pub unsafe extern "C" fn glfwSetWindowFocusCallback(
window: *mut GLFWwindow,
callback: Option<unsafe extern "C" fn(*mut GLFWwindow, i32)>,
) -> Option<unsafe extern "C" fn(*mut GLFWwindow, i32)>Expand description
@brief Sets the focus callback for the specified window.
This function sets the focus callback of the specified window, which is called when the window gains or loses input focus.
After the focus callback is called for a window that lost input focus, synthetic key and mouse button release events will be generated for all such that had been pressed. For more information, see @ref glfwSetKeyCallback and @ref glfwSetMouseButtonCallback.
@param[in] window The window whose callback to set.
@param[in] callback The new callback, or NULL to remove the currently set
callback.
@return The previously set callback, or NULL if no callback was set or the
library had not been [initialized](@ref intro_init).
@callback_signature @code void function_name(GLFWwindow* window, int focused) @endcode For more information about the callback parameters, see the [function pointer type](@ref GLFWwindowfocusfun).
@errors Possible errors include @ref GLFW_NOT_INITIALIZED.
@thread_safety This function must only be called from the main thread.
@sa @ref window_focus
@since Added in version 3.0.
@ingroup window