Add support for underline style and color in VT

src/buffer/out/OutputCellIterator.cpp

@@ -11,7 +11,7 @@
 #include "../../types/inc/GlyphWidth.hpp"
 #include "../../inc/conattrs.hpp"
 
-static constexpr TextAttribute InvalidTextAttribute{ INVALID_COLOR, INVALID_COLOR };
+static constexpr TextAttribute InvalidTextAttribute{ INVALID_COLOR, INVALID_COLOR, INVALID_COLOR };
 
 // Routine Description:
 // - This is a fill-mode iterator for one particular wchar. It will repeat forever if fillLimit is 0.

src/buffer/out/TextAttribute.cpp

@@ -7,7 +7,7 @@
 
 // Keeping TextColor compact helps us keeping TextAttribute compact,
 // which in turn ensures that our buffer memory usage is low.
-static_assert(sizeof(TextAttribute) == 12);
+static_assert(sizeof(TextAttribute) == 16);
 static_assert(alignof(TextAttribute) == 2);
 // Ensure that we can memcpy() and memmove() the struct for performance.
 static_assert(std::is_trivially_copyable_v<TextAttribute>);
@@ -156,6 +156,25 @@ uint16_t TextAttribute::GetHyperlinkId() const noexcept
     return _hyperlinkId;
 }
 
+TextColor TextAttribute::GetUnderlineColor() const noexcept
+{
+    return _underlineColor;
+}
+
+// Method description:
+// - Retrieves the underline style of the text.
+// - If the attribute is not the **current** attribute of the text buffer,
+//   (eg. reading an attribute from another part of the text buffer, which
+//   was modified using DECRARA), this might return an invalid style. In this
+//   case, treat the style as singly underlined.
+// Return value:
+// - The underline style.
+UnderlineStyle TextAttribute::GetUnderlineStyle() const noexcept
+{
+    const auto styleAttr = WI_EnumValue(_attrs & CharacterAttributes::UnderlineStyle);
+    return static_cast<UnderlineStyle>(styleAttr >> UNDERLINE_STYLE_SHIFT);
+}
+
 void TextAttribute::SetForeground(const TextColor foreground) noexcept
 {
     _foreground = foreground;
@@ -166,6 +185,13 @@ void TextAttribute::SetBackground(const TextColor background) noexcept
     _background = background;
 }
 
+void TextAttribute::SetUnderlineColor(const TextColor color) noexcept
+{
+    // Index16 colors are not supported for underline colors.
+    assert(!color.IsIndex16());
+    _underlineColor = color;
+}
+
 void TextAttribute::SetForeground(const COLORREF rgbForeground) noexcept
 {
     _foreground = TextColor(rgbForeground);
@@ -277,14 +303,12 @@ bool TextAttribute::IsCrossedOut() const noexcept
     return WI_IsFlagSet(_attrs, CharacterAttributes::CrossedOut);
 }
 
+// Method description:
+// - Returns true if the text is underlined with any underline style.
 bool TextAttribute::IsUnderlined() const noexcept
 {
-    return WI_IsFlagSet(_attrs, CharacterAttributes::Underlined);
-}
-
-bool TextAttribute::IsDoublyUnderlined() const noexcept
-{
-    return WI_IsFlagSet(_attrs, CharacterAttributes::DoublyUnderlined);
+    const auto style = GetUnderlineStyle();
+    return (style != UnderlineStyle::NoUnderline);
 }
 
 bool TextAttribute::IsOverlined() const noexcept
@@ -332,14 +356,14 @@ void TextAttribute::SetCrossedOut(bool isCrossedOut) noexcept
     WI_UpdateFlag(_attrs, CharacterAttributes::CrossedOut, isCrossedOut);
 }
 
