Open subwindow from parent window ctor

[olidem]

Hi!
I have a widget (or QDialog, does not matter) that should in some cases open a getOpenFilename dialog immediately.

But if I do this getOpenFIlename call in the constructor, I get an error... WA_state_created or so.

One Way aroud it i found already is to call

QTimer::singleShow(200, this, SLOT(openFile())

in the end of the constructor but I know that this can make problems and is jsut a hack.

How can I solve this in a stable way?

Is there an event or signal that informs me about when the dialog is ready to execute openFile() slot?

Thanks for your help in advance!

[spirit]

works fine


Test::Test(QWidget *parent)
: QWidget(parent)
{
QFileDialog::getOpenFileName();
}

another example


Test::Test(QWidget *parent)
: QWidget(parent)
{
QWidget *w = new QWidget();
w->setAttribute(Qt::WA_DeleteOnClose);
w->show();
}

without setting a parent.

[talk2amulya]

the reason why it doesnt work is that you are providing the constructor class as parent, right? if the dialog's parent isnt created, following assert fails:
Q_ASSERT(!parent ||parent->testAttribute(Qt::WA_WState_Created));
dont set a parent and it'll work

[olidem]

Great!
Thanks!
For me it does not make a difference, but as expected, now *before* the parent dialog pops up, the fileopen diag shows, and just after it has been closed, the parent diag is shown.

Just because I am interested:

Would it also be possible to first pop up the parent, and to overlay the fileopen diage then?

This is how it would happen by using my QTimer::singleShot workaround..

[spirit]

show in main() main window and then show a dialog. e.g.


int main(int argc, char **argv)
{
...
MainWindow mw;
mw.show();
Dialog d;
d.show();
...
}

[olidem]

Hmm, I think I didn't explain prcisely enough what I mean.

After your first replies, my (working) code looks as follows:



class EditCustomerImageDialog : public QDialog
{
Q_OBJECT

public:
EditCustomerImageDialog(Customer * c, QWidget * parent = 0, Qt::WindowFlags f = 0)
: QDialog(parent, f)
{
//...
openFile();
}
public slots:
void openFile()
{
QString filename = QFileDialog::getOpenFileName(
NULL, tr("Open face image"), "",
tr("Image Files (*.jpg)"));
//...
}
}


If I now open such a dialog from somewhere via


EditCustomerImageDialog d (new Customer);
d.exec();


what happens is that *first*, the openFileName Dialog pops up, nothing else.

*After* having chosen a file, and after the openfilediag has disappeared, then the EditCustomerDialog pops up.

Question:
Can I realise that the EditCustomerDialog pops up, and directly after that, the open FIle diag should pop up ???

[spirit]

did you try something like this?
main.cpp


...
int main(int argc, char **argv)
{
QApplication app(argc, argv);
EditCustomerImageDialog ecid;
ecid.show();
const QString fileName(QFileDialog::getOpenFileName(
NULL, tr("Open face image"), "",
tr("Image Files (*.jpg)")));
ecid.openFile(fileName);
return app.exec();
}

EditCustomerImageDialog.cpp


class EditCustomerImageDialog : public QDialog
{
Q_OBJECT

public:
EditCustomerImageDialog(Customer * c, QWidget * parent = 0, Qt::WindowFlags f = 0)
: QDialog(parent, f)
{
//...
//openFile();
}
public slots:
void openFile(const QString &fileName = QString())
{
QString tmpFileName = fileName;
if (tmpFileName.isEmpty())
tmpFileName = QFileDialog::getOpenFileName(
NULL, tr("Open face image"), "",
tr("Image Files (*.jpg)"));
//...
}
}

[olidem]

I know what you mean, but QDialog::show() returns immediately, while my ::exec() realisation blocks the caller. Ok, one can discuss for hours about this, it is a matter of taste, but I like the blocking thing more, also because this is just a modal dialog on top of my app, which is blocked while the dialog is shown.

Thanks again for your support, great people out here!

[spirit]

ok, another solution
cpp


Test::Test(QWidget *parent)
: QDialog(parent)
{
...
QMetaObject::invokeMethod(this, "showDialog", Qt::QueuedConnection);
...
}

void Test::showDialog()
{
QFileDialog::getOpenFileName(this);
}

h


private slots:
void showDialog();

[fifth]

For this situation is usually use a single shot timer, put something like


QTimer::singleShot(0, this, SLOT(openFile()));

at the end of your constructor for the main window. A time of zero will fire the slot after your window is visible.

ps Hopefully the above code is correct ;) i don't do much (any?) C++ put I think you'll get the idea.

[spirit]

For this situation is usually use a single shot timer, put something like


QTimer::singleShot(0, this, SLOT(openFile()));

at the end of your constructor for the main window. A time of zero will fire the slot after your window is visible.

ps Hopefully the above code is correct ;) i don't do much (any?) C++ put I think you'll get the idea.
your code has the same behavior as my, because


The default value for this property is 0. A QTimer with a timeout interval of 0 will time out as soon as all the events in the window system's event queue have been processed.

but I don't use a timer. :)

[fifth]

but I don't use a timer. :)

You win :p I didn't know about QMetaObject but will probably use your method now. It is more obvious in the code what is happening. ;)

For PyQt, just need to make sure you include the signature for the slot.


class MainWindow(QWidget):
def __init__(self, parent = None):
super(MainWindow, self).__init__(parent)

QMetaObject.invokeMethod(self, "showDialog", Qt.QueuedConnection);

@pyqtSignature("showDialog()")
def showDialog(self):
QFileDialog.getOpenFileName(self)