Rust-SDL2

Bindings for SDL2 in Rust

Changelog for 0.37.0

Overview

Rust-SDL2 is a library for talking to the new SDL2.0 libraries from Rust. Low-level C components are wrapped in Rust code to make them more idiomatic and abstract away inappropriate manual memory management.

Rust-SDL2 uses the MIT license, but SDL2 itself is under the zlib license.

Available rust features

• gfx to link against SDL2_gfx and have access to gfx features
• image to link against SDL2_image and have access to image reading and writing features
• mixer to link against SDL2_mixer and have access to sound mixing features
• ttf to link against SDL2_ttf and have access to various font features
• raw-window-handle to enable the crate raw-window-handle, which is useful to interop with various other backends.
• unsafe-textures to not have a lifetime in Texture structs. Texture are only freed when the program exits, or can be done manually through unsafe.
• use-bindgen to customize bindings instead of using pre-generated sdl_bindings which were created from a Linux environment. It generates your own custom SDL2 bindings, tailored to your distro. Useful for specific window-related scenarios.
• use-vcpkg to pull SDL2 from vcpkg instead of looking in your system.
• use-pkgconfig use pkg-config to detect where your library is located on your system. Mostly useful on unix systems for static linking.
• static-link to link to SDL2 statically instead of dynamically.
• use_mac_framework to use SDL2 from a Framework, on macOS only
• use_ios_framework to use SDL2 from a Framework, on iOS only
• bundled, which pulls the SDL repository and compiles it from source. More information below.

Documentation

Read the documentation here.

Requirements

Rust

We currently target the latest stable release of Rust.

SDL2.0 development libraries

SDL2 >= 2.0.26 is recommended to use these bindings; below 2.0.26, you may experience link-time errors as some functions are used here but are not defined in SDL2. If you experience this issue because you are on a LTS machine (for instance, Ubuntu), we definitely recommend you to use the feature "bundled" which will compile the lastest stable version of SDL2 for your project.

"Bundled" Feature

Since 0.31, this crate supports a feature named "bundled" which compiles SDL2 from source and links it automatically. While this should work for any architecture, you will need a C compiler (like gcc, clang, or MS's own compiler) to use this feature properly.

By default, macOS and Linux only load libraries from system directories like /usr/lib. If you wish to distribute the newly built libSDL2.so/libSDL2.dylib alongside your executable, you will need to add rpath to your executable. Add the following lines to build.rs script:

#[cfg(target_os="macos")]
println!("cargo:rustc-link-arg=-Wl,-rpath,@loader_path");

#[cfg(target_os="linux")]
println!("cargo:rustc-link-arg=-Wl,-rpath,$ORIGIN");

**This ONLY works with SDL2, NOT SDL2_image, SDL2_mixer, SDL2_ttf, SDL2_gfx`

Linux

Install these through your favourite package management tool, or via http://www.libsdl.org/

Ubuntu example:

sudo apt-get install libsdl2-dev

Fedora example:

sudo dnf install SDL2-devel

Arch example:
(Arch doesn't have separate regular and development packages, everything goes together.)

sudo pacman -S sdl2

You might also need a C compiler (gcc).

Static linking in Linux

You can choose to link SDL2 statically instead of dynamically with the static-link feature. On Linux, you will need to additionally do one of the following:

• use the bundled feature
• use the feature use-pkgconfig so that rustc knows where to look for your SDL2 libraries and its dependencies for static linking. This is required because there is no built-in way to find the resources needed to link statically SDL2 from your system
• install development libraries with vcpkg. Instructions to generate a static binary on Linux and other operating systems using vcpkg are here

macOS

Homebrew

On macOS, it's a good idea to install these via homebrew.

brew install sdl2

In recent versions of Homebrew, the installed libraries are usually linked into $(brew --prefix)/lib. If you are running an older version, the symlink for SDL might reside in /usr/local/lib.

To make linking libraries installed by Homebrew easier, do the following for your respective shell.

Add this line to your ~/.zshenv or ~/.bash_profile depending on whether you use ZSH or Bash.

export LIBRARY_PATH="$LIBRARY_PATH:$(brew --prefix)/lib"

MacPorts

You can also get sdl2 via macports.

sudo port install libsdl2

Then add the following to your ~/.bash_profile if not already present.

export LIBRARY_PATH="$LIBRARY_PATH:/opt/local/lib/"

If you're having issues with either Homebrew or MacPorts, see here.

