Convert to modern null checking now that it works in .NET Native. (#427)

This is mostly a find-and-replace of the == null and != null checks.
This makes the code consistent, modern, and safe from equality overloading errors.
I have not replaced them in the generated code.
I have made the C# generator output the "is not null" pattern.

Author: Simeon

LottieGen/MSBuildTask/LottieGen.cs

@@ -211,7 +211,7 @@ protected override string GenerateCommandLineCommands()
             AddArg(nameof(InputFile), InputFile!);
             AddArg(nameof(Language), Language!);
 
-            if (AdditionalInterface != null)
+            if (AdditionalInterface is not null)
             {
                 foreach (var value in AdditionalInterface)
                 {
@@ -238,7 +238,7 @@ protected override string GenerateCommandLineCommands()
 
             void AddOptional(string parameterName, object? value)
             {
-                if (value != null)
+                if (value is not null)
                 {
                     AddArg(parameterName, value.ToString());
                 }

LottieViewer/App.xaml.cs

@@ -87,11 +87,11 @@ protected override void OnWindowCreated(WindowCreatedEventArgs args)
 #pragma warning restore CS1591 // Missing XML comment for publicly visible type or member
         {
             var titleBar = ApplicationView.GetForCurrentView().TitleBar;
-            if (titleBar != null)
+            if (titleBar is not null)
             {
                 var backgroundColor = (SolidColorBrush)Current.Resources["BackgroundBrush"];
                 var foregroundColor = (SolidColorBrush)Current.Resources["ForegroundBrush"];
-                var inactiveBackgroundColor = (SolidColorBrush)Current.Resources["ToolsBackgroundBrush"];
+
                 titleBar.ButtonBackgroundColor = backgroundColor.Color;
                 titleBar.ButtonForegroundColor = foregroundColor.Color;
                 titleBar.BackgroundColor = backgroundColor.Color;

LottieViewer/MainPage.xaml.cs

@@ -157,9 +157,9 @@ async Task OnPickFileAsync()
                     // Ignore PickSingleFileAsync exceptions so they don't crash the process.
                 }
 
-                if (file == null)
+                if (file is null)
                 {
-                    // Used declined to pick anything.
+                    // User declined to pick anything.
                     return;
                 }
 

LottieViewer/PaletteColorPicker.xaml.cs

@@ -47,15 +47,15 @@ internal LottieVisualDiagnosticsViewModel? DiagnosticsViewModel
                     return;
                 }
 
-                if (_diagnosticsViewModel != null)
+                if (_diagnosticsViewModel is not null)
                 {
                     // Unhook form the previous DiagnosticsViewModel.
                     value.ThemePropertyBindings.CollectionChanged -= Value_CollectionChanged;
                 }
 
                 _diagnosticsViewModel = value;
 
-                if (_diagnosticsViewModel != null)
+                if (_diagnosticsViewModel is not null)
                 {
                     value.ThemePropertyBindings.CollectionChanged += Value_CollectionChanged;
                 }
@@ -182,7 +182,7 @@ void PaletteListBox_DoubleTapped(object sender, DoubleTappedRoutedEventArgs e)
             // the data context.
             static object? GetDataContext(DependencyObject obj)
             {
-                if (obj is FrameworkElement fe && fe.DataContext != null)
+                if (obj is FrameworkElement fe && fe.DataContext is not null)
                 {
                     return fe.DataContext;
                 }

LottieViewer/Scrubber.xaml.cs

@@ -61,14 +61,14 @@ internal LottieVisualDiagnosticsViewModel? DiagnosticsViewModel
             get => _diagnostics;
             set
             {
-                if (_diagnostics != null)
+                if (_diagnostics is not null)
                 {
                     _diagnostics.Markers.CollectionChanged -= Markers_CollectionChanged;
                 }
 
                 _diagnostics = value;
 
-                if (_diagnostics != null)
+                if (_diagnostics is not null)
                 {
                     _diagnostics.Markers.CollectionChanged += Markers_CollectionChanged;
                 }
@@ -201,7 +201,7 @@ protected override Size ArrangeOverride(Size finalSize)
             // Adjust the position of the markers.
             // Set the margin on each of the rectangles in the grid so that they match
             // the offsets of the markers in the view model.
-            if (_diagnostics != null)
+            if (_diagnostics is not null)
             {
                 for (var i = 0; i < _diagnostics.Markers.Count; i++)
                 {
@@ -381,7 +381,7 @@ protected override bool GoToStateCore(
                 var newState = state?.Name;
 
                 // Check whether we have already reported this state.
-                if (newState != null && _previousCommonState != newState)
+                if (newState is not null && _previousCommonState != newState)
                 {
                     _previousCommonState = newState;
                     scrubber.OnSliderVisualStateChange(newState);

