[ColorPicker][Accessibility] adding feature control ColorPicker with keyboard (#32371)

* [ColorPicker] Accessibility: adding feature move ColorPicker with arrow keys

* Removing shortcut for Esc, catching Esc, Enter and Space with low level keyboard hook.
Starting and disposing the hook only when ColorPicker is active.

* Remove code which allows disposing the keyboard hook only once

src/modules/colorPicker/ColorPickerUI/Helpers/AppStateHandler.cs

@@ -9,8 +9,8 @@ using System.Windows.Interop;
 using ColorPicker.Settings;
 using ColorPicker.ViewModelContracts;
 using Common.UI;
-using ManagedCommon;
 using Microsoft.PowerToys.Settings.UI.Library.Enumerations;
+using static ColorPicker.Helpers.NativeMethodsHelper;
 
 namespace ColorPicker.Helpers
 {
@@ -43,6 +43,12 @@ namespace ColorPicker.Helpers
 
         public event EventHandler AppClosed;
 
+        public event EventHandler EnterPressed;
+
+        public event EventHandler UserSessionStarted;
+
+        public event EventHandler UserSessionEnded;
+
         public void StartUserSession()
         {
             EndUserSession(); // Ends current user session if there's an active one.
@@ -62,10 +68,9 @@ namespace ColorPicker.Helpers
                     ShowColorPicker();
                 }
 
-                // Handle the escape key to close Color Picker locally when being spawn from PowerToys, since Keyboard Hooks from the KeyboardMonitor are heavy.
                 if (!(System.Windows.Application.Current as ColorPickerUI.App).IsRunningDetachedFromPowerToys())
                 {
-                    SetupEscapeGlobalKeyShortcut();
+                    UserSessionStarted?.Invoke(this, EventArgs.Empty);
                 }
             }
         }
@@ -85,10 +90,9 @@ namespace ColorPicker.Helpers
                         HideColorPicker();
                     }
 
-                    // Handle the escape key to close Color Picker locally when being spawn from PowerToys, since Keyboard Hooks from the KeyboardMonitor are heavy.
                     if (!(System.Windows.Application.Current as ColorPickerUI.App).IsRunningDetachedFromPowerToys())
                     {
-                        ClearEscapeGlobalKeyShortcut();
+                        UserSessionEnded?.Invoke(this, EventArgs.Empty);
                     }
 
                     SessionEventHelper.End();
@@ -213,62 +217,36 @@ namespace ColorPicker.Helpers
             _hwndSource = hwndSource;
         }
 
-        public IntPtr ProcessWindowMessages(IntPtr hwnd, int msg, IntPtr wparam, IntPtr lparam, ref bool handled)
+        public bool HandleEnterPressed()
         {
-            switch (msg)
+            if (!IsColorPickerVisible())
+            {
+                return false;
+            }
+
+            EnterPressed?.Invoke(this, EventArgs.Empty);
+            return true;
+        }
+
+        public bool HandleEscPressed()
         {
-                case NativeMethods.WM_HOTKEY:
             if (!BlockEscapeKeyClosingColorPickerEditor)
             {
-                        handled = EndUserSession();
+                return EndUserSession();
             }
             else
             {
-                        // If escape key is blocked it means a submenu is open.
-                        // Send the escape key to the Window to close that submenu.
-                        // Description for LPARAM in https://learn.microsoft.com/windows/win32/inputdev/wm-keyup#parameters
-                        // It's basically some modifiers + scancode for escape (1) + number of repetitions (1)
-                        handled = true;
-                        handled &= NativeMethods.PostMessage(_hwndSource.Handle, NativeMethods.WM_KEYDOWN, (IntPtr)NativeMethods.VK_ESCAPE, (IntPtr)0x00010001);
-
-                        // Need to make the value unchecked as a workaround for changes introduced in .NET 7
-                        // https://github.com/dotnet/roslyn/blob/main/docs/compilers/CSharp/Compiler%20Breaking%20Changes%20-%20DotNet%207.md#checked-operators-on-systemintptr-and-systemuintptr
-                        handled &= NativeMethods.PostMessage(_hwndSource.Handle, NativeMethods.WM_KEYUP, (IntPtr)NativeMethods.VK_ESCAPE, unchecked((IntPtr)0xC0010001));
+                return false;
+            }
         }
 
