Hi,

There is a preview (beta) of a Qt 4.2.1 binding for FreePascal:

http://users.pandora.be/Jan.Van.hijfte/qtforfpc/fpcqt4.html

(only compiled for Linux for the moment)

Please report if there any problems compiling
existing LCL/Qt code.

regards,

Den Jean

Den,

Your new Win32 libqt4intf.dll doesn't work with Lazarus and the Qt widgetset:

"The procedure entry point QCoreApplication_argc could not be located in the dynamic link library libqt4intf.dll."

The Qt widgetset does work with your 1.21 .dll, but only with FPC 2.0.4. If I compile a program with FPC 2.1.1, I get a "segmentation fault" error.

Thanks.

-Phil

On Monday 20 November 2006 16:46, Hess, Philip J wrote:

vacation for a week :-)

reading src/corelib/kernel/qcoreapplication.h I see

#ifdef QT_DEPRECATED
    static int argc() QT_DEPRECATED;
    static char **argv() QT_DEPRECATED;
#endif

I will look into this.

The Qt widgetset does work with your 1.21 .dll, but only with FPC 2.0.4. If I compile a program with FPC 2.1.1, I get a "segmentation fault" error.

FPC 2.1.1 is not stable, so you probably found a bug. The FPC team will love your bug report.
Most probably a bug where parameters are not passed compliant with the ABI.

Which fpc svn version ?
Can you pinpoint which qt4intf call -> then a small fpc qt sample should be made for the bug report.

regards,

Den Jean

Philip J wrote

"The procedure entry point QCoreApplication_argc could not be located in the dynamic link library libqt4intf.dll."

when you create a qt app you provide argc/argv
using the fpc rtl.
Retrieving these variables should be done via fpc rtl. So I do not think the fn is needed.

Using the function QCoreApplication_arguments which replace these deprecated ones, is more work.

regards,

Den Jean

Philip J wrote

The Qt widgetset does work with your 1.21 .dll, but only with FPC 2.0.4. If I compile a program with FPC 2.1.1, I get a "segmentation fault" error.

I tested the demo programs with fpc 2.1.1 svn 5473 on linux and I did not run into any problems

regards,

Den Jean

Den,

I've attached a backtrace of the crash with 1.21 libqt4intf.dll when compiled with FPC 2.1.1 (20061215 snapshot).

Can you take a might be an LCL or Qt widgetset bug or a bug in the .dll instead of an FPC bug. Maybe you can learn something from the backtrace before I post as an FPC bug.

The app does start up and paints the main form's outline, then displays an error message - but this stays up only a fraction of a second before it crashes - too quick for me to read what it says.

Thanks.

-Phil

Philip J wrote

Den, I've attached a backtrace of the crash with 1.21 libqt4intf.dll when compiled with FPC 2.1.1 (20061215 snapshot).

I just created Qt 4.2.2 binding which I tested
with fpc 2.0.4 release, latest fpc 2.0.5
and fpc 2.1.1 svn 5657 on all demo programs ->
no problems noted on linux.

When I created the windows version, I will do the same on windows.

Den Jean wrote

When I created the windows version, I will do the same on windows.

I just tested all demoes with fpc 2.1.1 Rev 5810
on windows with Qt 4.2.2 + Binding V1.26 and noticed no problems

Can you retest if with fpc 2.1.1 Rev >= 5810
to check if there still is a problem before we start digging further.

regards,

Den Jean

Den,

No difference with today's snapshot:

On Windows, my test program crashes at startup when compiled with 2.1.1, but starts up okay when compiled with 2.0.4. I used your latest libqt4intf.dll and qt4.pas.

Thanks.

-Phil

Philip J wrote

On Windows, my test program crashes at startup when compiled with 2.1.1, but starts up okay when compiled with 2.0.4. I used your latest libqt4intf.dll and qt4.pas.

the gdb backtrace does not help much.
I see probably wrong coordinates and a zero DC (probably wrong)

Is is possible to reduce the program source as much as possible (but that it still crashes) and send it to me, please

I can add manually code in the binding to inspect
parameters for correctness. If I see a difference between what pascal receives as parameter values and what
Qt.dll reports in the backtrace -> there is the bug

BOTTOM = 2090114328

#7 0x0046053e in TWINCONTROL__WMPAINT (MSG=
{MSG = 1056, DC = 0, PAINTSTRUCT = 0x0, RESULT = 0}, this=0xeb878) at wincontrol.inc:4718

regards,

Den Jean

I've attached an example of a simple project that crashes under FPC 2.1.1.

I used the 20070105 Lazarus snapshot with FPC 2.1.1.

I'm using Den's latest libqt4intf.dll (831,488 bytes).

I'm using QtCore4.dll and QtGui4.dll for Qt 4.2.1. And mingwm10.dll (dated 20050113).

It appears as though the number of controls on the form makes a difference. Try removing one of the 4 TBitBtn's from the form and see how it now works.

Thanks.

-Phil

I spent some time debugging it.
At some point an invalid Qt handle was passed
to the library, but where this handle became
corrupted was not clear.

constructor TQtDeviceContext.Create(WidgetHandle: THandle);
....
    Parent := TQtWidget(WidgetHandle).Widget;
    Widget := QPainter_create(QWidget_to_QPaintDevice(Parent));

The parent value obtained with the type cast for the 4th button of the demo project was invalid. (pointer value way different than with the other buttons.

With fpc 2.0.5 no problem, but with fpc 2.1.1 problems. After update of svn of today for both fpc 211 and lazarus & qt, the problem is gone. I am not sure where the problem was: fpc or lcl/qt

I hope it doesn't come back :-)

Yes, I think this has been fixed. I haven't seen this problem for a couple weeks now.

Thanks.

-Phil

Here's a fix for the tab order problem in the Qt widgetset. Also delete the SortListByTabOrder function since it isn't needed anymore.

Thanks.

procedure TQtMainWindow.setTabOrders;
var
  i: Integer;
  Form: TForm;
  List: TFPList;
begin
  Form := TForm(LCLObject);
  List := TFPList.Create;
  Form.GetTabOrderList(List);
  for i := 0 to List.Count - 2 do
  begin
    setTabOrder(TQtWidget(TWinControl(List.Items[i]).Handle),
     TQtWidget(TWinControl(List.Items[i + 1]).Handle));
    {$ifdef VerboseQt}
      WriteLn('Setting Tab Order first: ', TWinControl(List.Items[i]).Name, ' second: ',
       TWinControl(List.Items[i + 1]).Name);
    {$endif}
  end;
  { The last element points to the first }
  if List.Count > 1 then
  begin
    setTabOrder(TQtWidget(TWinControl(List.Items[List.Count - 1]).Handle),
     TQtWidget(TWinControl(List.Items[0]).Handle));
    {$ifdef VerboseQt}
      WriteLn('Setting Tab Order first: ', TWinControl(List.Items[List.Count - 1]).Name, ' second: ',
       TWinControl(List.Items[0]).Name);
    {$endif}
  end;
  List.Free;
end;

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Thanks, applied.