CXX-Qt is a set of Rust crates for creating bidirectional Rust ⇄ C++ bindings with Qt. It can be used to integrate Rust into C++ applications using CMake or used to build Rust applications with Cargo. CXX-Qt provides tools for implementing QObject subclasses in Rust which can be used from C++, QML, and JavaScript. It consists of two parts:

• cxx-qt-lib, a library of Rust bindings to common QtCore and QtGui classes made with CXX

• cxx-qt & cxx-qt-build, a pair of Rust & C++ code generators which are a superset of CXX plus additional attributes to interface with Qt's signals & slots and property system. The cxx-qt crate implements a macro for Rust code generation. cxx-qt-build is used in Cargo build scripts to generate and compile the corresponding C++ code.

The CXX-Qt Book walks through a minimal example step-by-step and documents CXX-Qt's features for the latest release. The examples folder contains demonstrations of using threading, QQmlExtensionPlugin, and various other features.

CXX-Qt is tested on CI on Linux, Windows, and macOS (all on x86). It should work on other platforms that Qt and Rust both support, however, these are not tested regularly.

CXX-Qt is in early development and the API changes frequently. For the latest documentation between releases, install mdBook and run mdbook serve in the book folder.

¹: maintained: supports Qt6 and repository has had nontrivial commits within last year as of August 2022

²: CXX-Qt and Rust Qt Binding Generator can be used to implement custom QObjects subclasses in Rust. C++ bindings for these QObject subclasses can be used in QWidgets applications, but these projects do not provide Rust bindings for QWidgets APIs.

Ensure that you have the following installed

• C++ compiler
• clang-format
• CMake v3.16+
• Qt 5 and/or Qt 6
• Rust toolchain
• mold, lld, or GNU ld.gold for Linux (lld is included in the XCode toolchain on macOS)

This repository's build system uses CMake, which calls Cargo under the hood to build all the examples and tests. One example can be built and run with Cargo directly without using CMake: cargo run -p qml-minimal-no-cmake (this example is also built in the CMake build). This example does not link with GNU ld.bfd which is the default linker on most Linux distributions; installing mold, lld, or GNU ld.gold (from GNU binutils but may be separate package) is required on Linux.

On Windows and macOS, CXX-Qt defaults to installing Qt from vcpkg. Prebuilt packages are automatically downloaded from GitHub Packages (this will take several minutes the first time you run CMake). If you already have Qt installed, you can disable this by adding -D VCPKG=OFF to the CMake configure step (the first call to cmake).

CXX-Qt defaults to building with Qt6. If you want to build with Qt5 when both are installed, or you want to tell vcpkg to use Qt5, add -D USE_QT5=ON to the CMake configure step.

cmake -S . -B build
cmake --build build

./build/examples/qml_minimal/example_qml_minimal

Testing assumes that cargo clippy and cargo fmt are available, you may need to install these with rustup component add clippy rustfmt.

For testing the book, it assumes that mdbook and mdbook-linkcheck are installed.

For license and memory testing, it assumes that you have reuse installed (eg via pip3 install reuse) and valgrind.

ctest --test-dir build

CXX-Qt is Copyright (C) 2022, Klarälvdalens Datakonsult AB, and is available under the terms of the MIT or the Apache-2.0 licenses.

Contact KDAB at [email protected] to inquire about additional features or services related to this project.

The following CMake source files are available under the BSD-3-Clause

• cmake/CompilerCaching.cmake - a helper for using sccache

CXX-Qt is supported and maintained by Klarälvdalens Datakonsult AB (KDAB).

The KDAB Group is the global No.1 software consultancy for Qt, C++ and OpenGL applications across desktop, embedded and mobile platforms.

The KDAB Group provides consulting and mentoring for developing Qt applications from scratch and in porting from all popular and legacy frameworks to Qt. We continue to help develop parts of Qt and are one of the major contributors to the Qt Project. We can give advanced or standard trainings anywhere around the globe on Qt as well as C++, OpenGL, 3D and more.

Please visit https://www.kdab.com to meet the people who write code like this.