[Lazarus] Issue with IDispatch.Invoke: Can't set Word.Application.Visible to false?

[Thierry Coq]

Hello,

I've trying to connect to a Word or Excel application with Lazarus 0.9.26.
The IDispatch does not work,
I've tried going to the "Invoke" API, and it still doesn't work.
I'm able to create a Word.Application objet, I'm even able to get the 
pointer to the "Visible" property.
I just can't set the Visible property to true: I get the error message:
// -2147352572 = DISP_E_PARAMNOTFOUND: parameter not found

Please see attached code.



Does somebody know how to call "Invoke" on IDispatch or better still, 
how to call directly methods and properties of Word or Excel objects in 
Lazarus?

BR
Thierry

object Form1: TForm1
  Left = 332
  Height = 300
  Top = 158
  Width = 400
  Caption = 'Form1'
  ClientHeight = 300
  ClientWidth = 400
  ParentFont = False
  LCLVersion = '0.9.26'
  object Button1: TButton
    Left = 96
    Height = 25
    Top = 70
    Width = 75
    Caption = 'Test'
    OnClick = Button1Click
    TabOrder = 0
  end
  object Memo1: TMemo
    Left = 24
    Height = 141
    Top = 121
    Width = 272
    Lines.Strings = (
      'Memo1'
    )
    TabOrder = 1
  end
end
{ Ceci est un fichier ressource généré automatiquement par Lazarus }

LazarusResources.Add('TForm1','FORMDATA',[
  'TPF0'#6'TForm1'#5'Form1'#4'Left'#3'L'#1#6'Height'#3','#1#3'Top'#3#158#0#5'Wi'
  +'dth'#3#144#1#7'Caption'#6#5'Form1'#12'ClientHeight'#3','#1#11'ClientWidth'#3
  +#144#1#10'ParentFont'#8#10'LCLVersion'#6#6'0.9.26'#0#7'TButton'#7'Button1'#4
  +'Left'#2'`'#6'Height'#2#25#3'Top'#2'F'#5'Width'#2'K'#7'Caption'#6#4'Test'#7
  +'OnClick'#7#12'Button1Click'#8'TabOrder'#2#0#0#0#5'TMemo'#5'Memo1'#4'Left'#2
  +#24#6'Height'#3#141#0#3'Top'#2'y'#5'Width'#3#16#1#13'Lines.Strings'#1#6#5'Me'
  +'mo1'#0#8'TabOrder'#2#1#0#0#0
]);
unit FMainTestWord;

{$mode objfpc}{$H+}

interface

uses
  Classes, SysUtils, FileUtil, LResources, Forms, Controls, Graphics, Dialogs,
  StdCtrls;

type

  { TForm1 }

  TForm1 = class(TForm)
    Button1: TButton;
    Memo1: TMemo;
    procedure Button1Click(Sender: TObject);
  private
    { private declarations }
  public
    { public declarations }
  end; 

var
  Form1: TForm1; 

implementation

uses Windows, Variants, ComObj, ActiveX;
{ TForm1 }

procedure TForm1.Button1Click(Sender: TObject);
const
  ServerName = 'Word.Application';
var
  Server     : OleVariant;
  Id : TCLSID;
  GuID : TGUID;
  aServer : IDispatch;
  aResult: HRESULT;
  Member: WideString;
  lDispID: Integer;
  Params: TDispParams;
  ExceptInfo : TExcepInfo;
  VarResult: OleVariant;
  ArgErr : DWord;
  LocalVariantArg : array[0..3] of TPROPVARIANT;
  dispidNamed :  DISPID;
begin
  if Assigned(InitProc) then
    TProcedure(InitProc);

  aServer := nil;
  Id := ProgIDToClassID(ServerName);
  GuID := ProgIDToClassID(ServerName);
  dispidNamed := DISPATCH_PROPERTYPUT;
  Member := 'Visible';
  ldispID := 0;

  FillChar(ExceptInfo, SizeOf(ExcepInfo),0);
  FillChar(Params, SizeOf(DispParams),0);
  FillChar(LocalVariantArg,SizeOf(LocalVariantArg),0);
  Params.rgvarg := @LocalVariantArg;

  Memo1.Lines.Clear;
  try
    //Server := CreateOleObject(ServerName);
    //Server := CreateComObject(GuiD);

   aResult := CoCreateInstance(GuiD,nil,CLSCTX_INPROC_SERVER or CLSCTX_LOCAL_SERVER, IDispatch, aServer);
   Memo1.Lines.Add('CoCreateInstance Result =' +IntToStr(aResult));


   //aServer.QueryInterface(IDispatch,Server)
   //Server := aServer;
  except
    Memo1.Lines.Add('Unable to start Word.');
    Exit;
  end;

  //Server.Visible := True;  {Make Word visible}
  aResult := aServer.GetIDsOfNames(GUID_NULL, @Member, 1, LOCALE_USER_DEFAULT, @lDispID);
  Memo1.Lines.Add('GetIDsOfNames on Visible Result =' +IntToStr(aResult));


  (* Params.rgvarg[0].VT := varError;
  Params.rgvarg[0].scode := DISP_E_PARAMNOTFOUND;
  Params.rgvarg[1].VT := varError;
  Params.rgvarg[1].scode := DISP_E_PARAMNOTFOUND;*)

  // the first parameter is a bool
  LocalVariantArg[0].VT := VT_BOOL;
  LocalVariantArg[0].boolVal := True;
  Params.cArgs := 1;
  Params.cNamedArgs := 1;
  Params.rgdispidNamedArgs:= @dispidNamed;

  aResult := aServer.Invoke( lDispID, GUID_NULL, 0, DISPATCH_PROPERTYPUT, Params,
                             @VarResult, @ExceptInfo, @ArgErr);
  Memo1.Lines.Add('Invoke on Visible Result =' +IntToStr(aResult));
  // -2147024809 = COR_E_ARGUMENT: wrong parameters
  // -2147352572 = DISP_E_PARAMNOTFOUND: parameter not found


  {Open existing document}  //Substitute your path and doc
  //Server.Documents.Open('c:\Test.doc');

end;

initialization
  {$I FMainTestWord.lrs}

end.

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