A C++ UI toolkit

SixtyFPS is a UI toolkit that supports different programming languages. SixtyFPS.cpp is the C++ API to interact with a SixtyFPS UI from C++.

The complete C++ documentation can be viewed online at

Warning: Pre-Alpha SixtyFPS is still in the early stages of development: APIs will change and important features are still being developed.

Installing or Building SixtyFPS

SixtyFPS comes with a CMake integration that automates the compilation step of the .60 markup language files and offers a CMake target for convenient linkage.

Note: We recommend using the Ninja generator of CMake for the most efficient build and .60 dependency tracking. You can select the CMake Ninja backend by passing -GNinja or settig the CMAKE_GENERATOR environment variable to Ninja.

Building from Sources

The recommended and most flexible way to use the C++ API is to build SixtyFPS from sources.

First you need to install the prerequisites:

  • Install Rust by following the Rust Getting Started Guide. Once this is done, you should have the rustc compiler and the cargo build system installed in your path.

  • cmake (3.16 or newer)

  • A C++ compiler that supports C++17 (e.g., MSVC 2019 on Windows)

You can include SixtyFPS in your CMake project using CMake’s FetchContent feature. Insert the following snippet into your CMakeLists.txt to make CMake download the latest release, compile it and make the CMake integration available:

    GIT_TAG v0.0.6
    SOURCE_SUBDIR api/sixtyfps-cpp

If you prefer to treat SixtyFPS as an external CMake package, then you can also build SixtyFPS from source like a regular CMake project, install it into a prefix directory of your choice and use find_package(SixtyFPS) in your CMakeLists.txt.

Binary Packages

The SixtyFPS continuous integration system is building binary packages to use with C++ so that you do not need to install a rust compiler. These binaries can be found by clicking on the last successful build of the master branch and downloading the cpp_bin artifact.

After extracting the artifact you can place the lib directory into your CMAKE_PREFIX_PATH and find_package(SixtyFPS) should succeed in locating the package.

Usage via CMake

A typical example looks like this:

cmake_minimum_required(VERSION 3.16)
project(my_application LANGUAGES CXX)

# Note: Use find_package(SixtyFPS) instead of the following three commands, if you prefer the package
# approach.
    GIT_TAG v0.0.6
    SOURCE_SUBDIR api/sixtyfps-cpp

add_executable(my_application main.cpp)
target_link_libraries(my_application PRIVATE SixtyFPS::SixtyFPS)
sixtyfps_target_60_sources(my_application my_application_ui.60)

The sixtyfps_target_60_sources cmake command allows you to add .60 files to your build. Finally it is necessary to link your executable or library against the SixtyFPS::SixtyFPS target.


Let’s make a UI for a todo list application using the SixtyFPS UI description language. Hopefully this should be self explainatory. Check out the documentation of the language for help

// file: my_application_ui.60
import { CheckBox, Button, ListView, LineEdit } from "sixtyfps_widgets.60";

export struct TodoItem := {
    title: string,
    checked: bool,

export MainWindow := Window {
    callback todo_added(string);
    property <[TodoItem]> todo_model;

    GridLayout {
        Row {
            text_edit := LineEdit {
                accepted(text) => { todo_added(text); }
            Button {
                text: "Add Todo";
                clicked => {
        list_view := ListView {
            rowspan: 2;
            row: 2;
            for todo in todo_model: Rectangle {
                height: 20px;
                GridLayout {
                    CheckBox {
                        text: todo.title;
                        checked: todo.checked;
                        toggled => {
                            todo.checked = checked;

We can compile this code using the sixtyfps_compiler binary:

sixtyfps_compiler my_application_ui.60 > my_application_ui.h

Note: You would usually not type this command yourself, this is done automatically by the build system. (that’s what the sixtyfps_target_60_sources cmake function does)

This will generate a my_application_ui.h header file. It basically contains the following code (edited for briefty)

#include <sixtyfps>

struct TodoItem {
    bool checked;
    sixtyfps::SharedString title;

struct MainWindow {
    inline auto create () -> sixtyfps::ComponentHandle<MainWindow>;

    inline auto get_todo_model () const -> std::shared_ptr<sixtyfps::Model<TodoItem>>;
    inline void set_todo_model (const std::shared_ptr<sixtyfps::Model<TodoItem>> &value) const;

    inline void invoke_todo_added (sixtyfps::SharedString arg_0) const;
    template<typename Functor> inline void on_todo_added (Functor && callback_handler) const;


We can then use this from out .cpp file

// include the generated file
#include "my_application_ui.h"

int main() {
    // Let's instantiate our window
    auto todo_app = MainWindow::create();

    // let's create a model:
    auto todo_model = std::make_shared<sixtyfps::VectorModel<TodoItem>>(std::vector {
        TodoItem { false, "Write documentation" },
    // set the model as the model of our view

    // let's connect our "add" button to add an item in the model
    todo_app->on_todo_added([todo_model](const sixtyfps::SharedString &s) {
         todo_model->push_back(TodoItem { false, s} );

    // Show the window and run the event loop

That’s it.

Check the rest of the documentation for the reference.