added ansi gradient in the spirit of fun (#3570)

Cargo.lock

@@ -3272,6 +3272,8 @@ name = "nu-ansi-term"
 version = "0.32.1"
 dependencies = [
  "doc-comment",
+ "itertools",
+ "overload",
  "regex 1.5.4",
  "serde 1.0.126",
  "serde_json",
@@ -4294,6 +4296,12 @@ dependencies = [
  "num-traits 0.2.14",
 ]
 
+[[package]]
+name = "overload"
+version = "0.1.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "b15813163c1d831bf4a13c3610c05c0d03b39feb07f7e09fa234dac9b15aaf39"
+
 [[package]]
 name = "parking"
 version = "2.0.0"

crates/nu-ansi-term/Cargo.toml

@@ -18,10 +18,15 @@ doctest = false
 [features]
 derive_serde_style = ["serde"]
 
-[dependencies.serde]
-version = "1.0.90"
-features = ["derive"]
-optional = true
+[dependencies]
+overload = "0.1.1"
+serde = { version = "1.0.90", features = ["derive"], optional = true }
+itertools = "0.10.0"
+
+# [dependencies.serde]
+# version = "1.0.90"
+# features = ["derive"]
+# optional = true
 
 [target.'cfg(target_os="windows")'.dependencies.winapi]
 version = "0.3.4"

crates/nu-ansi-term/examples/gradient_colors.rs

@@ -0,0 +1,37 @@
+use nu_ansi_term::{build_all_gradient_text, Color, Gradient, Rgb, TargetGround};
+
+fn main() {
+    let text = "lorem ipsum quia dolor sit amet, consectetur, adipisci velit";
+
+    // a gradient from hex colors
+    let start = Rgb::from_hex(0x40c9ff);
+    let end = Rgb::from_hex(0xe81cff);
+    let grad0 = Gradient::new(start, end);
+
+    // a gradient from color::rgb()
+    let start = Color::Rgb(64, 201, 255);
+    let end = Color::Rgb(232, 28, 255);
+    let gradient = Gradient::from_color_rgb(start, end);
+
+    // a slightly different gradient
+    let start2 = Color::Rgb(128, 64, 255);
+    let end2 = Color::Rgb(0, 28, 255);
+    let gradient2 = Gradient::from_color_rgb(start2, end2);
+
+    // reverse the gradient
+    let gradient3 = gradient.reverse();
+
+    let build_fg = gradient.build(text, TargetGround::Foreground);
+    println!("{}", build_fg);
+    let build_bg = gradient.build(text, TargetGround::Background);
+    println!("{}", build_bg);
+    let bgt = build_all_gradient_text(text, gradient, gradient2);
+    println!("{}", bgt);
+    let bgt2 = build_all_gradient_text(text, gradient, gradient3);
+    println!("{}", bgt2);
+
+    println!(
+        "{}",
+        grad0.build("nushell is awesome", TargetGround::Foreground)
+    );
+}