If you are using the SDL2 framework

You can download and install the SDL2 Mac OS X framework from: https://www.libsdl.org/download-2.0.php

To make the sdl2 crate link with the SDL2 framework, you will need to enable the use_mac_framework feature. To build and test the sdl2 crate with this feature, use:

cargo test --features use_mac_framework

To depend on the sdl2 crate with this feature enabled, put the following in your project's Cargo.toml file:

[dependencies.sdl2]
features = ["use_mac_framework"]
version = ...  # Whichever version you are using

Alternatively, you can re-export the feature in your package by putting the following in your Cargo.toml file:

[features]
default = []
use_sdl2_mac_framework = ["sdl2/use_mac_framework"]

Similarly for iOS you can follow the same process using the use_ios_framework feature. However official builds of the iOS framework are not available so you must compile your own SDL2.framework.

Using the iOS framework also requires adding the 'Frameworks' directory to your rpath so that the dynamic linker can find SDL2.framework inside your app bundle. This is done by adding this to your build.rs:

#[cfg(target_os="ios")]
println!("cargo:rustc-link-arg=-Wl,-rpath,@loader_path/Frameworks");

Static linking on macOS using vcpkg

Instructions to generate a static binary on macOS and other operating systems using vcpkg are here.

Windows (MSVC)

1. Download MSVC development libraries from http://www.libsdl.org/ (SDL2-devel-2.0.x-VC.zip).

2. Unpack SDL2-devel-2.0.x-VC.zip to a folder of your choosing (You can delete it afterwards).

3. Copy all lib files from

   SDL2-devel-2.0.x-VC\SDL2-2.0.x\lib\x64\

   to (for Rust 1.6 and above)

   C:\Program Files\Rust\lib\rustlib\x86_64-pc-windows-msvc\lib

   or to (for Rust versions 1.5 and below)

   C:\Program Files\Rust\bin\rustlib\x86_64-pc-windows-msvc\lib

   or to your library folder of choice, and ensure you have a system environment variable of

   LIB = C:\your\rust\library\folder

   For Rustup users, this folder will be in

   C:\Users\{Your Username}\.rustup\toolchains\{current toolchain}\lib\rustlib\{current toolchain}\lib

Where current toolchain is likely stable-x86_64-pc-windows-msvc.

4. Copy SDL2.dll from

   SDL2-devel-2.0.x-VC\SDL2-2.0.x\lib\x64\

   into your cargo project, right next to your Cargo.toml.

5. When you're shipping your game make sure to copy SDL2.dll to the same directory that your compiled exe is in, otherwise the game won't launch.

Static linking with MSVC

The MSVC development libraries provided by http://libsdl.org/ don't include a static library. This means that if you want to use the static-link feature with the windows-msvc toolchain, you have to do one of

• build an SDL2 static library yourself and copy it to your toolchain's lib directory; or
• also enable the bundled feature, which will build a static library for you; or
• use a static SDL2 library from vcpkg as described below.

Windows (MinGW)

1. Download mingw development libraries from http://www.libsdl.org/ (SDL2-devel-2.0.x-mingw.tar.gz).

2. Unpack to a folder of your choosing (You can delete it afterwards).

3. Copy all lib files from

   SDL2-devel-2.0.x-mingw\SDL2-2.0.x\x86_64-w64-mingw32\lib

   to (for Rust 1.6 and above)

   C:\Program Files\Rust\lib\rustlib\x86_64-pc-windows-gnu\lib

   or to (for Rust versions 1.5 and below)

   C:\Program Files\Rust\bin\rustlib\x86_64-pc-windows-gnu\lib

   or to your library folder of choice, and ensure you have a system environment variable of

   LIBRARY_PATH = C:\your\rust\library\folder

   For Rustup users, this folder will be in

   C:\Users\{Your Username}\.rustup\toolchains\{current toolchain}\lib\rustlib\{current toolchain}\lib

Where current toolchain is likely stable-x86_64-pc-windows-gnu.

4. Copy SDL2.dll from

   SDL2-devel-2.0.x-mingw\SDL2-2.0.x\x86_64-w64-mingw32\bin

   into your cargo project, right next to your Cargo.toml.

5. When you're shipping your game make sure to copy SDL2.dll to the same directory that your compiled exe is in, otherwise the game won't launch.

