Add RelayCommand to CheckBoxViewModel

Add RelayCommand to CheckBoxViewModel to enable/disable checkboxes in
option preview control depending on the state of other controls. The
StyleViewModel now makes use of this for Use Var feature.

src/Features/CSharp/Portable/CodeStyle/CSharpCodeStyleOptions.cs

@@ -17,8 +17,8 @@ internal static class CSharpCodeStyleOptions
         public static readonly Option<bool> UseVarWhenDeclaringLocals = new Option<bool>(FeatureName, "UseVarWhenDeclaringLocals", defaultValue: true);
 
         public static readonly Option<TypeInferencePreferenceOptions> UseImplicitTypingForLocals = new Option<TypeInferencePreferenceOptions>(FeatureName, "UseImplicitTypingForLocals", defaultValue: TypeInferencePreferenceOptions.ExplicitTyping);
-        public static readonly Option<bool> UseVarWhenTypeIsApparent = new Option<bool>(FeatureName, "UseImplicitTypingWhereApparent", defaultValue: true);
-        public static readonly Option<bool> DoNotUseVarForIntrinsicTypes = new Option<bool>(FeatureName, "NoImplicitTypingForIntrinsics", defaultValue: true);
+        public static readonly Option<bool> UseVarWhenTypeIsApparent = new Option<bool>(FeatureName, "UseImplicitTypingWhereApparent", defaultValue: false);
+        public static readonly Option<bool> DoNotUseVarForIntrinsicTypes = new Option<bool>(FeatureName, "NoImplicitTypingForIntrinsics", defaultValue: false);
     }
 
     public enum TypeInferencePreferenceOptions

src/VisualStudio/CSharp/Impl/Options/Formatting/StyleViewModel.cs

 // Copyright (c) Microsoft.  All Rights Reserved.  Licensed under the Apache License, Version 2.0.  See License.txt in the project root for license information.
 
 using System;
+using System.Collections.Generic;
 using Microsoft.CodeAnalysis;
 using Microsoft.CodeAnalysis.CSharp.CodeStyle;
 using Microsoft.CodeAnalysis.Options;
@@ -155,13 +156,18 @@ internal StyleViewModel(OptionSet optionSet, IServiceProvider serviceProvider) :
             // TODO (BalajiK): Localize all strings from here.
             Items.Add(new HeaderItemViewModel() { Header = "Type Inference preference for local declarations everywhere:" });
 
-            Items.Add(new RadioButtonViewModel<TypeInferencePreferenceOptions>("use implicit typing", s_ImplicitTypingPreview, "usevar", TypeInferencePreferenceOptions.ImplicitTyping, CSharpCodeStyleOptions.UseImplicitTypingForLocals, this, optionSet));
-            Items.Add(new RadioButtonViewModel<TypeInferencePreferenceOptions>("use explicit typing", s_ExplicitTypingPreview, "usevar", TypeInferencePreferenceOptions.ExplicitTyping, CSharpCodeStyleOptions.UseImplicitTypingForLocals, this, optionSet));
+            var implicitTypingOption = new RadioButtonViewModel<TypeInferencePreferenceOptions>("use implicit typing", s_ImplicitTypingPreview, "usevar", TypeInferencePreferenceOptions.ImplicitTyping, CSharpCodeStyleOptions.UseImplicitTypingForLocals, this, optionSet);
+            Items.Add(implicitTypingOption);
+            var explicitTypingOption = new RadioButtonViewModel<TypeInferencePreferenceOptions>("use explicit typing", s_ExplicitTypingPreview, "usevar", TypeInferencePreferenceOptions.ExplicitTyping, CSharpCodeStyleOptions.UseImplicitTypingForLocals, this, optionSet);
+            Items.Add(explicitTypingOption);
 
             Items.Add(new HeaderItemViewModel() { Header = "Type Inference preference for local declarations in special cases:" });
 
-            Items.Add(new CheckBoxOptionViewModel(CSharpCodeStyleOptions.UseVarWhenTypeIsApparent, "use var where typing is apparent", s_ImplicitTypingWhereApparentPreview, this, optionSet));
-            Items.Add(new CheckBoxOptionViewModel(CSharpCodeStyleOptions.DoNotUseVarForIntrinsicTypes, "use intrinsic types", s_ExplicitTypingForIntrinsicTypesPreview, this, optionSet));
+            var useVarWhereApparentChildControl = new CheckBoxOptionViewModel(CSharpCodeStyleOptions.UseVarWhenTypeIsApparent, "use var where typing is apparent", s_ImplicitTypingWhereApparentPreview, this, optionSet, _ => implicitTypingOption.IsChecked);
+            var useIntrinsicTypesChildControl = new CheckBoxOptionViewModel(CSharpCodeStyleOptions.DoNotUseVarForIntrinsicTypes, "use intrinsic types", s_ExplicitTypingForIntrinsicTypesPreview, this, optionSet, _ => implicitTypingOption.IsChecked);
+
+            Items.Add(useVarWhereApparentChildControl);
+            Items.Add(useIntrinsicTypesChildControl);
         }
     }
 }

src/VisualStudio/Core/Impl/Options/CheckBoxViewModel.cs

 // Copyright (c) Microsoft.  All Rights Reserved.  Licensed under the Apache License, Version 2.0.  See License.txt in the project root for license information.
 
