Suppress Userproperty printing with outlook mail items - delphi

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.