Implement UI for choosing default terminal inside Settings page (#9907)

Implement dropdown menu for choosing a default terminal application from inside the Windows Terminal Settings UI

## PR Checklist
* [x] Closes #9463 
* [x] I work here.
* [x] Manual tests passed
* [x] MicrosoftDocs/terminal#314 (and cross reference #9462)

## Detailed Description of the Pull Request / Additional comments
- Adds dropdown menu and a template card for displaying the available default applications (using the same lookup code as the console property sheet `console.dll`)
- Adds model to TSM for adapting the data for display and binding on XAML
- Lookup occurs on every page reload. Persistence only happens on Save Changes.
- Manifest changed for Terminal to add capability to opt-out of registry redirection so we can edit this setting

## Validation Steps Performed
- [x] Flipped the menu and pressed Save Changes and launched cmd from run box... it moved between the two.
- [x] Flipped system theme from light to dark and ensured secondary color looked good
- [x] Flipped the status with a different mechanism (conhost propsheet) and then reopened settings page and confirmed it loaded the updated status

.github/actions/spelling/dictionary/apis.txt

@@ -3,6 +3,7 @@ ACCESSDENIED
 alignof
 bitfield
 bitfields
+BUILDNUMBER
 CLASSNOTAVAILABLE
 cmdletbinding
 colspan
@@ -16,6 +17,7 @@ dcomp
 DERR
 dlldata
 DONTADDTORECENT
+DWORDLONG
 environstrings
 EXPCMDFLAGS
 EXPCMDSTATE
@@ -56,6 +58,7 @@ istream
 IStringable
 ITab
 ITaskbar
+IUri
 IVirtual
 LCID
 llabs
@@ -77,6 +80,8 @@ NOREDIRECTIONBITMAP
 ntprivapi
 oaidl
 ocidl
+osver
+OSVERSIONINFOEXW
 otms
 OUTLINETEXTMETRICW
 overridable

.github/actions/spelling/dictionary/microsoft.txt

@@ -43,8 +43,10 @@ systemroot
 taskkill
 tasklist
 tdbuildteamid
+unvirtualized
 VCRT
 vcruntime
+Virtualization
 visualstudio
 vscode
 VSTHRD

.github/actions/spelling/expect/expect.txt

@@ -170,6 +170,7 @@ blog
 Blt
 BLUESCROLL
 bmp
+BODGY
 BOLDFONT
 BOOLIFY
 bools
@@ -676,6 +677,7 @@ dwmapi
 dword
 dwrite
 dwriteglyphrundescriptionclustermap
+dwl
 dxgi
 dxgidwm
 dxinterop

src/cascadia/LocalTests_SettingsModel/SettingsModel.LocalTests.vcxproj

@@ -55,6 +55,7 @@
   <ItemGroup>
     <ProjectReference Include="$(OpenConsoleDir)\src\cascadia\TerminalSettingsModel\Microsoft.Terminal.Settings.ModelLib.vcxproj" />
     <ProjectReference Include="$(OpenConsoleDir)\src\types\lib\types.vcxproj" />
+    <ProjectReference Include="$(OpenConsoleDir)src\propslib\propslib.vcxproj" />
 
     <!-- If you don't reference these projects here, the
     _ConsoleGenerateAdditionalWinmdManifests step won't gather the winmd's -->

src/cascadia/TerminalSettingsEditor/Launch.cpp

@@ -19,11 +19,21 @@ namespace winrt::Microsoft::Terminal::Settings::Editor::implementation
 
         INITIALIZE_BINDABLE_ENUM_SETTING(LaunchMode, LaunchMode, LaunchMode, L"Globals_LaunchMode", L"Content");
         INITIALIZE_BINDABLE_ENUM_SETTING(WindowingBehavior, WindowingMode, WindowingMode, L"Globals_WindowingBehavior", L"Content");
+
+        // BODGY
+        // Xaml code generator for x:Bind to this will fail to find UnloadObject() on Launch class.
+        // To work around, check it ourselves on construction and FindName to force load.
+        // It's specified as x:Load=false in the XAML. So it only loads if this passes.
+        if (CascadiaSettings::IsDefaultTerminalAvailable())
+        {
+            FindName(L"DefaultTerminalDropdown");
+        }
     }
 
     void Launch::OnNavigatedTo(const NavigationEventArgs& e)
     {
         _State = e.Parameter().as<Editor::LaunchPageNavigationState>();
+        _State.Settings().RefreshDefaultTerminals();
     }
 
