Add an experimental setting for making suggestions RGB (microsoft#17416)

Adds `$profile:experimental.rainbowSuggestions`, which makes the
suggestion text all RGB. This sparks joy.

src/cascadia/TerminalControl/IControlAppearance.idl

@@ -19,5 +19,7 @@ namespace Microsoft.Terminal.Control
         Boolean RetroTerminalEffect { get; };
         String PixelShaderPath { get; };
         String PixelShaderImagePath { get; };
+
+        // NOTE! When adding something here, make sure to update ControlProperties.h too!
     };
 }

src/cascadia/TerminalControl/IControlSettings.idl

@@ -66,5 +66,7 @@ namespace Microsoft.Terminal.Control
         Boolean UseBackgroundImageForWindow { get; };
         Boolean RightClickContextMenu { get; };
         Boolean RepositionCursorWithMouse { get; };
+
+        // NOTE! When adding something here, make sure to update ControlProperties.h too!
     };
 }

src/cascadia/TerminalCore/ICoreAppearance.idl

@@ -122,5 +122,7 @@ namespace Microsoft.Terminal.Core
         Boolean IntenseIsBold;
         Boolean IntenseIsBright;
         AdjustTextMode AdjustIndistinguishableColors;
+
+        // NOTE! When adding something here, make sure to update ControlProperties.h too!
     };
 }

src/cascadia/TerminalCore/ICoreSettings.idl

@@ -27,7 +27,9 @@ namespace Microsoft.Terminal.Core
         Windows.Foundation.IReference<Microsoft.Terminal.Core.Color> StartingTabColor;
 
         Boolean AutoMarkPrompts;
+        Boolean RainbowSuggestions;
 
+        // NOTE! When adding something here, make sure to update ControlProperties.h too!
     };
 
 }

src/cascadia/TerminalCore/Terminal.cpp

@@ -95,6 +95,7 @@ void Terminal::UpdateSettings(ICoreSettings settings)
     _startingTitle = settings.StartingTitle();
     _trimBlockSelection = settings.TrimBlockSelection();
     _autoMarkPrompts = settings.AutoMarkPrompts();
+    _rainbowSuggestions = settings.RainbowSuggestions();
 
     _getTerminalInput().ForceDisableWin32InputMode(settings.ForceVTInput());
 
@@ -1586,7 +1587,7 @@ til::point Terminal::GetViewportRelativeCursorPosition() const noexcept
 
 void Terminal::PreviewText(std::wstring_view input)
 {
-    // Our suggestion text is default-on-default, in italics.
+    // Our default suggestion text is default-on-default, in italics.
     static constexpr TextAttribute previewAttrs{ CharacterAttributes::Italics, TextColor{}, TextColor{}, 0u, TextColor{} };
 
     auto lock = LockForWriting();
@@ -1626,11 +1627,43 @@ void Terminal::PreviewText(std::wstring_view input)
         // pad it out
         preview.insert(originalSize, expectedLenTillEnd - originalSize, L' ');
     }
-    snippetPreview.text = til::visualize_nonspace_control_codes(preview);
+
     // Build our composition data
+    // The text is just the trimmed command, with the spaces at the end.
+    snippetPreview.text = til::visualize_nonspace_control_codes(preview);
+
+    // The attributes depend on the $profile:experimental.rainbowSuggestions setting:.
     const auto len = snippetPreview.text.size();
     snippetPreview.attributes.clear();
-    snippetPreview.attributes.emplace_back(len, previewAttrs);
+
+    if (_rainbowSuggestions)
+    {
+        // Let's do something fun.
+
+        // Use the actual text length for the number of steps, not including the
+        // trailing spaces.
+        const float increment = 1.0f / originalSize;
+        for (auto i = 0u; i < originalSize; i++)
+        {
+            const auto color = til::color::from_hue(increment * i);
+            TextAttribute curr = previewAttrs;
+            curr.SetForeground(color);
+            snippetPreview.attributes.emplace_back(1, curr);
+        }
+
+        if (originalSize < len)
+        {
+            TextAttribute curr;
+            snippetPreview.attributes.emplace_back(len - originalSize, curr);
+        }
+    }
+    else
+    {
+        // Default:
+        // Use the default attribute we defined above.
+        snippetPreview.attributes.emplace_back(len, previewAttrs);
+    }
+
     snippetPreview.cursorPos = len;
     _activeBuffer().NotifyPaintFrame();
 }

src/cascadia/TerminalCore/Terminal.hpp

@@ -360,6 +360,7 @@ class Microsoft::Terminal::Core::Terminal final :
     bool _suppressApplicationTitle = false;
     bool _trimBlockSelection = false;
     bool _autoMarkPrompts = false;
+    bool _rainbowSuggestions = false;
 
     size_t _taskbarState = 0;
     size_t _taskbarProgress = 0;

src/cascadia/TerminalSettingsModel/MTSMSettings.h

@@ -96,7 +96,8 @@ Author(s):
     X(bool, AutoMarkPrompts, "autoMarkPrompts", false)                                                                                                         \
     X(bool, ShowMarks, "showMarksOnScrollbar", false)                                                                                                          \
     X(bool, RepositionCursorWithMouse, "experimental.repositionCursorWithMouse", false)                                                                        \
-    X(bool, ReloadEnvironmentVariables, "compatibility.reloadEnvironmentVariables", true)
+    X(bool, ReloadEnvironmentVariables, "compatibility.reloadEnvironmentVariables", true)                                                                      \
+    X(bool, RainbowSuggestions, "experimental.rainbowSuggestions", false)
 
