Qt – Dynamically creating and displaying an array of buttons inside QScrollArea

qtuser interface

My aim is to create an array of command link buttons dynamically on clicking a push button in and then display them all inside a vertical layout inside a QscrollArea. I get the data for the buttons from a database. For this I created a slot for the button and wrote the following code inside the slot function.

QCommandLinkButton *slotButtons[10];
for(int i=0; slotQuery.next(); i++)
{
    slotButtons[i] = new QCommandLinkButton;
    slotButtons[i]->setText(slotQuery.value(0).toString());
    slotButtons[i]->setDescription(slotQuery.value(1).toString());


    ui->scrollAreaSlots->layout()->addWidget(slotButtons[i]);
    ui->scrollAreaSlots->show();
    slotButtons[i]->show();


}

This compiles without errors but the buttons are not visible, even after calling show.
Could anyone tell me where I'm going wrong?

Update: If i remove all the "[i]"s and comment the loop; basically creating just a single command link button, it works perfectly. But it doesn't work for the loop. Is everything right with my looping?

Best Answer

The QScrollArea has one child widget which can contain other widgets.

When a QScrollArea widget is created with Qt Creator's UI designer, Qt Creator creates automatically a widget named scrollAreaWidgetContents. Buttons are then added to that widget's layout, which is not created automatically. The layout is created in the following code which also add the buttons:

QCommandLinkButton *slotButtons[10];
QVBoxLayout* layout = new QVBoxLayout(ui->scrollAreaWidgetContents);
for(int i=0; slotQuery.next(); i++)
{
    slotButtons[i] = new QCommandLinkButton;
    slotButtons[i]->setText(slotQuery.value(0).toString());
    slotButtons[i]->setDescription(slotQuery.value(1).toString());
    ui->scrollAreaWidgetContents->layout()->addWidget(slotButtons[i]);
}

Related Solutions

Qt – QLabel showing an image inside a QScrollArea

I know this is an old post - but in case you or anyone is still having a problem, it might help to set QScrollArea::widgetResizable to false.

At least, when I tried a similar thing, my vertical scrollbar was always disabled (even though I set the size of the scrollable widget to have a height larger than the viewport) until I set this to false.

When it's true, I think it updates the size of the scrollable widget, thus the scrollbars should not be needed. This allows you to do what it does in the example I guess, and implement a stretch-to-fit function. (actually what I'm trying to do is fit to width, with just a vertical scroll bar)

Qt – How do i resize the contents of a QScrollArea as more widgets are placed inside

If you're coming here from Google and not having luck with the accepted answer, that's because you're missing the other secret invocation: QScrollArea::setWidget. You must create and explicitly identify a single widget which is to be scrolled. It's not enough to just add the item as a child! Adding multiple items directly to the ScrollArea will also not work.

This script demonstrates a simple working example of QScrollArea:

from PySide.QtGui import *

app = QApplication([])

scroll = QScrollArea()
scroll.setWidgetResizable(True) # CRITICAL

inner = QFrame(scroll)
inner.setLayout(QVBoxLayout())

scroll.setWidget(inner) # CRITICAL

for i in range(40):
    b = QPushButton(inner)
    b.setText(str(i))
    inner.layout().addWidget(b)

scroll.show()
app.exec_()

Best Answer

Related Solutions

Qt – QLabel showing an image inside a QScrollArea

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