Draw on QTreeWidget With QPainter

Question

I'm working on a little program and I have a bunch of panels in it. I want it so that when I focus into a panel, it draws a thin inline around it to show that it is focused. I got it working with all my panels except my tree view.

Here's an example that works with a QWidget:

void Test::paintEvent(QPaintEvent *event)
{
    if(hasFocus())
    {
        QPainter painter(this);

        QPen pen(Qt::blue);
        pen.setWidth(1);
        painter.setPen(pen);

        painter.drawRect(geometry());

    }

    QWidget::paintEvent(event);
}

When I use the QPainter on the QTreeWidget I get these debug messages in the console:

QWidget::paintEngine: Should no longer be called
QPainter::begin: Paint device returned engine == 0, type: 1
QPainter::setPen: Painter not active
QPainter::drawRects: Painter not active

So my problem is that I can't use QPainter with the QTreeWidget so I am unable to draw my outline. Is there an alternative method I can use?

Why not use paintEvent in a QTreeWidget? You can call QTreeWidget::paintEvent(event) to perform the painting of the superclass — msrd0
That's what I'm already doing. I always call the superclass in the paint event, I did however forget to add it to the given example. But that's not my problem anyway. My problem is I need to draw a rect around the geometry of the QTreeWidget, which I cannot do with just by calling the superclass. I need like a QPainter or something... — David Ludwig
Why can't you create a QPainter therefore? A QTreeWidget should be a subclass of QWidget ... and btw you should add QWidget::paintEvent(event) outside of the if — msrd0
Try it and you'll see why. I don't know why it won't let me, but I get these messages in the debug output. I'll add them to the question — David Ludwig
You can try to create your own widget and add the QTreeWidget to it, that should work, but I don't know if that's the best option — msrd0

Kosovan Kosovan · Accepted Answer · 2014-11-16T11:44:59

You don't need paintEvent at all. Use just stylesheet (setStyleSheet() method):

QTreeWidget:focus{ border: 1px solid red}
QTreeWidget:!focus{}

Result:

enter image description here

Draw on QTreeWidget With QPainter

1 Answers