InvokeN(varRet2.pdispVal, L"Item", varParams, 1, &varRet3);
}
HRESULT InvokeN(IDispatch *pDisp, LPCOLESTR lpszName, VARIANT *varParams, int nParams, VARIANT *pvarRet)
{
if(pDisp == NULL)
return E_FAIL;
HRESULT hr;
DISPID dispid;
hr = pDisp->GetIDsOfNames(IID_NULL, (LPOLESTR*)&lpszName, 1, LOCALE_USER_DEFAULT, &dispid);
if (SUCCEEDED(hr))
{
DISPPARAMS dispparams = { varParams, NULL, nParams, 0};
return pDisp->Invoke(dispid, IID_NULL, LOCALE_USER_DEFAULT, DISPATCH_METHOD, &dispparams, pvarRet, NULL, NULL);
}
return hr;
}
解決:
而通過vc添加typelib中類,通過wpsapi.dll生成CDocument,CDocuments,CApplication三個類,然後調試跟到oledisp2.cpp中的
SCODE sc = m_lpDispatch->Invoke(dwDispID, IID_NULL, 0, wFlags,
&dispparams, pvarResult, &excepInfo, &nArgErr);
發現dispparams的iVal值為0x00000001
而我的錯誤代碼中iVal值為0xcccc0001
然後源代碼改為varParams[1].lVal = 0x00000001;
結果就傳回正确值S_OK了
原因:顯而易見,variant是union類型, iVal隻是lVal中的後半段記憶體,但是com處理invoke調用應該統一使用long,不會又是long又是int