How to include in a main QLabel a subset of widgets (e.g. QListView and QLabels) - qt

Question

In order to test a rotation of a QImage I created a quick application where I subclassed a QLabel as shown below. Basically the QLabel acts as MainWindow for me in this case.
Below is the lay-out I have:
Below is the lay-out I am trying to achieve:
Below the code
mainwindow.h
class MainWindow : public QLabel {
Q_OBJECT
public:
MainWindow(int argc, char** argv, QWidget *parent = {});
virtual ~MainWindow();
protected:
Q_SLOT void setImageMsg(const sensor_msgs::ImageConstPtr&);
Q_SIGNAL void newImageMsg(const sensor_msgs::ImageConstPtr&);
private:
ros::Subscriber sub;
ros::Subscriber sub_img_bw;
};
mainwindow.cpp
MainWindow::MainWindow(int argc, char** argv, QWidget *parent) : QLabel(parent) {
qRegisterMetaType<sensor_msgs::ImageConstPtr>();
#if QT_VERSION >= QT_VERSION_CHECK(5,0,0)
connect(this, &MainWindow::newImageMsg, this, &MainWindow::setImageMsg);
#else
connect(this, SIGNAL(newImageMsg(sensor_msgs::ImageConstPtr)), SLOT(setImageMsg(sensor_msgs::ImageConstPtr)));
#endif
ros::init(argc,argv,"MainWindow");
ros::NodeHandle n;
QComboBox *comboColorBckgd = new QComboBox(this);
QStringList sequence_len = QStringList() << tr("Bckgd Color") << tr("Green") << tr("Blue") << tr("Black");
comboColorBckgd->addItems(sequence_len);
QComboBox *comboColorBeam = new QComboBox(this);
QStringList sequence_len_beam = QStringList() << tr("Beam Color") << tr("R") << tr("G") << tr("B");
comboColorBeam->addItems(sequence_len_beam);
QGridLayout *grid = new QGridLayout(this);
grid->setColumnMinimumWidth(0, 10);
grid->addWidget(comboColorBckgd, 0, 0, Qt::AlignTop);
grid->addWidget(comboColorBeam, 0, 1, Qt::AlignTop);
comboColorBckgd->show();
comboColorBeam->show();
}
I am facing here the situation where I don't exactly understand why I can't divide the main QLabel in subsessions where :
one row has one QLabel and one QListView and
another row has 'QListViewandQLabel`
As shown in the layout I am trying to achieve.
Of course I tries to insert the necessary components in the function
`MainWindow::MainWindow(int argc, char** argv, QWidget *parent) : QLabel(parent) {
// .. desired componentns here
}
Despite I am able to add all the components my final layout is extremely disordered and everything falls under the single QLabel despite I am sure I set the QGridLayout correctly.
Maybe do I have to subclass a QGridLayout? I am confused.
I am not sure how to move on and I would like to thank anyone in advance for shedding light on what is happening or at lest pointing to a potential solution.

Answer 1

I'm not able to see your images for the layout you have and are trying to achieve so I may not totally understand your problem but...
Why do you have to subclass QLabel? I imagine that is causing your problems - QLabel is not expecting to have a child hierarchy underneath it and so it is probably conflicting with QLabel.
Instead of this parent/child hierarchy:
- MainWindow : public QLabel
-- QGridLayout
--- QComboBox
--- QComboBox
Have you tried:
- MainWindow : public QWidget (or QMainWindow?)
-- QGridLayout
--- QLabel (top level)
--- QComboBox
--- QComboBox