Add support for more SGR decorations (underline color, underline styl…

…e, rapid blink).

Fixes #67.

src/core/Text/Control/ControlBuilder.cs

@@ -572,15 +572,33 @@ public ControlBuilder SetBackgroundColor(byte r, byte g, byte b)
             .Print(gSpan[..gLen]).Print(";").Print(bSpan[..bLen]).Print("m");
     }
 
+    public ControlBuilder SetUnderlineColor(byte r, byte g, byte b)
+    {
+        Span<char> rSpan = stackalloc char[StackBufferSize];
+        Span<char> gSpan = stackalloc char[StackBufferSize];
+        Span<char> bSpan = stackalloc char[StackBufferSize];
+
+        _ = r.TryFormat(rSpan, out var rLen);
+        _ = g.TryFormat(gSpan, out var gLen);
+        _ = b.TryFormat(bSpan, out var bLen);
+
+        return Print(CSI).Print("58;2;").Print(rSpan[..rLen]).Print(";")
+            .Print(gSpan[..gLen]).Print(";").Print(bSpan[..bLen]).Print("m");
+    }
+
     public ControlBuilder SetDecorations(
         bool bold = false,
         bool faint = false,
         bool italic = false,
         bool underline = false,
+        bool curlyUnderline = false,
+        bool dottedUnderline = false,
+        bool dashedUnderline = false,
         bool blink = false,
+        bool rapidBlink = false,
         bool invert = false,
         bool invisible = false,
-        bool strike = false,
+        bool strikethrough = false,
         bool doubleUnderline = false,
         bool overline = false)
     {
@@ -601,15 +619,18 @@ void HandleMode(bool value, ReadOnlySpan<char> code)
             _ = Print(code);
         }
 
-        // TODO: Support more exotic decorations?
         HandleMode(bold, "1");
         HandleMode(faint, "2");
         HandleMode(italic, "3");
         HandleMode(underline, "4");
+        HandleMode(curlyUnderline, "4:3");
+        HandleMode(dottedUnderline, "4:4");
+        HandleMode(dashedUnderline, "4:5");
         HandleMode(blink, "5");
+        HandleMode(rapidBlink, "6");
         HandleMode(invert, "7");
         HandleMode(invisible, "8");
-        HandleMode(strike, "9");
+        HandleMode(strikethrough, "9");
         HandleMode(doubleUnderline, "21");
         HandleMode(overline, "53");
 

src/samples/attributes/Program.cs

@@ -21,23 +21,36 @@ await OutAsync(
         .SetDecorations(underline: true)
         .PrintLine("This text is underlined.")
         .ResetAttributes()
+        .SetDecorations(curlyUnderline: true)
+        .PrintLine("This text is underlined (curly).")
+        .ResetAttributes()
+        .SetDecorations(dottedUnderline: true)
+        .PrintLine("This text is underlined (dotted).")
+        .ResetAttributes()
+        .SetDecorations(dashedUnderline: true)
+        .PrintLine("This text is underlined (dashed).")
+        .ResetAttributes()
         .SetDecorations(blink: true)
         .PrintLine("This text is blinking.")
         .ResetAttributes()
+        .SetDecorations(rapidBlink: true)
+        .PrintLine("This text is rapidly blinking.")
+        .ResetAttributes()
         .SetDecorations(invert: true)
         .PrintLine("This text is inverted.")
         .ResetAttributes()
         .SetDecorations(invisible: true)
         .PrintLine("This text is invisible.")
-        .SetDecorations(strike: true)
-        .PrintLine("This text is struck through.")
         .ResetAttributes()
-        .SetDecorations(overline: true)
-        .PrintLine("This text is overlined.")
+        .SetDecorations(strikethrough: true)
+        .PrintLine("This text is struck through.")
         .ResetAttributes()
         .SetDecorations(doubleUnderline: true)
         .PrintLine("This text is doubly underlined.")
         .ResetAttributes()
+        .SetDecorations(overline: true)
+        .PrintLine("This text is overlined.")
+        .ResetAttributes()
         .OpenHyperlink(new("https://google.com"))
         .PrintLine("This is a Google hyperlink.")
         .CloseHyperlink()