SEBWIN-567: Implemented keyboard activator for taskbar.

SafeExamBrowser.Client/CompositionRoot.cs

@@ -303,6 +303,7 @@ namespace SafeExamBrowser.Client
 
 			context.Activators.Add(new ActionCenterKeyboardActivator(ModuleLogger(nameof(ActionCenterKeyboardActivator)), nativeMethods));
 			context.Activators.Add(new ActionCenterTouchActivator(ModuleLogger(nameof(ActionCenterTouchActivator)), nativeMethods));
+			context.Activators.Add(new TaskbarKeyboardActivator(ModuleLogger(nameof(TaskbarKeyboardActivator)), nativeMethods));
 			context.Activators.Add(new TaskviewKeyboardActivator(ModuleLogger(nameof(TaskviewKeyboardActivator)), nativeMethods));
 			context.Activators.Add(new TerminationActivator(ModuleLogger(nameof(TerminationActivator)), nativeMethods));
 

SafeExamBrowser.Client/Operations/ShellOperation.cs

@@ -118,6 +118,12 @@ namespace SafeExamBrowser.Client.Operations
 				{
 					terminationActivator.Start();
 				}
+
+				if (Context.Settings.Taskbar.EnableTaskbar && activator is ITaskbarActivator taskbarActivator)
+				{
+					taskbar.Register(taskbarActivator);
+					taskbarActivator.Start();
+				}
 			}
 		}
 

SafeExamBrowser.UserInterface.Contracts/SafeExamBrowser.UserInterface.Contracts.csproj

@@ -87,6 +87,7 @@
     <Compile Include="Shell\INotificationControl.cs" />
     <Compile Include="Shell\ISystemControl.cs" />
     <Compile Include="Shell\ITaskbar.cs" />
+    <Compile Include="Shell\ITaskbarActivator.cs" />
     <Compile Include="Shell\ITaskview.cs" />
     <Compile Include="Shell\ITaskviewActivator.cs" />
     <Compile Include="Shell\ITerminationActivator.cs" />

SafeExamBrowser.UserInterface.Contracts/Shell/ITaskbar.cs

@@ -57,6 +57,11 @@ namespace SafeExamBrowser.UserInterface.Contracts.Shell
 		/// </summary>
 		void Close();
 
+		/// <summary>
+		/// Puts the focus on the taskbar.
+		/// </summary>
+		void Focus(bool forward = true);
+
 		/// <summary>
 		/// Returns the absolute height of the taskbar (i.e. in physical pixels).
 		/// </summary>
@@ -72,14 +77,14 @@ namespace SafeExamBrowser.UserInterface.Contracts.Shell
 		/// </summary>
 		void InitializeText(IText text);
 
+		/// <summary>
+		/// Registers the specified activator for the taskbar.
+		/// </summary>
+		void Register(ITaskbarActivator activator);
+
 		/// <summary>
 		/// Shows the taskbar.
 		/// </summary>
 		void Show();
-
-		/// <summary>
-		/// Puts the focus on the taskbar.
-		/// </summary>
-		void Focus(bool forward = true);
 	}
 }

SafeExamBrowser.UserInterface.Contracts/Shell/ITaskbarActivator.cs

@@ -0,0 +1,23 @@
+/*
+ * 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/.
+ */
+
+using SafeExamBrowser.UserInterface.Contracts.Shell.Events;
+
+namespace SafeExamBrowser.UserInterface.Contracts.Shell
+{
+	/// <summary>
+	/// A module which can be used to activate the <see cref="ITaskbar"/>.
+	/// </summary>
+	public interface ITaskbarActivator : IActivator
+	{
+		/// <summary>
+		/// Fired when the taskbar should be activated (i.e. put into focus).
+		/// </summary>
+		event ActivatorEventHandler Activated;
+	}
+}

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

@@ -79,11 +79,11 @@ namespace SafeExamBrowser.UserInterface.Desktop.Windows
 
 		internal BrowserWindow(IBrowserControl browserControl, BrowserSettings settings, bool isMainWindow, IText text, ILogger logger)
 		{
+			this.browserControl = browserControl;
 			this.isMainWindow = isMainWindow;
+			this.logger = logger;
 			this.settings = settings;
 			this.text = text;
-			this.logger = logger;
-			this.browserControl = browserControl;
 
