Add support for other underline types and the ability to color them (#679)

examples/interactive-demo/src/test/attribute.rs

@@ -8,6 +8,10 @@ const ATTRIBUTES: [(style::Attribute, style::Attribute); 6] = [
     (style::Attribute::Bold, style::Attribute::NormalIntensity),
     (style::Attribute::Italic, style::Attribute::NoItalic),
     (style::Attribute::Underlined, style::Attribute::NoUnderline),
+    (style::Attribute::DoubleUnderlined, style::Attribute::NoUnderline),
+    (style::Attribute::Undercurled, style::Attribute::NoUnderline),
+    (style::Attribute::Underdotted, style::Attribute::NoUnderline),
+    (style::Attribute::Underdashed, style::Attribute::NoUnderline),
     (style::Attribute::Reverse, style::Attribute::NoReverse),
     (
         style::Attribute::CrossedOut,

src/style.rs

@@ -217,6 +217,25 @@ impl Command for SetBackgroundColor {
     }
 }
 
+/// A command that sets the the underline color.
+///
+/// See [`Color`](enum.Color.html) for more info.
+///
+/// [`SetColors`](struct.SetColors.html) can also be used to set both the foreground and background
+/// color with one command.
+///
+/// # Notes
+///
+/// Commands must be executed/queued for execution otherwise they do nothing.
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub struct SetUnderlineColor(pub Color);
+
+impl Command for SetUnderlineColor {
+    fn write_ansi(&self, f: &mut impl fmt::Write) -> fmt::Result {
+        write!(f, csi!("{}m"), Colored::UnderlineColor(self.0))
+    }
+}
+
 /// A command that optionally sets the foreground and/or background color.
 ///
 /// For example:
@@ -340,6 +359,11 @@ impl<D: Display> Command for PrintStyledContent<D> {
             reset_foreground = true;
         }
 
+        if let Some(ul) = style.underline_color {
+            execute_fmt(f, SetUnderlineColor(ul)).map_err(|_| fmt::Error)?;
+            reset_foreground = true;
+        }
+
         if !style.attributes.is_empty() {
             execute_fmt(f, SetAttributes(style.attributes)).map_err(|_| fmt::Error)?;
             reset = true;

src/style/content_style.rs

@@ -11,6 +11,8 @@ pub struct ContentStyle {
     pub foreground_color: Option<Color>,
     /// The background color.
     pub background_color: Option<Color>,
+    /// The underline color.
+    pub underline_color: Option<Color>,
     /// List of attributes.
     pub attributes: Attributes,
 }

src/style/stylize.rs

@@ -17,7 +17,7 @@ macro_rules! stylize_method {
             }
         }
     };
-    ($method_name_fg:ident, $method_name_bg:ident Color::$color:ident) => {
+    ($method_name_fg:ident, $method_name_bg:ident, $method_name_ul:ident Color::$color:ident) => {
         calculated_docs! {
             #[doc = concat!(
                 "Sets the foreground color to [`",
@@ -40,6 +40,17 @@ macro_rules! stylize_method {
             fn $method_name_bg(self) -> Self::Styled {
                 self.on(Color::$color)
             }
+
+            #[doc = concat!(
+                "Sets the underline color to [`",
+                stringify!($color),
+                "`](Color::",
+                stringify!($color),
+                ")."
+            )]
+            fn $method_name_ul(self) -> Self::Styled {
+                self.underline(Color::$color)
+            }
         }
     };
 }
@@ -77,6 +88,13 @@ pub trait Stylize: Sized {
         styled
     }
 
+    /// Sets the underline color.
+    fn underline(self, color: Color) -> Self::Styled {
+        let mut styled = self.stylize();
+        styled.as_mut().underline_color = Some(color);
+        styled
+    }
+
     /// Styles the content with the attribute.
     fn attribute(self, attr: Attribute) -> Self::Styled {
         let mut styled = self.stylize();
@@ -96,22 +114,22 @@ pub trait Stylize: Sized {
     stylize_method!(hidden Attribute::Hidden);
     stylize_method!(crossed_out Attribute::CrossedOut);
 