-void TextAttribute::SetUnderlined(bool isUnderlined) noexcept
-{
-    WI_UpdateFlag(_attrs, CharacterAttributes::Underlined, isUnderlined);
-}
-
-void TextAttribute::SetDoublyUnderlined(bool isDoublyUnderlined) noexcept
+// Method description:
+// - Sets underline style to singly, doubly, or one of the extended styles.
+// Arguments:
+// - style - underline style to set.
+void TextAttribute::SetUnderlineStyle(const UnderlineStyle style) noexcept
 {
-    WI_UpdateFlag(_attrs, CharacterAttributes::DoublyUnderlined, isDoublyUnderlined);
+    const auto shiftedStyle = WI_EnumValue(style) << UNDERLINE_STYLE_SHIFT;
+    _attrs = (_attrs & ~CharacterAttributes::UnderlineStyle) | static_cast<CharacterAttributes>(shiftedStyle);
 }
 
 void TextAttribute::SetOverlined(bool isOverlined) noexcept
@@ -374,6 +398,11 @@ void TextAttribute::SetDefaultBackground() noexcept
     _background = TextColor();
 }
 
+void TextAttribute::SetDefaultUnderlineColor() noexcept
+{
+    _underlineColor = TextColor{};
+}
+
 // Method description:
 // - Resets only the rendition character attributes, which includes everything
 //     except the Protected attribute.

src/buffer/out/TextAttribute.hpp

@@ -27,31 +27,55 @@ Revision History:
 #include "WexTestClass.h"
 #endif
 
+enum class UnderlineStyle
+{
+    NoUnderline = 0U,
+    SinglyUnderlined = 1U,
+    DoublyUnderlined = 2U,
+    CurlyUnderlined = 3U,
+    DottedUnderlined = 4U,
+    DashedUnderlined = 5U,
+    Max = DashedUnderlined
+};
+
 class TextAttribute final
 {
 public:
     constexpr TextAttribute() noexcept :
         _attrs{ CharacterAttributes::Normal },
         _foreground{},
         _background{},
-        _hyperlinkId{ 0 }
+        _hyperlinkId{ 0 },
+        _underlineColor{}
     {
     }
 
     explicit constexpr TextAttribute(const WORD wLegacyAttr) noexcept :
         _attrs{ gsl::narrow_cast<WORD>(wLegacyAttr & USED_META_ATTRS) },
         _foreground{ gsl::at(s_legacyForegroundColorMap, wLegacyAttr & FG_ATTRS) },
         _background{ gsl::at(s_legacyBackgroundColorMap, (wLegacyAttr & BG_ATTRS) >> 4) },
-        _hyperlinkId{ 0 }
+        _hyperlinkId{ 0 },
+        _underlineColor{}
     {
     }
 
     constexpr TextAttribute(const COLORREF rgbForeground,
-                            const COLORREF rgbBackground) noexcept :
+                            const COLORREF rgbBackground,
+                            const COLORREF rgbUnderline = INVALID_COLOR) noexcept :
         _attrs{ CharacterAttributes::Normal },
         _foreground{ rgbForeground },
         _background{ rgbBackground },
-        _hyperlinkId{ 0 }
+        _hyperlinkId{ 0 },
+        _underlineColor{ rgbUnderline }
+    {
+    }
+
+    constexpr TextAttribute(const CharacterAttributes attrs, const TextColor foreground, const TextColor background, const uint16_t hyperlinkId, const TextColor underlineColor) noexcept :
+        _attrs{ attrs },
+        _foreground{ foreground },
+        _background{ background },
+        _hyperlinkId{ hyperlinkId },
+        _underlineColor{ underlineColor }
     {
     }
 
