public void Clear()
{
// We do not need to call OLE32's VariantClear for primitive types or ByRefs
// to safe ourselves the cost of interop transition.
// ByRef indicates the memory is not owned by the VARIANT itself while
// primitive types do not have any resources to free up.
// Hence, only safearrays, BSTRs, interfaces and user types are
// handled differently.
VarEnum vt = VariantType;
if ((vt & VarEnum.VT_BYREF) != 0)
{
VariantType = VarEnum.VT_EMPTY;
}
else if (
((vt & VarEnum.VT_ARRAY) != 0) ||
((vt) == VarEnum.VT_BSTR) ||
((vt) == VarEnum.VT_UNKNOWN) ||
((vt) == VarEnum.VT_DISPATCH) ||
((vt) == VarEnum.VT_RECORD)
)
{
IntPtr variantPtr = UnsafeMethods.ConvertVariantByrefToPtr(ref this);
NativeMethods.VariantClear(variantPtr);
Debug.Assert(IsEmpty);
}
else
{
VariantType = VarEnum.VT_EMPTY;
}
}
internal static void InitVariantForObject(object obj, ref Variant variant)
{
Debug.Assert(obj != null);
// GetNativeVariantForObject is very expensive for values that marshal as VT_DISPATCH
// also is is extremely common scenario when object at hand is an RCW.
// Therefore we are going to test for IDispatch before defaulting to GetNativeVariantForObject.
IDispatch disp = obj as IDispatch;
if (disp != null)
{
variant.AsDispatch = obj;
return;
}
System.Runtime.InteropServices.Marshal.GetNativeVariantForObject(obj, UnsafeMethods.ConvertVariantByrefToPtr(ref variant));
}
public void SetAsByrefVariant(ref Variant value)
{
Debug.Assert(IsEmpty); // The setter can only be called once as VariantClear might be needed otherwise
VariantType = (VarEnum.VT_VARIANT | VarEnum.VT_BYREF);
_typeUnion._unionTypes._byref = UnsafeMethods.ConvertVariantByrefToPtr(ref value);
}
public static object GetObjectForVariant(Variant variant)
{
IntPtr ptr = UnsafeMethods.ConvertVariantByrefToPtr(ref variant);
return(System.Runtime.InteropServices.Marshal.GetObjectForNativeVariant(ptr));
}