glfwGetKeyName() returns null

Question

I'm currently working on the input system of a game engine in java, and I use GLFW for the window. I set up a callback system to catch when a key is pressed:

GLFW.glfwSetKeyCallback(window, (windowId, key, scancode, action, mods) -> {
    if (action == GLFW.GLFW_PRESS) {
        System.out.println(GLFW.glfwGetKeyName(key, scancode));
    }
});

And the problem is when I press space or enter or shift plus a different key it prints out null. My question is: how to use the mods attribute to capitalize the next key when I press shift or print out a new line when I press enter etc.

Answer 1

I don't know the solution for the first question, but the second one is easy.

Try using char callback. This one is different from key callback, as it only works with unicode characters being typed by user (letters are capitalized with Shift, CapsLock button also works). Also, if you want to detect modifier buttons being pressed while user types, try using charMods callback. Seems like the latter is marked for removal, so you can test whether the modifier button is pressed with glfwGetKey().

EDIT: Seems like I didn't understood you on the first one. glfwGetKeyName() is not designed to be used as text input method. Also note that it can display names for a limited range of buttons. What is more, when you press multiple keys, press event for each one is called in separate key callback event. You can't handle multiple key presses at once. (Modifier keys are put in mods argument of callback, but I can't tell by now whether they also trigger a key press event or not - check it yourself)