Polish the Background Image settings (microsoft#8778)

## Summary of the Pull Request

Two parts:
* Hide the BG image settings when no image is specified
* Add a checkbox for "Use desktop wallpaper". When that's checked, the BG image path input is hidden. Unchecking that box restores the path to what it was before.

## PR Checklist
* [x] Closes microsoft#8763
* [x] I work here

## Validation Steps Performed
Tested manually

src/cascadia/TerminalSettingsEditor/Converters.idl

@@ -0,0 +1,45 @@
+// Copyright (c) Microsoft Corporation.
+// Licensed under the MIT license.
+
+namespace Microsoft.Terminal.Settings.Editor
+{
+    runtimeclass FontWeightConverter : [default] Windows.UI.Xaml.Data.IValueConverter
+    {
+        FontWeightConverter();
+    };
+
+    runtimeclass InvertedBooleanToVisibilityConverter : [default] Windows.UI.Xaml.Data.IValueConverter
+    {
+        InvertedBooleanToVisibilityConverter();
+    };
+
+    runtimeclass ColorToBrushConverter : [default] Windows.UI.Xaml.Data.IValueConverter
+    {
+        ColorToBrushConverter();
+    };
+
+    runtimeclass ColorToHexConverter : [default] Windows.UI.Xaml.Data.IValueConverter
+    {
+        ColorToHexConverter();
+    };
+
+    runtimeclass PercentageConverter : [default] Windows.UI.Xaml.Data.IValueConverter
+    {
+        PercentageConverter();
+    };
+
+    runtimeclass StringIsEmptyConverter : [default] Windows.UI.Xaml.Data.IValueConverter
+    {
+        StringIsEmptyConverter();
+    };
+
+    runtimeclass StringIsNotDesktopConverter : [default] Windows.UI.Xaml.Data.IValueConverter
+    {
+        StringIsNotDesktopConverter();
+    };
+    runtimeclass DesktopWallpaperToEmptyStringConverter : [default] Windows.UI.Xaml.Data.IValueConverter
+    {
+        DesktopWallpaperToEmptyStringConverter();
+    };
+
+}

src/cascadia/TerminalSettingsEditor/Microsoft.Terminal.Settings.Editor.vcxproj

@@ -36,19 +36,25 @@
   <!-- ========================= Headers ======================== -->
   <ItemGroup>
     <ClInclude Include="ColorToBrushConverter.h">
-      <DependentUpon>ColorToBrushConverter.idl</DependentUpon>
+      <DependentUpon>Converters.idl</DependentUpon>
     </ClInclude>
     <ClInclude Include="ColorToHexConverter.h">
-      <DependentUpon>ColorToHexConverter.idl</DependentUpon>
+      <DependentUpon>Converters.idl</DependentUpon>
     </ClInclude>
     <ClInclude Include="FontWeightConverter.h">
-      <DependentUpon>FontWeightConverter.idl</DependentUpon>
+      <DependentUpon>Converters.idl</DependentUpon>
     </ClInclude>
     <ClInclude Include="InvertedBooleanToVisibilityConverter.h">
-      <DependentUpon>InvertedBooleanToVisibilityConverter.idl</DependentUpon>
+      <DependentUpon>Converters.idl</DependentUpon>
+    </ClInclude>
+    <ClInclude Include="StringIsEmptyConverter.h">
+      <DependentUpon>Converters.idl</DependentUpon>
+    </ClInclude>
+    <ClInclude Include="StringIsNotDesktopConverter.h">
+      <DependentUpon>Converters.idl</DependentUpon>
     </ClInclude>
     <ClInclude Include="PercentageConverter.h">
-      <DependentUpon>PercentageConverter.idl</DependentUpon>
+      <DependentUpon>Converters.idl</DependentUpon>
     </ClInclude>
     <ClInclude Include="EnumEntry.h">
       <DependentUpon>EnumEntry.idl</DependentUpon>
@@ -109,19 +115,25 @@
   <!-- ========================= Cpp Files ======================== -->
   <ItemGroup>
     <ClCompile Include="ColorToBrushConverter.cpp">
-      <DependentUpon>ColorToBrushConverter.idl</DependentUpon>
+      <DependentUpon>Converters.idl</DependentUpon>
     </ClCompile>
     <ClCompile Include="ColorToHexConverter.cpp">
-      <DependentUpon>ColorToHexConverter.idl</DependentUpon>
+      <DependentUpon>Converters.idl</DependentUpon>
     </ClCompile>
     <ClCompile Include="FontWeightConverter.cpp">
-      <DependentUpon>FontWeightConverter.idl</DependentUpon>
+      <DependentUpon>Converters.idl</DependentUpon>
     </ClCompile>
     <ClCompile Include="InvertedBooleanToVisibilityConverter.cpp">
-      <DependentUpon>InvertedBooleanToVisibilityConverter.idl</DependentUpon>
+      <DependentUpon>Converters.idl</DependentUpon>
+    </ClCompile>
+    <ClCompile Include="StringIsEmptyConverter.cpp">
+      <DependentUpon>Converters.idl</DependentUpon>
+    </ClCompile>
+    <ClCompile Include="StringIsNotDesktopConverter.cpp">
+      <DependentUpon>Converters.idl</DependentUpon>
     </ClCompile>
     <ClCompile Include="PercentageConverter.cpp">
-      <DependentUpon>PercentageConverter.idl</DependentUpon>
+      <DependentUpon>Converters.idl</DependentUpon>
     </ClCompile>
     <ClCompile Include="GlobalAppearance.cpp">
       <DependentUpon>GlobalAppearance.xaml</DependentUpon>
@@ -154,11 +166,7 @@
   </ItemGroup>
   <!-- ========================= idl Files ======================== -->
   <ItemGroup>
-    <Midl Include="ColorToBrushConverter.idl" />
-    <Midl Include="ColorToHexConverter.idl" />
-    <Midl Include="FontWeightConverter.idl" />
-    <Midl Include="InvertedBooleanToVisibilityConverter.idl" />
-    <Midl Include="PercentageConverter.idl" />
+    <Midl Include="Converters.idl" />
     <Midl Include="EnumEntry.idl" />
     <Midl Include="GlobalAppearance.idl">
       <DependentUpon>GlobalAppearance.xaml</DependentUpon>

