Allow Opacity to be set differently in both focused and unfocused ter…

…minals (#15974)

## Summary of the Pull Request
Closes #11092 

Allowing `opacity `to be set differently in both focused and unfocused
terminals

## References and Relevant Issues
#11092 , references: #7158 

## Detailed Description of the Pull Request / Additional comments

### Allowing Opacity to be set differently in both focused and unfocused
terminals:

![unfocused_opacity](https://github.com/microsoft/terminal/assets/15957528/1c38e40b-4678-43ec-b328-ad79d222579f)

![image](https://github.com/microsoft/terminal/assets/15957528/3e3342a8-7908-41db-9c37-26c89f7f2456)


![jolsen](https://github.com/microsoft/terminal/assets/15957528/68553507-d29e-4513-89ce-b1cd305d28b7)


![image](https://github.com/microsoft/terminal/assets/15957528/18864f60-91d0-4159-87da-2b2ee1637a4c)

## `_runtimeFocusedOpacity`

Mike also had to say something about this:
#2531 (comment)

Initially I had something like ` _setOpacity(newAppearance->Opacity());`

But with the introduction of unfocused opacity we encounter new
challenges:
When Adjusting the Opacity with **CTRL+SHIFT+Mouse Scroll Wheel** or
**Set background opacity** in command pallette, the Runtime opacity
changes, but when we go to unfocused and back to focused the opacity
changes back to focused opacity in Settings.

Also when adjusting opacity through the command palette the window
becomes unfocused and then focused again after setting background
opacity hence the ` _setOpacity(newAppearance->Opacity());` would
override the changes made through command palette

![runtimeFocusedOpacity](https://github.com/microsoft/terminal/assets/15957528/4de63057-d658-4b5e-99ad-7db050834ade)


![command_pallette_focusswitches](https://github.com/microsoft/terminal/assets/15957528/372526eb-cf0c-40f8-a4e5-a0739f1f0e05)

With the introduction of unfocused opacity we encounter new challenges.
The runtime opacity stores both the unfocused opacity and focused
opacity from settings at different moments. This all works well until we
combine this with Adjusting the Opacity with **CTRL+SHIFT+Mouse Scroll
Wheel** or **Set background opacity** in command pallette. This brings
the need for a separate Focused Opacity. When we change the runtime
opacity with scroll wheel or through command pallette this value needs
to be stored separately from the one in settings. So we can change back
to it when going to unfocused mode and back to focused instead of the
focused opacity defined in settings.

## `skipUnfocusedOpacity` solves Opacity going from solid to unfocused
to focused bug:

![skipUnfocusedOpacity_bug](https://github.com/microsoft/terminal/assets/15957528/ecc06dcf-fbef-4fef-a40f-68278fdbfb12)

## Validation Steps Performed

- Checked if unfocused Opacity works well when adjusting opacity through
Mouse Scroll Wheel or Command Palette and in combination with Acrylic as
mentioned in "Detailed Description of the Pull Request / Additional
comments"

## PR Checklist

- [x] Closes #11092 
- [ ] Tests added/passed
- [x] Documentation updated
- If checked, please file a pull request on [our docs
repo](https://github.com/MicrosoftDocs/terminal) and link it
here:(MicrosoftDocs/terminal#714)
- [ ] Schema updated (if necessary)

doc/cascadia/profiles.schema.json

@@ -273,6 +273,13 @@
         "useAcrylic":{
           "description": "When set to true, the window will have an acrylic material background when unfocused. When set to false, the window will have a plain, untextured background when unfocused.",
           "type": "boolean"
+        },
+        "opacity": {
+          "default": 100,
+          "description": "Sets the opacity of the window for the profile when unfocused. Accepts values from 0-100.",
+          "maximum": 100,
+          "minimum": 0,
+          "type": "number"
         }
       },
       "type": "object"

src/cascadia/TerminalControl/ControlCore.cpp

@@ -680,7 +680,14 @@ namespace winrt::Microsoft::Terminal::Control::implementation
         _setOpacity(Opacity() + adjustment);
     }
 
