SFML/doc/migration.md

Migration Guide

Welcome to SFML 3! The SFML Team has put a lot of effort into delivering a library that is both familiar to existing users while also making significant improvements. This document will walk you through how to upgrade your SFML 2 application to SFML 3.

One of the headline changes in SFML 3 is raising the C++ standard to C++17 thus bringing SFML into the world of modern C++! This change has enabled a vast number of internal improvements as well as new opportunities for improving the API that will be discussed in this document.

CMake Targets

SFML 3 uses modern CMake convention for library targets which entails having a namespace in front of the target name. These namespaces tell CMake "this is a target" whereas something like sfml-graphics might be a target or might be a precompiled library on disk like libsfml-graphics.so. Fixing this ambiguity leads to more useful error messages when a given target can't be found due to, for example, forgetting a find_package call. The component names used when calling find_package were also changed to capitalize the first letter.

v2 Target	v3 Target
sfml-system	SFML::System
sfml-window	SFML::Window
sfml-graphics	SFML::Graphics
sfml-network	SFML::Network
sfml-audio	SFML::Audio
sfml-main	SFML::Main

v2 Component	v3 Component
system	System
window	Window
graphics	Graphics
network	Network
audio	Audio
main	Main

v2:

find_package(SFML 2 REQUIRED COMPONENTS graphics audio network)
...
target_link_libraries(my_app PRIVATE sfml-graphics sfml-audio sfml-network)

v3:

find_package(SFML 3 REQUIRED COMPONENT Graphics Audio Network)
...
target_link_libraries(my_app PRIVATE SFML::Graphics SFML::Audio SFML::Network)

sf::Vector2<T> Parameters

A common pattern in SFML 2 was to use pairs of scalar parameters to represent concepts like sizes or positions. Take sf::Transformable::setPosition(float, float) for example. The two parameters combine to represent a position in world space.

SFML 3 takes all of the APIs with pairs of parameters like (float, float) or (unsigned int, unsigned int) and converts them to their corresponding sf::Vector2<T> type like sf::Vector2f or sf::Vector2u to make the interface more expressive and composable. This transition is often as simple as wrapping the two adjacement parameters with braces to construct the vector.

v2:

sf::VideoMode videoMode(480, 640, 24);
sf::CircleShape circle(10);
circle.setPosition(10, 20);
sf::IntRect rect(250, 400, 50, 100);

v3:

sf::VideoMode videoMode({480, 640}, 24);
sf::CircleShape circle(10);
circle.setPosition({10, 20});
sf::IntRect rect({250, 400}, {50, 100});

sf::Event

SFML 3 uses std::variant under the hood to implement a totally new, type-safe API for events. There are two main ways to use this new API. Check out the new EventHandling example program to see these methods in practice.

sf::Event::getIf<T>

The first option is based around sf::Event::getIf<T> and sf::Event::is<T>. getIf<T> works by providing a template parameter which must be an event subtype. Event subtypes are types like sf::Event::Resized or sf::Event::MouseMoved. If the template argument matches the active event subtype then a pointer to the data is returned. If that template argument is not the active event subtype then nullptr is returned. sf::Event::is<T> more simply returns true if T matches the active event subtype. is<T> is often used for subtypes like sf::Event::Closed which contain no data. Here's what that looks like:

while (window.isOpen())
{
    while (const std::optional event = window.pollEvent())
    {
        if (event->is<sf::Event::Closed>())
        {
            window.close();
        }
        else if (const auto* keyPressed = event->getIf<sf::Event::KeyPressed>())
        {
            if (keyPressed->scancode == sf::Keyboard::Scancode::Escape)
                window.close();
        }
    }

    // Remainder of main loop
}

Note how the API for getting events has changed slightly. sf::WindowBase::pollEvent and sf::WindowBase::waitEvent now return a std::optional<sf::Event>. These two functions might return an event but they might not. C++ lets you deduce the template parameter which is why you can write const std::optional event instead of const std::optional<sf::Event> event. const auto event is another valid choice if you prefer a more terse expression.

