How to underline a QLabel in a QGridLayout with Qt in C++? - c++

Question

I'm currently working with Qt 5.7-5.8 in C++ and I'm trying to underline a QLabel with a solid black line underneath it. Knowing my QLabel is inside a QGridLayout, I've tried this piece of code but it isn't displaying the line.
mViewerLayout->itemAtPosition(0, 0)->widget()->setStyleSheet("border-bottom: 8px solid black");
I've tried setting the object name and setting the stylesheet through its objectName(), I've tried writing "QWidget" instead of "QLabel" inside the quotation marks of setStyleSheet() function call in the code sample below, and I've tried without using the objectName().
mViewerLayout->itemAtPosition(0, 0)->widget()->setStyleSheet("QLabel {border-bottom: 8px solid black;}");
If I set the stylesheet to border: 8px solid black, then it works and covers all borders of the QLabel, but I only want to underline it and border-bottom doesn't seem to work, even though I know that's how you specify the bottom border in CSS, and even Qt documentation seems to specify this syntax. Can someone please correct me?

Answer 1

How about something like this:
QLabel * lab = static_cast<QLabel *>(mViewerLayout->itemAtPosition(0, 0)->widget());
QFont f = lab->font();
f.setUnderline(true);
lab->setFont(f);
I think that just using the built-in underline functionality will be easier and give a better result than trying to fake it.

Answer 2

The following style sheet on the QLabel should do the trick:
border-bottom-width: 1px;
border-bottom-style: solid;
border-radius: 0px;
There might be a better way, but what I see is that if you do not specify the radius, the line is not shown.
Full code to show the working:
#include <QApplication>
#include <QLabel>
#include <QLayout>
int main(int argc, char *argv[])
{
QApplication a(argc, argv);
QWidget widget;
QVBoxLayout *l = new QVBoxLayout(&widget);
QLabel label;
label.setText("This text is underlined");
label.setStyleSheet("border-bottom-width: 1px; border-bottom-style: solid; border-radius: 0px;");
l->addWidget(&label);
l->addWidget(new QWidget());
widget.show();
return a.exec();
}
The result is:
Do you perhaps have other stylesheets set on your application that is conflicting with the style set on the label?