Static linking with MinGW

If you want to use the static-link feature with the windows-gnu toolchain, then you will also need the following libraries:

libimm32.a
libversion.a
libdinput8.a
libdxguid.a

These files are not currently included with the windows-gnu toolchain, but can be downloaded here. For the x86_64 toolchain, you want the x86_64-win32-seh package, and for i686 you want the i686-win32-dwarf one.

You will find the aforementioned libraries under mingw64/x86_64-w64-mingw32/lib/ (for x86_64) or mingw32/i686-w64-mingw32/lib/ (for i686). Copy them to your toolchain's lib directory (the same one you copied the SDL .a files to).

Windows with build script

1. Download mingw and msvc development libraries from http://www.libsdl.org/ (SDL2-devel-2.0.x-mingw.tar.gz & SDL2-devel-2.0.x-VC.zip).
2. Unpack to folders of your choosing (You can delete it afterwards).
3. Create the following folder structure in the same folder as your Cargo.toml:

gnu-mingw\dll\32
gnu-mingw\dll\64
gnu-mingw\lib\32
gnu-mingw\lib\64
msvc\dll\32
msvc\dll\64
msvc\lib\32
msvc\lib\64

4. Copy the lib and dll files from the source archive to the directories we created in step 3 like so:

SDL2-devel-2.0.x-mingw.tar.gz\SDL2-2.0.x\i686-w64-mingw32\bin 		-> 	gnu-mingw\dll\32
SDL2-devel-2.0.x-mingw.tar.gz\SDL2-2.0.x\x86_64-w64-mingw32\bin 	-> 	gnu-mingw\dll\64
SDL2-devel-2.0.x-mingw.tar.gz\SDL2-2.0.x\i686-w64-mingw32\lib 		-> 	gnu-mingw\lib\32
SDL2-devel-2.0.x-mingw.tar.gz\SDL2-2.0.x\x86_64-w64-mingw32\lib 	-> 	gnu-mingw\lib\64
SDL2-devel-2.0.8-VC.zip\SDL2-2.0.x\lib\x86\*.dll	 		-> 	msvc\dll\32
SDL2-devel-2.0.8-VC.zip\SDL2-2.0.x\lib\x64\*.dll 			-> 	msvc\dll\64
SDL2-devel-2.0.8-VC.zip\SDL2-2.0.x\lib\x86\*.lib	 		-> 	msvc\lib\32
SDL2-devel-2.0.8-VC.zip\SDL2-2.0.x\lib\x64\*.lib	 		-> 	msvc\lib\64

5. Create a build script, if you don't already have one put this in your Cargo.toml under [package]:

build = "build.rs"

6. Create a file in the same directory as Cargo.toml called build.rs (if you didn't already have a build script) and paste this into it:

use std::env;
use std::path::PathBuf;

fn main() {
    let target = env::var("TARGET").unwrap();
    if target.contains("pc-windows") {
        let manifest_dir = PathBuf::from(env::var("CARGO_MANIFEST_DIR").unwrap());
        let mut lib_dir = manifest_dir.clone();
        let mut dll_dir = manifest_dir.clone();
        if target.contains("msvc") {
            lib_dir.push("msvc");
            dll_dir.push("msvc");
        }
        else {
            lib_dir.push("gnu-mingw");
            dll_dir.push("gnu-mingw");
        }
        lib_dir.push("lib");
        dll_dir.push("dll");
        if target.contains("x86_64") {
            lib_dir.push("64");
            dll_dir.push("64");
        }
        else {
            lib_dir.push("32");
            dll_dir.push("32");
        }
        println!("cargo:rustc-link-search=all={}", lib_dir.display());
        for entry in std::fs::read_dir(dll_dir).expect("Can't read DLL dir")  {
            let entry_path = entry.expect("Invalid fs entry").path();
            let file_name_result = entry_path.file_name();
            let mut new_file_path = manifest_dir.clone();
            if let Some(file_name) = file_name_result {
                let file_name = file_name.to_str().unwrap();
                if file_name.ends_with(".dll") {
                    new_file_path.push(file_name);
                    std::fs::copy(&entry_path, new_file_path.as_path()).expect("Can't copy from DLL dir");
                }
            }
        }
    }
}

7. On build the build script will copy the needed DLLs into the same directory as your Cargo.toml, you probably don't want to commit these to any Git repositories though so add the following line to your .gitignore file

/*.dll

8. When you're publish your game make sure to copy the corresponding SDL2.dll to the same directory that your compiled exe is in, otherwise the game won't launch.

