check if in zero document state

Hi:
I am working on a layer state management routine. I like to know when autocad is in zero document state, so I can disable all the control in my form. since there are no ThisDrawing, how I can get the AcadApplication? I am going to play with GetObject, GetInterfaceObject. If anyone can give me a right direction, I will appreciate a million.


thank you,
Wes

 

In Delphi but you should be able to adapt it:

Code:

unit Unit1;

interface

uses
Windows,
Messages,
SysUtils,
Variants,
Classes,
Graphics,
Controls,
Forms,
Dialogs,
ComObj,
StdCtrls,
AutoCAD_TLB;

type
TForm1 = class(TForm)
Button1: TButton;
Label1: TLabel;
Edit1: TEdit;
procedure Button1Click(Sender: TObject);
private
{ Private declarations }
public
{ Public declarations }
end;

var
Form1: TForm1;

implementation

{$R *.dfm}

//------------------------------------------------------------------------------

procedure ConnectToAcad(var Acad: AcadApplication);
var
Msg: string;
begin
try
Acad := IDispatch(GetActiveOleObject('AutoCAD.Application.16')) as
AcadApplication;
if not Acad.Visible then
begin
Acad.Visible := True;
end;
except
try
Acad := IDispatch(CreateOleObject('AutoCAD.Application.16')) as
AcadApplication;
Acad.Application.WindowState := acMax;
Acad.Visible := True;
except
Msg := 'Could not establish a connection to AutoCAD.';
ShowMessage(Msg);
Exit;
end;
end;
end;

//------------------------------------------------------------------------------

procedure TForm1.Button1Click(Sender: TObject);
var
Acad: AcadApplication;
DocCount: Integer;
begin
ConnectToAcad(Acad);
DocCount := Acad.Application.Documents.Count;
Edit1.Text := IntToStr(DocCount);
Acad := nil;
end;

//------------------------------------------------------------------------------

end.