src/cascadia/TerminalSettingsEditor/Microsoft.Terminal.Settings.Editor.vcxproj.filters

@@ -16,22 +16,10 @@
     <ClInclude Include="Utils.h" />
   </ItemGroup>
   <ItemGroup>
-    <Midl Include="ColorToBrushConverter.idl">
-      <Filter>Converters</Filter>
-    </Midl>
-    <Midl Include="ColorToHexConverter.idl">
-      <Filter>Converters</Filter>
-    </Midl>
-    <Midl Include="FontWeightConverter.idl">
-      <Filter>Converters</Filter>
-    </Midl>
-    <Midl Include="InvertedBooleanToVisibilityConverter.idl">
-      <Filter>Converters</Filter>
-    </Midl>
-    <Midl Include="PercentageConverter.idl">
+    <Midl Include="EnumEntry.idl" />
+    <Midl Include="Converters.idl">
       <Filter>Converters</Filter>
     </Midl>
-    <Midl Include="EnumEntry.idl" />
   </ItemGroup>
   <ItemGroup>
     <None Include="TerminalSettingsEditor.def" />

src/cascadia/TerminalSettingsEditor/Profiles.cpp

@@ -26,6 +26,37 @@ static const std::array<winrt::guid, 2> InBoxProfileGuids{
 
 namespace winrt::Microsoft::Terminal::Settings::Editor::implementation
 {
+    ProfileViewModel::ProfileViewModel(const Model::Profile& profile) :
+        _profile{ profile }
+    {
+        // Add a property changed handler to our own property changed event.
+        // When the BackgroundImagePath changes, we _also_ need to change the
+        // value of UseDesktopBGImage.
+        //
+        // We need to do this so if someone manually types "desktopWallpaper"
+        // into the path TextBox, we properly update the checkbox and stored
+        // _lastBgImagePath. Without this, then we'll permanently hide the text
+        // box, prevent it from ever being changed again.
+        PropertyChanged([this](auto&&, const Data::PropertyChangedEventArgs& args) {
+            if (args.PropertyName() == L"BackgroundImagePath")
+            {
+                _NotifyChanges(L"UseDesktopBGImage", L"BackgroundImageSettingsVisible");
+            }
+            else if (args.PropertyName() == L"IsBaseLayer")
+            {
+                _NotifyChanges(L"BackgroundImageSettingsVisible");
+            }
+        });
+
+        // Cache the original BG image path. If the user clicks "Use desktop
+        // wallpaper", then un-checks it, this is the string we'll restore to
+        // them.
+        if (BackgroundImagePath() != L"desktopWallpaper")
+        {
+            _lastBgImagePath = BackgroundImagePath();
+        }
+    }
+
     bool ProfileViewModel::CanDeleteProfile() const
     {
         const auto guid{ Guid() };
@@ -49,6 +80,40 @@ namespace winrt::Microsoft::Terminal::Settings::Editor::implementation
         }
     }
 
