LWJGL2 InputProcessor keyTyped() gets stuck after setWindowedMode() & setFullscreenMode()

Issue details

I’m trying to make the game switch from windowed / fullscreen modes by pressing ALT+ENTER. It works fine except after that, keyTyped() method gets fired indefinitely until another key is pressed. Could be because keyUp() never gets called but I don’t need that. (This does not happen on LWJGL3 backend)

Reproduction steps/code

Partial ApplicationListener & InputProcessor:

class TestGame implements ApplicationListener, InputProcessor {
    private static final String TAG = "TestGame";

    @Override
    public void create() {
        Gdx.input.setInputProcessor(this);
    }

    @Override
    public void render() {
        if(Gdx.input.isKeyPressed(com.badlogic.gdx.Input.Keys.ALT_LEFT) &&
                Gdx.input.isKeyPressed(com.badlogic.gdx.Input.Keys.ENTER)) {
            if(Gdx.graphics.isFullscreen()) {
                Gdx.app.log(TAG, "Switching to windowed mode");
                Gdx.graphics.setWindowedMode(Gdx.graphics.getWidth(), Gdx.graphics.getHeight());
            }
            else {
                Gdx.app.log(TAG, "Switching to fullscreen mode");
                Gdx.graphics.setFullscreenMode(Gdx.graphics.getDisplayMode());
            }
        }
    }

    @Override
    public boolean keyDown(int keycode) {
        Gdx.app.log(TAG, "keyDown: " + keycode);
        return false;
    }

    @Override
    public boolean keyUp(int keycode) {
        Gdx.app.log(TAG, "keyUp: " + keycode);
        return false;
    }

    @Override
    public boolean keyTyped(char character) {
        Gdx.app.log(TAG, "keyTyped: " + (int)character);
        return false;
    }
}

LwjglApplicationConfiguration config = new LwjglApplicationConfiguration();
Graphics.DisplayMode display = LwjglApplicationConfiguration.getDesktopDisplayMode();
config.width = display.width;
config.height = display.height;
config.fullscreen = false;
new LwjglApplication(new TestGame(), config);

Version of LibGDX and/or relevant dependencies

1.9.9-SNAPSHOT

Stacktrace

“keyTyped: 13” should not happen repeatedly after switching modes:

[TestGame] keyDown: 57
[TestGame] keyTyped: 0
[TestGame] keyDown: 66
[TestGame] keyTyped: 13
[TestGame] Switching to fullscreen mode
[TestGame] keyTyped: 13
[TestGame] keyTyped: 13
[TestGame] keyTyped: 13
[TestGame] keyTyped: 13
[TestGame] keyTyped: 13
[TestGame] keyTyped: 13
[TestGame] keyTyped: 13
[TestGame] keyTyped: 13
[TestGame] keyTyped: 13
[TestGame] keyTyped: 13
[TestGame] keyTyped: 13
[TestGame] keyTyped: 13
[TestGame] keyTyped: 13
[TestGame] keyTyped: 13
[TestGame] keyTyped: 13
[TestGame] keyTyped: 13
[TestGame] keyTyped: 13
[TestGame] keyDown: 57
[TestGame] keyTyped: 0
[TestGame] keyDown: 66
[TestGame] keyTyped: 13
[TestGame] Switching to windowed mode
[TestGame] keyTyped: 13
[TestGame] keyTyped: 13
[TestGame] keyTyped: 13
[TestGame] keyTyped: 13
[TestGame] keyTyped: 13
[TestGame] keyTyped: 13
[TestGame] keyTyped: 13
[TestGame] keyTyped: 13
[TestGame] keyTyped: 13
[TestGame] keyTyped: 13
[TestGame] keyTyped: 13
[TestGame] keyTyped: 13
[TestGame] keyTyped: 13
[TestGame] keyTyped: 13
[TestGame] keyTyped: 13
[TestGame] keyTyped: 13

Please select the affected platforms

• Android
• iOS (robovm)
• iOS (MOE)
• HTML/GWT
• Windows
• Linux
• MacOS

[code-disaster]

Your input processor doesn’t do anything (besides logging).

Gdx.input.isKeyPressed() is true as long as you hold down those keys. You run this on render(), which means you are trying to toggle fullscreen mode at 60 (or more) frames per second.

A more practical approach is to trigger the toggle on keyDown() or keyUp() in your listener. Since it’s not advised to change modes in callbacks/event handlers, you should use postRunnable() so that the mode switch is done at start of the next render frame.

[someguy233]

You’re right. Moving the mode switch to keyUp() solves the issue. But, there is still no keyUp event for the ALT key. But that’s fine since keyTyped() doesn’t get called for the ALT key anyway.

Thanks!.

        @Override
        public boolean keyUp(int keycode) {
            Gdx.app.log(TAG, "keyUp: " + keycode);
            if(keycode == Input.Keys.ENTER && Gdx.input.isKeyPressed(Input.Keys.ALT_LEFT)) {
                if(Gdx.graphics.isFullscreen()) {
                    Gdx.app.log(TAG, "Switching to windowed mode");
                    Gdx.graphics.setWindowedMode(Gdx.graphics.getWidth(), Gdx.graphics.getHeight());
                }
                else {
                    Gdx.app.log(TAG, "Switching to fullscreen mode");
                    Gdx.graphics.setFullscreenMode(Gdx.graphics.getDisplayMode());
                }
            }
            return false;
        }