sf::WindowBase::handleEvents

The second option for processing events is via the new sf::WindowBase::handleEvents function. This functions performs event visitation. What this means is that you can provide callbacks which take different event subtypes as arguments. Alternatively you may provide an object (or objects) with operator() implementations which handle the event subtypes you want to process. Notably you do not have to provide callbacks for all possible event subtypes. Depending on the current active event subtype, the corresponding callback is called. Here's what that looks like:

const auto onClose = [&window](const sf::Event::Closed&)
{
    window.close();
};

const auto onKeyPressed = [&window](const sf::Event::KeyPresssed& keyPressed)
{
    if (keyPressed.scancode == sf::Keyboard::Scancode::Escape)
        window.close();
};

while (window.isOpen())
{
    window.handleEvents(onClose, onKeyPressed);

    // Remainder of main loop
}

Window Styles and States

A new sf::State enumeration was added for specifying the state of the window which means whether the window is floating or fullscreen. Here's a before-and-after showing how this affects constructing a window.

v2:

sf::RenderWindow window(sf::VideoMode::getFullscreenModes().at(0), "Title", sf::Style::Fullscreen);

v3:

sf::RenderWindow window(sf::VideoMode::getFullscreenModes().at(0), "Title", sf::State::Fullscreen);

Scoped Enumerations

SFML 3 converts all old style unscoped enumerations to scoped enumerations. This improves the type safety of the interface. This means that the name of the enumeration is now part of the namespace required to access values of that enumeration.

For example, take the enumeration sf::Keyboard::Key. sf::Keyboard::A becomes sf::Keyboard::Key::A. The name of the enumeration now appears as a nested namespace when accessing one of the enumeration's values.

Here is a complete list of all enumerations which have undergone this change:

• sf::BlendMode::Equation
• sf::BlendMode::Factor
• sf::Cursor::Type
• sf::Ftp::Response::Status
• sf::Ftp::TransferMode
• sf::Http::Request::Method
• sf::Http::Response::Status
• sf::Joystick::Axis
• sf::Keyboard::Key
• sf::Keyboard::Scan
• sf::Mouse::Button
• sf::Mouse::Wheel
• sf::PrimitiveType
• sf::Sensor::Type
• sf::Shader::Type
• sf::Socket::Status
• sf::Socket::Type
• sf::SoundSource::Status
• sf::VertexBuffer::Usage

sf::Rect<T>

sf::Rect<T> has been refactored from 4 scalar values into 2 sf::Vector2<T>s. Its two data members are sf::Vector2<T>s named position and size. This means that sf::Rect<T>::getPosition() and sf::Rect<T>::getSize() have been removed in favor of directly accessing the position and size data members. The 4-parameter constructor was also removed in favor of the constructor which takes two sf::Vector2<T>s.

v2:

sf::FloatRect rect(10, 20, 30, 40);
sf::Vector2f position = rect.getPosition();
sf::Vector2f size = rect.getSize();

v3:

sf::FloatRect rect({10, 20}, {30, 40});
sf::Vector2f position = rect.position;
sf::Vectro2f size = rect.size;

The two overloads of sf::Rect<T>::intersects have been replaced with one unified function called sf::Rect<T>::findIntersection which returns a std::optional<Rect<T>>. This optional contains the overlapping area if the rectangles overlap. Otherwise the optional is empty.

sf::IntRect rect1({0, 0}, {200, 200});
sf::IntRect rect2({100, 100}, {200, 200});
std::optional<sf::IntRect> intersection = rect1.findIntersection(rect2);
// position={100, 100} size={100, 100}

sf::Angle

All angles are now represented with a strong type named sf::Angle. This type provides two functions for creating angles called sf::degrees(float) and sf::radians(float) which construct an angle from either some value of degrees or radians. Operators (+, -, etc.) are provided to perform mathematical operations with angles. If you need access to the raw angle as a float then you can use either sf::Angle::asDegrees() or sf::Angle::asRadians().

v2:

sf::RectangleShape shape(sf::Vector2f(50, 50));
shape.setRotation(90);
std::cout << "Rotation: " << shape.getRotation() << '\n';

v3:

sf::RectangleShape shape({50, 50});
shape.setRotation(sf::degrees(90));
std::cout << "Rotation: " << shape.getRotation().asDegrees() << '\n';

Renamed Functions

A number of functions have new names but otherwise have not changed their semantics.

v2	v3
sf::Font::loadFromFile	sf::Font::openFromFile
sf::Socket::getHandle	sf::Socket::getNativeHandle
sf::WindowBase::getSystemHandle	sf::WindowBase::getNativeHandle
sf::Texture::create	sf::Texture::resize
sf::RenderTexture::create	sf::RenderTexture::resize
sf::Image::create	sf::Image::resize
sf::Sound::getLoop	sf::Sound::isLooping
sf::Sound::setLoop	sf::Sound::setLooping
sf::SoundStream::getLoop	sf::SoundStream::isLooping
sf::SoundStream::setLoop	sf::SoundStream::setLooping

Removal of Default Constructors

The default constructors sf::Sound::Sound(), sf::Text::Text(), and sf::Sprite::Sprite() were removed. They can be replaced by the corresponding constructors which accept a resource type.

v2	v3
sf::Sound::Sound()	sf::Sound::Sound(const sf::SoundBuffer&)
sf::Text::Text()	sf::Text::Text(const sf::Font&)
sf::Sprite::Sprite()	sf::Sprite::Sprite(const sf::Texture&)

Now that these classes are guaranteed to be holding a reference to their corresponding resource type, the functions used to access to those resources can return a reference instead of a pointer. These functions are sf::Sound::getBuffer(), sf::Text::getFont(), and sf::Sprite::getTexture().

std::optional Usage

SFML 3 makes liberal use of std::optional to express when a given function may not return a value. Some of these usages have already been mentioned like sf::WindowBase::pollEvent. Here are some more places where SFML 3 makes use of std::optional.

• sf::IpAddress uses std::optional to express how resolving an address from a string may not yield a usable IP address.
• sf::Image::saveToMemory returns a std::optional because the sf::Image may be empty or the underlying implementation may fail.
• sf::SoundFileReader::open returns a std::optional because the stream being opened may not be valid.
• sf::Music::onLoop and sf::SoundStream::onLoop returns a std::optional because if the objects are not in a looping state then there is nothing to return.
• sf::InputStream uses std::optional in various places. Instead of returning -1 to signal an error, std::nullopt can be returned.

LearnCpp.com is a great place to learn more about using std::optional. Read more about that here.

Fixed Width Integers

SFML 2 contained various typedefs for fixed width integers. Those are now replaced with the fixed width integers provided in the <cstdint> header from the standard library.

v2	v3
sf::Int8	std::int8_t
sf::Uint8	std::uint8_t
sf::Int16	std::int16_t
sf::Uint16	std::uint16_t
sf::Int32	std::int32_t
sf::Uint32	std::uint32_t
sf::Int64	std::int64_t
sf::Uint64	std::uint64_t

New Constructors for Loading Resources

The following classes gained constructors that allow for loading/opening resources in a single expression. Upon failure they throw an sf::Exception.