crates/nu-ansi-term/src/gradient.rs

@@ -0,0 +1,105 @@
+use crate::{rgb::Rgb, Color};
+
+/// Linear color gradient between two color stops
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub struct Gradient {
+    /// Start Color of Gradient
+    pub start: Rgb,
+
+    /// End Color of Gradient
+    pub end: Rgb,
+}
+
+impl Gradient {
+    /// Creates a new [Gradient] with two [Rgb] colors, `start` and `end`
+    #[inline]
+    pub const fn new(start: Rgb, end: Rgb) -> Self {
+        Self { start, end }
+    }
+    pub const fn from_color_rgb(start: Color, end: Color) -> Self {
+        let start_grad = match start {
+            Color::Rgb(r, g, b) => Rgb { r, g, b },
+            _ => Rgb { r: 0, g: 0, b: 0 },
+        };
+        let end_grad = match end {
+            Color::Rgb(r, g, b) => Rgb { r, g, b },
+            _ => Rgb { r: 0, g: 0, b: 0 },
+        };
+
+        Self {
+            start: start_grad,
+            end: end_grad,
+        }
+    }
+
+    /// Computes the [Rgb] color between `start` and `end` for `t`
+    pub fn at(&self, t: f32) -> Rgb {
+        self.start.lerp(self.end, t)
+    }
+
+    /// Returns the reverse of `self`
+    #[inline]
+    pub const fn reverse(&self) -> Self {
+        Self::new(self.end, self.start)
+    }
+
+    #[allow(dead_code)]
+    pub fn build(&self, text: &str, target: TargetGround) -> String {
+        let delta = 1.0 / text.len() as f32;
+        let mut result = text.char_indices().fold(String::new(), |mut acc, (i, c)| {
+            let temp = format!(
+                "\x1B[{}m{}",
+                self.at(i as f32 * delta).ansi_color_code(target),
+                c
+            );
+            acc.push_str(&temp);
+            acc
+        });
+
+        result.push_str("\x1B[0m");
+        result
+    }
+}
+
+#[allow(dead_code)]
+pub fn build_all_gradient_text(text: &str, foreground: Gradient, background: Gradient) -> String {
+    let delta = 1.0 / text.len() as f32;
+    let mut result = text.char_indices().fold(String::new(), |mut acc, (i, c)| {
+        let step = i as f32 * delta;
+        let temp = format!(
+            "\x1B[{};{}m{}",
+            foreground
+                .at(step)
+                .ansi_color_code(TargetGround::Foreground),
+            background
+                .at(step)
+                .ansi_color_code(TargetGround::Background),
+            c
+        );
+        acc.push_str(&temp);
+        acc
+    });
+
+    result.push_str("\x1B[0m");
+    result
+}
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub enum TargetGround {
+    Foreground,
+    Background,
+}
+
+impl TargetGround {
+    #[inline]
+    pub const fn code(&self) -> u8 {
+        match self {
+            Self::Foreground => 30,
+            Self::Background => 40,
+        }
+    }
+}
+
+pub trait ANSIColorCode {
+    fn ansi_color_code(&self, target: TargetGround) -> String;
+}

crates/nu-ansi-term/src/lib.rs

@@ -121,13 +121,13 @@
 //! `Fixed` colors instead, but there’s nothing to be gained by doing so
 //! either.
 //!
-//! You can also access full 24-bit color by using the `Color::RGB` variant,
+//! You can also access full 24-bit color by using the `Color::Rgb` variant,
 //! which takes separate `u8` arguments for red, green, and blue:
 //!
 //! ```
-//! use nu_ansi_term::Color::RGB;
+//! use nu_ansi_term::Color::Rgb;
 //!
-//! RGB(70, 130, 180).paint("Steel blue");
+//! Rgb(70, 130, 180).paint("Steel blue");
 //! ```
 //!
 //! ## Combining successive colored strings
@@ -233,7 +233,7 @@
 #![crate_type = "rlib"]
 #![crate_type = "dylib"]
 #![warn(missing_copy_implementations)]
-#![warn(missing_docs)]
+// #![warn(missing_docs)]
 #![warn(trivial_casts, trivial_numeric_casts)]
 // #![warn(unused_extern_crates, unused_qualifications)]
 
@@ -265,3 +265,9 @@ mod util;
 pub use util::*;
 
 mod debug;
+
+pub mod gradient;
+pub use gradient::*;
+
+mod rgb;
+pub use rgb::*;

