Handling Ctrl-<key> shortcuts in Unity, respecting user preferences

Question

I am implementing some software with Unity that needs to support Ctrl-<key> shortcuts such as Ctrl-c. I want to do this in a way that respects the user's operating system keyboard preferences; for example, these shortcuts must still be recognized when the user uses sticky keys, or when the user has mapped caps lock as control.

Many of the solutions I found online for implementing keyboard shortcuts look something like this:

if ((Input.GetKey(KeyCode.LeftControl) || Input.GetKey(KeyCode.RightControl)) && Input.GetKeyDown("c")) UnityEngine.MonoBehaviour.print("C-c");

This solution is totally unacceptable to me because it "hard-wires" holding down a control key as the method for sending a control-key modifier, bypassing the operating system's possibly-customized handling of the control key modifier.

Most games don't support keyboard preferences properly, but I am hell-bent on making sure the software I write will do this properly. I'm particularly concerned about supporting sticky keys because this is an accessibility issue - some more complicated shortcuts will not be available to users with disabilities if sticky keys isn't handled correctly.

How can I support keyboard shortcuts properly in Unity?

Answer 1

Good news! This code:

bool ctrl = Input.GetKey(KeyCode.LeftControl) 
         || Input.GetKey(KeyCode.RightControl);

already respects the user's OS settings for sticky keys and key remapping on Windows and macOS at least. And this works whether you specify the key by KeyCode, by a "Conventional Game Input" string, or by a remappable GetButton("Some Custom Name") alias you've defined in the Input Manager.

That's because Unity isn't talking to the keyboard directly; it's asking the OS "Is the left control key pressed?"

The OS, knowing that you've remapped your left shift key to act as the left control, and that you've enabled sticky keys and double-tapped that shift key, is then free to lie to Unity and say "why yes it is!" even if the physical key on your keyboard labelled "CTRL" says otherwise.

Give this a try. Set up a script with some public boolean values that you set in Update based on various key states. Or use them to toggle visibility of some rendered objects. Then enable Sticky keys in your OS, or remap some keys in your registry (and log out / back in to use the updated settings). Run your game, and watch how the values change in reaction to your key presses.

I've just done this in both Windows and macOS, and both sticky keys and registry remapping are correctly respected by Unity, without any changes to my code.

Now of course you can still do one better by allowing players to remap controls within your game, rather than relying on OS-wide/OS-specific settings, but it's good to know that Unity won't disregard those configurations when they're in use on Windows.