In libgdx, how do I get input from the back button?

Question

For my game, I'd like the Android back button to take you to the pause menu, instead of minimizing the game. From what I've googled, I know I need to call

Gdx.input.setCatchBackKey(true);

But how do I actually check for the button press? input.isKeyDown(Keys.BACK) doesn't seem to do anything.

score 78 · Accepted Answer · answered Aug 30 '11 at 09:37

78

I solved the problem like this:

public class MyApplication implements ApplicationListener, InputProcessor {
   // !! Remember to override all other required methods !!
   ...

   @Override
   public void create() {
        Gdx.input.setInputProcessor(this);
        Gdx.input.setCatchBackKey(true);
        // rest of your stuff...
   }

   ...

   @Override
   public boolean keyDown(int keycode) {
        if(keycode == Keys.BACK){
           // Do your optional back button handling (show pause menu?)
        }
        return false;
   }

   ...
}

Not copypasta stuff but hopefully this helps you out. :)

answered Aug 30 '11 at 09:37

raaste

796
6
4

1

I would rather do this in my Screen class, which would give me finer control – Anuj Feb 16 '12 at 04:06
2

In case you want to handle it in Screens, http://gamedev.stackexchange.com/questions/114972/handling-back-button-in-android-without-implementing-inputprocessor/114985#114985 – kingAm Jan 16 '16 at 20:27
3

2022 use: Gdx.input.setCatchKey(Input.Keys.BACK, true) – Владислав Шестернин Jan 13 '22 at 12:47

score 31 · Answer 2 · answered Feb 20 '12 at 06:58

31

You can use Gdx.input.isKeyPressed method.

if (Gdx.input.isKeyPressed(Keys.BACK)){
  // Do something
}

answered Feb 20 '12 at 06:58

ilhami

411
4
5

This is life savior. It's strange why InputProcessor is getting event for back "button" when that class is used for detecting keyboard - for desktop devices. It would be more logical to get this event in GestureListener class. Not to mention that you can set only one InputProcessor. – MilanG Oct 12 '14 at 15:30
2

@MilanG you can set multiple inputprocessors using a multiplexer, see example here http://stackoverflow.com/a/20048019/22194 – codeulike Oct 13 '15 at 14:48
In case you want to handle it in Screens, http://gamedev.stackexchange.com/questions/114972/handling-back-button-in-android-without-implementing-inputprocessor/114985#114985 – kingAm Jan 16 '16 at 20:27
Make sure you use `isKeyJustPressed`, not `isKeyPressed`. Just trying it out on my Android, it would sometimes register twice with the latter, which is probably not desirable. – Keenan Thompson Jun 10 '18 at 06:33

score 21 · Answer 3 · answered Nov 18 '13 at 12:38

First create an InputProcessor to handle the back key actions and then add it to a multiplexer so that other components still receive similar events.

      InputProcessor backProcessor = new InputAdapter() {
            @Override
            public boolean keyDown(int keycode) {

                if ((keycode == Keys.ESCAPE) || (keycode == Keys.BACK) )

                // Maybe perform other operations before exiting
                Gdx.app.exit();
                return false;
            }
        };


        InputMultiplexer multiplexer = new InputMultiplexer(mStage,
                backProcessor);
        Gdx.input.setInputProcessor(multiplexer);

And enable catching the back key.

Gdx.input.setCatchBackKey(true);

That's all there is. Good luck!

score 2 · Answer 4 · answered Jul 17 '13 at 10:26

2

You can use Gdx.input.isKeyPressed(Keys.BACK) but if you want that Activity does not closes you can handle this as:

Gdx.input.setCatchBackKey(true);

answered Jul 17 '13 at 10:26

Muhammad Aamir Ali

20,419
10
66
57

In libgdx, how do I get input from the back button?

4 Answers4

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