+using System;
+using System.Windows.Input;
 using Microsoft.CodeAnalysis.Options;
 using Microsoft.VisualStudio.LanguageServices.Implementation.Utilities;
 
@@ -15,6 +17,9 @@ internal string GetPreview()
         }
 
         private bool _isChecked;
+        private RelayCommand _enableCommand;
+
+        private readonly Predicate<object> _canExecute;
         private readonly string _truePreview;
         private readonly string _falsePreview;
 
@@ -28,6 +33,8 @@ public CheckBoxOptionViewModel(IOption option, string description, string previe
             _truePreview = preview;
             _falsePreview = preview;
             _info = info;
+            _canExecute = null;
+
             SetProperty(ref _isChecked, (bool)options.GetOption(new OptionKey(option, option.IsPerLanguage ? info.Language : null)));
         }
 
@@ -38,6 +45,20 @@ public CheckBoxOptionViewModel(IOption option, string description, string truePr
             _truePreview = truePreview;
             _falsePreview = falsePreview;
             _info = info;
+            _canExecute = null;
+
+            SetProperty(ref _isChecked, (bool)options.GetOption(new OptionKey(option, option.IsPerLanguage ? info.Language : null)));
+        }
+
+        public CheckBoxOptionViewModel(IOption option, string description, string preview, AbstractOptionPreviewViewModel info, OptionSet options, Predicate<object> canExecute)
+        {
+            this.Option = option;
+            Description = description;
+            _truePreview = preview;
+            _falsePreview = preview;
+            _info = info;
+            _canExecute = canExecute;
+
             SetProperty(ref _isChecked, (bool)options.GetOption(new OptionKey(option, option.IsPerLanguage ? info.Language : null)));
         }
 
@@ -54,5 +75,21 @@ public bool IsChecked
                 _info.SetOptionAndUpdatePreview(_isChecked, Option, GetPreview());
             }
         }
+
+
+        public ICommand EnableCommand
+        {
+            get
+            {
+                if (_enableCommand == null)
+                {
+                    _enableCommand = _canExecute == null
+                        ? new RelayCommand(_ => { })
+                        : new RelayCommand(_ => { }, _canExecute);
+                }
+
+                return _enableCommand;
+            }
+        }
     }
 }

src/VisualStudio/Core/Impl/Options/OptionPreviewControl.xaml

@@ -27,6 +27,7 @@
                     <StackPanel Orientation="Horizontal">
                         <CheckBox x:Uid="OptionCheckBox" 
                                         IsChecked="{Binding IsChecked, Mode=TwoWay}" 
+                                        Command="{Binding EnableCommand}"
                                         Width="Auto"
                                         Focusable="False"
                                         Margin="20, 0, 0, 0">
@@ -42,7 +43,7 @@
                 <DataTemplate DataType="{x:Type options:AbstractRadioButtonViewModel}">
                     <StackPanel Orientation="Horizontal">
                         <RadioButton x:Uid="OptionRadioButton" 
-                                        IsChecked="{Binding IsChecked, Mode=TwoWay}" 
+                                        IsChecked="{Binding IsChecked, Mode=TwoWay}"
                                         Width="Auto"
                                         Focusable="False"
                                         GroupName="{Binding GroupName, Mode=OneWay}"

src/VisualStudio/Core/Impl/Options/RelayCommand.cs

+// Copyright (c) Microsoft.  All Rights Reserved.  Licensed under the Apache License, Version 2.0.  See License.txt in the project root for license information.
+
+using System;
+using System.Diagnostics;
+using System.Windows.Input;
+
+namespace Microsoft.VisualStudio.LanguageServices.Implementation.Options
+{
+    public class RelayCommand : ICommand
+    {
+        readonly Action<object> _execute;
+        readonly Predicate<object> _canExecute;
+
+        public RelayCommand(Action<object> execute)
+        : this(execute, null)
+        {
+        }
+
+        public RelayCommand(Action<object> execute, Predicate<object> canExecute)
+        {
+            if (execute == null)
+                throw new ArgumentNullException(nameof(execute));
+
+            _execute = execute;
+            _canExecute = canExecute;
+        }
+
+        [DebuggerStepThrough]
+        public bool CanExecute(object parameter)
+        {
+            return _canExecute == null ? true : _canExecute(parameter);
+        }
+
+        public event EventHandler CanExecuteChanged
+        {
+            add { CommandManager.RequerySuggested += value; }
+            remove { CommandManager.RequerySuggested -= value; }
+        }
+
+        public void Execute(object parameter)
+        {
+            _execute(parameter);
+        }
+    }
+}

src/VisualStudio/Core/Impl/ServicesVisualStudioImpl.csproj

@@ -322,6 +322,7 @@
     <Compile Include="Options\InternalOptionSerializer.cs" />
     <Compile Include="Options\PerLanguageOptionBinding.cs" />
     <Compile Include="Options\RadioButtonViewModel.cs" />
+    <Compile Include="Options\RelayCommand.cs" />
     <Compile Include="RoslynVisualStudioWorkspace.cs" />
   </ItemGroup>
   <ItemGroup>