+    bool ProfileViewModel::UseDesktopBGImage()
+    {
+        return BackgroundImagePath() == L"desktopWallpaper";
+    }
+
+    void ProfileViewModel::UseDesktopBGImage(const bool useDesktop)
+    {
+        if (useDesktop)
+        {
+            // Stash the current value of BackgroundImagePath. If the user
+            // checks and un-checks the "Use desktop wallpaper" button, we want
+            // the path that we display in the text box to remain unchanged.
+            //
+            // Only stash this value if it's not the special "desktopWallpaper"
+            // value.
+            if (BackgroundImagePath() != L"desktopWallpaper")
+            {
+                _lastBgImagePath = BackgroundImagePath();
+            }
+            BackgroundImagePath(L"desktopWallpaper");
+        }
+        else
+        {
+            // Restore the path we had previously cached. This might be the
+            // empty string.
+            BackgroundImagePath(_lastBgImagePath);
+        }
+    }
+
+    bool ProfileViewModel::BackgroundImageSettingsVisible()
+    {
+        return IsBaseLayer() || BackgroundImagePath() != L"";
+    }
+
     void ProfilePageNavigationState::DeleteProfile()
     {
         auto deleteProfileArgs{ winrt::make_self<DeleteProfileEventArgs>(_Profile.Guid()) };

src/cascadia/TerminalSettingsEditor/Profiles.h

@@ -15,10 +15,14 @@ namespace winrt::Microsoft::Terminal::Settings::Editor::implementation
     struct ProfileViewModel : ProfileViewModelT<ProfileViewModel>, ViewModelHelper<ProfileViewModel>
     {
     public:
-        ProfileViewModel(const Model::Profile& profile) :
-            _profile{ profile } {}
+        ProfileViewModel(const Model::Profile& profile);
 
         bool CanDeleteProfile() const;
+
+        bool UseDesktopBGImage();
+        void UseDesktopBGImage(const bool useDesktop);
+        bool BackgroundImageSettingsVisible();
+
         GETSET_PROPERTY(bool, IsBaseLayer, false);
 
         PERMANENT_OBSERVABLE_PROJECTED_SETTING(_profile, Guid);
@@ -62,6 +66,7 @@ namespace winrt::Microsoft::Terminal::Settings::Editor::implementation
 
     private:
         Model::Profile _profile;
+        winrt::hstring _lastBgImagePath;
     };
 
     struct DeleteProfileEventArgs :

src/cascadia/TerminalSettingsEditor/Profiles.idl

@@ -12,6 +12,8 @@ namespace Microsoft.Terminal.Settings.Editor
     {
         Boolean CanDeleteProfile { get; };
         Boolean IsBaseLayer;
+        Boolean UseDesktopBGImage;
+        Boolean BackgroundImageSettingsVisible { get; };
 
         OBSERVABLE_PROJECTED_SETTING(String, Name);
         OBSERVABLE_PROJECTED_SETTING(Guid, Guid);

src/cascadia/TerminalSettingsEditor/Profiles.xaml

@@ -30,6 +30,10 @@ the MIT License. See LICENSE in the project root for license information. -->
             <local:PercentageConverter x:Key="PercentageConverter"/>
             <local:FontWeightConverter x:Key="FontWeightConverter"/>
             <local:InvertedBooleanToVisibilityConverter x:Key="InvertedBooleanToVisibilityConverter"/>
+            <local:StringIsEmptyConverter x:Key="StringIsEmptyConverter"/>
+            <local:StringIsNotDesktopConverter x:Key="StringIsNotDesktopConverter"/>
+            <local:DesktopWallpaperToEmptyStringConverter x:Key="DesktopWallpaperToEmptyStringConverter"/>
+
         </ResourceDictionary>
     </Page.Resources>
 
