[SOLVED]Form2.Show Exception Error

[IndianaJones]

Hi all,

I have encountered the following error message when I call the Form2 from the Form1 in the oncreate event.
Is it a bug or restriction for carbon?
Thanks.

FPC 2.4.2-0
Lazarus SVN 29176
Leopard 10.5.8

[Blaazen]

I think you call Form2 too early. At that time (Form1 OnCreate) is not Form2 created yet.
Try it call later.

[jw]

this doesn't just happen on mac i've had to create what i call a start timer that gets set enabled:=true in the form.activate event and wait for an interval of 1000 or so and have the timer make the calls to open the next form.

or make the call to from2 from form1.onactivate

[xenblaise]

unit Unit1;
{$mode objfpc}{$H+} 

interface

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

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

var
  Form1: TForm1;

implementation
uses unit2;

procedure TForm1.Button1Click(Sender: TObject);
begin
Form2.Show;
Form2.Label1.Caption := 'this is label1 in form_2 called by form_1';
end;

initialization
  {$I unit1.lrs}

end.

unit Unit2;

{$mode objfpc}{$H+} 

interface

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

type
  TForm2 = class(TForm)
    Button1: TButton;
    Label1: TLabel;
    procedure Button1Click(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }

  end;

var
  Form2: TForm2;

implementation
uses unit1;

procedure TForm2.Button1Click(Sender: TObject);
begin
Form1.Show;
Form1.Label1.Caption := 'this is label1 in form_1 called by form_2';
end;

initialization
  {$I unit2.lrs}

end.

[IndianaJones]

@xenablaise
What would be the case if it is not triggered from the Button click event?

@Blaazen
  Form2:=TForm2.Create(nil);
  Form2.Show;

works in the oncreate event, but Form2 lost its focus, Form1 activated after this procedure executed.

Thanks

[Blaazen]

OK, I didn't know you create Form2 this way. So you have at least two possibilities...

1) This will show Form2 and after you close it, Form1 will be shown.

Code: [Select]

procedure TForm1.FormCreate(Sender: TObject);
begin
 Form2:=TForm.Create(nil);
 Form2.ShowModal;
end;   

2) Show Form2 later

Code: [Select]

procedure TForm1.FormActivate(Sender: TObject);
begin
  Form2.Show;
  Form1.OnActivate:=nil;  //this ensures that OnActivate is raised only once
end;

procedure TForm1.FormCreate(Sender: TObject);
begin
 Form2:=TForm.Create(nil);
end; 

[IndianaJones]

Thanks Blaazen for the answer, the case was solved.

[xenblaise]

What would be the case if it is not triggered from the Button click event?

procedure TForm1.FormCreate(Sender: TObject);
begin
Form2.Show;
//or
//Form2.ShowModal;
Form2.Caption := 'this is form_2 called by form_1';
end;

You don't need to create the form2 to show it, because it is made already in your main project .lpr