     IInspectable Launch::CurrentDefaultProfile()
@@ -37,21 +47,4 @@ namespace winrt::Microsoft::Terminal::Settings::Editor::implementation
         const auto profile{ winrt::unbox_value<Model::Profile>(value) };
         _State.Settings().GlobalSettings().DefaultProfile(profile.Guid());
     }
-
-    // TODO GH#9463 - Complete hookup of Terminal UX to choose defapp.
-    Windows::Foundation::Collections::IObservableVector<IInspectable> Launch::DefaultTerminals()
-    {
-        Windows::Foundation::Collections::IObservableVector<IInspectable> vec;
-        return vec;
-    }
-
-    IInspectable Launch::CurrentDefaultTerminal()
-    {
-        return nullptr;
-    }
-
-    void Launch::CurrentDefaultTerminal(const IInspectable& value)
-    {
-        value;
-    }
 }

src/cascadia/TerminalSettingsEditor/Launch.h

@@ -28,10 +28,6 @@ namespace winrt::Microsoft::Terminal::Settings::Editor::implementation
         IInspectable CurrentDefaultProfile();
         void CurrentDefaultProfile(const IInspectable& value);
 
-        Windows::Foundation::Collections::IObservableVector<IInspectable> DefaultTerminals();
-        IInspectable CurrentDefaultTerminal();
-        void CurrentDefaultTerminal(const IInspectable& value);
-
         WINRT_PROPERTY(Editor::LaunchPageNavigationState, State, nullptr);
 
         GETSET_BINDABLE_ENUM_SETTING(LaunchMode, Model::LaunchMode, State().Settings().GlobalSettings, LaunchMode);

src/cascadia/TerminalSettingsEditor/Launch.idl

@@ -17,9 +17,6 @@ namespace Microsoft.Terminal.Settings.Editor
 
         IInspectable CurrentDefaultProfile;
 
-        IInspectable CurrentDefaultTerminal;
-        IObservableVector<IInspectable> DefaultTerminals { get; };
-
         IInspectable CurrentLaunchMode;
         IObservableVector<Microsoft.Terminal.Settings.Editor.EnumEntry> LaunchModeList { get; };
 

src/cascadia/TerminalSettingsEditor/Launch.xaml

@@ -70,16 +70,63 @@
                 </local:SettingContainer>
 
                 <!--  Default Terminal  -->
-                <!--  TODO GH#9463 - Complete hookup of Terminal UX to choose defapp.  -->
-                <!--
-                <local:SettingContainer x:Uid="Globals_DefaultTerminal">
+                <local:SettingContainer x:Name="DefaultTerminalDropdown"
+                                        x:Uid="Globals_DefaultTerminal"
+                                        x:Load="false">
                     <ComboBox x:Name="DefaultTerminal"
-                              x:Load="False"
-                              ItemsSource="{x:Bind DefaultTerminals, Mode=OneWay}"
-                              SelectedItem="{x:Bind CurrentDefaultTerminal, Mode=TwoWay}"
-                              Style="{StaticResource ComboBoxSettingStyle}" />
+                              ItemsSource="{x:Bind State.Settings.DefaultTerminals, Mode=OneWay}"
+                              SelectedItem="{x:Bind State.Settings.CurrentDefaultTerminal, Mode=TwoWay}"
+                              Style="{StaticResource ComboBoxSettingStyle}">
+                        <ComboBox.ItemTemplate>
+                            <DataTemplate x:DataType="SettingsModel:DefaultTerminal">
+                                <Grid HorizontalAlignment="Stretch"
+                                      VerticalAlignment="Stretch"
+                                      ColumnSpacing="8">
+
+                                    <Grid.ColumnDefinitions>
+                                        <!--  icon  -->
+                                        <ColumnDefinition Width="24" />
+                                        <!--  profile name and author  -->
+                                        <ColumnDefinition Width="*" />
+                                        <!--  version  -->
+                                        <ColumnDefinition Width="48" />
+                                    </Grid.ColumnDefinitions>
+
+                                    <Grid.RowDefinitions>
+                                        <!--  profile name  -->
+                                        <RowDefinition Height="*" />
+                                        <!--  author and version  -->
+                                        <RowDefinition Height="*" />
+                                    </Grid.RowDefinitions>
+
+                                    <IconSourceElement Grid.Row="0"
+                                                       Grid.RowSpan="2"
+                                                       Grid.Column="0"
+                                                       Width="24"
+                                                       Height="24"
+                                                       VerticalAlignment="Center"
+                                                       IconSource="{x:Bind Icon, Mode=OneWay, Converter={StaticResource IconSourceConverter}}" />
+
+                                    <TextBlock Grid.Row="0"
+                                               Grid.Column="1"
+                                               Grid.ColumnSpan="2"
+                                               Text="{x:Bind Name}" />
+
+                                    <TextBlock Grid.Row="1"
+                                               Grid.Column="1"
+                                               Foreground="{StaticResource SystemBaseMediumColor}"
+                                               Text="{x:Bind Author}" />
+
+                                    <TextBlock Grid.Row="1"
+                                               Grid.Column="2"
+                                               Foreground="{StaticResource SystemBaseMediumColor}"
+                                               Text="{x:Bind Version}" />
+
+                                </Grid>
+                            </DataTemplate>
+                        </ComboBox.ItemTemplate>
+                    </ComboBox>
                 </local:SettingContainer>
-                -->
 