crates/nu-ansi-term/src/rgb.rs

@@ -0,0 +1,173 @@
+// Code liberally borrowed from here
+// https://github.com/navierr/coloriz
+use std::ops;
+use std::u32;
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub struct Rgb {
+    /// Red
+    pub r: u8,
+    /// Green
+    pub g: u8,
+    /// Blue
+    pub b: u8,
+}
+
+impl Rgb {
+    /// Creates a new [Rgb] color
+    #[inline]
+    pub const fn new(r: u8, g: u8, b: u8) -> Self {
+        Self { r, g, b }
+    }
+
+    /// Creates a new [Rgb] color with a hex code
+    #[inline]
+    pub const fn from_hex(hex: u32) -> Self {
+        Self::new((hex >> 16) as u8, (hex >> 8) as u8, hex as u8)
+    }
+
+    pub fn from_hex_string(hex: String) -> Self {
+        if hex.chars().count() == 8 && hex.starts_with("0x") {
+            // eprintln!("hex:{:?}", hex);
+            let (_, value_string) = hex.split_at(2);
+            // eprintln!("value_string:{:?}", value_string);
+            let int_val = u64::from_str_radix(value_string, 16);
+            match int_val {
+                Ok(num) => Self::new(
+                    ((num & 0xff0000) >> 16) as u8,
+                    ((num & 0xff00) >> 8) as u8,
+                    (num & 0xff) as u8,
+                ),
+                // Don't fail, just make the color black
+                // Should we fail?
+                _ => Self::new(0, 0, 0),
+            }
+        } else {
+            // Don't fail, just make the color black.
+            // Should we fail?
+            Self::new(0, 0, 0)
+        }
+    }
+
+    /// Creates a new [Rgb] color with three [f32] values
+    pub fn from_f32(r: f32, g: f32, b: f32) -> Self {
+        Self::new(
+            (r.clamp(0.0, 1.0) * 255.0) as u8,
+            (g.clamp(0.0, 1.0) * 255.0) as u8,
+            (b.clamp(0.0, 1.0) * 255.0) as u8,
+        )
+    }
+
+    /// Creates a grayscale [Rgb] color
+    #[inline]
+    pub const fn gray(x: u8) -> Self {
+        Self::new(x, x, x)
+    }
+
+    /// Creates a grayscale [Rgb] color with a [f32] value
+    pub fn gray_f32(x: f32) -> Self {
+        Self::from_f32(x, x, x)
+    }
+
+    /// Creates a new [Rgb] color from a [HSL] color
+    // pub fn from_hsl(hsl: HSL) -> Self {
+    //     if hsl.s == 0.0 {
+    //         return Self::gray_f32(hsl.l);
+    //     }
+
+    //     let q = if hsl.l < 0.5 {
+    //         hsl.l * (1.0 + hsl.s)
+    //     } else {
+    //         hsl.l + hsl.s - hsl.l * hsl.s
+    //     };
+    //     let p = 2.0 * hsl.l - q;
+    //     let h2c = |t: f32| {
+    //         let t = t.clamp(0.0, 1.0);
+    //         if 6.0 * t < 1.0 {
+    //             p + 6.0 * (q - p) * t
+    //         } else if t < 0.5 {
+    //             q
+    //         } else if 1.0 < 1.5 * t {
+    //             p + 6.0 * (q - p) * (1.0 / 1.5 - t)
+    //         } else {
+    //             p
+    //         }
+    //     };
+
+    //     Self::from_f32(h2c(hsl.h + 1.0 / 3.0), h2c(hsl.h), h2c(hsl.h - 1.0 / 3.0))
+    // }
+
+    /// Computes the linear interpolation between `self` and `other` for `t`
+    pub fn lerp(&self, other: Self, t: f32) -> Self {
+        let t = t.clamp(0.0, 1.0);
+        self * (1.0 - t) + other * t
+    }
+}
+
+impl From<(u8, u8, u8)> for Rgb {
+    fn from((r, g, b): (u8, u8, u8)) -> Self {
+        Self::new(r, g, b)
+    }
+}
+
+impl From<(f32, f32, f32)> for Rgb {
+    fn from((r, g, b): (f32, f32, f32)) -> Self {
+        Self::from_f32(r, g, b)
+    }
+}
+
+use crate::ANSIColorCode;
+use crate::TargetGround;
+impl ANSIColorCode for Rgb {
+    fn ansi_color_code(&self, target: TargetGround) -> String {
+        format!("{};2;{};{};{}", target.code() + 8, self.r, self.g, self.b)
+    }
+}
+
+overload::overload!(
+    (lhs: ?Rgb) + (rhs: ?Rgb) -> Rgb {
+        Rgb::new(
+            lhs.r.saturating_add(rhs.r),
+            lhs.g.saturating_add(rhs.g),
+            lhs.b.saturating_add(rhs.b)
+        )
+    }
+);
+
+overload::overload!(
+    (lhs: ?Rgb) - (rhs: ?Rgb) -> Rgb {
+        Rgb::new(
+            lhs.r.saturating_sub(rhs.r),
+            lhs.g.saturating_sub(rhs.g),
+            lhs.b.saturating_sub(rhs.b)
+        )
+    }
+);
+
+overload::overload!(
+    (lhs: ?Rgb) * (rhs: ?f32) -> Rgb {
+        Rgb::new(
+            (lhs.r as f32 * rhs.clamp(0.0, 1.0)) as u8,
+            (lhs.g as f32 * rhs.clamp(0.0, 1.0)) as u8,
+            (lhs.b as f32 * rhs.clamp(0.0, 1.0)) as u8
+        )
+    }
+);
+
+overload::overload!(
+    (lhs: ?f32) * (rhs: ?Rgb) -> Rgb {
+        Rgb::new(
+            (rhs.r as f32 * lhs.clamp(0.0, 1.0)) as u8,
+            (rhs.g as f32 * lhs.clamp(0.0, 1.0)) as u8,
+            (rhs.b as f32 * lhs.clamp(0.0, 1.0)) as u8
+        )
+    }
+);
+
+overload::overload!(
+    -(rgb: ?Rgb) -> Rgb {
+        Rgb::new(
+            255 - rgb.r,
+            255 - rgb.g,
+            255 - rgb.b)
+    }
+);

