QScrollArea issue with vertical scroll - c++

Question

I have read few pages about QScrollArea, and I couldn't solve my issue. I have the next code:
QDialog *window = new QDialog;
window->resize(300, 300);
for(int i = 0; i < 50; ++i)
{
QLabel *label = new QLabel(window);
label->move(10, i * 15);
label->setText("Text");
}
QScrollArea *area = new QScrollArea;
area->setWidget(window);
area->show();
It seems that the vertical scroll from QScrollArea doesn't appear. I can't use QVBoxLayout because on my QDialog I don't have only QLabels aligned vertically ( this is just a simplified version of my QDialog ).

Answer 1

The QScrollArea won't get scrollbars unless the QWidget inside grows. Just moving some QLabels out of bounds doesn't make the parent QWidget grow, especially without a QLayout.
But if you manually resize them so that the QWidget is bigger than the QScrollAreay, you'll get scroll bars as expected :
QDialog *window = new QDialog;
window->resize(300, 600); //< 600px high widget
for(int i = 0; i < 50; ++i)
{
QLabel *label = new QLabel(window);
label->move(10, i * 15);
label->setText("Text");
}
QScrollArea *area = new QScrollArea;
area->setWidget(window);
area->resize(300,300); //< Inside a 300px high scrollarea, expect scrollbars!
area->show();
Note that now you will have both scroll bars, because the vertical scroll bar means there isn't enough room for our 300px width anymore. You can forcefully hide the horizontal scroll bar with area->setHorizontalScrollBarPolicy(Qt::ScrollBarAlwaysOff);
You could also always force a vertical scroll bar to appear with area->setVerticalScrollBarPolicy(Qt::ScrollBarAlwaysOn);, but this by itself wouldn't solve your problem. You'd still have a 300px widget inside a 300px area, and the scrollbar wouldn't have any space to move.
Making sure the QWidget is big enough for everything it contains is what you'll want to do, the QScrollArea will adapt. Usually we use layouts for that, but you can make it work by hand as well.