Conflict between showing QDialog and updating QGLWidget

? Offline

Hi,

I've a qt project that was implemented using qt3 and then ported to qt4 using qt3support.

Before porting I was showing a dialog then updating in a QGLWidget, this was working with no error

here is a sample of the code

@
QDialog* dlg = new QDialog();
dlg->show();
dlg->raise();
dlg->activateWindow();

// code for updating QGLWidget by updating the scene graph matrix
....
@

after porting this code produces an errors like that "QPainter::setPen: Painter not active" which means I'm using
painter outside paint event, however I don't.

after some investigation I guessed that I need to wait until the dialog is fully painted then go update the QGLWidget.
However I didn't find any signals in QWidget or QDialog that tells me that the dialog has finished painting.

To test my guessing I have placed a message box after showing the dialog and before accessing the QGLWindget
and this worked successfully but for sure this isn't appropriate solution.

@
QDialog* dlg = new QDialog();
dlg->show();
dlg->raise();
dlg->activateWindow();
QMessage::critical(NULL , "test" , "Wait till the dialog finishes showing all items");

// code for updating QGLWidget by updating the scene graph matrix
....
@

So is there any way to avoid this error or any way to tell me that the dialog finished painting?

SGaist

Hi,

There's something not clear here. Where/when do you call that dialog ?

? Offline

Hi,

The dialog is shown after pressing a button in my application,
This button functionality is to zoom in the QGLWidget and show the QDialog to use it in some functionality later.

Hint: the QGLWidget is initialized and already showing a view, after pressing the button we just zoom in to certain area.

SGaist

Where are you creating that dialog ? From the QGLWidget or from somewhere else ?

? Offline

From somewhere else.

SGaist

What version of Qt are you using ? On what OS ?

Can you replicate that with a minimal code sample ?

? Offline

QT version : 4.8.3 with qt3 support
OS : RHEL 5.7

What is not clear in the sample code I provided before?

SGaist

You sample code just shows that you are creating a dialog, showing it and also show a QMessageBox.

It doesn't tell how you do it with your application nor does it allow to test your use case to reproduce your problem

? Offline

Here is a sample from all the code I think you may need to understand the problem

my dialog code , dialog is inherited from QWidget

@MyDialogClass::MyDialogClass(QWidget* parent, const char* name, Qt::WindowFlags fl)
: QWidget(parent, name, fl)
{
setupUi(this);
init();
}

MyDialogClass::setupUi(Qwidget* myDialog)
{
if (myDialog->objectName().isEmpty())
myDialog->setObjectName(QString::fromUtf8("untitled"));
myDialog->resize(379, 161);
vboxLayout = new QVBoxLayout(myDialog);
vboxLayout->setSpacing(6);
vboxLayout->setContentsMargins(11, 11, 11, 11);
vboxLayout->setObjectName(QString::fromUtf8("vboxLayout"));
hboxLayout = new QHBoxLayout();
hboxLayout->setSpacing(6);
hboxLayout->setObjectName(QString::fromUtf8("hboxLayout"));
textLabel1_2 = new QLabel(myDialog);
textLabel1_2->setObjectName(QString::fromUtf8("textLabel1_2"));
textLabel1_2->setWordWrap(false);

    hboxLayout->addWidget(textLabel1_2);

    lineEdit = new QLineEdit(myDialog);
    lineEdit->setObjectName(QString::fromUtf8("lineEdit"));
    QSizePolicy sizePolicy(static_cast<QSizePolicy::Policy>(3), static_cast<QSizePolicy::Policy>(0));
    sizePolicy.setHorizontalStretch(0);
    sizePolicy.setVerticalStretch(0);
    sizePolicy.setHeightForWidth(m_summaryLE->sizePolicy().hasHeightForWidth());
    lineEdit->setSizePolicy(sizePolicy);
    lineEdit->setReadOnly(true);

    hboxLayout->addWidget(lineEdit);

    toolButton = new QToolButton(myDialog);
    tooButton->setObjectName(QString::fromUtf8("first button"));
    QSizePolicy sizePolicy1(static_cast<QSizePolicy::Policy>(5), static_cast<QSizePolicy::Policy>(5));
    sizePolicy1.setHorizontalStretch(0);
    sizePolicy1.setVerticalStretch(0);
    sizePolicy1.setHeightForWidth(tooButton->sizePolicy().hasHeightForWidth());
    tooButton->setSizePolicy(sizePolicy1);

    hboxLayout->addWidget(tooButton);


    vboxLayout->addLayout(hboxLayout);

....

    QMetaObject::connectSlotsByName(myDialog);

}

MyDialogClass::init()
{
//connect signals of buttons
connect(firstButton, SIGNAL(clicked()),this, SIGNAL(FirstButtonAction()));
....
// End of connecting signals.
}@

the myGLCanvas code, it is inherited from QGLWidget

@myGLCanvas::setProjectionMatrix()
{
QGLWidget::makeCurrent();
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
glOrtho(clipL, clipR, clipB, clipT, -1, 1);
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
glTranslatef(0., 0., 0.0);
}

myGLCanvas::zoom(point p1, point p2)
{
// setting clipR , clipL , clipT , clipB variable from points p1, p2

setProjectionMatrix();
// make paintGl update the scene
update = true;
}

myGlCanvas::paintGl()
{
glLoadIdentity();
....
myGLWindow *de = viewer->getEditorWindow();
if (update)
{
FormState menuBarState = de->getMenuBarState();
if (formState == Closing || formState == ClosingRedraw ||
menuBarState == Closing)
{
if (formState == Closing || formState == ClosingRedraw)
{
formState = Hidden;
}
if (menuBarState == Closing)
{
de->setMenuBarState(Hidden);
}
update();
}
else
{
de->setWaitCursor("Drawing ...");

      update = false;

      emit canvasAboutRedraw();
      drawCanvasArea(drawArea);
      emit canvasRedrawn();
      de->restoreCursor(false);
    }
}
....

}
@

the code producing the error, it is slot of clicking a button from the main window of my application

@void zoomAndShowDialogBtnClickedSlot()
{
std::vector<point> zoomPoints = getZoomPoints();
MyDialogClass* myDialog = new MyDialogClass();

QStringList typesQ;
for(int i=0; i<items.size(); ++i)
{
typesQ.append(items[i]);
}
myDialog->setTypeList(typesQ);
if(typesQ.size() > 0)
{
myDialog->setType(typesQ[0]);
}

myDialog->setTitleName("title ");

myDialog->show();
myDialog->raise();
myDialog->activateWindow();

// zoom in the QGLWidget
// myGLCanvas is already initiated and viewing contents, we just need to zoom in it
myGLCanvas->zoom(points.at(0),points.at(1));

}@