Have a combobox inside a message box - c++

Question

I want to create a combobox inside a message box and return the selected value to be used later.
I can do the same on the window itself but not sure how to do that inside a combobox.
MainWindow::MainWindow(QWidget *parent) :
QMainWindow(parent),
ui(new Ui::MainWindow)
{
ui->setupUi(this);
ui->comboBox->addItem("Red");
ui->comboBox->addItem("Blue");
ui->comboBox->addItem("Green");
ui->comboBox->addItem("Yellow");
ui->comboBox->addItem("Pink");
ui->comboBox->addItem("Purple");
}
MainWindow::~MainWindow()
{
delete ui;
}
void MainWindow::on_pushButton_clicked()
{
QMessageBox::about(this,"Choose color of rectangle", ui->comboBox->currentText() );
}

Answer 1

If I understand you correct you would like to show a combobox in a separate dialog window for the user to select some option.
One of the ways to do that, would be to subclass QDialog. If a combo field and a button to accept is sufficient the class could look as below:
class CustomDialog : public QDialog
{
public:
CustomDialog(const QStringList& items)
{
setLayout(new QHBoxLayout());
box = new QComboBox;
box->addItems(items);
layout()->addWidget(box);
QPushButton* ok = new QPushButton("ok");
layout()->addWidget(ok);
connect(ok, &QPushButton::clicked, this, [this]()
{
accept();
});
}
QComboBox* comboBox() { return box; }
private:
QComboBox* box;
};
To use the class object you can call exec to display it modally. Then you can verify whether the user accepted the choice by pressing the ok button and take proper action.
QStringList itemList({"item1", "item2", "item3"});
CustomDialog dialog(itemList);
if (dialog.exec() == QDialog::Accepted)
{
// take proper action here
qDebug() << dialog.comboBox()->currentText();
}
Similar approach is implemented in the QMessageBox class where a number of options can be specified to alter the displayed contents (for example button configuration or check box existance).
EDIT:
To use the sample code in your own project you should put the latter section I posted into your on_pushButton_clicked() slot. Substitute the itemList with your color names list. Then put the CustomDialog class to a separate file which you include in main and you should be good to go.