Proof-of-concept desktop keyboard navigation

SafeExamBrowser.Browser.Contracts/Events/LoseFocusRequestedEventHandler.cs

@@ -0,0 +1,15 @@
+/*
+ * Copyright (c) 2022 ETH Zürich, Educational Development and Technology (LET)
+ * 
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * 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.Browser.Contracts.Events
+{
+	/// <summary>
+	/// Event handler used to indicate that the user wants to move the focus away from the item.
+	/// </summary>
+	public delegate void LoseFocusRequestedEventHandler(bool forward);
+}

SafeExamBrowser.Browser.Contracts/Events/TabPressedEventHandler.cs

@@ -0,0 +1,15 @@
+/*
+ * Copyright (c) 2022 ETH Zürich, Educational Development and Technology (LET)
+ * 
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * 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.Browser.Contracts.Events
+{
+	/// <summary>
+	/// Event handler used to indicate that the user pressed the tab key to move the focus forward or backward.
+	/// </summary>
+	public delegate void TabPressedEventHandler(bool forward);
+}

SafeExamBrowser.Browser.Contracts/IBrowserApplication.cs

@@ -6,6 +6,7 @@
  * file, You can obtain one at http://mozilla.org/MPL/2.0/.
  */
 
+using System;
 using SafeExamBrowser.Applications.Contracts;
 using SafeExamBrowser.Browser.Contracts.Events;
 
@@ -30,5 +31,16 @@ public interface IBrowserApplication : IApplication
 		/// Event fired when the browser application detects a request to terminate SEB.
 		/// </summary>
 		event TerminationRequestedEventHandler TerminationRequested;
+
+		/// <summary>
+		/// Event fired when the user tries to focus the taskbar.
+		/// </summary>
+		event LoseFocusRequestedEventHandler LoseFocusRequested;
+
+		/// <summary>
+		/// Transfers the focus to the browser window.
+		/// <paramref name="forward">If true, the first focusable element in the browser window receives focus (passing forward of focus). Otherwise, the last element.</paramref>
+		/// </summary>
+		void Focus(bool forward);
 	}
 }

SafeExamBrowser.Browser.Contracts/SafeExamBrowser.Browser.Contracts.csproj

@@ -57,6 +57,8 @@
     <Compile Include="Events\DownloadEventArgs.cs" />
     <Compile Include="Events\DownloadFinishedCallback.cs" />
     <Compile Include="Events\DownloadRequestedEventHandler.cs" />
+    <Compile Include="Events\TabPressedEventHandler.cs" />
+    <Compile Include="Events\LoseFocusRequestedEventHandler.cs" />
     <Compile Include="Events\SessionIdentifierDetectedEventHandler.cs" />
     <Compile Include="Events\TerminationRequestedEventHandler.cs" />
     <Compile Include="Filters\IRequestFilter.cs" />

SafeExamBrowser.Browser/BrowserApplication.cs

@@ -58,6 +58,7 @@ public class BrowserApplication : IBrowserApplication
 
 		public event DownloadRequestedEventHandler ConfigurationDownloadRequested;
 		public event SessionIdentifierDetectedEventHandler SessionIdentifierDetected;
+		public event LoseFocusRequestedEventHandler LoseFocusRequested;
 		public event TerminationRequestedEventHandler TerminationRequested;
 		public event WindowsChangedEventHandler WindowsChanged;
 
@@ -195,6 +196,7 @@ private void CreateNewWindow(PopupRequestedEventArgs args = default)
 			window.ResetRequested += Window_ResetRequested;
 			window.SessionIdentifierDetected += (i) => SessionIdentifierDetected?.Invoke(i);
 			window.TerminationRequested += () => TerminationRequested?.Invoke();
+			window.LoseFocusRequested += (forward) => LoseFocusRequested?.Invoke(forward);
 
 			window.InitializeControl();
 			windows.Add(window);
@@ -457,5 +459,13 @@ private void Window_ResetRequested()
 			CreateNewWindow();
 			logger.Info("Successfully reset browser.");
 		}
+
+		public void Focus(bool forward)
+		{
+			windows.ForEach(window =>
+			{
+				window.Focus(forward);
+			});
+		}
 	}
 }