LottieViewer/ViewModel/LottieVisualDiagnosticsViewModel.cs

@@ -32,7 +32,7 @@ public object? DiagnosticsObject
                 ThemePropertyBindings.Clear();
                 ThemingPropertySet = null;
 
-                if (LottieVisualDiagnostics != null)
+                if (LottieVisualDiagnostics is not null)
                 {
                     // Populate the issues list.
                     foreach (var issue in LottieVisualDiagnostics.JsonParsingIssues.
@@ -46,7 +46,7 @@ public object? DiagnosticsObject
 
                     // Populate the marker info.
                     var composition = LottieVisualDiagnostics.LottieComposition;
-                    if (composition != null)
+                    if (composition is not null)
                     {
                         var framesPerSecond = composition.FramesPerSecond;
                         var duration = composition.Duration.TotalSeconds;
@@ -81,7 +81,7 @@ public object? DiagnosticsObject
                     }
 
                     ThemingPropertySet = LottieVisualDiagnostics.ThemingPropertySet;
-                    if (LottieVisualDiagnostics.ThemePropertyBindings != null)
+                    if (LottieVisualDiagnostics.ThemePropertyBindings is not null)
                     {
                         foreach (var binding in LottieVisualDiagnostics.ThemePropertyBindings)
                         {
@@ -91,7 +91,7 @@ public object? DiagnosticsObject
                 }
 
                 var propertyChangedCallback = PropertyChanged;
-                if (propertyChangedCallback != null)
+                if (propertyChangedCallback is not null)
                 {
                     propertyChangedCallback(this, new PropertyChangedEventArgs(nameof(DurationText)));
                     propertyChangedCallback(this, new PropertyChangedEventArgs(nameof(FileName)));

samples/LottieSamples/AnimatedVisuals/LottieLogo1_Modified.cs

@@ -86,7 +86,7 @@ public Color BackgroundColor
             set
             {
                 _themeBackgroundColor = value;
-                if (_themeProperties != null)
+                if (_themeProperties is not null)
                 {
                     _themeProperties.InsertVector4("BackgroundColor", ColorAsVector4((Color)_themeBackgroundColor));
                 }
@@ -99,7 +99,7 @@ public Color HighlightColor
             set
             {
                 _themeHighlightColor = value;
-                if (_themeProperties != null)
+                if (_themeProperties is not null)
                 {
                     _themeProperties.InsertVector4("HighlightColor", ColorAsVector4((Color)_themeHighlightColor));
                 }
@@ -112,7 +112,7 @@ public Color TextColor
             set
             {
                 _themeTextColor = value;
-                if (_themeProperties != null)
+                if (_themeProperties is not null)
                 {
                     _themeProperties.InsertVector4("TextColor", ColorAsVector4((Color)_themeTextColor));
                 }

samples/LottieSamples/MainPage.xaml.cs

@@ -59,7 +59,7 @@ private void NavView_Loaded(object sender, RoutedEventArgs e)
 
         private void NavView_ItemInvoked(NavigationView sender, NavigationViewItemInvokedEventArgs args)
         {
-            if (args.InvokedItemContainer != null)
+            if (args.InvokedItemContainer is not null)
             {
                 var navItemTag = args.InvokedItemContainer.Tag.ToString();
                 NavView_Navigate(navItemTag, args.RecommendedNavigationTransitionInfo);
@@ -79,7 +79,7 @@ private void NavView_Navigate(string navItemTag, NavigationTransitionInfo transi
 
         private void On_Navigated(object sender, NavigationEventArgs e)
         {
-            if (ContentFrame.SourcePageType != null)
+            if (ContentFrame.SourcePageType is not null)
             {
                 var item = _pages.FirstOrDefault(p => p.Page == e.SourcePageType);
 

samples/LottieSamples/Scenarios/AsyncPage.xaml.cs

@@ -92,7 +92,7 @@ private async Task PlaySegmentsAsync(Segment? segmentForPlayerA, Segment? segmen
             var tasks = new[] { segmentForPlayerA?.PlayAsync(PlayerA), segmentForPlayerB?.PlayAsync(PlayerB) };
 
             // Wait for the segments to finish.
-            await Task.WhenAll(tasks.Where(t => t != null).ToArray());
+            await Task.WhenAll(tasks.Where(t => t is not null).ToArray());
 
             // Remove the highlight drawn around the playing players.
             UpdatePlayerHighlights(false, false);

source/Animatables/ColorGradientStop.cs

@@ -36,7 +36,7 @@ public override string ToString()
         static string ToHex(double value) => ((byte)(value * 255)).ToString("X2");
 
         public bool Equals(ColorGradientStop? other)
-            => other != null && other.Offset == Offset && other.Color.Equals(Color);
+            => other is not null && other.Offset == Offset && other.Color.Equals(Color);
 
         public override bool Equals(object? obj)
             => Equals(obj as ColorGradientStop);