And now your project should build and run on any Windows computer!

Windows (MSVC with vcpkg)

1. Install MS build tools and vcpkg
2. Install the needed SDL2 libs: vcpkg.exe install sdl2-ttf:x64-windows sdl2:x64-windows
3. Open a x64 native tools prompt (x64 Native Tools Command Prompt for VS 2019)
4. set env vars:

SET PATH=%PATH%;C:\Users\my_user\dev\vcpkg\installed\x64-windows\bin
SET INCLUDE=%INCLUDE%;C:\Users\my_user\dev\vcpkg\installed\x64-windows\include
SET LIB=%LIB%;C:\Users\my_user\dev\vcpkg\installed\x64-windows\lib

5. cargo build

Windows, Linux and macOS with vcpkg

Another method of getting the development libraries is with vcpkg. To set up a project to build a static binary on Windows (MSVC), Linux or macOS that is buildable like this:

cargo install cargo-vcpkg
cargo vcpkg build
cargo build

add the following your Cargo.toml:

[dependencies.sdl2]
version = "0.37"
default-features = false
features = ["ttf","image","gfx","mixer","static-link","use-vcpkg"]

[package.metadata.vcpkg]
dependencies = ["sdl2", "sdl2-image[libjpeg-turbo,tiff,libwebp]", "sdl2-ttf", "sdl2-gfx", "sdl2-mixer"]
git = "https://github.com/microsoft/vcpkg"
rev = "2024.05.24" # release 2024.05.24 # to check for a new one, check https://github.com/microsoft/vcpkg/releases

[package.metadata.vcpkg.target]
x86_64-pc-windows-msvc = { triplet = "x64-windows-static-md" }

More information on the cargo vcpkg tool is here.

Installation

If you're using cargo to manage your project, you can download through Crates.io:

    [dependencies]
    sdl2 = "0.37"

Alternatively, pull it from GitHub to obtain the latest version from master

    [dependencies.sdl2]
    git = "https://github.com/rust-sdl2/rust-sdl2"

Otherwise, clone this repo and run cargo

cargo build

You can enable features such as ttf, image, gfx and mixer by adding this instead:

    [dependencies.sdl2]
    version = "0.37"
    default-features = false
    features = ["ttf","image","gfx","mixer"]

Those features need their respective libraries, which can be found at these locations : (the install process is the same as SDL2)

• image, ttf, mixer
• gfx

What about sdl2_net ?

As of now, sdl2_net is meaningless compared to what other crates such as serde and bincode can offer. We highly recommend using those to develop anything UDP or TCP related (along with futures or TCP/UDP from the standard library).

If you still want an implementation of sdl2_net, you can try to add it in this repo as a feature via a Pull Request. A somewhat outdated version of this binding can be found here

Demo

We have several simple example projects included:

cargo run --example demo

You can see the full list in the examples/ folder. Some examples require some features, you can enable them like so:

cargo run --example gfx-demo --features "gfx"

Replace "gfx" by the feature(s) needed for the example you want.

About the unsafe_textures feature

In the sdl2::render module, Texture has by default lifetimes to prevent it from out-living its parent TextureCreator. These lifetimes are sometimes too hard to deal with in Rust, and so you have the option to enable the unsafe_textures feature.

This removes the lifetimes on the Textures, at the cost of optional manual memory management. If you want to manually destroy the Textures you use, you can call the destroy method of your Textures, but beware that it should not be called if none of the parents (Canvas or TextureCreator) are alive. If you do not call this method, the memory will simply be freed when the last Canvas or the last TextureCreator will be freed.

There is no online documentation for this feature, however you can build it yourself in your project by enabling the feature in your Cargo.toml, running cargo doc and accessing target/doc/sdl2/index.html via a browser.

Generating sdl2-sys with bindgen

The sdl2-sys that was generated for this crate is very generic and can be used on a lot of platforms with very few limitations. However, you may sometimes face trouble when using platform-specific features of SDL2, for instance the WindowManager category.

The feature "use-bindgen" allows you to avoid this limitation by generating the proper bindings depending on your target. It will take the headers based on what pkg-config outputs (if you enabled the feature "use-pkg-config") and generate bindings based on them. If you don't have pkg-config or disabled the feature, it will try to get the headers in SDL-2.0.8/include of this crate instead.

If somehow you have your own headers that you want to use (use a beta version, an older version, ...), you can set the environment variable "SDL2_INCLUDE_PATH" and those headers will be used by bindgen instead.

Using sdl2-sys to provide SDL2 headers/library

If you are creating a *-sys crate for a library which requires SDL2, you can use sdl2-sys to provide both the compiled library and the headers for SDL2.

Follow the following process to get the header directory. In the Cargo.toml for your crate, add sdl2-sys as a dependency (not a build-dependency). Cargo will then provide your build script with an environment variable DEP_SDL2_INCLUDE which is populated with the include directory for SDL2. If there is more than one directory, they are combined with : as a separator. Pass these directories to whatever is building your C/C++.

Once everything is linked together, there will be a single copy of SDL2 (the one provided by sdl2-sys) for all C, C++, and Rust code.

For more discussion see the corresponding issue

OpenGL

There are two ways to use OpenGL:

• As a backend for sdl2::render, where everything is done for you by sdl2. It is the default for linux devices.
• Manually, using only sdl2 as a "shell" for your window (akin to glutin and winit crates), and still use sdl2's joystick, events, audio, text input, ect capabilities.

If you want to use OpenGL, you also need the gl-rs package. If you're using cargo, just add these lines to your Cargo.toml:

    [dependencies.gl]
    git = "https://github.com/bjz/gl-rs"

You have two options to use OpenGL with sdl2:

• Use OpenGL with Canvas and use sdl2::render
• Use OpenGL directly on the Window "shell" and use manual OpenGL calls to render something

Use sdl2::render

First, find the OpenGL driver from SDL:

fn find_sdl_gl_driver() -> Option<u32> {
    for (index, item) in sdl2::render::drivers().enumerate() {
        if item.name == "opengl" {
            return Some(index as u32);
        }
    }
    None
}

fn main() {
    let sdl_context = sdl2::init().unwrap();
    let video_subsystem = sdl_context.video().unwrap();
    let window = video_subsystem.window("Window", 800, 600)
        .opengl() // this line DOES NOT enable opengl, but allows you to create/get an OpenGL context from your window.
        .build()
        .unwrap();
    let canvas = window.into_canvas()
        .index(find_sdl_gl_driver().unwrap())
        .build()
        .unwrap();

    // ...
}

If you don't plan to use OpenGL calls via the gl-rs crate, you can stop here. SDL2 will automatically use the OpenGL backend

If you plan to have your own calls intertwined with the sdl2 calls, you need to use the context of your canvas first:

// initialization
gl::load_with(|name| video_subsystem.gl_get_proc_address(name) as *const _);

// sdl::render creates a context for you, if you use a Canvas you need to use it.
canvas.window().gl_set_context_to_current();

// ... in the main loop ...
unsafe {
    gl::ClearColor(0.6, 0.0, 0.8, 1.0);
    gl::Clear(gl::COLOR_BUFFER_BIT);
}
canvas.present();

Be wary though, sdl2 has its own internal state which you should avoid messing with. Avoid using manual OpenGL in the middle of SDL2 calls, or make sure to restore the previous state.

Use OpenGL calls manually

extern crate sdl2;
extern crate gl;

use sdl2::event::Event;
use sdl2::keyboard::Keycode;
use sdl2::video::GLProfile;

fn main() {
    let sdl_context = sdl2::init().unwrap();
    let video_subsystem = sdl_context.video().unwrap();
    
    let gl_attr = video_subsystem.gl_attr();
    gl_attr.set_context_profile(GLProfile::Core);
    gl_attr.set_context_version(3, 3);

    let window = video_subsystem.window("Window", 800, 600)
        .opengl()
        .build()
        .unwrap();

    // Unlike the other example above, nobody created a context for your window, so you need to create one.
    let ctx = window.gl_create_context().unwrap();
    gl::load_with(|name| video_subsystem.gl_get_proc_address(name) as *const _);
    
    debug_assert_eq!(gl_attr.context_profile(), GLProfile::Core);
    debug_assert_eq!(gl_attr.context_version(), (3, 3));

    let mut event_pump = sdl_context.event_pump().unwrap();

    'running: loop {
        unsafe {
            gl::ClearColor(0.6, 0.0, 0.8, 1.0);
            gl::Clear(gl::COLOR_BUFFER_BIT);
        }

        window.gl_swap_window();
        for event in event_pump.poll_iter() {
            match event {
                Event::Quit {..} | Event::KeyDown { keycode: Some(Keycode::Escape), .. } => {
                    break 'running
                },
                _ => {}
            }
        }
        ::std::thread::sleep(::std::time::Duration::new(0, 1_000_000_000u32 / 60));
    }
}

As mentionned above, this method is useful when you don't care about sdl2's render capabilities, but you do care about its audio, controller and other neat features that sdl2 has.

You don't have to worry about messing with the state intertwined with sdl2 or a version you don't like: SDL2 will never call any OpenGL function outside the render module.

Vulkan

To use Vulkan, you need a Vulkan library for Rust. This example uses the Vulkano library. Other libraries may use different data types for raw Vulkan object handles. The procedure to interface SDL2's Vulkan functions with these will be different for each one.

First, make sure you enable the raw-window-handle feature.

extern crate sdl2;
extern crate vulkano;

use sdl2::event::Event;
use sdl2::keyboard::Keycode;
use vulkano::instance::{Instance, InstanceCreateInfo, InstanceExtensions};
use vulkano::swapchain::Surface;
use vulkano::VulkanLibrary;

fn main() {
    let sdl_context = sdl2::init().unwrap();
    let video_subsystem = sdl_context.video().unwrap();

    let window = video_subsystem
        .window("Window Title - My Vulkano-SDL2 application", 1024, 768)
        .vulkan()
        .build()
        .unwrap();

    let instance_extensions =
        InstanceExtensions::from_iter(window.vulkan_instance_extensions().unwrap());

    let instance = Instance::new(
        VulkanLibrary::new().unwrap(),
        InstanceCreateInfo {
            enabled_extensions: instance_extensions,
            ..Default::default()
        },
    )
    .unwrap();

    // SAFETY: Be sure not to drop the `window` before the `Surface` or vulkan `Swapchain`!
    // (SIGSEGV otherwise)
    let surface = unsafe { Surface::from_window_ref(instance.clone(), &window) };

    let mut event_pump = sdl_context.event_pump().unwrap();

    'running: loop {
        for event in event_pump.poll_iter() {
            match event {
                Event::Quit { .. }
                | Event::KeyDown {
                    keycode: Some(Keycode::Escape),
                    ..
                } => {
                    break 'running;
                }
                _ => {}
            }
        }
        ::std::thread::sleep(::std::time::Duration::new(0, 1_000_000_000u32 / 60));
    }
}

Support for raw-window-handle

raw-window-handle can be enabled using the feature name:

[dependencies.sdl2]
version = "0.37"
features = ["raw-window-handle"]

An example working with wgpu is also available:

cargo run --example raw-window-handle-with-wgpu --features raw-window-handle

sdl2 with raw-window-handle on macOS:

On macOS the RawWindowHandle.ns_view field is returned null. Libraries consuming the RawWindowHandle (such as wgpu) should determine a sane default for ns_view. If they do not, please file an issue with the associated project.

raw-window-handle on Android

On some platforms, including Android, SDL2 tries to create the OpenGL context by itself even without creating a renderer. This can manifest in errors like VK_ERROR_NATIVE_WINDOW_IN_USE_KHR when initializing Vulkan or GLES. Add the following code before creating a window to fix the errors:

sdl2::hint::set("SDL_VIDEO_EXTERNAL_CONTEXT", "1")

When things go wrong

Rust, and Rust-SDL2, are both still heavily in development, and you may run into teething issues when using this. Before panicking, check that you're using the latest version of both Rust and Cargo, check that you've updated Rust-SDL2 to the latest version, and run cargo clean. If that fails, please let us know on the issue tracker.

Contributing

Any Pull Request is welcome, however small your contribution may be ! There are, however, conditions to contribute:

• New features must be properly documented, be it via examples or inline documentation (via cargo doc). Documentation must be for the end user as well as your next fellow contributor.
• Breaking changes must have a proper argumentation with it. While the pre-1.0 state of this crate allows us to be somewhat unstable, useless breaking changes will be denied.
• Minor changes, breaking changes and new features added via Pull Request must be added in the changelog file. It is now mandatory to log your changes in the changelog. A short description with a link to your commit/pull request within GitHub is fine. Internal, documentation or meta-changes (travis build change, README instructions updates, ...) don't have to be added in the changelog.