@@ -87,7 +111,6 @@ class TextAttribute final
     bool IsInvisible() const noexcept;
     bool IsCrossedOut() const noexcept;
     bool IsUnderlined() const noexcept;
-    bool IsDoublyUnderlined() const noexcept;
     bool IsOverlined() const noexcept;
     bool IsReverseVideo() const noexcept;
     bool IsProtected() const noexcept;
@@ -98,8 +121,7 @@ class TextAttribute final
     void SetBlinking(bool isBlinking) noexcept;
     void SetInvisible(bool isInvisible) noexcept;
     void SetCrossedOut(bool isCrossedOut) noexcept;
-    void SetUnderlined(bool isUnderlined) noexcept;
-    void SetDoublyUnderlined(bool isDoublyUnderlined) noexcept;
+    void SetUnderlineStyle(const UnderlineStyle underlineStyle) noexcept;
     void SetOverlined(bool isOverlined) noexcept;
     void SetReverseVideo(bool isReversed) noexcept;
     void SetProtected(bool isProtected) noexcept;
@@ -118,8 +140,11 @@ class TextAttribute final
     TextColor GetForeground() const noexcept;
     TextColor GetBackground() const noexcept;
     uint16_t GetHyperlinkId() const noexcept;
+    TextColor GetUnderlineColor() const noexcept;
+    UnderlineStyle GetUnderlineStyle() const noexcept;
     void SetForeground(const TextColor foreground) noexcept;
     void SetBackground(const TextColor background) noexcept;
+    void SetUnderlineColor(const TextColor color) noexcept;
     void SetForeground(const COLORREF rgbForeground) noexcept;
     void SetBackground(const COLORREF rgbBackground) noexcept;
     void SetIndexedForeground(const BYTE fgIndex) noexcept;
@@ -131,6 +156,7 @@ class TextAttribute final
 
     void SetDefaultForeground() noexcept;
     void SetDefaultBackground() noexcept;
+    void SetDefaultUnderlineColor() noexcept;
     void SetDefaultRenditionAttributes() noexcept;
 
     bool BackgroundIsDefault() const noexcept;
@@ -147,8 +173,8 @@ class TextAttribute final
         // global ^ local == false: the foreground attribute is the visible foreground, so we care about the backgrounds being identical
         const auto checkForeground = (inverted != IsReverseVideo());
         return !IsAnyGridLineEnabled() && // grid lines have a visual representation
-               // crossed out, doubly and singly underlined have a visual representation
-               WI_AreAllFlagsClear(_attrs, CharacterAttributes::CrossedOut | CharacterAttributes::DoublyUnderlined | CharacterAttributes::Underlined) &&
+               // styled underline and crossed out have a visual representation
+               !IsUnderlined() && WI_IsFlagClear(_attrs, CharacterAttributes::CrossedOut) &&
                // hyperlinks have a visual representation
                !IsHyperlink() &&
                // all other attributes do not have a visual representation
@@ -175,6 +201,7 @@ class TextAttribute final
     uint16_t _hyperlinkId; // sizeof: 2, alignof: 2
     TextColor _foreground; // sizeof: 4, alignof: 1
     TextColor _background; // sizeof: 4, alignof: 1
+    TextColor _underlineColor; // sizeof: 4, alignof: 1
 
 #ifdef UNIT_TESTING
     friend class TextBufferTests;

src/cascadia/TerminalCore/Terminal.cpp

@@ -287,7 +287,7 @@ std::wstring_view Terminal::GetWorkingDirectory() noexcept
         // but after the resize, we'll want to make sure that the new buffer's
         // current attributes (the ones used for printing new text) match the
         // old buffer's.
-        const auto oldBufferAttributes = _mainBuffer->GetCurrentAttributes();
+        const auto& oldBufferAttributes = _mainBuffer->GetCurrentAttributes();
         newTextBuffer = std::make_unique<TextBuffer>(bufferSize,
                                                      TextAttribute{},
                                                      0, // temporarily set size to 0 so it won't render.

src/host/ut_host/OutputCellIteratorTests.cpp

@@ -11,7 +11,7 @@ using namespace WEX::Common;
 using namespace WEX::Logging;
 using namespace WEX::TestExecution;
 
-static constexpr TextAttribute InvalidTextAttribute{ INVALID_COLOR, INVALID_COLOR };
+static constexpr TextAttribute InvalidTextAttribute{ INVALID_COLOR, INVALID_COLOR, INVALID_COLOR };
 
 class OutputCellIteratorTests
 {