-    void ControlCore::_setOpacity(const double opacity)
+    // Method Description:
+    // - Updates the opacity of the terminal
+    // Arguments:
+    // - opacity: The new opacity to set.
+    // - focused (default == true): Whether the window is focused or unfocused.
+    // Return Value:
+    // - <none>
+    void ControlCore::_setOpacity(const double opacity, bool focused)
     {
         const auto newOpacity = std::clamp(opacity,
                                            0.0,
@@ -694,6 +701,10 @@ namespace winrt::Microsoft::Terminal::Control::implementation
         // Update our runtime opacity value
         _runtimeOpacity = newOpacity;
 
+        //Stores the focused runtime opacity separately from unfocused opacity
+        //to transition smoothly between the two.
+        _runtimeFocusedOpacity = focused ? newOpacity : _runtimeFocusedOpacity;
+
         // Manually turn off acrylic if they turn off transparency.
         _runtimeUseAcrylic = newOpacity < 1.0 && _settings->UseAcrylic();
 
@@ -824,6 +835,7 @@ namespace winrt::Microsoft::Terminal::Control::implementation
         _cellWidth = CSSLengthPercentage::FromString(_settings->CellWidth().c_str());
         _cellHeight = CSSLengthPercentage::FromString(_settings->CellHeight().c_str());
         _runtimeOpacity = std::nullopt;
+        _runtimeFocusedOpacity = std::nullopt;
 
         // Manually turn off acrylic if they turn off transparency.
         _runtimeUseAcrylic = _settings->Opacity() < 1.0 && _settings->UseAcrylic();
@@ -874,21 +886,29 @@ namespace winrt::Microsoft::Terminal::Control::implementation
             _renderEngine->SetRetroTerminalEffect(newAppearance->RetroTerminalEffect());
             _renderEngine->SetPixelShaderPath(newAppearance->PixelShaderPath());
 
+            // Incase EnableUnfocusedAcrylic is disabled and Focused Acrylic is set to true,
+            // the terminal should ignore the unfocused opacity from settings.
+            // The Focused Opacity from settings should be ignored if overridden at runtime.
+            bool useFocusedRuntimeOpacity = focused || (!_settings->EnableUnfocusedAcrylic() && UseAcrylic());
+            double newOpacity = useFocusedRuntimeOpacity ?
+                                    FocusedOpacity() :
+                                    newAppearance->Opacity();
+            _setOpacity(newOpacity, focused);
+
             // No need to update Acrylic if UnfocusedAcrylic is disabled
             if (_settings->EnableUnfocusedAcrylic())
             {
                 // Manually turn off acrylic if they turn off transparency.
                 _runtimeUseAcrylic = Opacity() < 1.0 && newAppearance->UseAcrylic();
+            }
 
-                // Update the renderer as well. It might need to fall back from
-                // cleartype -> grayscale if the BG is transparent / acrylic.
-                _renderEngine->EnableTransparentBackground(_isBackgroundTransparent());
-                _renderer->NotifyPaintFrame();
-
-                auto eventArgs = winrt::make_self<TransparencyChangedEventArgs>(Opacity());
+            // Update the renderer as well. It might need to fall back from
+            // cleartype -> grayscale if the BG is transparent / acrylic.
+            _renderEngine->EnableTransparentBackground(_isBackgroundTransparent());
+            _renderer->NotifyPaintFrame();
 
-                _TransparencyChangedHandlers(*this, *eventArgs);
-            }
+            auto eventArgs = winrt::make_self<TransparencyChangedEventArgs>(Opacity());
+            _TransparencyChangedHandlers(*this, *eventArgs);
 
             _renderer->TriggerRedrawAll(true, true);
         }

src/cascadia/TerminalControl/ControlCore.h

@@ -246,6 +246,7 @@ namespace winrt::Microsoft::Terminal::Control::implementation
         bool ShouldShowSelectOutput();
 
         RUNTIME_SETTING(double, Opacity, _settings->Opacity());
+        RUNTIME_SETTING(double, FocusedOpacity, FocusedAppearance().Opacity());
         RUNTIME_SETTING(bool, UseAcrylic, _settings->UseAcrylic());
 
         // -------------------------------- WinRT Events ---------------------------------
@@ -386,7 +387,7 @@ namespace winrt::Microsoft::Terminal::Control::implementation
         void _updateAntiAliasingMode();
         void _connectionOutputHandler(const hstring& hstr);
         void _updateHoveredCell(const std::optional<til::point> terminalPosition);
-        void _setOpacity(const double opacity);
+        void _setOpacity(const double opacity, const bool focused = true);
 
         bool _isBackgroundTransparent();
         void _focusChanged(bool focused);