crates/nu-ansi-term/src/style.rs

@@ -364,7 +364,7 @@ pub enum Color {
     /// [cc]: https://upload.wikimedia.org/wikipedia/commons/1/15/Xterm_256color_chart.svg
     Fixed(u8),
 
-    /// A 24-bit RGB color, as specified by ISO-8613-3.
+    /// A 24-bit Rgb color, as specified by ISO-8613-3.
     Rgb(u8, u8, u8),
 }
 
@@ -546,7 +546,7 @@ impl Color {
     /// ```
     /// use nu_ansi_term::Color;
     ///
-    /// let style = Color::RGB(31, 31, 31).on(Color::White);
+    /// let style = Color::Rgb(31, 31, 31).on(Color::White);
     /// println!("{}", style.paint("eyyyy"));
     /// ```
     pub fn on(self, background: Color) -> Style {
@@ -584,13 +584,13 @@ mod serde_json_tests {
         let colors = &[
             Color::Red,
             Color::Blue,
-            Color::RGB(123, 123, 123),
+            Color::Rgb(123, 123, 123),
             Color::Fixed(255),
         ];
 
         assert_eq!(
             serde_json::to_string(&colors).unwrap(),
-            String::from("[\"Red\",\"Blue\",{\"RGB\":[123,123,123]},{\"Fixed\":255}]")
+            String::from("[\"Red\",\"Blue\",{\"Rgb\":[123,123,123]},{\"Fixed\":255}]")
         );
     }
 
@@ -599,7 +599,7 @@ mod serde_json_tests {
         let colors = &[
             Color::Red,
             Color::Blue,
-            Color::RGB(123, 123, 123),
+            Color::Rgb(123, 123, 123),
             Color::Fixed(255),
         ];
 

crates/nu-command/src/commands.rs

@@ -146,6 +146,7 @@ pub(crate) use autoview::Autoview;
 pub(crate) use cd::Cd;
 
 pub(crate) use ansi::Ansi;
+pub(crate) use ansi::AnsiGradient;
 pub(crate) use ansi::AnsiStrip;
 pub(crate) use append::Command as Append;
 pub(crate) use autoenv::Autoenv;

crates/nu-command/src/commands/ansi/command.rs

@@ -331,7 +331,7 @@ pub fn str_to_ansi(s: &str) -> Option<String> {
         // OSC escape (Operating system command)
         "osc" | "escape_right" => Some("\x1b]".to_string()),
 
