How to draw a linear gradient arc with Qt QPainter?

Question

I\'m trying to develop a custom QProgressBar that will look like the following image :

Answer 1

This solution is not exactly what you're after; the gradient goes from top to bottom, rather than around the circle:

#include 

class Widget : public QWidget
{
public:
    Widget() {
        resize(200, 200);
    }

    void paintEvent(QPaintEvent *) {
        QPainter painter(this);
        painter.setRenderHint(QPainter::Antialiasing);

        const QRectF bounds(0, 0, width(), height());
        painter.fillRect(bounds, "#1c1c1c");

        QPen pen;
        pen.setCapStyle(Qt::RoundCap);
        pen.setWidth(20);

        QLinearGradient gradient;
        gradient.setStart(bounds.width() / 2, 0);
        gradient.setFinalStop(bounds.width() / 2, bounds.height());
        gradient.setColorAt(0, "#1c1c1c");
        gradient.setColorAt(1, "#28ecd6");

        QBrush brush(gradient);
        pen.setBrush(brush);
        painter.setPen(pen);

        QRectF rect = QRectF(pen.widthF() / 2.0, pen.widthF() / 2.0, width() - pen.widthF(), height() - pen.widthF());
        painter.drawArc(rect, 90 * 16, 0.65 * -360 * 16);
    }
};

int main(int argc, char *argv[])
{
    QApplication app(argc, argv);

    Widget w;
    w.show();

    return app.exec();
}

However, it is an arc with a linear gradient! :p