extern "C++Qt"

• QObjects
• Methods
• Signals

#[cxx_qt::bridge]
mod ffi {
    extern "C++Qt" {

    }
}

The extern "C++Qt" section of a CXX-Qt bridge declares Qt types and signatures to be made available to Rust, and gives the paths of the headers which contain the corresponding Qt declarations.

A bridge module may contain zero or more extern "C++Qt" blocks.

This complements the extern "C++" CXX section but allows for declaring Qt specific features on C++ types.

QObjects

Types defined in C++ that are made available to Rust, but only behind an indirection.

This is the same as CXX Opaque C++ types.

#[cxx_qt::bridge]
mod ffi {
    extern "C++Qt" {
        include!(<QtWidgets/QPushButton>);
        type QPushButton;
    }
}

Methods

Methods can be specified on the Qt type in the same way as extern "RustQt" blocks.

This is the same as CXX Functions and member functions.

#[cxx_qt::bridge]
mod ffi {
    unsafe extern "C++" {
        include!("cxx-qt-lib/qstring.h");
        type QString = cxx_qt_lib::QString;
    }

    extern "C++Qt" {
        include!(<QtWidgets/QPushButton>);
        type QPushButton;

        fn text(self: &QPushButton) -> QString;
        fn setText(self: Pin<&mut QPushButton>, text: &QString);
    }
}

Signals

Signals can be specified on the Qt type in the same way as extern "RustQt" blocks.

#[cxx_qt::bridge]
mod ffi {
    extern "C++Qt" {
        include!(<QtWidgets/QPushButton>);
        type QPushButton;

        #[qsignal]
        fn clicked(self: Pin<&mut QPushButton>, checked: bool);
    }
}

This then causes CXX-Qt to generate Rust methods to connect to the #[qsignal] with a closure, in the same way as a #[qsignal] in a extern "RustQt" block.

Note using pub(self) as the visibility of the signal allows for declaring private signals