Qt Slot With Arguments

To use Qt from Rust, add the crates as dependencies to your Cargo.toml, for example:

Each crate re-exports its dependencies, so, for example, you can access qt_core as qt_widgets::qt_core without adding an explicit dependency. You can also add them as direct dependencies for convenience, but make sure to use compatible versions.

The Qt signals/slots and property system are based on the ability to introspect the objects at runtime. Introspection means being able to list the methods and properties of an object and have all kinds of information about them such as the type of their arguments. QtScript and QML would have hardly been possible without that ability. Therefore it is not usually necessary to use QtCore.SLOT for Qt slots. However, doing so is more efficient as it avoids a conversion to Python and back to C. Qt allows a signal to be connected to a slot that requires fewer arguments than the signal passes. The extra arguments are quietly discarded. PyQt4 slots can be used in the same way.

See rust-qt/examples repository to see how to use the API provided by Qt crates.

Most of the Qt API is translated to Rust as-is when possible. Identifiers are modified according to Rust’s naming convention. Overloaded methods (methods accepting multiple sets of argument types) are wrapped as distinct Rust methods with suffixes that distinguish between them.

In many cases, you can address the Qt documentation and translate examples from it almost directly to Rust code. Crate documentation (available on docs.rs or through cargo doc) features embedded Qt documentation.

In addition, Rust crates provide some helpers to improve ergonomics:

Qt application objects (QApplication, QGuiApplication, QCoreApplication) require argc and argv to be present, and these are not available directly in Rust. Use init helpers to initialize the application correctly:

qt_core provides API for using signals and slots conveniently. You can connect built-in signals to built-in slots like this:

You can also connect signals to Rust closures (see basic_form example:

You can also create and emit signals:

Compatibility of signal’s and slot’s arguments is checked at compile time.

Note that each set of argument types requires a separate Rust type of signal or slot (e.g. SlotNoArgs, SlotOfInt, etc.). Other crates may also provide new signal and slot objects (e.g. qt_widgets::SlotOfQTreeWidgetItem).

QString::from_std_str, QString::to_std_string, QByteArray::from_slice, and impl<'a> From<&'a QString> for String provide conversions from Qt’s types to Rust types and back.

Qt Slot With Arguments Definition

QFlags generic type mimics the functionality of C++'s QFlags class.

Qt Slot With Default Arguments

qdbg function from qt_core wraps a printable (with QDebug) Qt object into a shim object that implements Rust’s fmt::Debug.