SafeExamBrowser.Browser/BrowserControl.cs

@@ -15,6 +15,7 @@
 using SafeExamBrowser.Configuration.Contracts.Cryptography;
 using SafeExamBrowser.I18n.Contracts;
 using SafeExamBrowser.UserInterface.Contracts.Browser;
+using SafeExamBrowser.UserInterface.Contracts.Browser.Data;
 using SafeExamBrowser.UserInterface.Contracts.Browser.Events;
 
 namespace SafeExamBrowser.Browser
@@ -143,5 +144,19 @@ public void Zoom(double level)
 		{
 			control.BrowserCore.SetZoomLevel(level);
 		}
+
+		/// <summary>
+		/// Executes the given Javascript code in the browser.
+		/// </summary>
+		public async void ExecuteJavascript(string javascript, Action<JavascriptResult> callback)
+		{
+			var result = await this.control.EvaluateScriptAsync(javascript);
+			callback(new JavascriptResult()
+			{
+				Message = result.Message,
+				Result = result.Result,
+				Success = result.Success
+			});
+		}
 	}
 }

SafeExamBrowser.Browser/BrowserWindow.cs

@@ -80,6 +80,7 @@ private WindowSettings WindowSettings
 		internal event PopupRequestedEventHandler PopupRequested;
 		internal event ResetRequestedEventHandler ResetRequested;
 		internal event SessionIdentifierDetectedEventHandler SessionIdentifierDetected;
+		internal event LoseFocusRequestedEventHandler LoseFocusRequested;
 		internal event TerminationRequestedEventHandler TerminationRequested;
 
 		public event IconChangedEventHandler IconChanged;
@@ -162,6 +163,8 @@ internal void InitializeControl()
 			keyboardHandler.ZoomInRequested += ZoomInRequested;
 			keyboardHandler.ZoomOutRequested += ZoomOutRequested;
 			keyboardHandler.ZoomResetRequested += ZoomResetRequested;
+			keyboardHandler.TabPressed += TabPressed;
+			keyboardHandler.FocusAddressBarRequested += FocusAddressBarRequested;
 			resourceHandler.SessionIdentifierDetected += (id) => SessionIdentifierDetected?.Invoke(id);
 			requestHandler.QuitUrlVisited += RequestHandler_QuitUrlVisited;
 			requestHandler.RequestBlocked += RequestHandler_RequestBlocked;
@@ -189,7 +192,7 @@ internal void InitializeControl()
 
 		internal void InitializeWindow()
 		{
-			window = uiFactory.CreateBrowserWindow(Control, settings, isMainWindow);
+			window = uiFactory.CreateBrowserWindow(Control, settings, isMainWindow, this.logger);
 			window.AddressChanged += Window_AddressChanged;
 			window.BackwardNavigationRequested += Window_BackwardNavigationRequested;
 			window.Closed += Window_Closed;
@@ -198,6 +201,7 @@ internal void InitializeWindow()
 			window.FindRequested += Window_FindRequested;
 			window.ForwardNavigationRequested += Window_ForwardNavigationRequested;
 			window.HomeNavigationRequested += HomeNavigationRequested;
+			window.LoseFocusRequested += Window_LoseFocusRequested;
 			window.ReloadRequested += ReloadRequested;
 			window.ZoomInRequested += ZoomInRequested;
 			window.ZoomOutRequested += ZoomOutRequested;
@@ -454,6 +458,11 @@ private void KeyboardHandler_FindRequested()
 			}
 		}
 
+		private void FocusAddressBarRequested()
+		{
+			window.FocusAddressBar();
+		}
+
 		private ChromiumHostControl LifeSpanHandler_CreatePopup()
 		{
 			var args = new PopupRequestedEventArgs();
@@ -655,6 +664,11 @@ private void Window_ForwardNavigationRequested()
 			Control.NavigateForwards();
 		}
 