                 <!--  Start on User Login  -->
                 <local:SettingContainer x:Uid="Globals_StartOnUserLogin">

src/cascadia/TerminalSettingsEditor/Resources/en-US/Resources.resw

@@ -226,7 +226,7 @@
     <comment>A description for what the default profile is and when it's used.</comment>
   </data>
   <data name="Globals_DefaultTerminal.Header" xml:space="preserve">
-    <value>Default terminal</value>
+    <value>Default terminal application</value>
     <comment>Header for a drop down that permits the user to select which installed Terminal application will launch when command line tools like CMD are run from the Windows Explorer run box or start menu or anywhere else that they do not already have a graphical window assigned.</comment>
   </data>
   <data name="Globals_DefaultTerminal.HelpText" xml:space="preserve">

src/cascadia/TerminalSettingsModel/CascadiaSettings.cpp

@@ -48,7 +48,9 @@ CascadiaSettings::CascadiaSettings(const bool addDynamicProfiles) :
     _allProfiles{ winrt::single_threaded_observable_vector<Model::Profile>() },
     _activeProfiles{ winrt::single_threaded_observable_vector<Model::Profile>() },
     _warnings{ winrt::single_threaded_vector<SettingsLoadWarnings>() },
-    _deserializationErrorMessage{ L"" }
+    _deserializationErrorMessage{ L"" },
+    _defaultTerminals{ winrt::single_threaded_observable_vector<Model::DefaultTerminal>() },
+    _currentDefaultTerminal{ nullptr }
 {
     if (addDynamicProfiles)
     {
@@ -82,6 +84,9 @@ winrt::Microsoft::Terminal::Settings::Model::CascadiaSettings CascadiaSettings::
     settings->_userSettings = _userSettings;
     settings->_defaultSettings = _defaultSettings;
 
+    settings->_defaultTerminals = _defaultTerminals;
+    settings->_currentDefaultTerminal = _currentDefaultTerminal;
+
     _CopyProfileInheritanceTree(settings);
 
     return *settings;
@@ -999,3 +1004,81 @@ winrt::hstring CascadiaSettings::ApplicationVersion()
 
     return RS_(L"ApplicationVersionUnknown");
 }
+
+// Method Description:
+// - Forces a refresh of all default terminal state
+// Arguments:
+// - <none>
+// Return Value:
+// - <none> - Updates internal state
+void CascadiaSettings::RefreshDefaultTerminals()
+{
+    _defaultTerminals.Clear();
+
+    for (const auto& term : Model::DefaultTerminal::Available())
+    {
+        _defaultTerminals.Append(term);
+    }
+
+    _currentDefaultTerminal = Model::DefaultTerminal::Current();
+}
+
+// Helper to do the version check
+static bool _isOnBuildWithDefTerm() noexcept
+{
+    OSVERSIONINFOEXW osver{ 0 };
+    osver.dwOSVersionInfoSize = sizeof(osver);
+    osver.dwBuildNumber = 21359;
+
+    DWORDLONG dwlConditionMask = 0;
+    VER_SET_CONDITION(dwlConditionMask, VER_BUILDNUMBER, VER_GREATER_EQUAL);
+
+    return VerifyVersionInfoW(&osver, VER_BUILDNUMBER, dwlConditionMask);
+}
+
+// Method Description:
+// - Determines if we're on an OS platform that supports
+//   the default terminal handoff functionality.
+// Arguments:
+// - <none>
+// Return Value:
+// - True if OS supports default terminal. False otherwise.
+bool CascadiaSettings::IsDefaultTerminalAvailable() noexcept
+{
+    // Cached on first use since the OS version shouldn't change while we're running.
+    static bool isAvailable = _isOnBuildWithDefTerm();
+    return isAvailable;
+}
+
+// Method Description:
+// - Returns an iterable collection of all available terminals.
+// Arguments:
+// - <none>
+// Return Value:
+// - an iterable collection of all available terminals that could be the default.
+IObservableVector<winrt::Microsoft::Terminal::Settings::Model::DefaultTerminal> CascadiaSettings::DefaultTerminals() const noexcept
+{
+    return _defaultTerminals;
+}
+
+// Method Description:
+// - Returns the currently selected default terminal application
+// Arguments:
+// - <none>
+// Return Value:
+// - the selected default terminal application
+winrt::Microsoft::Terminal::Settings::Model::DefaultTerminal CascadiaSettings::CurrentDefaultTerminal() const noexcept
+{
+    return _currentDefaultTerminal;
+}
+
+// Method Description:
+// - Sets the current default terminal application
+// Arguments:
+// - terminal - Terminal from `DefaultTerminals` list to set as default
+// Return Value:
+// - <none>
+void CascadiaSettings::CurrentDefaultTerminal(winrt::Microsoft::Terminal::Settings::Model::DefaultTerminal terminal)
+{
+    _currentDefaultTerminal = terminal;
+}