• sf::InputSoundFile
• sf::OutputSoundFile
• sf::Music
• sf::SoundBuffer
• sf::Font
• sf::Image
• sf::RenderTexture
• sf::Shader
• sf::Texture
• sf::FileInputStream
• sf::Cursor

SFML 3 still supports the SFML 2 style of error handling in addition to these new constructors.

v2:

sf::SoundBuffer soundBuffer;
if (!soundBuffer.loadFromFile("sound.wav"))
{
    // Handle error
}

v3:

sf::SoundBuffer soundBuffer;
if (!soundBuffer.loadFromFile("sound.wav"))
{
    // Handle error
}

// OR

const sf::SoundBuffer soundBuffer("sound.wav");

sf::Vector2<T> and sf::Vector3<T> Utility Functions

sf::Vector2<T> and sf::Vector3<T> gained a number of new functions for performing common mathematic operations on vectors.

sf::Vector2<T> Function	Description
Vector2(T, sf::Angle)	Construct from polar coordinates
length()	Get length
lengthSq()	Get length squared
normalized()	Get vector normalized to unit circle
angleTo(sf::Vector2)	Get angle to another vector
angle()	Get angle from X axis
rotatedBy(sf::Angle)	Get vector rotated by a given angle
projectedOnto(sf::Vector2)	Get vector projected onto another vector
perpendicular()	Get perpendicular vector
dot(sf::Vector2)	Get dot product
cross(sf::Vector2)	Get Z component of cross product
cwiseMul(sf::Vector2)	Get component-wise multiple
cwiseDiv(sf::Vector2)	Get component-wise divisor

sf::Vector3<T> Function	Description
length()	Get length
lengthSq()	Get length squared
normalized()	Get vector normalized to unit circle
dot(sf::Vector3)	Get dot product
cross(sf::Vector3)	Get cross product
cwiseMul(sf::Vector3)	Get component-wise multiple
cwiseDiv(sf::Vector3)	Get component-wise divisor

Threading Primitives

sf::Lock, sf::Mutex, sf::Thread, sf::ThreadLocal, and sf::ThreadLocalPtr were removed and replaced with their equivalents from the standard library. The standard library provides multiple options for threads, locks, and mutexes among other threading primitives.

v2	v3
sf::Lock	std::lock_guard or std::unique_lock
sf::Mutex	std::mutex or std::recursive_mutex
sf::Thread	std::thread or std::jthread (requires C++20)
sf::ThreadLocal	thread_local
sf::ThreadLocalPtr	thread_local

Deprecated APIs

SFML 3 removes all of the deprecated APIs in SFML 2.

Deprecated API	Replacement
sf::Event::MouseWheelEvent	sf::Event::MouseWheelScrolled
sf::RenderWindow::capture	See 1
sf::RenderTexture::create	sf::RenderTexture::resize
sf::Shader::setParameter	sf::Shader::setUniform
sf::Text::setColor	sf::Text::setFillColor
sf::Text::getColor	sf::Text::getFillColor
sf::PrimitiveType::LinesStrip	sf::PrimitiveType::LineStrip
sf::PrimitiveType::TrianglesStrip	sf::PrimitiveType::TriangleStrip
sf::PrimitiveType::TrianglesFan	sf::PrimitiveType::TriangleFan
sf::PrimitiveType::Quads	See 2

1. sf::RenderWindow::capture can be recreated by using an sf::Texture and its sf::Texture::update(const Window&) function to copy its contents into an sf::Image instead.
2. sf::PrimitiveType::Quads can be replaced by another primitive type. This is not a drop-in replacement but rather will require refactoring your code to work with a new geometry. One viable option is to use sf::PrimitiveType::Triangles where two adjacent triangles join to form what was previously one quad.

Other Minor Changes

SFML 3 includes various smaller changes that ought to be mentioned.

• Reverted to default value of CMake's BUILD_SHARED_LIBS which means SFML now builds static libraries by default
• Changed sf::String interface to use std::u16string and std::u32string
• Removed sf::ContextSettings constructor in favor of aggregate initialization
• Removed sf::View::reset in favor of sf::View::operator=
• Added new sf::CoordinateType enumeration to sf::RenderStates::RenderStates
• Removed sf::Vertex constructors in favor of aggregate initialization
• Renamed sf::Mouse::Button::XButton1 and sf::Mouse::Button::XButton2 enumerators to sf::Mouse::Button::Extra1 and sf::Mouse::Button::Extra2