How to add a slot to a QWidget? - c++

Question

I have a QMainWindow, which has a QAction whose signal triggered() is connected to a slot about2().
...
connect(mAboutAction2, SIGNAL(triggered()), this, SLOT(about2()));
...
void occQt::about2() //UI
{
QWidget* pWidget = new QWidget;
QPushButton* okbtn = new QPushButton(tr("ok"));
QPushButton* cancelbtn = new QPushButton(tr("cancel"));
btnlayout->addWidget(okbtn);
btnlayout->addWidget(cancelbtn);
dlglayout->setMargin(50);
dlglayout->addLayout(gridlayout);
dlglayout->addStretch(40);
dlglayout->addLayout(btnlayout);
pWidget->setLayout(dlglayout);
pWidget->setWindowTitle(tr("Make a Box by custom."));
pWidget->show();
connect(okbtn, SIGNAL(clicked()), pWidget, SLOT(make_a_box()));
connect(cancelbtn, SIGNAL(clicked()), pWidget, SLOT(close()));
}
void occQt::make_a_box()
{
TopoDS_Shape aTopoBox = BRepPrimAPI_MakeBox(3.0, 4.0, 95.0).Shape();
Handle_AIS_Shape anAisBox = new AIS_Shape(aTopoBox);
anAisBox->SetColor(Quantity_NOC_AZURE);
mContext->Display(anAisBox);
}
When I run the slot about2(), the UI opens. I can close it when I click the cancelbtn, but I can't enter the slot make_a_box().
Where can I add this slot in order to make this code working?

Answer 1

This is ok and runs fine, because the slot you are using is located at the right place : in your occQt class.
// You connect the signal FROM the action TO "this", i.e. your class
connect(mAboutAction2, SIGNAL(triggered()), this, SLOT(about2()));
void occQt::about2() //UI
{
QWidget* pWidget = new QWidget;
QPushButton* okbtn = new QPushButton(tr("ok"));
QPushButton* cancelbtn = new QPushButton(tr("cancel"));
btnlayout->addWidget(okbtn);
btnlayout->addWidget(cancelbtn);
dlglayout->setMargin(50);
dlglayout->addLayout(gridlayout);
dlglayout->addStretch(40);
dlglayout->addLayout(btnlayout);
pWidget->setLayout(dlglayout);
pWidget->setWindowTitle(tr("Make a Box by custom."));
pWidget->show();
Now, this is not ok :
// You connect the signal FROM the button to pWidget, which doesn't have a slot make_a_box()
connect(okbtn, SIGNAL(clicked()), pWidget, SLOT(make_a_box()));
The slot make_a_box() doesn't exist for pWidget, which is a QWidget. You are trying to connect a signal to a slot that does not exist.
You have to define this slot in your occQt class, and connect the signal clicked() of the button to your slot in your class :
// Now, you connect the signal FROM the button to "this", which is your class and has a slot make_a_box()
connect(okbtn, SIGNAL(clicked()), this, SLOT(make_a_box()));
In your .h file, you will have :
private slots :
void make_a_box();
And in your .cpp file :
void occQt::make_a_box()
{
TopoDS_Shape aTopoBox = BRepPrimAPI_MakeBox(3.0, 4.0, 95.0).Shape();
Handle_AIS_Shape anAisBox = new AIS_Shape(aTopoBox);
anAisBox->SetColor(Quantity_NOC_AZURE);
mContext->Display(anAisBox);
}