Scroll Area in QDockWidget

Andaharoo

I'm trying to add a scroll area to a dock widget. I've tried a lot of different random things. I'll share what I think should be correct. From what I've seen widgets like QScrollArea and QDockWidget have setWidget functions where you set the "content widget." Then in each content widget you'll probably set a layout.

So in my dock constructor I do this:

// Create the dock content widget and layout
QWidget* dockContentsWidget = new QWidget();
setWidget(dockContentsWidget);
QVBoxLayout* dockLayout = new QVBoxLayout();
dockContentsWidget->setLayout(dockLayout);

// Create the scroll area and content widget
QScrollArea* scrollArea = new QScrollArea();
scrollArea->setContentsMargins(10, 10, 10, 10);
dockLayout->addWidget(scrollArea);
QWidget* bgWidget = new QWidget();
bgWidget->setStyleSheet("QWidget { background-color: #3A3A3A; }");
scrollArea->setWidget(bgWidget);
// Create the scroll area contents layout
vertLayout = new QVBoxLayout();
vertLayout->setAlignment(Qt::AlignTop);
vertLayout->setMargin(0);
vertLayout->setSpacing(0);
bgWidget->setLayout(vertLayout);

But this simply shows nothing. The dock widget shows but nothing is in it. Previously I did not consider content widgets and had this:

QScrollArea* parentWidget = new QScrollArea();
parentWidget->setWidgetResizable(true);
parentWidget->setContentsMargins(10, 10, 10, 10);
setWidget(parentWidget);

QVBoxLayout* parentLayout = new QVBoxLayout();
parentWidget->setLayout(parentLayout);

QWidget* bgWidget = new QWidget();
bgWidget->setStyleSheet("QWidget { background-color: #3A3A3A; }");
parentLayout->addWidget(bgWidget);

vertLayout = new QVBoxLayout();
vertLayout->setAlignment(Qt::AlignTop);
vertLayout->setMargin(0);
vertLayout->setSpacing(0);
bgWidget->setLayout(vertLayout);

This worked but the scroll area did not. It would just scrunch everything together on resize. Any help would be greatly appeciated.

SGaist

Hi,

Out of curiosity, why not put the QScrollArea directly in the QDockWidget ? dockContentsWidget seems to be there only to contain scrollArea which looks a bit like a waste of resources.

Andaharoo

@SGaist Is that not what I tried on the second chunk of code (my first attempt). setWidget(QScrollArea)? Everything showed in this one. But the scrollbar never pops up and everything just "scrunches" down on resize.

mrjj

@Andaharoo
Hi
unless you set a MinimumSize on the widgets you put in Scroll Area, they are just "flatten"
when more is added. They have a very small minimum for pure QWidgets.

SGaist

I think the following does what you want:

int main(int argc, char **argv)
{
    QApplication app(argc, argv);
    QDockWidget dock;
    QScrollArea *area = new QScrollArea;
    dock.setWidget(area);
    QWidget *widget = new QWidget;
    area->setWidget(widget);
    widget->setStyleSheet("background-color: #3A3A3A;");
    widget->setMinimumSize(400, 400);
    dock.show();
    return app.exec();
}

Andaharoo

@mrjj How can I get it to update the minimum size based on the contents in the widget. I thought I'd be able to get this to work automatically?
In my case I have a

Dock Widget
    Widget Container for background elements and for different color
        Item 1
        Item 2
        ...

It's kind of a list widget.

Resizing the dock however, results in this:

mrjj

Hi
What are each item ? ( i mean what type of class )
Normally one would use QListWidget/view for such list and it knows its size automatically.
There is http://doc.qt.io/qt-5/qfontmetrics.html
to know text sizes but i need to understand why you have this issue in first place.

Andaharoo

@mrjj Each row is a QWidget with a horizontal layout. This makes a lot of things I do with it easier. Initially I explored the qlistwidget option but decided it was too difficult to do what I wanted to do. That's besides the point though.

Each row contains a QPushButton (with eye icon), an extension to qlabel I made called ButtonLabel (for drag and drop), and another optional QPushButton for polygon color.

What's preventing the minimum size information from getting to the parent?

mrjj

@Andaharoo
well you need to set some minimum on the "row" it seems.