src/cascadia/TerminalSettingsModel/CascadiaSettings.h

@@ -98,6 +98,13 @@ namespace winrt::Microsoft::Terminal::Settings::Model::implementation
 
         winrt::guid GetProfileForArgs(const Model::NewTerminalArgs& newTerminalArgs) const;
 
+        void RefreshDefaultTerminals();
+
+        static bool IsDefaultTerminalAvailable() noexcept;
+        Windows::Foundation::Collections::IObservableVector<Model::DefaultTerminal> DefaultTerminals() const noexcept;
+        Model::DefaultTerminal CurrentDefaultTerminal() const noexcept;
+        void CurrentDefaultTerminal(Model::DefaultTerminal terminal);
+
     private:
         com_ptr<GlobalAppSettings> _globals;
         Windows::Foundation::Collections::IObservableVector<Model::Profile> _allProfiles;
@@ -106,6 +113,9 @@ namespace winrt::Microsoft::Terminal::Settings::Model::implementation
         Windows::Foundation::IReference<SettingsLoadErrors> _loadError;
         hstring _deserializationErrorMessage;
 
+        Windows::Foundation::Collections::IObservableVector<Model::DefaultTerminal> _defaultTerminals;
+        Model::DefaultTerminal _currentDefaultTerminal;
+
         std::vector<std::unique_ptr<::Microsoft::Terminal::Settings::Model::IDynamicProfileGenerator>> _profileGenerators;
 
         std::string _userSettingsString;

src/cascadia/TerminalSettingsModel/CascadiaSettings.idl

@@ -4,6 +4,7 @@
 import "GlobalAppSettings.idl";
 import "Profile.idl";
 import "TerminalWarnings.idl";
+import "DefaultTerminal.idl";
 
 namespace Microsoft.Terminal.Settings.Model
 {
@@ -42,5 +43,10 @@ namespace Microsoft.Terminal.Settings.Model
         void UpdateColorSchemeReferences(String oldName, String newName);
 
         Guid GetProfileForArgs(NewTerminalArgs newTerminalArgs);
+
+        void RefreshDefaultTerminals();
+        static Boolean IsDefaultTerminalAvailable { get; };
+        Windows.Foundation.Collections.IObservableVector<DefaultTerminal> DefaultTerminals { get; };
+        DefaultTerminal CurrentDefaultTerminal;
     }
 }

src/cascadia/TerminalSettingsModel/CascadiaSettingsSerialization.cpp

@@ -1323,6 +1323,7 @@ const Json::Value& CascadiaSettings::_GetDisabledProfileSourcesJsonObject(const
 // Method Description:
 // - Write the current state of CascadiaSettings to our settings file
 // - Create a backup file with the current contents, if one does not exist
+// - Persists the default terminal handler choice to the registry
 // Arguments:
 // - <none>
 // Return Value:
@@ -1348,6 +1349,9 @@ void CascadiaSettings::WriteSettingsToDisk() const
 
     const auto styledString{ Json::writeString(wbuilder, ToJson()) };
     _WriteSettings(styledString, settingsPath);
+
+    // Persists the default terminal choice
+    Model::DefaultTerminal::Current(_currentDefaultTerminal);
 }
 
 // Method Description: