From 86e0b45a2fbc990027306871d090f2d849df6ad2 Mon Sep 17 00:00:00 2001
From: Nikita Iryupin <iryupnik@cvut.cz>
Date: Mon, 3 May 2021 16:25:22 +0200
Subject: [PATCH] [FIXED] Previous bug fixed

---
 src/game.js | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/src/game.js b/src/game.js
index 75a10fd..e36b662 100644
--- a/src/game.js
+++ b/src/game.js
@@ -11,17 +11,21 @@ export function init() {
 }
 
 export class Game {
+    _pageIsInView = true;
+
     constructor(width = 416, height = 416, ctx) {
         this.gameField = new GameField(width, height, ctx, canvas);
         this.gameKeyAdapter = new TankKeyAdapter(this.gameField.tank);
+
+        window.addEventListener("blur", () => { this._pageIsInView = false; });
+        window.addEventListener("focus", () => { this._pageIsInView = true; });
     }
 
     start() {
         let prevEv;
         let holding = (ev) => {
             if (!prevEv || prevEv.key != ev.key) return;
-            if (document.visibilityState == "hidden") {
-                alert("I'm hidden");
+            if (!this._pageIsInView) {
                 prevEv = undefined;
                 return;
             }