 // Intentionally omitted Profile settings:
 // * Name

src/cascadia/TerminalSettingsModel/Profile.idl

@@ -87,6 +87,7 @@ namespace Microsoft.Terminal.Settings.Model
         INHERITABLE_PROFILE_SETTING(Boolean, RepositionCursorWithMouse);
 
         INHERITABLE_PROFILE_SETTING(Boolean, ReloadEnvironmentVariables);
+        INHERITABLE_PROFILE_SETTING(Boolean, RainbowSuggestions);
 
     }
 }

src/cascadia/TerminalSettingsModel/TerminalSettings.cpp

@@ -343,10 +343,9 @@ namespace winrt::Microsoft::Terminal::Settings::Model::implementation
         _ShowMarks = Feature_ScrollbarMarks::IsEnabled() && profile.ShowMarks();
 
         _RightClickContextMenu = profile.RightClickContextMenu();
-
         _RepositionCursorWithMouse = profile.RepositionCursorWithMouse();
-
         _ReloadEnvironmentVariables = profile.ReloadEnvironmentVariables();
+        _RainbowSuggestions = profile.RainbowSuggestions();
     }
 
     // Method Description:

src/cascadia/TerminalSettingsModel/TerminalSettings.h

@@ -112,6 +112,7 @@ namespace winrt::Microsoft::Terminal::Settings::Model::implementation
         INHERITABLE_SETTING(Model::TerminalSettings, bool, IntenseIsBright);
 
         INHERITABLE_SETTING(Model::TerminalSettings, Microsoft::Terminal::Core::AdjustTextMode, AdjustIndistinguishableColors, Core::AdjustTextMode::Never);
+        INHERITABLE_SETTING(Model::TerminalSettings, bool, RainbowSuggestions, false);
 
         // ------------------------ End of Core Settings -----------------------
 

src/cascadia/WindowsTerminal/AppHost.cpp

@@ -1128,33 +1128,14 @@ void AppHost::_stopFrameTimer()
 //   is called as the `_frameTimer` Tick callback, roughly 60 times per second.
 void AppHost::_updateFrameColor(const winrt::Windows::Foundation::IInspectable&, const winrt::Windows::Foundation::IInspectable&)
 {
-    // First, a couple helper functions:
-    static const auto saturateAndToColor = [](const float a, const float b, const float c) -> til::color {
-        return til::color{
-            base::saturated_cast<uint8_t>(255.f * std::clamp(a, 0.f, 1.f)),
-            base::saturated_cast<uint8_t>(255.f * std::clamp(b, 0.f, 1.f)),
-            base::saturated_cast<uint8_t>(255.f * std::clamp(c, 0.f, 1.f))
-        };
-    };
-
-    // Helper for converting a hue [0, 1) to an RGB value.
-    // Credit to https://www.chilliant.com/rgb2hsv.html
-    static const auto hueToRGB = [&](const float H) -> til::color {
-        float R = abs(H * 6 - 3) - 1;
-        float G = 2 - abs(H * 6 - 2);
-        float B = 2 - abs(H * 6 - 4);
-        return saturateAndToColor(R, G, B);
-    };
-
-    // Now, the main body of work.
     // - Convert the time delta between when we were started and now, to a hue. This will cycle us through all the colors.
     // - Convert that hue to an RGB value.
     // - Set the frame's color to that RGB color.
     const auto now = std::chrono::high_resolution_clock::now();
     const std::chrono::duration<float> delta{ now - _started };
     const auto seconds = delta.count() / 4; // divide by four, to make the effect slower. Otherwise it flashes way to fast.
     float ignored;
-    const auto color = hueToRGB(modf(seconds, &ignored));
+    const auto color = til::color::from_hue(modf(seconds, &ignored));
 
     _frameColorHelper(_window->GetHandle(), color);
 }

src/cascadia/inc/ControlProperties.h

@@ -49,7 +49,8 @@
     X(winrt::hstring, StartingTitle)                                                                              \
     X(bool, DetectURLs, true)                                                                                     \
     X(bool, AutoMarkPrompts)                                                                                      \
-    X(bool, RepositionCursorWithMouse, false)
+    X(bool, RepositionCursorWithMouse, false)                                                                     \
+    X(bool, RainbowSuggestions)
 
 // --------------------------- Control Settings ---------------------------
 //  All of these settings are defined in IControlSettings.

src/inc/til/color.h

@@ -186,6 +186,20 @@ namespace til // Terminal Implementation Library. Also: "Today I Learned"
         }
 #endif
 
+        // Helper for converting a hue [0, 1) to an RGB value.
+        // Credit to https://www.chilliant.com/rgb2hsv.html
+        static til::color from_hue(float hue)
+        {
+            const float R = abs(hue * 6 - 3) - 1;
+            const float G = 2 - abs(hue * 6 - 2);
+            const float B = 2 - abs(hue * 6 - 4);
+            return color{
+                base::saturated_cast<uint8_t>(255.f * std::clamp(R, 0.f, 1.f)),
+                base::saturated_cast<uint8_t>(255.f * std::clamp(G, 0.f, 1.f)),
+                base::saturated_cast<uint8_t>(255.f * std::clamp(B, 0.f, 1.f))
+            };
+        }
+
         constexpr bool operator==(const til::color& other) const
         {
             return abgr == other.abgr;