Update RadialGauge to use KeyboardAccelerators (#4456)

* Update RadialGauge to use KeyboardAccelerators

Replace KeyDown event handling by KeyboardAccelerators. This does not change the behavior. It improves performance by not reacting to just any key stroke. I also removes the call to CoreWindow.GetKeyState - an API that doesn't exist in WinUI 3.

* Update RadialGauge.cs

Fixed StyleCop issues

* Formatted code, fixed remaining regressions

* Update Microsoft.Toolkit.Uwp.UI.Controls.Input/RadialGauge/RadialGauge.cs

Co-authored-by: Nikola Metulev <nmetulev@users.noreply.github.com>
Co-authored-by: Arlo <arlo.godfrey@outlook.com>

Author: 3 people

Microsoft.Toolkit.Uwp.UI.Controls.Input/RadialGauge/RadialGauge.cs

@@ -193,34 +193,10 @@ private void ThemeListener_ThemeChanged(ThemeListener sender)
             OnColorsChanged();
         }
 
-        private void RadialGauge_KeyDown(object sender, KeyRoutedEventArgs e)
-        {
-            double step = SmallChange;
-            var ctrl = Window.Current.CoreWindow.GetKeyState(VirtualKey.Control);
-            if (ctrl.HasFlag(CoreVirtualKeyStates.Down))
-            {
-                step = LargeChange;
-            }
-
-            step = Math.Max(StepSize, step);
-            if ((e.Key == VirtualKey.Left) || (e.Key == VirtualKey.Down))
-            {
-                Value = Math.Max(Minimum, Value - step);
-                e.Handled = true;
-                return;
-            }
-
-            if ((e.Key == VirtualKey.Right) || (e.Key == VirtualKey.Up))
-            {
-                Value = Math.Min(Maximum, Value + step);
-                e.Handled = true;
-            }
-        }
-
         private void RadialGauge_Unloaded(object sender, RoutedEventArgs e)
         {
             // Unregister event handlers.
-            KeyDown -= RadialGauge_KeyDown;
+            KeyboardAccelerators.Clear();
             ThemeListener.ThemeChanged -= ThemeListener_ThemeChanged;
             PointerReleased -= RadialGauge_PointerReleased;
             Unloaded -= RadialGauge_Unloaded;
@@ -439,10 +415,58 @@ protected override void OnApplyTemplate()
             _tickBrush = ReadLocalValue(TickBrushProperty) as SolidColorBrush;
             _foreground = ReadLocalValue(ForegroundProperty) as SolidColorBrush;
 
-            // Register event handlers.
+            // Small step
+            AddKeyboardAccelerator(VirtualKeyModifiers.None, VirtualKey.Left, (_, kaea) =>
+            {
+                Value = Math.Max(Minimum, Value - Math.Max(StepSize, SmallChange));
+                kaea.Handled = true;
+            });
+
+            AddKeyboardAccelerator(VirtualKeyModifiers.None, VirtualKey.Up, (_, kaea) =>
+            {
+                Value = Math.Min(Maximum, Value + Math.Max(StepSize, SmallChange));
+                kaea.Handled = true;
+            });
+
+            AddKeyboardAccelerator(VirtualKeyModifiers.None, VirtualKey.Right, (_, kaea) =>
+            {
+                Value = Math.Min(Maximum, Value + Math.Max(StepSize, SmallChange));
+                kaea.Handled = true;
+            });
+
+            AddKeyboardAccelerator(VirtualKeyModifiers.None, VirtualKey.Down, (_, kaea) =>
+            {
+                Value = Math.Max(Minimum, Value - Math.Max(StepSize, SmallChange));
+                kaea.Handled = true;
+            });
+
+            // Large step
+            AddKeyboardAccelerator(VirtualKeyModifiers.Control, VirtualKey.Left, (_, kaea) =>
+            {
+                Value = Math.Max(Minimum, Value - Math.Max(StepSize, LargeChange));
+                kaea.Handled = true;
+            });
+
+            AddKeyboardAccelerator(VirtualKeyModifiers.Control, VirtualKey.Up, (_, kaea) =>
+            {
+                Value = Math.Min(Maximum, Value + Math.Max(StepSize, LargeChange));
+                kaea.Handled = true;
+            });
+
+            AddKeyboardAccelerator(VirtualKeyModifiers.Control, VirtualKey.Right, (_, kaea) =>
+            {
+                Value = Math.Min(Maximum, Value + Math.Max(StepSize, LargeChange));
+                kaea.Handled = true;
+            });
+
+            AddKeyboardAccelerator(VirtualKeyModifiers.Control, VirtualKey.Down, (_, kaea) =>
+            {
+                Value = Math.Max(Minimum, Value - Math.Max(StepSize, LargeChange));
+                kaea.Handled = true;
+            });
+
             PointerReleased += RadialGauge_PointerReleased;
             ThemeListener.ThemeChanged += ThemeListener_ThemeChanged;
-            KeyDown += RadialGauge_KeyDown;
 
             // Apply color scheme.
             OnColorsChanged();
@@ -830,5 +854,19 @@ private double RoundToMultiple(double number, double multiple)
 
             return number + modulo;
         }
+
+        private void AddKeyboardAccelerator(
+            VirtualKeyModifiers keyModifiers,
+            VirtualKey key,
+            TypedEventHandler<KeyboardAccelerator, KeyboardAcceleratorInvokedEventArgs> handler)
+        {
+            var accelerator = new KeyboardAccelerator()
+            {
+                Modifiers = keyModifiers,
+                Key = key
+            };
+            accelerator.Invoked += handler;
+            KeyboardAccelerators.Add(accelerator);
+        }
     }
 }