I create a new QWidget object and I want to know when the close button is pressed.
I have tried the following code:
pWindow = new QWidget();
connect(pWindow , SIGNAL(triggered()), this, SLOT(processCloseButtonWindowsClicked()));
but it give an error:
no signal triggered of pWindow
How to achieve this?
QWidget does not have a triggered signal.
I would suggest you to:
Subclass QWidget and reimplement QWidget::closeEvent
Check QEvent::spontaneous to differentiate between a click of the close button and the call to QWidget::close
According to your app's logic either call QWidget::closeEvent(event); to close the widget, or QEvent::ignore to leave it open
I have prepared an example for you of how to implement the proposed solution:
#include <QMainWindow>
#include <QCloseEvent>
#include <QPushButton>
class FooWidget : public QWidget
{
Q_OBJECT
public:
explicit FooWidget(QWidget *parent = nullptr) :
QWidget(parent) {
auto *button = new QPushButton(tr("Close"), this);
connect(button, &QPushButton::clicked, this, &FooWidget::close);
resize(300, 200);
setWindowTitle("Foo");
}
protected:
void closeEvent(QCloseEvent *event) override {
if (event->spontaneous()) {
qDebug("The close button was clicked");
// do event->ignore();
// or QWidget::closeEvent(event);
} else {
QWidget::closeEvent(event);
}
}
};
class MainWindow : public QMainWindow
{
Q_OBJECT
FooWidget *pWindow;
public:
explicit MainWindow(QWidget *parent = nullptr) :
QMainWindow(parent),
pWindow(new FooWidget()) {
pWindow->show();
}
};
void QWidget::closeEvent(QCloseEvent *event) will be the possible way I would go with.
You can read the documentation here.
Before check if Qt have a class for what you want to do. Maybe you want to use QDialog instead of QWidget for what you want to archive.
The following code suppose you want to delete the widget when the X is clicked and you just want to know when to do something. Try connecting the signal from the base class QObject of your widget when it is Destroyed:
-Your Widget
-attribute setted to destroy your widget after X(closebotton is clicked) or the close() handler is triggered
-connect the destroyed() signal to whatever slot you want to do something before it is destroyed
pWindow = new QWidget();
pWindow->setAttribute(Qt::WA_DeleteOnClose,true);
connect(pWindow , SIGNAL(destroyed()), this,SLOT(processCloseButtonWindowsClicked()));
for more info:
