Support customizing colors

README.md

@@ -25,8 +25,12 @@ Arguments:
   <IMAGE>  Path to image to pick colors from
 
 Options:
-  -c, --colors <COLORS>  Number of colors to generate (excluding bold colors) [default:8]
-  -b, --no-bold          Skip generating bold color variants
-  -h, --help             Print help
-  -V, --version          Print version
+  -c, --colors <COLORS>          Number of colors to generate (excluding bold colors) [default: 8]
+  -b, --no-bold                  Skip generating bold color variants
+      --bold-delta <BOLD_DELTA>  How much lightness should be added to bold colors [default: 0.2]
+      --rotate-hue <ROTATE_HUE>  Rotate colors along the hue axis [default: 0]
+      --lighten <LIGHTEN>        Lighten/darken colors [default: 0]
+      --saturate <SATURATE>      Saturate/desaturate colors [default: 0]
+  -h, --help                     Print help
+  -V, --version                  Print version
 ```

src/main.rs

@@ -15,6 +15,18 @@ struct Args {
     /// Skip generating bold color variants
     #[arg(short = 'b', long)]
     no_bold: bool,
+    /// How much lightness should be added to bold colors
+    #[arg(long, default_value_t = 0.2, value_parser = validate_color_delta, allow_hyphen_values = true)]
+    bold_delta: f64,
+    /// Rotate colors along the hue axis
+    #[arg(long, default_value_t = 0.0, allow_hyphen_values = true)]
+    rotate_hue: f64,
+    /// Lighten/darken colors
+    #[arg(long, default_value_t = 0.0, value_parser = validate_color_delta, allow_hyphen_values = true)]
+    lighten: f64,
+    /// Saturate/desaturate colors
+    #[arg(long, default_value_t = 0.0, value_parser = validate_color_delta, allow_hyphen_values = true)]
+    saturate: f64,
 }
 
 fn main() -> Result<()> {
@@ -41,10 +53,18 @@ fn main() -> Result<()> {
     if !args.no_bold {
         // Create second pairs of lighter colors
         let bold_colors = colors.clone();
-        let bold_colors = bold_colors.iter().map(|c| c.lighten(0.2));
+        let bold_colors = bold_colors.iter().map(|c| c.lighten(args.bold_delta));
         colors.extend(bold_colors);
     }
 
+    // Apply color transformations, if any
+    let colors: Vec<_> = colors
+        .into_iter()
+        .map(|c| c.rotate_hue(args.rotate_hue))
+        .map(|c| c.lighten(args.lighten))
+        .map(|c| c.saturate(args.saturate))
+        .collect();
+
     let brush = Brush::from_mode(Some(ansi::Mode::TrueColor));
 
     // Print colors with formatting turned off for pipes
@@ -61,3 +81,15 @@ fn main() -> Result<()> {
 
     Ok(())
 }
+
+/// Make sure that input value is between -1.0 and 1.0
+fn validate_color_delta(s: &str) -> Result<f64, String> {
+    let num = s
+        .parse()
+        .map_err(|_| format!("`{s}` is not a valid floating point number"))?;
+    if num >= -1.0 && num <= 1.0 {
+        Ok(num)
+    } else {
+        Err(format!("{num} is not in range [-1.0,1.0]"))
+    }
+}