-        // Ansi RGB - Needs to be 32;2;r;g;b or 48;2;r;g;b
+        // Ansi Rgb - Needs to be 32;2;r;g;b or 48;2;r;g;b
         // assuming the rgb will be passed via command and no here
         "rgb_fg" => Some("\x1b[38;2;".to_string()),
         "rgb_bg" => Some("\x1b[48;2;".to_string()),

crates/nu-command/src/commands/ansi/gradient.rs

@@ -0,0 +1,326 @@
+use crate::prelude::*;
+use nu_ansi_term::{build_all_gradient_text, gradient::TargetGround, Gradient, Rgb};
+use nu_engine::WholeStreamCommand;
+use nu_errors::ShellError;
+use nu_protocol::ShellTypeName;
+use nu_protocol::{Primitive, Signature, SyntaxShape, UntaggedValue, Value};
+use nu_source::Tag;
+
+pub struct SubCommand;
+
+impl WholeStreamCommand for SubCommand {
+    fn name(&self) -> &str {
+        "ansi gradient"
+    }
+
+    fn signature(&self) -> Signature {
+        Signature::build("ansi gradient")
+            .named(
+                "fgstart",
+                SyntaxShape::String,
+                "foreground gradient start color in hex (0x123456)",
+                Some('a'),
+            )
+            .named(
+                "fgend",
+                SyntaxShape::String,
+                "foreground gradient end color in hex",
+                Some('b'),
+            )
+            .named(
+                "bgstart",
+                SyntaxShape::String,
+                "background gradient start color in hex",
+                Some('c'),
+            )
+            .named(
+                "bgend",
+                SyntaxShape::String,
+                "background gradient end color in hex",
+                Some('d'),
+            )
+            .rest(
+                SyntaxShape::ColumnPath,
+                "optionally, draw gradients using text from column paths",
+            )
+    }
+
+    fn usage(&self) -> &str {
+        "draw text with a provided start and end code making a gradient"
+    }
+
+    fn run(&self, args: CommandArgs) -> Result<OutputStream, ShellError> {
+        operate(args)
+    }
+
+    fn examples(&self) -> Vec<Example> {
+        vec![
+            Example {
+            description: "draw text in a gradient with foreground start and end colors",
+            example:
+                "echo 'Hello, Nushell! This is a gradient.' | ansi gradient --fgstart 0x40c9ff --fgend 0xe81cff",
+            result: None,
+        },
+        Example {
+            description: "draw text in a gradient with foreground start and end colors and background start and end colors",
+            example:
+                "echo 'Hello, Nushell! This is a gradient.' | ansi gradient --fgstart 0x40c9ff --fgend 0xe81cff --bgstart 0xe81cff --bgend 0x40c9ff",
+            result: None,
+        },
+        Example {
+            description: "draw text in a gradient by specifying foreground start color - end color is assumed to be black",
+            example:
+                "echo 'Hello, Nushell! This is a gradient.' | ansi gradient --fgstart 0x40c9ff",
+            result: None,
+        },
+        Example {
+            description: "draw text in a gradient by specifying foreground end color - start color is assumed to be black",
+            example:
+                "echo 'Hello, Nushell! This is a gradient.' | ansi gradient --fgend 0xe81cff",
+            result: None,
+        },
+        ]
+    }
+}
+
+fn operate(args: CommandArgs) -> Result<OutputStream, ShellError> {
+    let args = args.evaluate_once()?;
+    let fgstart: Option<Value> = args.get_flag("fgstart")?;
+    let fgend: Option<Value> = args.get_flag("fgend")?;
+    let bgstart: Option<Value> = args.get_flag("bgstart")?;
+    let bgend: Option<Value> = args.get_flag("bgend")?;
+    let column_paths: Vec<_> = args.rest(0)?;
+
+    let fgs_hex = fgstart.map(|color| Rgb::from_hex_string(color.convert_to_string()));
+    let fge_hex = fgend.map(|color| Rgb::from_hex_string(color.convert_to_string()));
+    let bgs_hex = bgstart.map(|color| Rgb::from_hex_string(color.convert_to_string()));
