SEBWIN-477: Minor refactoring.

SafeExamBrowser.Client/ClientController.cs

@@ -217,24 +217,11 @@ namespace SafeExamBrowser.Client
 			if (Server != null)
 			{
 				Server.LockScreenConfirmed += Server_LockScreenConfirmed;
-				Server.TerminationRequested += Server_TerminationRequested;
 				Server.LockScreenRequested += Server_LockScreenRequested;
+				Server.TerminationRequested += Server_TerminationRequested;
 			}
 		}
 
-		private void Server_LockScreenRequested(string message)
-		{
-			logger.Info("Received lock screen event from SEB Server.");
-			var title = text.Get(TextKey.LockScreen_Title);
-			ShowLockScreen(message, title, Enumerable.Empty<LockScreenOption>());
-		}
-
-		private void Server_LockScreenConfirmed()
-		{
-			logger.Info("Closing lock screen as requested by the server...");
-			lockScreen?.Cancel();
-		}
-
 		private void Taskbar_LoseFocusRequested(bool forward)
 		{
 			Browser.Focus(forward);
@@ -277,8 +264,8 @@ namespace SafeExamBrowser.Client
 			if (Server != null)
 			{
 				Server.LockScreenConfirmed -= Server_LockScreenConfirmed;
-				Server.TerminationRequested -= Server_TerminationRequested;
 				Server.LockScreenRequested -= Server_LockScreenRequested;
+				Server.TerminationRequested -= Server_TerminationRequested;
 			}
 
 			foreach (var activator in context.Activators.OfType<ITerminationActivator>())
@@ -659,6 +646,19 @@ namespace SafeExamBrowser.Client
 			shutdown.Invoke();
 		}
 
+		private void Server_LockScreenConfirmed()
+		{
+			logger.Info("Closing lock screen as requested by the server...");
+			lockScreen?.Cancel();
+		}
+
+		private void Server_LockScreenRequested(string message)
+		{
+			logger.Info("Received lock screen event from SEB Server.");
+			var title = text.Get(TextKey.LockScreen_Title);
+			ShowLockScreen(message, title, Enumerable.Empty<LockScreenOption>());
+		}
+
 		private void Server_TerminationRequested()
 		{
 			logger.Info("Attempting to shutdown as requested by the server...");
@@ -787,11 +787,11 @@ namespace SafeExamBrowser.Client
 		private LockScreenResult ShowLockScreen(string message, string title, IEnumerable<LockScreenOption> options)
 		{
 			var hasQuitPassword = !string.IsNullOrEmpty(Settings.Security.QuitPasswordHash);
-			lockScreen = uiFactory.CreateLockScreen(message, title, options);
 			var result = default(LockScreenResult);
 
 			logger.Info("Showing lock screen...");
 			PauseActivators();
+			lockScreen = uiFactory.CreateLockScreen(message, title, options);
 			lockScreen.Show();
 
 			if (Settings.SessionMode == SessionMode.Server)
@@ -808,11 +808,11 @@ namespace SafeExamBrowser.Client
 			{
 				result = lockScreen.WaitForResult();
 
-				if (result.Canceled) 
+				if (result.Canceled)
 				{
 					logger.Info("The lock screen has been automaticaly canceled.");
 					unlocked = true;
-				} 
+				}
 				else if (hasQuitPassword)
 				{
 					var passwordHash = hashAlgorithm.GenerateHashFor(result.Password);

SafeExamBrowser.Server.Contracts/Events/LockScreenRequestedEventHandler.cs

@@ -1,14 +1,16 @@
-using System;
+/*
-using System.Collections.Generic;
+ * Copyright (c) 2022 ETH Zürich, Educational Development and Technology (LET)
-using System.Linq;
+ * 
-using System.Text;
+ * This Source Code Form is subject to the terms of the Mozilla Public
-using System.Threading.Tasks;
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/.
+ */
 
 namespace SafeExamBrowser.Server.Contracts.Events
 {
 	/// <summary>
-	/// Event handler used to handle a requested lock screen from SEB Server
+	/// Event handler used to indicate that a lock screen instruction has been received.
 	/// </summary>
-	public delegate void LockScreenRequestedEventHandler(String message);
+	public delegate void LockScreenRequestedEventHandler(string message);
-	
+
 }

SafeExamBrowser.Server.Contracts/IServerProxy.cs

@@ -30,7 +30,7 @@ namespace SafeExamBrowser.Server.Contracts
 		event ServerEventHandler LockScreenConfirmed;
 
 		/// <summary>
-		/// Event fired when proxy receives a lock screen instruction.
+		/// Event fired when the proxy receives a lock screen instruction.
 		/// </summary>
 		event LockScreenRequestedEventHandler LockScreenRequested;
 
@@ -47,13 +47,18 @@ namespace SafeExamBrowser.Server.Contracts
 		/// <summary>
 		/// Event fired when the proxy detects an instruction to terminate SEB.
 		/// </summary>
-		event TerminationRequestedEventHandler TerminationRequested; 
+		event TerminationRequestedEventHandler TerminationRequested;
 
 		/// <summary>
 		/// Attempts to initialize a connection with the server.
 		/// </summary>
 		ServerResponse Connect();
 
+		/// <summary>
+		/// Sends a lock screen confirm notification to the server.
+		/// </summary>
+		ServerResponse ConfirmLockScreen();
+
 		/// <summary>
 		/// Terminates a connection with the server.
 		/// </summary>
@@ -62,7 +67,7 @@ namespace SafeExamBrowser.Server.Contracts
 		/// <summary>
 		/// Retrieves a list of all currently available exams, or a list containing the specified exam.
 		/// </summary>
-		ServerResponse<IEnumerable<Exam>> GetAvailableExams(string examId = default(string));
+		ServerResponse<IEnumerable<Exam>> GetAvailableExams(string examId = default);
 
 		/// <summary>
 		/// Retrieves the URI of the configuration file for the given exam.
@@ -84,16 +89,16 @@ namespace SafeExamBrowser.Server.Contracts
 		/// </summary>
 		void Initialize(string api, string connectionToken, string examId, string oauth2Token, ServerSettings settings);
 
+		/// <summary>
+		/// Sends a lock screen notification to the server.
+		/// </summary>
+		ServerResponse LockScreen(string message = default);
+
 		/// <summary>
 		/// Sends a lower hand notification to the server.
 		/// </summary>
 		ServerResponse LowerHand();
 
-		/// <summary>
-		/// Sends a lock screen confirm notification to the server.
-		/// </summary>
-		ServerResponse ConfirmLockScreen();
-
 		/// <summary>
 		/// Sends the given user session identifier of a LMS and thus establishes a connection with the server.
 		/// </summary>
@@ -112,11 +117,6 @@ namespace SafeExamBrowser.Server.Contracts
 		/// <summary>
 		/// Sends a raise hand notification to the server.
 		/// </summary>
-		ServerResponse RaiseHand(string message = default(string));
+		ServerResponse RaiseHand(string message = default);
-
-		/// <summary>
-		/// Sends a lock screen notification to the server.
-		/// </summary>
-		ServerResponse LockScreen(string message = default(string));
 	}
 }

SafeExamBrowser.Server/Data/Attributes.cs

@@ -15,12 +15,11 @@ namespace SafeExamBrowser.Server.Data
 		internal bool AllowChat { get; set; }
 		internal int Id { get; set; }
 		internal ProctoringInstructionEventArgs Instruction { get; set; }
+		internal string Message { get; set; }
 		internal bool ReceiveAudio { get; set; }
 		internal bool ReceiveVideo { get; set; }
 		internal string Type { get; set; }
 
-		internal string Message { get; set; }
-
 		internal Attributes()
 		{
 			Instruction = new ProctoringInstructionEventArgs();

SafeExamBrowser.Server/Data/Instructions.cs

@@ -10,10 +10,10 @@ namespace SafeExamBrowser.Server.Data
 {
 	internal sealed class Instructions
 	{
+		internal const string LOCK_SCREEN = "SEB_FORCE_LOCK_SCREEN";
 		internal const string NOTIFICATION_CONFIRM = "NOTIFICATION_CONFIRM";
 		internal const string PROCTORING = "SEB_PROCTORING";
 		internal const string PROCTORING_RECONFIGURATION = "SEB_RECONFIGURE_SETTINGS";
 		internal const string QUIT = "SEB_QUIT";
-		internal const string LOCK_SCREEN = "SEB_FORCE_LOCK_SCREEN";
 	}
 }

SafeExamBrowser.Server/Parser.cs

@@ -216,6 +216,9 @@ namespace SafeExamBrowser.Server
 
 			switch (instruction)
 			{
+				case Instructions.LOCK_SCREEN:
+					ParseLockScreenInstruction(attributes, attributesJson);
+					break;
 				case Instructions.NOTIFICATION_CONFIRM:
 					ParseNotificationConfirmation(attributes, attributesJson);
 					break;
@@ -225,9 +228,6 @@ namespace SafeExamBrowser.Server
 				case Instructions.PROCTORING_RECONFIGURATION:
 					ParseReconfigurationInstruction(attributes, attributesJson);
 					break;
-				case Instructions.LOCK_SCREEN:
-					ParseLockScreenInstruction(attributes, attributesJson);
-					break;
 			}
 
 			return attributes;

SafeExamBrowser.Server/ServerProxy.cs

@@ -50,15 +50,14 @@ namespace SafeExamBrowser.Server
 
 		private ApiVersion1 api;
 		private string connectionToken;
-		private int currentPowerSupplyValue;
 		private bool connectedToPowergrid;
+		private int currentLockScreenId;
+		private int currentPowerSupplyValue;
+		private int currentRaisHandId;
 		private int currentWlanValue;
 		private string examId;
-		private int notificationId;
-		private int currentRaisHandId;
-		private int currentLockScreenId;
-
 		private HttpClient httpClient;
+		private int notificationId;
 		private string oauth2Token;
 		private int pingNumber;
 		private ServerSettings settings;
@@ -472,12 +471,15 @@ namespace SafeExamBrowser.Server
 					{
 						switch (instruction)
 						{
-							case Instructions.NOTIFICATION_CONFIRM when attributes.Type == "raisehand":
+							case Instructions.LOCK_SCREEN:
-								Task.Run(() => HandConfirmed?.Invoke());
+								Task.Run(() => LockScreenRequested?.Invoke(attributes.Message));
 								break;
 							case Instructions.NOTIFICATION_CONFIRM when attributes.Type == "lockscreen":
 								Task.Run(() => LockScreenConfirmed?.Invoke());
 								break;
+							case Instructions.NOTIFICATION_CONFIRM when attributes.Type == "raisehand":
+								Task.Run(() => HandConfirmed?.Invoke());
+								break;
 							case Instructions.PROCTORING:
 								Task.Run(() => ProctoringInstructionReceived?.Invoke(attributes.Instruction));
 								break;
@@ -487,9 +489,6 @@ namespace SafeExamBrowser.Server
 							case Instructions.QUIT:
 								Task.Run(() => TerminationRequested?.Invoke());
 								break;
-							case Instructions.LOCK_SCREEN:
-								Task.Run(() => LockScreenRequested?.Invoke(attributes.Message));
-								break;
 						}
 
 						if (instructionConfirmation != default)

SafeExamBrowser.UserInterface.Contracts/Windows/Data/LockScreenResult.cs

@@ -15,9 +15,8 @@ namespace SafeExamBrowser.UserInterface.Contracts.Windows.Data
 	/// </summary>
 	public class LockScreenResult
 	{
-
 		/// <summary>
-		/// This is been set if the lock screen was canceled from another process (E.g.: from SEB Server instruction)
+		/// Indicates that the lock screen has been canceled (e.g. via a server instruction).
 		/// </summary>
 		public bool Canceled { get; set; }
 

SafeExamBrowser.UserInterface.Contracts/Windows/ILockScreen.cs

@@ -15,13 +15,14 @@ namespace SafeExamBrowser.UserInterface.Contracts.Windows
 	/// </summary>
 	public interface ILockScreen : IWindow
 	{
+		/// <summary>
+		/// Cancels the <see cref="WaitForResult"/> operation and closes the lock screen.
+		/// </summary>
+		void Cancel();
+
 		/// <summary>
 		/// Waits for the user to provide the required input to unlock the application.
 		/// </summary>
 		LockScreenResult WaitForResult();
-		/// <summary>
-		/// This cancel a waiting thread for LockScreenResult and force the lock screen to close
-		/// </summary>
-		void Cancel();
 	}
 }

SafeExamBrowser.UserInterface.Desktop/Windows/LockScreen.xaml.cs

@@ -27,8 +27,8 @@ namespace SafeExamBrowser.UserInterface.Desktop.Windows
 	{
 		private readonly AutoResetEvent autoResetEvent;
 		private readonly IText text;
-		private bool canceled = false;
 
+		private bool canceled;
 		private IList<Window> windows;
 
 		event WindowClosedEventHandler IWindow.Closed
@@ -57,6 +57,12 @@ namespace SafeExamBrowser.UserInterface.Desktop.Windows
 			Dispatcher.Invoke(Activate);
 		}
 
+		public void Cancel()
+		{
+			canceled = true;
+			autoResetEvent.Set();
+		}
+
 		public new void Close()
 		{
 			Dispatcher.Invoke(CloseAll);
@@ -87,6 +93,7 @@ namespace SafeExamBrowser.UserInterface.Desktop.Windows
 			});
 
 			result.Canceled = canceled;
+
 			return result;
 		}
 
@@ -174,11 +181,5 @@ namespace SafeExamBrowser.UserInterface.Desktop.Windows
 				autoResetEvent.Set();
 			}
 		}
-
-		public void Cancel()
-		{
-			canceled = true;
-			autoResetEvent.Set();
-		}
 	}
 }

SafeExamBrowser.UserInterface.Mobile/Windows/LockScreen.xaml.cs

@@ -27,8 +27,8 @@ namespace SafeExamBrowser.UserInterface.Mobile.Windows
 	{
 		private readonly AutoResetEvent autoResetEvent;
 		private readonly IText text;
-		private bool canceled = false;
 
+		private bool canceled;
 		private IList<Window> windows;
 
 		event WindowClosedEventHandler IWindow.Closed
@@ -57,6 +57,12 @@ namespace SafeExamBrowser.UserInterface.Mobile.Windows
 			Dispatcher.Invoke(Activate);
 		}
 
+		public void Cancel()
+		{
+			canceled = true;
+			autoResetEvent.Set();
+		}
+
 		public new void Close()
 		{
 			Dispatcher.Invoke(CloseAll);
@@ -87,6 +93,7 @@ namespace SafeExamBrowser.UserInterface.Mobile.Windows
 			});
 
 			result.Canceled = canceled;
+
 			return result;
 		}
 
@@ -174,11 +181,5 @@ namespace SafeExamBrowser.UserInterface.Mobile.Windows
 				autoResetEvent.Set();
 			}
 		}
-
-		public void Cancel()
-		{
-			canceled = true;
-			autoResetEvent.Set();
-		}
 	}
 }