Receive mouse inputs in inactive region - c++

Question

I have horizontal slider element which is disabled. I want to enable it when I click on it. As the slider is disabled I am unable to capture mouse events on it.
Thanks in advance

Answer 1

I must admit that my first suggestion was wrong:
However, if the slider is disabled the mouse event will be captured probably by something else - I would expect the parent widget.
That expectation was wrong.
I found out about this by trying myself in an MCVE.
For my luck, the other option – using an event filter – does work.
Sample testQClickDisabled.cc:
// Qt header:
#include <QtWidgets>
void populate(QListWidget &qLst)
{
for (int i = 1; i <= 20; ++i) {
qLst.addItem(QString("item %0").arg(i));
}
}
class EventFilter: public QObject {
private:
QListWidget &qLst;
public:
EventFilter(QListWidget &qLst): QObject(), qLst(qLst)
{
qApp->installEventFilter(this);
}
~EventFilter() { qApp->removeEventFilter(this); }
EventFilter(const EventFilter&) = delete;
EventFilter& operator=(const EventFilter&) = delete;
protected:
virtual bool eventFilter(QObject *pQObj, QEvent *pQEvent) override;
};
bool EventFilter::eventFilter(QObject *pQObj, QEvent *pQEvent)
{
if (QScrollBar *const pQScrBar = dynamic_cast<QScrollBar*>(pQObj)) {
if (pQScrBar == qLst.verticalScrollBar()
&& pQEvent->type() == QEvent::MouseButtonPress) {
qDebug() << "Vertical scrollbar hit.";
pQScrBar->setEnabled(true);
}
}
return QObject::eventFilter(pQObj, pQEvent);
}
// main application
int main(int argc, char **argv)
{
qDebug() << "Qt Version:" << QT_VERSION_STR;
QApplication app(argc, argv);
// setup GUI
QListWidget qLst;
qLst.setVerticalScrollBarPolicy(Qt::ScrollBarAlwaysOn);
qLst.verticalScrollBar()->setEnabled(false);
qLst.resize(200, 200);
qLst.show();
populate(qLst);
EventFilter qEventFilter(qLst);
// runtime loop
return app.exec();
}
Output:

Answer 2

I would just use a sibling MouseArea, like this:
Slider {
id: slider
enabled: false
}
MouseArea {
anchors.fill: slider
visible: !slider.enabled
onClicked: slider.enabled = true
}