+    let bge_hex = bgend.map(|color| Rgb::from_hex_string(color.convert_to_string()));
+
+    let result: Vec<Value> = args
+        .input
+        .map(move |v| {
+            if column_paths.is_empty() {
+                action(&v, v.tag(), fgs_hex, fge_hex, bgs_hex, bge_hex)
+            } else {
+                let mut ret = v;
+
+                for path in &column_paths {
+                    ret = ret.swap_data_by_column_path(
+                        path,
+                        Box::new(move |old| {
+                            action(old, old.tag(), fgs_hex, fge_hex, bgs_hex, bge_hex)
+                        }),
+                    )?;
+                }
+
+                Ok(ret)
+            }
+        })
+        .collect::<Result<Vec<Value>, _>>()?;
+
+    Ok(OutputStream::from_stream(result.into_iter()))
+}
+
+fn action(
+    input: &Value,
+    tag: impl Into<Tag>,
+    fg_start: Option<Rgb>,
+    fg_end: Option<Rgb>,
+    bg_start: Option<Rgb>,
+    bg_end: Option<Rgb>,
+) -> Result<Value, ShellError> {
+    let tag = tag.into();
+
+    match &input.value {
+        UntaggedValue::Primitive(Primitive::String(astring)) => {
+            match (fg_start, fg_end, bg_start, bg_end) {
+                (None, None, None, None) => {
+                    // Error - no colors
+                    Err(ShellError::labeled_error(
+                        "please supply color parameters",
+                        "please supply foreground and/or background color parameters",
+                        Tag::unknown(),
+                    ))
+                }
+                (None, None, None, Some(bg_end)) => {
+                    // Error - missing bg_start, so assume black
+                    let bg_start = Rgb::new(0, 0, 0);
+                    let gradient = Gradient::new(bg_start, bg_end);
+                    let gradient_string = gradient.build(astring, TargetGround::Background);
+                    Ok(UntaggedValue::string(gradient_string).into_value(tag))
+                }
+                (None, None, Some(bg_start), None) => {
+                    // Error - missing bg_end, so assume black
+                    let bg_end = Rgb::new(0, 0, 0);
+                    let gradient = Gradient::new(bg_start, bg_end);
+                    let gradient_string = gradient.build(astring, TargetGround::Background);
+                    Ok(UntaggedValue::string(gradient_string).into_value(tag))
+                }
+                (None, None, Some(bg_start), Some(bg_end)) => {
+                    // Background Only
+                    let gradient = Gradient::new(bg_start, bg_end);
+                    let gradient_string = gradient.build(astring, TargetGround::Background);
+                    Ok(UntaggedValue::string(gradient_string).into_value(tag))
+                }
+                (None, Some(fg_end), None, None) => {
+                    // Error - missing fg_start, so assume black
+                    let fg_start = Rgb::new(0, 0, 0);
+                    let gradient = Gradient::new(fg_start, fg_end);
+                    let gradient_string = gradient.build(astring, TargetGround::Foreground);
+                    Ok(UntaggedValue::string(gradient_string).into_value(tag))
+                }
+                (None, Some(fg_end), None, Some(bg_end)) => {
+                    // missin fg_start and bg_start, so assume black
+                    let fg_start = Rgb::new(0, 0, 0);
+                    let bg_start = Rgb::new(0, 0, 0);
+                    let fg_gradient = Gradient::new(fg_start, fg_end);
+                    let bg_gradient = Gradient::new(bg_start, bg_end);
+                    let gradient_string =
+                        build_all_gradient_text(astring, fg_gradient, bg_gradient);
+                    Ok(UntaggedValue::string(gradient_string).into_value(tag))
+                }
+                (None, Some(fg_end), Some(bg_start), None) => {
+                    // Error - missing fg_start and bg_end
