QToolTip Style Sheet not working if using QToolTip::showText

Question

I'm trying to use QSS to customize the look of the tool-tip, it works. However, if I try showing the tooltip using QToolTip::showText function, it won't work as intended which means that the QToolTip style sheet doesn't apply to it probably?

My purpose: When changing a slider value I want to show a rectangle somewhere near the slider, so I thought the tooltip was the easiest way to do it? If you don't understand what I mean, I'm trying to make sliders in Qt feel like Windows 10 UWP so if you want to understand what I mean look for example any slider in Windows like go to Settings->System->Sound and see how their slider works. I've done everything they have except that rectangle which shows when value get changed.

What I'm trying to do:

In the style sheet

QToolTip
{
color: red;
}

In my custom Slider class (inherited from QSlider)

class FSlider : public QSlider
{
    Q_OBJECT
public:
    FSlider(QWidget *parent = 0) : QSlider(parent) { connect(this, SIGNAL(valueChanged(int)), this, SLOT(notifyValueChanged(int))); }
protected:
    void mousePressEvent(QMouseEvent* event);
    void mouseReleaseEvent(QMouseEvent* event);
    bool event(QEvent* event);

private slots:
    void notifyValueChanged(int Value);
};

void FSlider::notifyValueChanged(int Value)
{
    QStyleOptionSlider opt;
    initStyleOption(&opt);
    QRect sliderHandle = style()->subControlRect(QStyle::CC_Slider, &opt, QStyle::SC_SliderHandle);
    QToolTip::setFont(QFont("Segoe UI", 13, 400));
    QToolTip::showText(mapToGlobal(QPoint(sliderHandle.x() - sliderHandle.width() - 2, sliderHandle.y() - sliderHandle.height() - 30)), QString::asprintf("%i", Value));
}

Thanks for reading !

Answer 1

I had the same issue at first with Qt 5.12.2. I was missing the third argument to QToolTip::showText. I had to add the parent widget. In that case, the CSS that I had applied to the tooltip in mainwindow.ui applied to the QToolTip . Without the parent, it is a separate window shown on the position specified and has no knowledge of the css.