How to round QWidget corners

Question

I wonder if there is there a way to round Qt widget corners?

from PyQt4 import QtCore, QtGui

class Custom(QtGui.QWidget):
    def __init__(self, *args, **kwargs):
        QtGui.QWidget.__init__(self, *args, **kwargs)
        self.setWindowOpacity(0.9)
        self.setWindowFlags(QtCore.Qt.Popup|QtCore.Qt.FramelessWindowHint)
        self.setWindowTitle('Custom')
        self.resize(440,220)
        self.move(QtGui.QCursor.pos())

    def closeEvent(self, event):
        event.accept()
        sys.exit(app.exec_())

    def mousePressEvent(self, event):
        self.close() 

if __name__ == "__main__":
    app = QtGui.QApplication(sys.argv)
    w = Custom()
    w.show()
    sys.exit(app.exec_())

score 17 · Accepted Answer · answered Feb 11 '16 at 07:44

You can use QWidget.setMask(self, QRegion) for it.

An example in C++:

QWidget *widget = new QWidget;
widget->resize(300, 200);

const int radius = 10;

QPainterPath path;
path.addRoundedRect(widget->rect(), radius, radius);
QRegion mask = QRegion(path.toFillPolygon().toPolygon());
widget->setMask(mask);

widget->show();

score 5 · Answer 2 · edited May 23 '17 at 11:46

SOLUTION:

Here is working Python solution outlined by hank using C++:

import sys
from PySide import QtCore, QtGui

class Custom(QtGui.QWidget):
    def __init__(self, *args, **kwargs):
        QtGui.QWidget.__init__(self, *args, **kwargs)
        self.setWindowOpacity(0.9)
        self.setWindowFlags(QtCore.Qt.Popup|QtCore.Qt.FramelessWindowHint)
        self.setWindowTitle('Custom')

        radius = 40.0
        path = QtGui.QPainterPath()
        self.resize(440,220)
        path.addRoundedRect(QtCore.QRectF(self.rect()), radius, radius)
        mask = QtGui.QRegion(path.toFillPolygon().toPolygon())
        self.setMask(mask)
        self.move(QtGui.QCursor.pos())

    def closeEvent(self, event):
        event.accept()
        sys.exit(app.exec_())

    def mousePressEvent(self, event):
        self.close() 

if __name__ == "__main__":
    app = QtGui.QApplication(sys.argv)
    w = Custom()
    w.show()
    sys.exit(app.exec_())

score 0 · Answer 3 · edited Feb 01 '23 at 13:19

It works if your widget is static, but if you want to resize it and still have rounded corners, there is the paintEvent method you need to override. It should look like this:

void Widget::paintEvent(QPaintEvent *event)
{
    const int radius = 7;

    QPainterPath path;
    path.addRoundedRect(rect(), radius, radius);
    QRegion mask = QRegion(path.toFillPolygon().toPolygon());
    setMask(mask);

    QWidget::paintEvent(event);
}

How to round QWidget corners

3 Answers3

SOLUTION:

Linked