+                    let fg_start = Rgb::new(0, 0, 0);
+                    let bg_end = Rgb::new(0, 0, 0);
+                    let fg_gradient = Gradient::new(fg_start, fg_end);
+                    let bg_gradient = Gradient::new(bg_start, bg_end);
+                    let gradient_string =
+                        build_all_gradient_text(astring, fg_gradient, bg_gradient);
+                    Ok(UntaggedValue::string(gradient_string).into_value(tag))
+                }
+                (None, Some(fg_end), Some(bg_start), Some(bg_end)) => {
+                    // Error - missing fg_start, so assume black
+                    let fg_start = Rgb::new(0, 0, 0);
+                    let fg_gradient = Gradient::new(fg_start, fg_end);
+                    let bg_gradient = Gradient::new(bg_start, bg_end);
+                    let gradient_string =
+                        build_all_gradient_text(astring, fg_gradient, bg_gradient);
+                    Ok(UntaggedValue::string(gradient_string).into_value(tag))
+                }
+                (Some(fg_start), None, None, None) => {
+                    // Error - missing fg_end, so assume black
+                    let fg_end = Rgb::new(0, 0, 0);
+                    let gradient = Gradient::new(fg_start, fg_end);
+                    let gradient_string = gradient.build(astring, TargetGround::Foreground);
+                    Ok(UntaggedValue::string(gradient_string).into_value(tag))
+                }
+                (Some(fg_start), None, None, Some(bg_end)) => {
+                    // Error - missing fg_end, bg_start, so assume black
+                    let fg_end = Rgb::new(0, 0, 0);
+                    let bg_start = Rgb::new(0, 0, 0);
+                    let fg_gradient = Gradient::new(fg_start, fg_end);
+                    let bg_gradient = Gradient::new(bg_start, bg_end);
+                    let gradient_string =
+                        build_all_gradient_text(astring, fg_gradient, bg_gradient);
+                    Ok(UntaggedValue::string(gradient_string).into_value(tag))
+                }
+                (Some(fg_start), None, Some(bg_start), None) => {
+                    // Error - missing fg_end, bg_end, so assume black
+                    let fg_end = Rgb::new(0, 0, 0);
+                    let bg_end = Rgb::new(0, 0, 0);
+                    let fg_gradient = Gradient::new(fg_start, fg_end);
+                    let bg_gradient = Gradient::new(bg_start, bg_end);
+                    let gradient_string =
+                        build_all_gradient_text(astring, fg_gradient, bg_gradient);
+                    Ok(UntaggedValue::string(gradient_string).into_value(tag))
+                }
+                (Some(fg_start), None, Some(bg_start), Some(bg_end)) => {
+                    // Error - missing fg_end, so assume black
+                    let fg_end = Rgb::new(0, 0, 0);
+                    let fg_gradient = Gradient::new(fg_start, fg_end);
+                    let bg_gradient = Gradient::new(bg_start, bg_end);
+                    let gradient_string =
+                        build_all_gradient_text(astring, fg_gradient, bg_gradient);
+                    Ok(UntaggedValue::string(gradient_string).into_value(tag))
+                }
+                (Some(fg_start), Some(fg_end), None, None) => {
+                    // Foreground Only
+                    let gradient = Gradient::new(fg_start, fg_end);
+                    let gradient_string = gradient.build(astring, TargetGround::Foreground);
+                    Ok(UntaggedValue::string(gradient_string).into_value(tag))
+                }
+                (Some(fg_start), Some(fg_end), None, Some(bg_end)) => {
+                    // Error - missing bg_start, so assume black
+                    let bg_start = Rgb::new(0, 0, 0);
+                    let fg_gradient = Gradient::new(fg_start, fg_end);
+                    let bg_gradient = Gradient::new(bg_start, bg_end);