 			InitializeComponent();
 			InitializeBrowserWindow(browserControl);
@@ -214,12 +214,15 @@ namespace SafeExamBrowser.UserInterface.Desktop.Windows
 			if (e.Key == Key.Tab)
 			{
 				var hasShift = (Keyboard.Modifiers & ModifierKeys.Shift) == ModifierKeys.Shift;
+
 				if (Toolbar.IsKeyboardFocusWithin && hasShift)
 				{
 					var firstActiveElementInToolbar = Toolbar.PredictFocus(FocusNavigationDirection.Right);
-					if (firstActiveElementInToolbar is System.Windows.UIElement)
+
+					if (firstActiveElementInToolbar is UIElement)
 					{
-						var control = firstActiveElementInToolbar as System.Windows.UIElement;
+						var control = firstActiveElementInToolbar as UIElement;
+
 						if (control.IsKeyboardFocusWithin)
 						{
 							this.LoseFocusRequested?.Invoke(false);
@@ -257,6 +260,7 @@ namespace SafeExamBrowser.UserInterface.Desktop.Windows
 			{
 				var hasCtrl = (Keyboard.Modifiers & ModifierKeys.Control) == ModifierKeys.Control;
 				var hasShift = (Keyboard.Modifiers & ModifierKeys.Shift) == ModifierKeys.Shift;
+
 				if (BrowserControlHost.IsFocused && hasCtrl)
 				{
 					if (Findbar.Visibility == Visibility.Hidden || hasShift)
@@ -273,6 +277,7 @@ namespace SafeExamBrowser.UserInterface.Desktop.Windows
 					var focusedElement = FocusManager.GetFocusedElement(this);
 					var focusedControl = focusedElement as System.Windows.Controls.Control;
 					var prevFocusedControl = tabKeyDownFocusElement as System.Windows.Controls.Control;
+
 					if (focusedControl != null && prevFocusedControl != null)
 					{
 						//var commonAncestor = focusedControl.FindCommonVisualAncestor(prevFocusedControl);
@@ -452,14 +457,14 @@ namespace SafeExamBrowser.UserInterface.Desktop.Windows
 			var javascript = @"
 if (typeof __SEB_focusElement === 'undefined') {
   __SEB_focusElement = function (forward) {
-    var items = [].map
+	var items = [].map
-      .call(document.body.querySelectorAll(['input', 'select', 'a[href]', 'textarea', 'button', '[tabindex]']), function(el, i) { return { el, i } })
+	  .call(document.body.querySelectorAll(['input', 'select', 'a[href]', 'textarea', 'button', '[tabindex]']), function(el, i) { return { el, i } })
-      .filter(function(e) { return e.el.tabIndex >= 0 && !e.el.disabled && e.el.offsetParent; })
+	  .filter(function(e) { return e.el.tabIndex >= 0 && !e.el.disabled && e.el.offsetParent; })
-      .sort(function(a,b) { return a.el.tabIndex === b.el.tabIndex ? a.i - b.i : (a.el.tabIndex || 9E9) - (b.el.tabIndex || 9E9); })
+	  .sort(function(a,b) { return a.el.tabIndex === b.el.tabIndex ? a.i - b.i : (a.el.tabIndex || 9E9) - (b.el.tabIndex || 9E9); })
-    var item = items[forward ? 1 : items.length - 1];
+	var item = items[forward ? 1 : items.length - 1];
-    if (item && item.focus && typeof item.focus !== 'function')
+	if (item && item.focus && typeof item.focus !== 'function')
-        throw ('item.focus is not a function, ' + typeof item.focus)
+		throw ('item.focus is not a function, ' + typeof item.focus)
-    setTimeout(function () { item && item.focus && item.focus(); }, 20);
+	setTimeout(function () { item && item.focus && item.focus(); }, 20);
   }
 }";
 			this.browserControl.ExecuteJavascript(javascript, result =>
@@ -593,7 +598,7 @@ if (typeof __SEB_focusElement === 'undefined') {
 
 		public void FocusToolbar(bool forward)
 		{
-			this.Dispatcher.BeginInvoke((Action)(async () =>
+			this.Dispatcher.BeginInvoke((Action) (async () =>
 			{
 				this.Activate();
 				await Task.Delay(50);
@@ -613,7 +618,7 @@ if (typeof __SEB_focusElement === 'undefined') {
 
 		public void FocusBrowser()
 		{
-			this.Dispatcher.BeginInvoke((Action)(async () =>
+			this.Dispatcher.BeginInvoke((Action) (async () =>
 			{
 				this.FocusToolbar(false);
 				await Task.Delay(100);
@@ -630,7 +635,7 @@ if (typeof __SEB_focusElement === 'undefined') {
 
 		public void FocusAddressBar()
 		{
-			this.Dispatcher.BeginInvoke((Action)(async () =>
+			this.Dispatcher.BeginInvoke((Action) (() =>
 			{
 				this.UrlTextBox.Focus();
 			}));

