Suppress Userproperty printing with outlook mail items

Question

I need to suppress the printing of outlook userproperties programmatically added to a mail item. I had seen the following question that has a solution for dot.net here Suppressing Outlook Field Printing but i'm having trouble translating the code to delphi. My main problem is the invokemember line i'm guessing i need to use userproperty.invoke somehow in delphi but i'm clueless on how i should use the parameters that the invoke methode requires. Can someone help me translate the solution from that question to delphi code ?

Answer 1

Thanks with the help of the people from addin-express i have a working solution... that seems to work for outlook 2016 still have to test other outlook versions. The problem was that i did not know what parameters to use for the invoke function.

I'm posting my function here

function TAddInModule.RemoveUserPropertyPrintFlag( 
  var aUserProperty: UserProperty): Boolean; 
const 
  propID: integer = 107; 
  removePrinterFlag: integer = $4; 
var 
  res: OleVariant; 
  disp : TDispParams; 
  flags: Integer; 

  dispIDs: array[0..0] of TDispID; 
  args: array [0..0] of TVariantArg; 
begin 
   Result := False; 
   disp.cNamedArgs:= 0; 
   disp.cArgs:= 0; 
   if aUserProperty.Invoke(propID, GUID_NULL, LOCALE_USER_DEFAULT, DISPATCH_PROPERTYGET, disp, @res, nil, nil) = S_OK then 
   begin 
     if TVarData(res).VType = varInteger then 
     begin 
       flags := TVarData(res).VInteger; 
       args[0].vt := VT_INT; 
       args[0].intVal := flags and (not removePrinterFlag); 
       disp.cArgs := 1; 
       disp.cNamedArgs := 1; 
       dispIDs[0]:= DISPID_PROPERTYPUT; 
       disp.rgdispidNamedArgs := @dispIDs; 
       disp.rgvarg := @args; 
       Result:= aUserProperty.Invoke(propID, GUID_NULL, LOCALE_USER_DEFAULT, DISPATCH_PROPERTYPUT, disp, nil, nil, nil) = S_OK; 
     end; 
   end; 
end; 

The translated code to delphi from the answer of the other stackoverflow should be something like this (not tested):

function TAddInModule.SuppressUserPropertyPrinting(mailItem: _MailItem) : HResult;  
const  
  propID: integer = 107;  
  removePrinterFlag: integer = $4;  
var  
  props: UserProperties;  
  prop: UserProperty;  
  i: integer;  
  res: OleVariant;  
  disp : TDispParams;  
  flags: Integer;  
  dispIDs: array[0..0] of TDispID;  

  args: array [0..0] of TVariantArg;  
begin  
  props := mailItem.UserProperties;  
  if props.Count > 0 then begin  
    for i := 1 to props.Count do begin  
       prop := props.Item(i);  

       disp.cNamedArgs:= 0;  
       disp.cArgs:= 0;  
       Result:= prop.Invoke(propID, GUID_NULL, LOCALE_USER_DEFAULT, DISPATCH_PROPERTYGET, disp, @res, nil, nil);  

       if TVarData(res).VType = varInteger then begin  
         flags := TVarData(res).VInteger;  

         args[0].vt := VT_INT;  
         args[0].intVal := flags and (not removePrinterFlag);  
         disp.cArgs := 1;  
         disp.cNamedArgs := 1;  
         dispIDs[0]:= DISPID_PROPERTYPUT;  
         disp.rgdispidNamedArgs := @dispIDs; 
         disp.rgvarg := @args; 
         Result:= prop.Invoke(propID, GUID_NULL, LOCALE_USER_DEFAULT, DISPATCH_PROPERTYPUT, disp, nil, nil, nil);  
       end;  

       prop := nil;  
    end;  
  end;  
  props := nil;  
end; 

Answer 2

You will need to use IDispatch.Invoke() in Delphi. Disp id is 107 and the value must be a variant of type varInteger and the value of 4. There are quite a few examples of calling IDispatch.Invoke in the VCL source code.

If using Redemption (I am its author) is an option, it explicitly exposes the RDOUserProperty.Printable property.