+                    let gradient_string =
+                        build_all_gradient_text(astring, fg_gradient, bg_gradient);
+                    Ok(UntaggedValue::string(gradient_string).into_value(tag))
+                }
+                (Some(fg_start), Some(fg_end), Some(bg_start), None) => {
+                    // Error - missing bg_end, so assume black
+                    let bg_end = Rgb::new(0, 0, 0);
+                    let fg_gradient = Gradient::new(fg_start, fg_end);
+                    let bg_gradient = Gradient::new(bg_start, bg_end);
+                    let gradient_string =
+                        build_all_gradient_text(astring, fg_gradient, bg_gradient);
+                    Ok(UntaggedValue::string(gradient_string).into_value(tag))
+                }
+                (Some(fg_start), Some(fg_end), Some(bg_start), Some(bg_end)) => {
+                    // Foreground and Background Gradient
+                    let fg_gradient = Gradient::new(fg_start, fg_end);
+                    let bg_gradient = Gradient::new(bg_start, bg_end);
+                    let gradient_string =
+                        build_all_gradient_text(astring, fg_gradient, bg_gradient);
+                    Ok(UntaggedValue::string(gradient_string).into_value(tag))
+                }
+            }
+        }
+        other => {
+            let got = format!("got {}", other.type_name());
+
+            Err(ShellError::labeled_error(
+                "value is not string",
+                got,
+                tag.span,
+            ))
+        }
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::ShellError;
+    use super::{action, SubCommand};
+    use nu_ansi_term::Rgb;
+    use nu_protocol::UntaggedValue;
+    use nu_source::Tag;
+
+    #[test]
+    fn examples_work_as_expected() -> Result<(), ShellError> {
+        use crate::examples::test as test_examples;
+
+        test_examples(SubCommand {})
+    }
+
+    // #[test]
+    // fn test_stripping() {
+    //     let input_string =
+    //         UntaggedValue::string("\u{1b}[3;93;41mHello\u{1b}[0m \u{1b}[1;32mNu \u{1b}[1;35mWorld")
+    //             .into_untagged_value();
+    //     let expected = UntaggedValue::string("Hello Nu World").into_untagged_value();
+
+    //     let actual = action(&input_string, Tag::unknown()).unwrap();
+    //     assert_eq!(actual, expected);
+    // }
+
+    #[test]
+    fn test_fg_gradient() {
+        let input_string = UntaggedValue::string("Hello, World!").into_untagged_value();
+        let expected = UntaggedValue::string("\u{1b}[38;2;64;201;255mH\u{1b}[38;2;76;187;254me\u{1b}[38;2;89;174;254ml\u{1b}[38;2;102;160;254ml\u{1b}[38;2;115;147;254mo\u{1b}[38;2;128;133;254m,\u{1b}[38;2;141;120;254m \u{1b}[38;2;153;107;254mW\u{1b}[38;2;166;94;254mo\u{1b}[38;2;179;80;254mr\u{1b}[38;2;192;67;254ml\u{1b}[38;2;205;53;254md\u{1b}[38;2;218;40;254m!\u{1b}[0m").into_untagged_value();
+        let fg_start = Rgb::from_hex_string("0x40c9ff".to_string());
+        let fg_end = Rgb::from_hex_string("0xe81cff".to_string());
+        let actual = action(
+            &input_string,
+            Tag::unknown(),
+            Some(fg_start),
+            Some(fg_end),
+            None,
+            None,
+        )
+        .unwrap();
+        assert_eq!(actual, expected);
+    }
+}

crates/nu-command/src/commands/ansi/mod.rs

@@ -1,5 +1,7 @@
 mod command;
+mod gradient;
 mod strip;
 
 pub use command::Command as Ansi;
+pub use gradient::SubCommand as AnsiGradient;
 pub use strip::SubCommand as AnsiStrip;

crates/nu-command/src/commands/default_context.rs

@@ -111,6 +111,7 @@ pub fn create_default_context(interactive: bool) -> Result<EvaluationContext, Bo
             whole_stream_command(BuildString),
             whole_stream_command(Ansi),
             whole_stream_command(AnsiStrip),
+            whole_stream_command(AnsiGradient),
             whole_stream_command(Char),
             // Column manipulation
             whole_stream_command(DropColumn),