[DUG] Returning a WideString in an Invoke Param

[Phil Middlemiss]

The Invoke method is the only way of handling the IDispInterface  
events. The Automation wizard automatically generates the Invoke stub 
and leaves it up to the programmer to fill it in. The code works fine 
when I'm just passing integer values etc, but this is the first time 
I've needed to use a VAR parameter in an IDispInterface event.

The TDispParams is a record (tagDISPPARAMS) in ActiveX.pas.

Phil.

Conor Boyd wrote:
> I just use WideStrings in COM parameters without any conversions at all
> in D7 and BDS2006.
>
> However, is TDispParams a class?
>
> Surely you'll have to do some sort of streaming for the TDispParams
> type?
>
> C.
>
> -----Original Message-----
> From: delphi-bounces at ns3.123.co.nz [mailto:delphi-bounces at ns3.123.co.nz]
> On Behalf Of Phil Middlemiss
>
> I have an automation object with events. One of the events has a couple
> of VAR parameters which I'm not quite sure how to handle. Here is the
> code that is NOT working:
>
> procedure TT3SDKEvents.DoInvoke(Sender : TObject; DispID: Integer; const
> IID: TGUID;
>   LocaleID: Integer; Flags: Word; var Params: TDispParams; VarResult,
> ExcepInfo,
>   ArgErr: Pointer);
>     case DispID of
>
>     ...
>
>     4: { OnIdentify }
>       if assigned(FOnIdentify) then
>         begin
>         //initialise the values
>         layermanagerid :=  WideCharToString(Params.rgvarg[1].bStrVal);
>         appname := WideCharToString(Params.rgvarg[0].bstrVal);
>         if assigned(FOnIdentify) then
>           FOnIdentify(layermanagerid, appname);
>         Params.rgvarg[1].bstrVal := PWideChar(layermanagerid);
>         Params.rgvarg[0].bstrVal := PWideChar(appname);
>         end;
>     end;
> end;
>
> The above code just ends up returning an empty string - I've checked to
> make sure that the call to FOnIdentify is indeed returning values.
> So the question is: how should I be returning a widestring in the
> TDispParams?
>
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>
>
>
>   
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