@@ -291,19 +295,31 @@ the MIT License. See LICENSE in the project root for license information. -->
 
                         <!--Background Image-->
                         <ContentPresenter Style="{StaticResource SettingContainerStyle}">
-                            <StackPanel Orientation="Horizontal">
-                                <TextBox x:Uid="Profile_BackgroundImage"
-                                         x:Name="BackgroundImage"
-                                         Text="{x:Bind State.Profile.BackgroundImagePath, Mode=TwoWay}"
-                                         Style="{StaticResource TextBoxSettingStyle}"/>
-                                <Button x:Uid="Profile_BackgroundImageBrowse"
-                                        Click="BackgroundImage_Click"
-                                        Style="{StaticResource BrowseButtonStyle}"/>
+                        </ContentPresenter>
+
+                        <ContentPresenter Style="{StaticResource SettingContainerStyle}">
+                            <StackPanel Orientation="Vertical">
+                                <StackPanel Orientation="Horizontal">
+                                    <TextBox x:Uid="Profile_BackgroundImage"
+                                             x:Name="BackgroundImage"
+                                             Text="{x:Bind State.Profile.BackgroundImagePath, Mode=TwoWay, Converter={StaticResource DesktopWallpaperToEmptyStringConverter}}"
+                                             IsEnabled="{x:Bind State.Profile.BackgroundImagePath, Mode=OneWay, Converter={StaticResource StringIsNotDesktopConverter}}"
+                                             Style="{StaticResource TextBoxSettingStyle}"/>
+                                    <Button x:Uid="Profile_BackgroundImageBrowse"
+                                            Click="BackgroundImage_Click"
+                                            IsEnabled="{x:Bind State.Profile.BackgroundImagePath, Mode=OneWay, Converter={StaticResource StringIsNotDesktopConverter}}"
+                                            Style="{StaticResource BrowseButtonStyle}"/>
+                                </StackPanel>
+                                <CheckBox x:Uid="Profile_UseDesktopImage"
+                                          x:Name="UseDesktopImageCheckBox"
+                                          IsChecked="{x:Bind State.Profile.UseDesktopBGImage, Mode=TwoWay}"
+                                          Style="{StaticResource CheckBoxSettingStyle}"/>
                             </StackPanel>
                         </ContentPresenter>
 
                         <!--Background Image Stretch Mode-->
-                        <ContentPresenter Style="{StaticResource SettingContainerStyle}">
+                        <ContentPresenter Style="{StaticResource SettingContainerStyle}"
+                                          Visibility="{x:Bind State.Profile.BackgroundImageSettingsVisible, Mode=OneWay}">
                             <muxc:RadioButtons x:Uid="Profile_BackgroundImageStretchMode"
                                                ItemsSource="{x:Bind BackgroundImageStretchModeList, Mode=OneWay}"
                                                SelectedItem="{x:Bind CurrentBackgroundImageStretchMode, Mode=TwoWay}"
@@ -312,7 +328,8 @@ the MIT License. See LICENSE in the project root for license information. -->
                         </ContentPresenter>
 
                         <!--Background Image Alignment-->
-                        <ContentPresenter Style="{StaticResource SettingContainerStyle}">
+                        <ContentPresenter Style="{StaticResource SettingContainerStyle}"
+                                          Visibility="{x:Bind State.Profile.BackgroundImageSettingsVisible, Mode=OneWay}">
                             <StackPanel HorizontalAlignment="Left">
                                 <TextBlock x:Uid="Profile_BackgroundImageAlignment"
                                            Style="{StaticResource CustomSettingHeaderStyle}"
@@ -468,7 +485,8 @@ the MIT License. See LICENSE in the project root for license information. -->
                         </ContentPresenter>
 
                         <!--Background Image Opacity-->
-                        <ContentPresenter Style="{StaticResource SettingContainerStyle}">
+                        <ContentPresenter Style="{StaticResource SettingContainerStyle}"
+                                          Visibility="{x:Bind State.Profile.BackgroundImageSettingsVisible, Mode=OneWay}">
                             <StackPanel>
                                 <TextBlock x:Uid="Profile_BackgroundImageOpacity"
                                            Style="{StaticResource SliderHeaderStyle}"/>