+		private void Window_LoseFocusRequested(bool forward)
+		{
+			LoseFocusRequested?.Invoke(forward);
+		}
+
 		private void ZoomInRequested()
 		{
 			if (settings.AllowPageZoom && CalculateZoomPercentage() < 300)
@@ -688,6 +702,43 @@ private void ZoomResetRequested()
 			}
 		}
 
+		private void TabPressed(bool shiftPressed)
+		{
+			this.Control.ExecuteJavascript("document.activeElement.tagName", result =>
+			{
+				var tagName = result.Result as string;
+				if (tagName != null)
+				{
+					if (tagName.ToUpper() == "BODY")
+					{
+						// this means the user is now at the start of the focus / tabIndex chain in the website
+						if (shiftPressed)
+						{
+							window.FocusToolbar(!shiftPressed);
+						}
+						else
+						{
+							this.LoseFocusRequested?.Invoke(true);
+						}
+					}
+				}
+			});
+		}
+
+		internal void Focus(bool forward)
+		{
+			if (forward)
+			{
+				window.FocusToolbar(forward);
+			}
+			else
+			{
+				window.FocusBrowser();
+
+				this.Activate();
+			}
+		}
+
 		private double CalculateZoomPercentage()
 		{
 			return (zoomLevel * 25.0) + 100.0;

SafeExamBrowser.Browser/Handlers/KeyboardHandler.cs

@@ -8,6 +8,7 @@
 
 using System.Windows.Forms;
 using CefSharp;
+using SafeExamBrowser.Browser.Contracts.Events;
 using SafeExamBrowser.UserInterface.Contracts;
 
 namespace SafeExamBrowser.Browser.Handlers
@@ -20,6 +21,10 @@ internal class KeyboardHandler : IKeyboardHandler
 		internal event ActionRequestedEventHandler ZoomInRequested;
 		internal event ActionRequestedEventHandler ZoomOutRequested;
 		internal event ActionRequestedEventHandler ZoomResetRequested;
+		internal event ActionRequestedEventHandler FocusAddressBarRequested;
+		internal event TabPressedEventHandler TabPressed;
+
+		private int? currentKeyDown = null;
 
 		public bool OnKeyEvent(IWebBrowser browserControl, IBrowser browser, KeyType type, int keyCode, int nativeKeyCode, CefEventFlags modifiers, bool isSystemKey)
 		{
@@ -38,6 +43,11 @@ public bool OnKeyEvent(IWebBrowser browserControl, IBrowser browser, KeyType typ
 					HomeNavigationRequested?.Invoke();
 				}
 
+				if (ctrl && keyCode == (int) Keys.L)
+				{
+					FocusAddressBarRequested?.Invoke();
+				}
+
 				if ((ctrl && keyCode == (int) Keys.Add) || (ctrl && keyCode == (int) Keys.Oemplus) || (ctrl && shift && keyCode == (int) Keys.D1))
 				{
 					ZoomInRequested?.Invoke();
@@ -52,8 +62,14 @@ public bool OnKeyEvent(IWebBrowser browserControl, IBrowser browser, KeyType typ
 				{
 					ZoomResetRequested?.Invoke();
 				}
+
+				if (keyCode == (int)Keys.Tab && keyCode == currentKeyDown)
+				{
+					TabPressed?.Invoke(shift);
+				}
 			}
 
+			currentKeyDown = null;
 			return false;
 		}
 
@@ -66,6 +82,11 @@ public bool OnPreKeyEvent(IWebBrowser browserControl, IBrowser browser, KeyType
 				return true;
 			}
 
+			if (type == KeyType.RawKeyDown || type == KeyType.KeyDown)
+			{
+				currentKeyDown = keyCode;
+			}
+
 			return false;
 		}
 	}