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

@@ -20,8 +20,9 @@ namespace SafeExamBrowser.UserInterface.Desktop.Windows
 {
 	internal partial class Taskbar : Window, ITaskbar
 	{
+		private readonly ILogger logger;
+
 		private bool allowClose;
-		private ILogger logger;
 		private bool isQuitButtonFocusedAtKeyDown;
 		private bool isFirstChildFocusedAtKeyDown;
 
@@ -82,6 +83,23 @@ namespace SafeExamBrowser.UserInterface.Desktop.Windows
 			Dispatcher.Invoke(base.Close);
 		}
 
+		public void Focus(bool forward)
+		{
+			Dispatcher.BeginInvoke((Action) (() =>
+			{
+				Activate();
+
+				if (forward)
+				{
+					SetFocusWithin(ApplicationStackPanel.Children[0]);
+				}
+				else
+				{
+					QuitButton.Focus();
+				}
+			}));
+		}
+
 		public int GetAbsoluteHeight()
 		{
 			return Dispatcher.Invoke(() =>
@@ -121,6 +139,13 @@ namespace SafeExamBrowser.UserInterface.Desktop.Windows
 			});
 		}
 
+		private void InitializeTaskbar()
+		{
+			Closing += Taskbar_Closing;
+			Loaded += (o, args) => InitializeBounds();
+			QuitButton.Clicked += QuitButton_Clicked;
+		}
+
 		public void InitializeText(IText text)
 		{
 			Dispatcher.Invoke(() =>
@@ -131,11 +156,21 @@ namespace SafeExamBrowser.UserInterface.Desktop.Windows
 			});
 		}
 
+		public void Register(ITaskbarActivator activator)
+		{
+			activator.Activated += Activator_Activated;
+		}
+
 		public new void Show()
 		{
 			Dispatcher.Invoke(base.Show);
 		}
 
+		private void Activator_Activated()
+		{
+			(this as ITaskbar).Focus(true);
+		}
+
 		private void QuitButton_Clicked(CancelEventArgs args)
 		{
 			QuitButtonClicked?.Invoke(args);
@@ -160,17 +195,10 @@ namespace SafeExamBrowser.UserInterface.Desktop.Windows
 			}
 		}
 
-		private void InitializeTaskbar()
-		{
-			Closing += Taskbar_Closing;
-			Loaded += (o, args) => InitializeBounds();
-			QuitButton.Clicked += QuitButton_Clicked;
-		}
-
 		private void Window_KeyDown(object sender, System.Windows.Input.KeyEventArgs e)
 		{
-			this.isQuitButtonFocusedAtKeyDown = this.QuitButton.IsKeyboardFocusWithin;
+			isQuitButtonFocusedAtKeyDown = QuitButton.IsKeyboardFocusWithin;
-			this.isFirstChildFocusedAtKeyDown = this.ApplicationStackPanel.Children[0].IsKeyboardFocusWithin;
+			isFirstChildFocusedAtKeyDown = ApplicationStackPanel.Children[0].IsKeyboardFocusWithin;
 		}
 
 		private void Window_KeyUp(object sender, System.Windows.Input.KeyEventArgs e)
@@ -178,36 +206,20 @@ namespace SafeExamBrowser.UserInterface.Desktop.Windows
 			if (e.Key == System.Windows.Input.Key.Tab)
 			{
 				var shift = System.Windows.Input.Keyboard.IsKeyDown(System.Windows.Input.Key.LeftShift);
-				if (!shift && this.ApplicationStackPanel.Children[0].IsKeyboardFocusWithin && this.isQuitButtonFocusedAtKeyDown)
+				if (!shift && ApplicationStackPanel.Children[0].IsKeyboardFocusWithin && isQuitButtonFocusedAtKeyDown)
 				{
-					this.LoseFocusRequested?.Invoke(true);
+					LoseFocusRequested?.Invoke(true);
 					e.Handled = true;
 				}
-				else if (shift && this.QuitButton.IsKeyboardFocusWithin && this.isFirstChildFocusedAtKeyDown)
+				else if (shift && QuitButton.IsKeyboardFocusWithin && isFirstChildFocusedAtKeyDown)
 				{
-					this.LoseFocusRequested?.Invoke(false);
+					LoseFocusRequested?.Invoke(false);
 					e.Handled = true;
 				}
 			}
 
