VKFW: C++ Bindings for GLFW

It's easy to notice how similar VKFW API is to Vulkan-Hpp. That's by design. The goal is to provide a middle step helping your code look and feel like C++ in contrast with having to call C function when interacting with underlying OS. It focuses on features like type safety with enums and bitfields, STL containers and optional exception support.

If you find any bugs or problems, I'd appreciate an issue.

Getting Started

All you need is to include vkfw/vkfw.hpp and you're ready to go. That is to say, you still need to link against glfw. These are just bindings, not a full-fledged library.

Minimum Requirements

VKFW requires a C++11 capable compiler to compile. The following compilers are expected to work:

• Visual Studio >= 2015
• GCC >= 4.8.2
• Clang >= 3.3

Note that there are advantages of going with a more modern compiler: std::string_view, std::span, etc.

Usage

Default API

As these bindings are mainly designed to work with Vulkan, GLFW_CLIENT_API hint is set to GLFW_NO_API by default. So if you require OpenGL support, you need to explicitly set this hint.

namespace vkfw

To avoid name collisions with the GLFW C API the C++ bindings reside in the vkfw namespace. The rules apply to the naming:

• All functions, enums, handles, and structs have the glfw/GLFW prefix removed. In addition to this the first letter of functions is lower case, and the first letter of structs is upper case
  • glfwInit can be accessed as vkfw::init
  • GLFWwindow can be accessed as vkfw::Window
• Enums are mapped to scoped enums to provide compile time type safety. The names have been changed to 'e' + CamelCase with GLFW_ prefix removed.
  • GLFW_KEY_C is now vkfw::Key::eC
  • GLFW_JOYSTICK_2 is now vkfw::Joystick::e2
  • GLFW_ARROW_CURSOR is now vkfw::Cursor::eArrow

Handles

VKFW declares a class for all handles to ensure full type safety and to add support for member functions on handles. A member function has been added to a handle class for each function which accepts the corresoinding handle as first parameter. Instead of glfwSetWindowTitle(&window, title) one can write

• window.setTitle(title) (available only in "enhanced" mode)
• vkfw::setWindowTitle(window, title) (available only if "enhanced" mode is disabled)
• glfwSetWindowTitle(window, title) (yes, really, the compatibility with original GLFW API is not broken. vkfw::Window is implicitly convertible to GLFWwindow *, so you can call a glfw alternative if you choose to, for example, to avoid an unwanted exceptions from a specific function call, etc.)

Return values, Error Codes & Exceptions

By default VKFW has exceptions enabled. This means than VKFW checks both the return value of the function and the error code returned by vkfw::getError() (glfwGetError()). If it indicates a failure a std::runtime_error will be thrown.

If exception handling is disabled (by defining VKFW_HPP_NO_EXCEPTIONS), the type of vkfw::ResultValue<SomeType>::type is a struct holding a vkfw::Result success indicator and the value itself. This struct supports unpacking the return values by using std::tie, alternatively you can just access struct members as you normally would, for example:

auto [result_code, my_brand_new_window] = vkfw::createWindow(...);
// OR
vkfw::Result result_code;
vkfw::Window my_brand_new_window;
std::tie(result_code, my_brand_new_window) = vkfw::createWindow(...);
// OR
auto create_window_output = vkfw::createWindow(...);
auto result_code = create_window_output.result;
auto my_brand_new_window = create_window_output.value;

C++17: [[nodiscard]]

With C++17 and above, some functions are attributed with [[nodiscard]], resulting in a warning if you don't use the return value. You can switch those warnings off by defining VKFW_HPP_NO_NODISCARD_WARNINGS.

UniqueHandle for automatic resource management

VKFW provides a vkfw::UniqueHandle<Type> interface. For each GLFW handle type vkfw::Type there is a unique handle vkfw::UniqueType which will delete the underlying GLFW resource upon destruction, e.g. vkfw::UniqueWindow is the unique handle for vkfw::Window.

For each function which constructs a GLFW handle of type vkfw::Type VKFW provides a second version which returns a vkfw::UniqueType. E.g. for vkfw::createWindow(...) there is vkfw::createWindowUnique(...).

As all the deleters are known at compiler time and don't need to store anything extra - the only downside is a slight compilation time increase.

Callbacks

To allow using lambdas as callbacks, GLFWwindow user pointer is used internally to store std::function objects instead of c-style function pointers. These objects are accessible through vkfw::Window::callbacks() (or accessWindowCallbacks(GLFWwindow *) if enhanced mode is disabled) function and can be set directly, for example:

my_window.callbacks().on_key = [](vkfw::Window const &, vkfw::Key key, int32_t, 
                                  vkfw::KeyAction action, vkfw::ModifierKeyFlags) {
  std::cout << vkfw::to_string(action) << ' ' << vkfw::to_string(key) << ".\n";
};

Supported callbacks:

