Michael Jolley 6acb793184
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CmdPal: Null pattern matching based on is expression rather than overridable operators (#40972)
What the title says. 😄 

Rather than relying on the potentially overloaded `!=` or `==` operators
when checking for null, now we'll use the `is` expression (possibly
combined with the `not` operator) to ensure correct checking. Probably
overkill for many of these classes, but decided to err on the side of
consistency. Would matter more on classes that may be inherited or
extended.

Using `is` and `is not` will provide us a guarantee that no
user-overloaded equality operators (`==`/`!=`) is invoked when a
`expression is null` is evaluated.

In code form, changed all instances of:

```c#
something != null

something == null
```

to:

```c#
something is not null

something is null
```

The one exception was checking null on a `KeyChord`. `KeyChord` is a
struct which is never null so VS will raise an error when trying this
versus just providing a warning when using `keyChord != null`. In
reality, we shouldn't do this check because it can't ever be null. In
the case of a `KeyChord` it **would** be a `KeyChord` equivalent to:

```c#
KeyChord keyChord = new ()
{
    Modifiers = 0,
    Vkey = 0,
    ScanCode = 0
};
```
2025-08-18 06:07:28 -05:00

179 lines
6.7 KiB
C#

// 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 Microsoft.UI.Xaml;
using Microsoft.UI.Xaml.Controls;
using Microsoft.UI.Xaml.Markup;
using Windows.System;
namespace Microsoft.CmdPal.UI.Controls;
[TemplatePart(Name = KeyPresenter, Type = typeof(ContentPresenter))]
[TemplateVisualState(Name = "Normal", GroupName = "CommonStates")]
[TemplateVisualState(Name = "Disabled", GroupName = "CommonStates")]
[TemplateVisualState(Name = "Default", GroupName = "StateStates")]
[TemplateVisualState(Name = "Error", GroupName = "StateStates")]
public sealed partial class KeyVisual : Control
{
private const string KeyPresenter = "KeyPresenter";
private KeyVisual? _keyVisual;
private ContentPresenter _keyPresenter = new();
public object Content
{
get => GetValue(ContentProperty);
set => SetValue(ContentProperty, value);
}
public static readonly DependencyProperty ContentProperty = DependencyProperty.Register("Content", typeof(object), typeof(KeyVisual), new PropertyMetadata(default(string), OnContentChanged));
public VisualType VisualType
{
get => (VisualType)GetValue(VisualTypeProperty);
set => SetValue(VisualTypeProperty, value);
}
public static readonly DependencyProperty VisualTypeProperty = DependencyProperty.Register("VisualType", typeof(VisualType), typeof(KeyVisual), new PropertyMetadata(default(VisualType), OnSizeChanged));
public bool IsError
{
get => (bool)GetValue(IsErrorProperty);
set => SetValue(IsErrorProperty, value);
}
public static readonly DependencyProperty IsErrorProperty = DependencyProperty.Register("IsError", typeof(bool), typeof(KeyVisual), new PropertyMetadata(false, OnIsErrorChanged));
public KeyVisual()
{
this.DefaultStyleKey = typeof(KeyVisual);
this.Style = GetStyleSize("TextKeyVisualStyle");
}
protected override void OnApplyTemplate()
{
IsEnabledChanged -= KeyVisual_IsEnabledChanged;
_keyVisual = this;
_keyPresenter = (ContentPresenter)_keyVisual.GetTemplateChild(KeyPresenter);
Update();
SetEnabledState();
SetErrorState();
IsEnabledChanged += KeyVisual_IsEnabledChanged;
base.OnApplyTemplate();
}
private static void OnContentChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
{
((KeyVisual)d).Update();
}
private static void OnSizeChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
{
((KeyVisual)d).Update();
}
private static void OnIsErrorChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
{
((KeyVisual)d).SetErrorState();
}
private void Update()
{
if (_keyVisual is null)
{
return;
}
if (_keyVisual.Content is not null)
{
if (_keyVisual.Content.GetType() == typeof(string))
{
_keyVisual.Style = GetStyleSize("TextKeyVisualStyle");
_keyVisual._keyPresenter.Content = _keyVisual.Content;
}
else
{
_keyVisual.Style = GetStyleSize("IconKeyVisualStyle");
switch ((int)_keyVisual.Content)
{
/* We can enable other glyphs in the future
case 13: // The Enter key or button.
_keyVisual._keyPresenter.Content = "\uE751"; break;
case 8: // The Back key or button.
_keyVisual._keyPresenter.Content = "\uE750"; break;
case 16: // The right Shift key or button.
case 160: // The left Shift key or button.
case 161: // The Shift key or button.
_keyVisual._keyPresenter.Content = "\uE752"; break; */
case 38: _keyVisual._keyPresenter.Content = "\uE0E4"; break; // The Up Arrow key or button.
case 40: _keyVisual._keyPresenter.Content = "\uE0E5"; break; // The Down Arrow key or button.
case 37: _keyVisual._keyPresenter.Content = "\uE0E2"; break; // The Left Arrow key or button.
case 39: _keyVisual._keyPresenter.Content = "\uE0E3"; break; // The Right Arrow key or button.
case 91: // The left Windows key
case 92: // The right Windows key
var winIcon = XamlReader.Load(@"<PathIcon xmlns=""http://schemas.microsoft.com/winfx/2006/xaml/presentation"" Data=""M683 1229H0V546h683v683zm819 0H819V546h683v683zm-819 819H0v-683h683v683zm819 0H819v-683h683v683z"" />") as PathIcon;
var winIconContainer = new Viewbox
{
Child = winIcon,
HorizontalAlignment = HorizontalAlignment.Center,
VerticalAlignment = VerticalAlignment.Center,
};
var iconDimensions = GetIconSize();
winIconContainer.Height = iconDimensions;
winIconContainer.Width = iconDimensions;
_keyVisual._keyPresenter.Content = winIconContainer;
break;
default: _keyVisual._keyPresenter.Content = ((VirtualKey)_keyVisual.Content).ToString(); break;
}
}
}
}
public Style GetStyleSize(string styleName)
{
return VisualType == VisualType.Small
? (Style)App.Current.Resources["Small" + styleName]
: VisualType == VisualType.SmallOutline
? (Style)App.Current.Resources["SmallOutline" + styleName]
: VisualType == VisualType.TextOnly
? (Style)App.Current.Resources["Only" + styleName]
: (Style)App.Current.Resources["Default" + styleName];
}
public double GetIconSize()
{
return VisualType == VisualType.Small || VisualType == VisualType.SmallOutline
? (double)App.Current.Resources["SmallIconSize"]
: (double)App.Current.Resources["DefaultIconSize"];
}
private void KeyVisual_IsEnabledChanged(object sender, DependencyPropertyChangedEventArgs e)
{
SetEnabledState();
}
private void SetErrorState()
{
VisualStateManager.GoToState(this, IsError ? "Error" : "Default", true);
}
private void SetEnabledState()
{
VisualStateManager.GoToState(this, IsEnabled ? "Normal" : "Disabled", true);
}
}
public enum VisualType
{
Small,
SmallOutline,
TextOnly,
Large,
}