-			this.isQuitButtonFocusedAtKeyDown = false;
+			isQuitButtonFocusedAtKeyDown = false;
-			this.isFirstChildFocusedAtKeyDown = false;
+			isFirstChildFocusedAtKeyDown = false;
-		}
-
-		void ITaskbar.Focus(bool forward)
-		{
-			this.Dispatcher.BeginInvoke((Action)(() =>
-			{
-				base.Activate();
-				if (forward)
-				{
-					this.SetFocusWithin(this.ApplicationStackPanel.Children[0]);
-				}
-				else
-				{
-					this.QuitButton.Focus();
-				}
-			}));
 		}
 
 		private bool SetFocusWithin(UIElement uIElement)
@@ -215,15 +227,17 @@ namespace SafeExamBrowser.UserInterface.Desktop.Windows
 			if (uIElement.Focusable)
 			{
 				uIElement.Focus();
+
 				return true;
 			}
 
 			if (uIElement is System.Windows.Controls.Panel)
 			{
 				var panel = uIElement as System.Windows.Controls.Panel;
+
 				for (var i = 0; i < panel.Children.Count; i++)
 				{
-					if (this.SetFocusWithin(panel.Children[i]))
+					if (SetFocusWithin(panel.Children[i]))
 					{
 						return true;
 					}
@@ -235,9 +249,10 @@ namespace SafeExamBrowser.UserInterface.Desktop.Windows
 			{
 				var control = uIElement as System.Windows.Controls.ContentControl;
 				var content = control.Content as UIElement;
+
 				if (content != null)
 				{
-					return this.SetFocusWithin(content);
+					return SetFocusWithin(content);
 				}
 			}
 

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

@@ -33,12 +33,12 @@ namespace SafeExamBrowser.UserInterface.Mobile.Windows
 	internal partial class BrowserWindow : Window, IBrowserWindow
 	{
 		private readonly bool isMainWindow;
+		private readonly ILogger logger;
 		private readonly BrowserSettings settings;
 		private readonly IText text;
 
 		private WindowClosedEventHandler closed;
 		private WindowClosingEventHandler closing;
-		private ILogger logger;
 
 		private WindowSettings WindowSettings
 		{
@@ -54,7 +54,7 @@ namespace SafeExamBrowser.UserInterface.Mobile.Windows
 		public event ActionRequestedEventHandler DeveloperConsoleRequested;
 		public event FindRequestedEventHandler FindRequested;
 		public event ActionRequestedEventHandler ForwardNavigationRequested;
-		public event LoseFocusRequestedEventHandler LoseFocusRequested;
+		public event LoseFocusRequestedEventHandler LoseFocusRequested { add { } remove { } }
 		public event ActionRequestedEventHandler HomeNavigationRequested;
 		public event ActionRequestedEventHandler ReloadRequested;
 		public event ActionRequestedEventHandler ZoomInRequested;
@@ -76,9 +76,9 @@ namespace SafeExamBrowser.UserInterface.Mobile.Windows
 		internal BrowserWindow(IBrowserControl browserControl, BrowserSettings settings, bool isMainWindow, IText text, ILogger logger)
 		{
 			this.isMainWindow = isMainWindow;
+			this.logger = logger;
 			this.settings = settings;
 			this.text = text;
-			this.logger = logger;
 
 			InitializeComponent();
 			InitializeBrowserWindow(browserControl);

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

@@ -19,8 +19,8 @@ namespace SafeExamBrowser.UserInterface.Mobile.Windows
 {
 	internal partial class Taskbar : Window, ITaskbar
 	{
+		private readonly ILogger logger;
 		private bool allowClose;
-		private ILogger logger;
 
 		public bool ShowClock
 		{
@@ -32,7 +32,7 @@ namespace SafeExamBrowser.UserInterface.Mobile.Windows
 			set { Dispatcher.Invoke(() => QuitButton.Visibility = value ? Visibility.Visible : Visibility.Collapsed); }
 		}
 
-		public event LoseFocusRequestedEventHandler LoseFocusRequested;
+		public event LoseFocusRequestedEventHandler LoseFocusRequested { add { } remove { } }
 		public event QuitButtonClickedEventHandler QuitButtonClicked;
 
 		internal Taskbar(ILogger logger)
@@ -79,6 +79,20 @@ namespace SafeExamBrowser.UserInterface.Mobile.Windows
 			Dispatcher.Invoke(base.Close);
 		}
 