SafeExamBrowser.Client/ClientController.cs

@@ -188,6 +188,7 @@ private void RegisterEvents()
 			Browser.ConfigurationDownloadRequested += Browser_ConfigurationDownloadRequested;
 			Browser.SessionIdentifierDetected += Browser_SessionIdentifierDetected;
 			Browser.TerminationRequested += Browser_TerminationRequested;
+			Browser.LoseFocusRequested += Browser_LoseFocusRequested;
 			ClientHost.ExamSelectionRequested += ClientHost_ExamSelectionRequested;
 			ClientHost.MessageBoxRequested += ClientHost_MessageBoxRequested;
 			ClientHost.PasswordRequested += ClientHost_PasswordRequested;
@@ -198,6 +199,7 @@ private void RegisterEvents()
 			displayMonitor.DisplayChanged += DisplayMonitor_DisplaySettingsChanged;
 			runtime.ConnectionLost += Runtime_ConnectionLost;
 			systemMonitor.SessionSwitched += SystemMonitor_SessionSwitched;
+			taskbar.LoseFocusRequested += Taskbar_LoseFocusRequested;
 			taskbar.QuitButtonClicked += Shell_QuitButtonClicked;
 
 			foreach (var activator in context.Activators.OfType<ITerminationActivator>())
@@ -211,6 +213,16 @@ private void RegisterEvents()
 			}
 		}
 
+		private void Taskbar_LoseFocusRequested(bool forward)
+		{
+			this.Browser.Focus(forward);
+		}
+
+		private void Browser_LoseFocusRequested(bool forward)
+		{
+			this.taskbar.Focus(forward);
+		}
+
 		private void DeregisterEvents()
 		{
 			actionCenter.QuitButtonClicked -= Shell_QuitButtonClicked;
@@ -226,6 +238,7 @@ private void DeregisterEvents()
 				Browser.ConfigurationDownloadRequested -= Browser_ConfigurationDownloadRequested;
 				Browser.SessionIdentifierDetected -= Browser_SessionIdentifierDetected;
 				Browser.TerminationRequested -= Browser_TerminationRequested;
+				Browser.LoseFocusRequested -= Browser_LoseFocusRequested;
 			}
 
 			if (ClientHost != null)

SafeExamBrowser.I18n.Contracts/TextKey.cs

@@ -24,12 +24,19 @@ public enum TextKey
 		Browser_LoadErrorTitle,
 		Browser_Name,
 		Browser_Tooltip,
+		BrowserWindow_BackwardButton,
 		BrowserWindow_DeveloperConsoleMenuItem,
 		BrowserWindow_Downloading,
 		BrowserWindow_DownloadCancelled,
 		BrowserWindow_DownloadComplete,
+		BrowserWindow_DownloadsButton,
 		BrowserWindow_FindCaseSensitive,
 		BrowserWindow_FindMenuItem,
+		BrowserWindow_ForwardButton,
+		BrowserWindow_HomeButton,
+		BrowserWindow_MenuButton,
+		BrowserWindow_ReloadButton,
+		BrowserWindow_UrlTextBox,
 		BrowserWindow_ZoomMenuItem,
 		Build,
 		ExamSelectionDialog_Cancel,

SafeExamBrowser.I18n/Data/de.xml

@@ -48,6 +48,27 @@
     <Entry key="BrowserWindow_FindMenuItem">
         Seite durchsuchen...
     </Entry>
+    <Entry key="BrowserWindow_ReloadButton">
+        Neu laden
+    </Entry>
+    <Entry key="BrowserWindow_BackwardButton">
+        Rückwärts
+    </Entry>
+    <Entry key="BrowserWindow_ForwardButton">
+        Vorwärts
+    </Entry>
+    <Entry key="BrowserWindow_DownloadsButton">
+        Download
+    </Entry>
+    <Entry key="BrowserWindow_HomeButton">
+        Home
+    </Entry>
+    <Entry key="BrowserWindow_MenuButton">
+        Menü
+    </Entry>
+    <Entry key="BrowserWindow_UrlTextBox">
+        URL eingeben
+    </Entry>
     <Entry key="BrowserWindow_ZoomMenuItem">
         Seiten-Zoom
     </Entry>