/// <summary>
/// Look for type info using IDispatch.GetTypeInfo
/// </summary>
/// <param name="dispatch">IDispatch object</param>
/// <remarks>
/// Some COM objects just don't expose type info. In these cases, this method will return null.
/// Some COM objects do intend to expose type info, but may not be able to do so if the type library
/// is not properly registered. This will be considered an error.
/// </remarks>
/// <returns>Type info</returns>
internal static ComTypes.ITypeInfo GetITypeInfoFromIDispatch(IDispatch dispatch)
{
int hresult = dispatch.TryGetTypeInfoCount(out uint typeCount);
if (typeCount == 0)
{
// COM objects should return a type count of 0 to indicate that type info is not exposed.
// Some COM objects may return a non-success HRESULT when type info is not supported, so
// we only check the count and not the HRESULT in this case.
return(null);
}
Marshal.ThrowExceptionForHR(hresult);
Debug.Assert(typeCount == 1);
IntPtr typeInfoPtr;
hresult = dispatch.TryGetTypeInfo(0, 0, out typeInfoPtr);
if (!ComHresults.IsSuccess(hresult))
{
// Word.Basic always returns this because of an incorrect implementation of IDispatch.GetTypeInfo
// Any implementation that returns E_NOINTERFACE is likely to do so in all environments
if (hresult == ComHresults.E_NOINTERFACE)
{
return(null);
}
// This assert is potentially over-restrictive since COM components can behave in quite unexpected ways.
// However, asserting the common expected cases ensures that we find out about the unexpected scenarios, and
// can investigate the scenarios to ensure that there is no bug in our own code.
Debug.Assert(hresult == ComHresults.TYPE_E_LIBNOTREGISTERED);
Marshal.ThrowExceptionForHR(hresult);
}
if (typeInfoPtr == IntPtr.Zero)
{
Marshal.ThrowExceptionForHR(ComHresults.E_FAIL);
}
ComTypes.ITypeInfo typeInfo = null;
try
{
typeInfo = Marshal.GetObjectForIUnknown(typeInfoPtr) as ComTypes.ITypeInfo;
}
finally
{
Marshal.Release(typeInfoPtr);
}
return(typeInfo);
}
public static void CheckThrowException(int hresult, ref ExcepInfo excepInfo, uint argErr, string message)
{
if (ComHresults.IsSuccess(hresult))
{
return;
}
switch (hresult)
{
case ComHresults.DISP_E_BADPARAMCOUNT:
// The number of elements provided to DISPPARAMS is different from the number of arguments
// accepted by the method or property.
throw Error.DispBadParamCount(message);
case ComHresults.DISP_E_BADVARTYPE:
//One of the arguments in rgvarg is not a valid variant type.
break;
case ComHresults.DISP_E_EXCEPTION:
// The application needs to raise an exception. In this case, the structure passed in pExcepInfo
// should be filled in.
throw excepInfo.GetException();
case ComHresults.DISP_E_MEMBERNOTFOUND:
// The requested member does not exist, or the call to Invoke tried to set the value of a
// read-only property.
throw Error.DispMemberNotFound(message);
case ComHresults.DISP_E_NONAMEDARGS:
// This implementation of IDispatch does not support named arguments.
throw Error.DispNoNamedArgs(message);
case ComHresults.DISP_E_OVERFLOW:
// One of the arguments in rgvarg could not be coerced to the specified type.
throw Error.DispOverflow(message);
case ComHresults.DISP_E_PARAMNOTFOUND:
// One of the parameter DISPIDs does not correspond to a parameter on the method. In this case,
// puArgErr should be set to the first argument that contains the error.
break;
case ComHresults.DISP_E_TYPEMISMATCH:
// One or more of the arguments could not be coerced. The index within rgvarg of the first
// parameter with the incorrect type is returned in the puArgErr parameter.
throw Error.DispTypeMismatch(argErr, message);
case ComHresults.DISP_E_UNKNOWNINTERFACE:
// The interface identifier passed in riid is not IID_NULL.
break;
case ComHresults.DISP_E_UNKNOWNLCID:
// The member being invoked interprets string arguments according to the LCID, and the
// LCID is not recognized.
break;
case ComHresults.DISP_E_PARAMNOTOPTIONAL:
// A required parameter was omitted.
throw Error.DispParamNotOptional(message);
}
Marshal.ThrowExceptionForHR(hresult);
}