Name	Type	GLFW Setter
on_window_move	std::function<void(window_type, int, int)>	glfwSetWindowPosCallback
on_window_resize	std::function<void(window_type, size_t, size_t)>	glfwSetWindowSizeCallback
on_window_close	std::function<void(window_type)>	glfwSetWindowCloseCallback
on_window_refresh	std::function<void(window_type)>	glfwSetWindowRefreshCallback
on_window_focus	std::function<void(window_type, bool)>	glfwSetWindowFocusCallback
on_window_iconify	std::function<void(window_type, bool)>	glfwSetWindowIconifyCallback
on_window_maximize	std::function<void(window_type, bool)>	glfwSetWindowMaximizeCallback
on_framebuffer_resize	std::function<void(window_type, size_t, size_t)>	glfwSetFramebufferSizeCallback
on_window_content_scale_change	std::function<void(window_type, float, float)>	glfwSetWindowContentScaleCallback
on_mouse_button	std::function<void(window_type, MouseButton, MouseButtonAction, ModifierKeyFlags)>	glfwSetMouseButtonCallback
on_cursor_move	std::function<void(window_type, double, double)>	glfwSetCursorPosCallback
on_cursor_enter	std::function<void(window_type, bool)>	glfwSetCursorEnterCallback
on_scroll	std::function<void(window_type, double, double)>	glfwSetScrollCallback
on_key	std::function<void(window_type, Key, int32_t, KeyAction, ModifierKeyFlags)>	glfwSetKeyCallback
on_character	std::function<void(window_type, uint32_t)>	glfwSetCharCallback
on_drop	std::function<void(window_type, std::vector<string_type>)>	glfwSetDropCallback

Note that the remaining callbacks are not affected as they have no relation to windows, mainly error callback and connection-disconection callbacks (for monitors, etc)

Hints and Attributes

Hint and attribute values are checked at compile time. For example, glfwSetWindowAttrib(my_window, GLFW_RESIZABLE, GLFW_TRUE) becomes my_window.set<vkfw::Attribute::eResizable>(true) (or vkfw::set<vkfw::Attribute::eResizable>(my_window, true) if enhanced more is disabled). You no longer need to double check whether attribute can even be set: SFINAE garanties that there will be no set overload for, say, vkfw::Attribute::eTransparentFramebuffer. Same with hints, they can be either set in GLFW-style, using vkfw::windowHint<...>(...) (and vkfw::initHint<...>(...)) function template, or by passing a vkfw::WindowHints object to vkfw::createWindow(...) (and a vkfw::InitHints object to vkfw::init(...)). In enhanced mode, the last optional parameter of vkfw::createWindow(..., bool reset_hints = true) decides whether to return currently set hint values to default before applying passed vkfw::WindowHints object.

Configuration Options

VKFW_DISABLE_ENHANCED_MODE

When this is defined before including vkfw.hpp, you essentially disable all enhanced functionality.

All you then get is improved compile time error detection, via scoped enums and bitmasks, as well as a compile time checked attribute/hint getters/setters.

VKFW_NO_EXCEPTIONS

When a vkfw function returns an error value code, an exception is thrown unless this preprocessor definition is defined before including vkfw.hpp.

VKFW_NO_SMART_HANDLE

The UniqueHandle helper class and all the unique handle types and functions returning them are not compiled if this precompiler definition is defined.

VKFW_NO_STD_FUNCTION_CALLBACKS

Disables c++ callbacks based on std::function. Define this if you cannot afford an extra function call per event for extra usability. Note, that original callbacks do not use enum classes and it's your responcibility to cast the values correctly inside the callback itself. Or you can just use original preprocessor definitions.

VKFW_NO_NODISCARD_WARNINGS

With C++17, most vkfw-functions returning something are declared with the [[nodiscard]] attribute. The attribute can be removed by defining this before including vkfw.hpp.

VKFW_NO_INCLUDE_VULKAN and VKFW_INCLUDE_GL

VKFW includes vulkan.h by default (same as GLFW with GLFW_INCLUDE_VULKAN defined) - this preprocessor definition prevents it (resulting in same behavior as GLFW with GLFW_INCLUDE_NONE defined). If you need GLFW to include OpenGL header, you also need to define VKFW_INCLUDE_GL (default GLFW behavior).

VKFW_NO_INCLUDE_VULKAN_HPP

VKFW includes vulkan.hpp by default. This preprocessor definition allows to disable the inclusion. When it is not defined, some of the vulkan.hpp helpers are used (like UniqueHandle), otherwise an alternatives are declared.

VKFW_NO_LEADING_e_IN_ENUMS

Removes leading e from enum values, for example vkfw::Key::eA becomes vkfw::Key::A and vkfw::Key::e1 becomes vkfw::Key::_1.

VKFW_NAMESPACE

By default, the namespace used with vkfw.hpp is vkfw. By defining VKFW_HPP_NAMESPACE before including vkfw.hpp, you can adjust this.

VKFW_NO_STRUCT_CONSTRUCTORS

In order to support designated initializers (c++20 feature) a struct must not have constructors, so this preprocessor definition just removes them outright. For example:

vkfw::WindowHints hints {
    .clientAPI = vkfw::ClientAPI::eOpenGL,
    .contextVersionMajor = 4u,
    .contextVersionMinor = 1u
};

VKFW_NO_SPACESHIP_OPERATOR

If for some reason you prefer not to have a spaceship operator used even if your compiler supports it, you can define this option to fall back on conventional comparison operators.

VKFW_NO_STRING_VIEW

Define this if you prefer char const * to std::string_view even if your compiler supports it.

VKFW_NO_SPAN

Define this if you prefer c style arrays / std::vectors to std::span even if your compiler supports it.

VKFW_INLINE

This preprocessor definition is set to be the compiler-dependent attribute used to mark functions as inline. If your compiler happens to need some different attribute, you can set this define accordingly before including vkfw.hpp.

VKFW_HPP_ASSERT

Define this one if you need an alternative assertion, by default <cassert> is used. Mainly, this allow to introduce your own function with the same interface as assert to be used instead.

VKFW_HPP_ASSERT_ON_RESULT

Allows to replace an assertion call used to check success codes if exceptions are disabled. By default VKFW_HPP_ASSERT is used.

See Also

• Original GLFW C API
• Vulkan-Hpp - similar bindings for Khronos Vulkan API
• VKMA - similar bindings for GPUOpen VulkanMemoryAllocator.