Refactoring code to use the "visibilitychange" event

Using the "visiblitychange" event instead of relying on a "trick" related to RAF being disabled when a window is not open allows us to have cleaner code.
Bonus: the recursive call to "setTimeout" is gone, so the stacktrace growing indefinitely is gone too.
This should make the application a bit more stable.

front/src/Phaser/Game/GameScene.ts

@@ -183,6 +183,7 @@ export class GameScene extends ResizableScene implements CenterListener {
     private messageSubscription: Subscription|null = null;
     private popUpElements : Map<number, DOMElement> = new Map<number, Phaser.GameObjects.DOMElement>();
     private originalMapUrl: string|undefined;
+    private onVisibilityChangeCallback: () => void;
 
     constructor(private room: Room, MapUrlFile: string, customKey?: string|undefined) {
         super({
@@ -202,6 +203,7 @@ export class GameScene extends ResizableScene implements CenterListener {
         this.connectionAnswerPromise = new Promise<RoomJoinedMessageInterface>((resolve, reject): void => {
             this.connectionAnswerPromiseResolve = resolve;
         })
+        this.onVisibilityChangeCallback = this.onVisibilityChange.bind(this);
     }
 
     //hook preload scene
@@ -499,6 +501,8 @@ export class GameScene extends ResizableScene implements CenterListener {
         if (!this.room.isDisconnected()) {
             this.connect();
         }
+
+        document.addEventListener('visibilitychange', this.onVisibilityChangeCallback);
     }
 
     /**
@@ -620,6 +624,7 @@ export class GameScene extends ResizableScene implements CenterListener {
                         self.chatModeSprite.setVisible(false);
                         self.openChatIcon.setVisible(false);
                         audioManager.restoreVolume();
+                        self.onVisibilityChange();
                     }
                 }
             })
@@ -918,6 +923,8 @@ ${escapedMessage}
         for(const iframeEvents of this.iframeSubscriptionList){
             iframeEvents.unsubscribe();
         }
+
+        document.removeEventListener('visibilitychange', this.onVisibilityChangeCallback);
     }
 
     private removeAllRemotePlayers(): void {
@@ -1510,4 +1517,14 @@ ${escapedMessage}
             });
         }
     }
+
+    private onVisibilityChange(): void {
+        if (document.visibilityState === 'visible') {
+            mediaManager.focusCamera();
+        } else {
+            if (this.simplePeer.getNbConnections() === 0) {
+                mediaManager.blurCamera();
+            }
+        }
+    }
 }

front/src/Phaser/Login/EnableCameraScene.ts

@@ -247,7 +247,6 @@ export class EnableCameraScene extends Phaser.Scene {
 
     update(time: number, delta: number): void {
         this.soundMeterSprite.setVolume(this.soundMeter.getVolume());
-        mediaManager.updateScene();
 
         const middleX = this.getMiddleX();
         this.tweens.add({

front/src/WebRtc/MediaManager.ts

@@ -63,9 +63,6 @@ export class MediaManager {
     private previousConstraint : MediaStreamConstraints;
     private focused : boolean = true;
 
-    private lastUpdateScene : Date = new Date();
-    private setTimeOutlastUpdateScene? : NodeJS.Timeout;
-
     private hasCamera = true;
 
     private triggerCloseJistiFrame : Map<String, Function> = new Map<String, Function>();
@@ -134,8 +131,6 @@ export class MediaManager {
         this.previousConstraint = JSON.parse(JSON.stringify(this.constraintsMedia));
         this.pingCameraStatus();
 
-        this.checkActiveUser(); //todo: desactivated in case of bug
-
         //FIX ME SOUNDMETER: check stalability of sound meter calculation
         /*this.mySoundMeterElement = (HtmlUtils.getElementByIdOrFail('mySoundMeter'));
         this.mySoundMeterElement.childNodes.forEach((value: ChildNode, index) => {
@@ -147,7 +142,6 @@ export class MediaManager {
     }
 
     public updateScene(){
-        this.lastUpdateScene = new Date();
         //FIX ME SOUNDMETER: check stalability of sound meter calculation
         //this.updateSoudMeter();
     }
@@ -785,22 +779,6 @@ export class MediaManager {
         this.userInputManager = userInputManager;
         discussionManager.setUserInputManager(userInputManager);
     }
-    //check if user is active
-    private checkActiveUser(){
-        if(this.setTimeOutlastUpdateScene){
-            clearTimeout(this.setTimeOutlastUpdateScene);
-        }
-        this.setTimeOutlastUpdateScene = setTimeout(() => {
-            const now = new Date();
-            //if last update is more of 10 sec
-            if( (now.getTime() - this.lastUpdateScene.getTime()) > 10000 && this.remoteVideo.size === 0) {
-                this.blurCamera();
-            }else if((now.getTime() - this.lastUpdateScene.getTime()) <= 10000){
-                this.focusCamera();
-            }
-            this.checkActiveUser();
-        }, this.focused ? 10000 : 1000);
-    }
 
     public setShowReportModalCallBacks(callback: ShowReportCallBack){
         this.showReportModalCallBacks.add(callback);