-    stylize_method!(black, on_black Color::Black);
+    stylize_method!(black, on_black, underline_black Color::Black);
-    stylize_method!(dark_grey, on_dark_grey Color::DarkGrey);
+    stylize_method!(dark_grey, on_dark_grey, underline_dark_grey Color::DarkGrey);
-    stylize_method!(red, on_red Color::Red);
+    stylize_method!(red, on_red, underline_red Color::Red);
-    stylize_method!(dark_red, on_dark_red Color::DarkRed);
+    stylize_method!(dark_red, on_dark_red, underline_dark_red Color::DarkRed);
-    stylize_method!(green, on_green Color::Green);
+    stylize_method!(green, on_green, underline_green Color::Green);
-    stylize_method!(dark_green, on_dark_green Color::DarkGreen);
+    stylize_method!(dark_green, on_dark_green, underline_dark_green Color::DarkGreen);
-    stylize_method!(yellow, on_yellow Color::Yellow);
+    stylize_method!(yellow, on_yellow, underline_yellow Color::Yellow);
-    stylize_method!(dark_yellow, on_dark_yellow Color::DarkYellow);
+    stylize_method!(dark_yellow, on_dark_yellow, underline_dark_yellow Color::DarkYellow);
-    stylize_method!(blue, on_blue Color::Blue);
+    stylize_method!(blue, on_blue, underline_blue Color::Blue);
-    stylize_method!(dark_blue, on_dark_blue Color::DarkBlue);
+    stylize_method!(dark_blue, on_dark_blue, underline_dark_blue Color::DarkBlue);
-    stylize_method!(magenta, on_magenta Color::Magenta);
+    stylize_method!(magenta, on_magenta, underline_magenta Color::Magenta);
-    stylize_method!(dark_magenta, on_dark_magenta Color::DarkMagenta);
+    stylize_method!(dark_magenta, on_dark_magenta, underline_dark_magenta Color::DarkMagenta);
-    stylize_method!(cyan, on_cyan Color::Cyan);
+    stylize_method!(cyan, on_cyan, underline_cyan Color::Cyan);
-    stylize_method!(dark_cyan, on_dark_cyan Color::DarkCyan);
+    stylize_method!(dark_cyan, on_dark_cyan, underline_dark_cyan Color::DarkCyan);
-    stylize_method!(white, on_white Color::White);
+    stylize_method!(white, on_white, underline_white Color::White);
-    stylize_method!(grey, on_grey Color::Grey);
+    stylize_method!(grey, on_grey, underline_grey Color::Grey);
 }
 
 macro_rules! impl_stylize_for_display {

src/style/types/attribute.rs

@@ -100,6 +100,17 @@ Attribute! {
     Italic = 3,
     /// Underlines the text.
     Underlined = 4,
+
+    // Other types of underlining
+    /// Double underlines the text.
+    DoubleUnderlined = 2,
+    /// Undercurls the text.
+    Undercurled = 3,
+    /// Underdots the text.
+    Underdotted = 4,
+    /// Underdashes the text.
+    Underdashed = 5,
+
     /// Makes the text blinking (< 150 per minute).
     SlowBlink = 5,
     /// Makes the text blinking (>= 150 per minute).
@@ -163,7 +174,10 @@ impl Attribute {
     /// Returns the SGR attribute value.
     ///
     /// See <https://en.wikipedia.org/wiki/ANSI_escape_code#SGR_parameters>
-    pub fn sgr(self) -> i16 {
+    pub fn sgr(self) -> String {
-        SGR[self as usize]
+        if (self as usize) > 4 && (self as usize) < 9 {
+            return "4:".to_string() + SGR[self as usize].to_string().as_str()
+        }
+        SGR[self as usize].to_string()
     }
 }

src/style/types/colored.rs

@@ -16,6 +16,8 @@ pub enum Colored {
     ForegroundColor(Color),
     /// A background color.
     BackgroundColor(Color),
+    /// An underline color.
+    UnderlineColor(Color),
 }
 
 impl Colored {
@@ -39,16 +41,18 @@ impl Colored {
     ///
     /// See also: [`Color::parse_ansi`].
     pub fn parse_ansi(ansi: &str) -> Option<Self> {
-        use Colored::{BackgroundColor, ForegroundColor};
+        use Colored::{BackgroundColor, ForegroundColor, UnderlineColor};
 
         let values = &mut ansi.split(';');
 
         let output = match parse_next_u8(values)? {
             38 => return Color::parse_ansi_iter(values).map(ForegroundColor),
             48 => return Color::parse_ansi_iter(values).map(BackgroundColor),
+            58 => return Color::parse_ansi_iter(values).map(UnderlineColor),
 
             39 => ForegroundColor(Color::Reset),
             49 => BackgroundColor(Color::Reset),
+            59 => UnderlineColor(Color::Reset),
 
             _ => return None,
         };
@@ -82,6 +86,14 @@ impl fmt::Display for Colored {
                     color = new_color;
                 }
             }
+            Colored::UnderlineColor(new_color) => {
+                if new_color == Color::Reset {
+                    return f.write_str("59");
+                } else {
+                    f.write_str("58;")?;
+                    color = new_color;
+                }
+            }
         }
 
         match color {

src/style/types/colors.rs

@@ -63,6 +63,10 @@ impl From<Colored> for Colors {
                 foreground: None,
                 background: Some(color),
             },
+            Colored::UnderlineColor(color) => Colors {
+                foreground: None,
+                background: Some(color),
+            }
         }
     }
 }