-                    break;
-            }
-
-            return IntPtr.Zero;
-        }
-
-        public void SetupEscapeGlobalKeyShortcut()
+        internal void MoveCursor(int xOffset, int yOffset)
         {
-            if (_hwndSource == null)
-            {
-                return;
-            }
-
-            _hwndSource.AddHook(ProcessWindowMessages);
-            if (!NativeMethods.RegisterHotKey(_hwndSource.Handle, _globalHotKeyId, NativeMethods.MOD_NOREPEAT, NativeMethods.VK_ESCAPE))
-            {
-                Logger.LogWarning("Couldn't register the hotkey for Esc.");
-            }
-        }
-
-        public void ClearEscapeGlobalKeyShortcut()
-        {
-            if (_hwndSource == null)
-            {
-                return;
-            }
-
-            if (!NativeMethods.UnregisterHotKey(_hwndSource.Handle, _globalHotKeyId))
-            {
-                Logger.LogWarning("Couldn't unregister the hotkey for Esc.");
-            }
-
-            _hwndSource.RemoveHook(ProcessWindowMessages);
+            POINT lpPoint;
+            GetCursorPos(out lpPoint);
+            lpPoint.X += xOffset;
+            lpPoint.Y += yOffset;
+            SetCursorPos(lpPoint.X, lpPoint.Y);
         }
     }
 }

src/modules/colorPicker/ColorPickerUI/Helpers/NativeMethodsHelper.cs

@@ -0,0 +1,34 @@
+// Copyright (c) Microsoft Corporation
+// The Microsoft Corporation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for more information.
+
+using System.Runtime.InteropServices;
+using System.Windows;
+
+namespace ColorPicker.Helpers
+{
+    internal class NativeMethodsHelper
+    {
+        /// <summary>
+        /// Struct representing a point.
+        /// </summary>
+        [StructLayout(LayoutKind.Sequential)]
+        public struct POINT
+        {
+            public int X;
+            public int Y;
+
+            public static implicit operator Point(POINT point)
+            {
+                return new Point(point.X, point.Y);
+            }
+        }
+
+        [DllImport("user32")]
+        [return: MarshalAs(UnmanagedType.Bool)]
+        internal static extern bool SetCursorPos(int x, int y);
+
+        [DllImport("user32.dll")]
+        internal static extern bool GetCursorPos(out POINT lpPoint);
+    }
+}

src/modules/colorPicker/ColorPickerUI/Keyboard/KeyboardMonitor.cs

@@ -22,8 +22,9 @@ namespace ColorPicker.Keyboard
 
         private List<string> _activationKeys = new List<string>();
         private GlobalKeyboardHook _keyboardHook;
-        private bool disposedValue;
         private bool _activationShortcutPressed;
+        private int keyboardMoveSpeed;
+        private Key lastArrowKeyPressed = Key.None;
 
         [ImportingConstructor]
         public KeyboardMonitor(AppStateHandler appStateHandler, IUserSettings userSettings)
@@ -80,6 +81,39 @@ namespace ColorPicker.Keyboard
                 }
             }
 
+            if ((virtualCode == KeyInterop.VirtualKeyFromKey(Key.Space) || virtualCode == KeyInterop.VirtualKeyFromKey(Key.Enter)) && (e.KeyboardState == GlobalKeyboardHook.KeyboardState.KeyDown))
+            {
+                e.Handled = _appStateHandler.HandleEnterPressed();
+                return;
+            }
+
+            if (virtualCode == KeyInterop.VirtualKeyFromKey(Key.Back) && e.KeyboardState == GlobalKeyboardHook.KeyboardState.KeyDown)
+            {
+                e.Handled = _appStateHandler.HandleEscPressed();
+                return;
+            }
+
+            if (CheckMoveNeeded(virtualCode, Key.Up, e, 0, -1))
+            {
+                e.Handled = true;
+                return;
+            }
+            else if (CheckMoveNeeded(virtualCode, Key.Down, e, 0, 1))
+            {
+                e.Handled = true;
+                return;
+            }
+            else if (CheckMoveNeeded(virtualCode, Key.Left, e, -1, 0))
+            {
+                e.Handled = true;
+                return;
+            }
+            else if (CheckMoveNeeded(virtualCode, Key.Right, e, 1, 0))
+            {
+                e.Handled = true;
+                return;
+            }
+
             var name = Helper.GetKeyName((uint)virtualCode);
 
             // If the last key pressed is a modifier key, then currentlyPressedKeys cannot possibly match with _activationKeys
@@ -115,6 +149,35 @@ namespace ColorPicker.Keyboard
             }
         }
 
