Pointing to a function that is a class member - glfw setKeycallback

Question

I\'m writing a glfw app, in which I\'ve wrapped the function callse into a simple class. Im having trouble setting the key callback. My class is defined as:

Answer 1

I had the same problem and after reading this thread I came up with a similar solution. I think it is a bit cleaner this way. It's based on static function but it is nested inside the class where we set all things.

Header looks like this:

class Application
    {
    public:
        ...
    private:
        ...
        void MousePositionCallback(GLFWwindow* window, double positionX, double positionY);
        void KeyboardCallback(GLFWwindow* window, int key, int scancode, int action, int mods);
        ...
        class GLFWCallbackWrapper
        {
        public:
            GLFWCallbackWrapper() = delete;
            GLFWCallbackWrapper(const GLFWCallbackWrapper&) = delete;
            GLFWCallbackWrapper(GLFWCallbackWrapper&&) = delete;
            ~GLFWCallbackWrapper() = delete;

            static void MousePositionCallback(GLFWwindow* window, double positionX, double positionY);
            static void KeyboardCallback(GLFWwindow* window, int key, int scancode, int action, int mods);
            static void SetApplication(Application *application);
        private:
            static Application* s_application;
        };
    };

And the source code:

void Application::GLFWCallbackWrapper::MousePositionCallback(GLFWwindow* window, double positionX, double positionY)
{
    s_application->MousePositionCallback(window, positionX, positionY);
}

void Application::GLFWCallbackWrapper::KeyboardCallback(GLFWwindow* window, int key, int scancode, int action, int mods)
{
    s_application->KeyboardCallback(window, key, scancode, action, mods);
}

void Application::GLFWCallbackWrapper::SetApplication(Application* application)
{
    GLFWCallbackWrapper::s_application = application;
}

Application* Application::GLFWCallbackWrapper::s_application = nullptr;

void Application::MousePositionCallback(GLFWwindow* window, double positionX, double positionY)
{
    ...
}

void Application::KeyboardCallback(GLFWwindow* window, int key, int scancode, int action, int mods)
{
    ...
}

void Application::SetCallbackFunctions()
{
    GLFWCallbackWrapper::SetApplication(this);
    glfwSetCursorPosCallback(m_window, GLFWCallbackWrapper::MousePositionCallback);
    glfwSetKeyCallback(m_window, GLFWCallbackWrapper::KeyboardCallback);
}