gdjs.RuntimeGamePixiRenderer.prototype.isFullScreen does not detect users pressing escape

[jonasfj]

gdjs.RuntimeGamePixiRenderer.prototype.isFullScreen does not detect that users press escape and leave fullscreen mode.

This is easy to see from source for RuntimeGamePixiRenderer.

To Reproduce

• Create an object that is show/hide depending on "The game is in fullscreen" condition.
• Enter fullscreen mode
• Exit fullscreen mode using escape (or back button on Android)
• Now the "The game is in fullscreen" condition is still true, while the user is not in fullscreen anymore.

Classic application for this is a fullscreen button, which is only visible when not in fullscreen mode

Solution

• Listen for the fullscreenchange event, which will work after PR #2161
• Listen for events webkitfullscreenchange, mozfullscreenchange
• In the event handler use document.fullscreenElement != null to test if we're fullscreen mode and do:

  // In RuntimeGamePixiRenderer do:
  this._isFullscreen = false;
  this._resizeCanvas();
  this._notifySceneForResize = true;

Other details

• Chrome 87.0.4280.88 / Linux / GDevelop 5.0.0-beta104

[jonasfj]

For anyone looking to work around this issue the following code-snippet should do:

// This ensures that we restore state when user exits fullscreen using escape
if (!window._gdjsFullScreenPatch) {
    window._gdjsFullScreenPatch = true;
    const game = runtimeScene.getGame();
    document.addEventListener('fullscreenchange', () => {
        game.getRenderer().setFullScreen(document.fullscreenElement != null);
    });
    document.addEventListener('webkitfullscreenchange', () => {
        game.getRenderer().setFullScreen(document.fullscreenElement != null);
    });
    document.addEventListener('mozfullscreenchange', () => {
        game.getRenderer().setFullScreen(document.fullscreenElement != null);
    });
}

Running it once in the beginning of an initial scene should be sufficient.

(this is not something I would suggest as an official patch, just a quick hack to workaround the issue)