RxQt

The Reactive Extensions for Qt.

Example

#include <rxqt.hpp>
#include <QApplication>
#include <QWidget>
#include <QVBoxLayout>
#include <QPushButton>
#include <QLineEdit>
#include <QLabel>

using namespace std::chrono;

namespace Rx {
    using namespace rxcpp;
    using namespace rxcpp::sources;
    using namespace rxcpp::operators;
    using namespace rxcpp::util;
}

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

    rxqt::run_loop rxqt_run_loop;

    auto widget = std::make_unique<QWidget>();
    auto layout = new QVBoxLayout;
    widget->setLayout(layout);

    auto button = new QPushButton("Click me");
    auto label = new QLabel;

    layout->addWidget(button);
    layout->addWidget(label);

    auto count = std::make_shared<int>(0);

    rxqt::from_signal(button, &QPushButton::clicked)
            .map([=](const auto&){ return (*count) += 1; })
            .debounce(milliseconds(QApplication::doubleClickInterval()))
            .tap([=](int){ (*count) = 0; })
            .subscribe([label](int x){ label->setText(QString("%1-ple click.").arg(x)); });

    rxqt::from_signal(button, &QPushButton::pressed)
            .subscribe([=](const auto&){ label->setText(QString()); });

    widget->show();
    return app.exec();
}

APIs

from_signal

observable<T> rxqt::from_signal(const QObject* sender, PointerToMemberFunction signal);

Convert Qt signal to an observable. T is decided as following.

Signal parameter type(s)	T	Note
void	long	Count of signal emission
A0	A0
A0, A1, ..., An (n > 1)	tuple<A0, A1, ..., An>

template<size_t N>
observable<T> rxqt::from_signal(const QObject* sender, PointerToMemberFunction signal);

Convert Qt signal, as N-ary function, to an observable. This can be used to convert private signals.

auto o = from_signal(q, &QFileSystemWatcher::fileChanged); // ERROR. o is observable<tuple<QString, QFileSystemWatcher::QPrivateSignal>> where last type is private member.
auto o = from_signal<1>(q, &QFileSystemWatcher::fileChanged); // OK. o is observable<QString>

from_event

observable<QEvent*> rxqt::from_event(QObject* object, QEvent::Type type);

Convert Qt event to an observable.

run_loop

Provide an interface between the Qt event loop and RxCpp's run loop scheduler. This enables use of timed RxCpp operators (such as delay and debounce) with RxQt.

Using run_loop requires an object of type run_loop to be live while the Qt event loop is active. This can be achieved most simply through use of a local variable defined after the Qt application object has been instantiated in main, or wherever the applicaiton object is instantiated. The example below gives an example of appropriate instantiation of the run_loop, together with a main window class of MainWindow:

int main(int argc, char* argv[])
{
   QApplication a(argc, argv);
   MainWindow w;
   rxqt::run_loop rxqt_run_loop;
   w.show();
   return a.exec();
}

Contribution

Issues or Pull Requests are welcomed :)

Requirement

• RxCpp (minimum of v4.0 for use of rxqt::run_loop)