+        private bool CheckMoveNeeded(int virtualCode, Key key, GlobalKeyboardHookEventArgs e, int xMove, int yMove)
+        {
+            if (virtualCode == KeyInterop.VirtualKeyFromKey(key))
+            {
+                if (e.KeyboardState == GlobalKeyboardHook.KeyboardState.KeyDown && _appStateHandler.IsColorPickerVisible())
+                {
+                    if (lastArrowKeyPressed == key)
+                    {
+                        keyboardMoveSpeed++;
+                    }
+                    else
+                    {
+                        keyboardMoveSpeed = 1;
+                    }
+
+                    lastArrowKeyPressed = key;
+                    _appStateHandler.MoveCursor(keyboardMoveSpeed * xMove, keyboardMoveSpeed * yMove);
+                    return true;
+                }
+                else if (e.KeyboardState == GlobalKeyboardHook.KeyboardState.KeyUp)
+                {
+                    lastArrowKeyPressed = Key.None;
+                    keyboardMoveSpeed = 0;
+                }
+            }
+
+            return false;
+        }
+
         private static bool ArraysAreSame(List<string> first, List<string> second)
         {
             if (first.Count != second.Count || (first.Count == 0 && second.Count == 0))
@@ -157,18 +220,10 @@ namespace ColorPicker.Keyboard
         }
 
         protected virtual void Dispose(bool disposing)
-        {
-            if (!disposedValue)
-            {
-                if (disposing)
         {
             _keyboardHook?.Dispose();
         }
 
-                disposedValue = true;
-            }
-        }
-
         public void Dispose()
         {
             // Do not change this code. Put cleanup code in 'Dispose(bool disposing)' method

src/modules/colorPicker/ColorPickerUI/ViewModels/MainViewModel.cs

@@ -25,6 +25,7 @@ namespace ColorPicker.ViewModels
         private readonly ZoomWindowHelper _zoomWindowHelper;
         private readonly AppStateHandler _appStateHandler;
         private readonly IUserSettings _userSettings;
+        private KeyboardMonitor _keyboardMonitor;
 
         /// <summary>
         /// Backing field for <see cref="OtherColor"/>
@@ -53,6 +54,7 @@ namespace ColorPicker.ViewModels
             _zoomWindowHelper = zoomWindowHelper;
             _appStateHandler = appStateHandler;
             _userSettings = userSettings;
+            _keyboardMonitor = keyboardMonitor;
 
             NativeEventWaiter.WaitForEventLoop(
                 Constants.ShowColorPickerSharedEvent(),
@@ -77,16 +79,36 @@ namespace ColorPicker.ViewModels
 
             _userSettings.ShowColorName.PropertyChanged += (s, e) => { OnPropertyChanged(nameof(ShowColorName)); };
 
+            _appStateHandler.EnterPressed += AppStateHandler_EnterPressed;
+            _appStateHandler.UserSessionStarted += AppStateHandler_UserSessionStarted;
+            _appStateHandler.UserSessionEnded += AppStateHandler_UserSessionEnded;
+
             // Only start a local keyboard low level hook if running as a standalone.
             // Otherwise, the global keyboard hook from runner will be used to activate Color Picker through ShowColorPickerSharedEvent
-            // and the Escape key will be registered as a shortcut by appStateHandler when ColorPicker is being used.
-            // This is much lighter than using a local low level keyboard hook.
+            // The appStateHandler starts and disposes a low level hook when ColorPicker is being used.
+            // The hook catches the Esc, Space, Enter and Arrow key presses.
+            // This is much lighter than using a permanent local low level keyboard hook.
             if ((System.Windows.Application.Current as ColorPickerUI.App).IsRunningDetachedFromPowerToys())
             {
                 keyboardMonitor?.Start();
             }
         }
 
+        private void AppStateHandler_UserSessionEnded(object sender, EventArgs e)
+        {
+            _keyboardMonitor.Dispose();
+        }
+
+        private void AppStateHandler_UserSessionStarted(object sender, EventArgs e)
+        {
+            _keyboardMonitor?.Start();
+        }
+
+        private void AppStateHandler_EnterPressed(object sender, EventArgs e)
+        {
+            MouseInfoProvider_OnMouseDown(null, default(System.Drawing.Point));
+        }
+
         /// <summary>
         /// Gets the current selected color as a <see cref="Brush"/>
         /// </summary>