Delphi: Get the RTF for a paragraph in a rich edit

To the best of my knowledge, the only way to get the RTF for a portion of the contents in a rich edit control---without changing the selection---is as follows:

1. Obtain an ITextRange as described in a previous post.


2. Call ITextRange.Copy(), passing it a pointer to a variant. (Otherwise it will copy the text to the clipboard.)


3. The variant should now contain an IDataObject interface pointer.


4. Call IDataObject.GetData() requesting CF_RTF.

I tried to follow this plan, passing an Unassigned Variant to ITextRange.Copy(), but found that it was still Unassigned afterwards. I decided to get hold of proper declarations for ITextRange so that I need not go via Variant IDispatch. I found tom_TLB.pas on a Japanese site and took a copy. The file had obviously been produced by some automatic means. It declared ITextRange.Copy() as:

procedure Copy(out pVar: OleVariant); safecall;

Sadly, using tom_TLB.pas did not help: my variant was still Unassigned. I noticed in the documentation for ITextRange.Copy() has some strange requirements for its argument:

pVar->vt = (VT_UNKNOWN | VT_BYREF)
pVar is not null
pVar->ppunkVal is not null

By tracing into Delphi's call I found that Delphi was clearing my Variant and setting it to Unassigned on the way in. Clearly it could never satisfy the requirement that pVar->vt = (VT_UNKNOWN | VT_BYREF). To work around this, I build my variant argument manually:

1. Change the declaration of ITextRange.Copy to:
   procedure Copy(pVar: PVariantArg); safecall;


2. Construct the argument manually:
   

   var
      data_var: IUnknown;
      data_var_arg: TVariantArg;
   begin
      data_var := range.FormattedText;  // Copy range to ensure no interference.
      data_var_arg.vt := VT_UNKNOWN or VT_BYREF;
      data_var_arg.wReserved1 := 0;
      data_var_arg.wReserved2 := 0;
      data_var_arg.wReserved2 := 0;
      data_var_arg.punkVal := @data_var;
      range.Copy(@data_var_arg);



3. Your IDataObject will now be in data_var:
   OleCheck(IUnknown(data_var).QueryInterface(IDataObject, data));

Id love to know of a simpler way.