+		public void Focus(bool fromTop)
+		{
+			Activate();
+
+			if (fromTop)
+			{
+				ApplicationStackPanel.Children[0].Focus();
+			}
+			else
+			{
+				QuitButton.Focus();
+			}
+		}
+
 		public int GetAbsoluteHeight()
 		{
 			return Dispatcher.Invoke(() =>
@@ -118,6 +132,13 @@ namespace SafeExamBrowser.UserInterface.Mobile.Windows
 			});
 		}
 
+		private void InitializeTaskbar()
+		{
+			Closing += Taskbar_Closing;
+			Loaded += (o, args) => InitializeBounds();
+			QuitButton.Clicked += QuitButton_Clicked;
+		}
+
 		public void InitializeText(IText text)
 		{
 			Dispatcher.Invoke(() =>
@@ -126,11 +147,21 @@ namespace SafeExamBrowser.UserInterface.Mobile.Windows
 			});
 		}
 
+		public void Register(ITaskbarActivator activator)
+		{
+			activator.Activated += Activator_Activated;
+		}
+
 		public new void Show()
 		{
 			Dispatcher.Invoke(base.Show);
 		}
 
+		private void Activator_Activated()
+		{
+			(this as ITaskbar).Focus(true);
+		}
+
 		private void QuitButton_Clicked(CancelEventArgs args)
 		{
 			QuitButtonClicked?.Invoke(args);
@@ -154,25 +185,5 @@ namespace SafeExamBrowser.UserInterface.Mobile.Windows
 				e.Cancel = true;
 			}
 		}
-
-		private void InitializeTaskbar()
-		{
-			Closing += Taskbar_Closing;
-			Loaded += (o, args) => InitializeBounds();
-			QuitButton.Clicked += QuitButton_Clicked;
-		}
-
-		void ITaskbar.Focus(bool fromTop)
-		{
-			base.Activate();
-			if (fromTop)
-			{
-				this.ApplicationStackPanel.Children[0].Focus();
-			}
-			else
-			{
-				this.QuitButton.Focus();
-			}
-		}
 	}
 }

SafeExamBrowser.UserInterface.Shared/Activators/TaskbarKeyboardActivator.cs

@@ -0,0 +1,52 @@
+/*
+ * 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/.
+ */
+
+using System.Windows.Input;
+using SafeExamBrowser.Logging.Contracts;
+using SafeExamBrowser.UserInterface.Contracts.Shell;
+using SafeExamBrowser.UserInterface.Contracts.Shell.Events;
+using SafeExamBrowser.WindowsApi.Contracts;
+using SafeExamBrowser.WindowsApi.Contracts.Events;
+
+namespace SafeExamBrowser.UserInterface.Shared.Activators
+{
+	public class TaskbarKeyboardActivator : KeyboardActivator, ITaskbarActivator
+	{
+		private readonly ILogger logger;
+		private bool leftWindows;
+
+		public event ActivatorEventHandler Activated;
+
+		public TaskbarKeyboardActivator(ILogger logger, INativeMethods nativeMethods) : base(nativeMethods)
+		{
+			this.logger = logger;
+		}
+
+		protected override bool Process(Key key, KeyModifier modifier, KeyState state)
+		{
+			var changed = false;
+			var pressed = state == KeyState.Pressed;
+
+			if (key == Key.LWin)
+			{
+				changed = leftWindows != pressed;
+				leftWindows = pressed;
+			}
+
+			if (leftWindows && changed)
+			{
+				logger.Debug("Detected activation sequence for taskbar.");
+				Activated?.Invoke();
+
+				return true;
+			}
+
+			return false;
+		}
+	}
+}

SafeExamBrowser.UserInterface.Shared/SafeExamBrowser.UserInterface.Shared.csproj

@@ -66,6 +66,7 @@
     <Compile Include="Activators\ActionCenterKeyboardActivator.cs" />
     <Compile Include="Activators\ActionCenterTouchActivator.cs" />
     <Compile Include="Activators\KeyboardActivator.cs" />
+    <Compile Include="Activators\TaskbarKeyboardActivator.cs" />
     <Compile Include="Activators\TaskviewKeyboardActivator.cs" />
     <Compile Include="Activators\TerminationActivator.cs" />
     <Compile Include="Activators\TouchActivator.cs" />