From b36a1a7d24b329837a411cf3a06fab35584e809e Mon Sep 17 00:00:00 2001
From: Max Bradbury <max@tinybird.info>
Date: Sun, 16 May 2021 11:45:53 +0100
Subject: [PATCH] to_string() for Colour

---
 src/colour.rs | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/src/colour.rs b/src/colour.rs
index a045785..58a27f4 100644
--- a/src/colour.rs
+++ b/src/colour.rs
@@ -1,3 +1,5 @@
+use std::fmt;
+
 use serde_derive::{Serialize, Deserialize};
 
 #[derive(Debug, Eq, PartialEq, Serialize, Deserialize)]
@@ -24,6 +26,12 @@ impl From<Vec<u8>> for Colour {
     }
 }
 
+impl fmt::Display for Colour {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        write!(f, "#{}", hex::encode([self.red, self.green, self.blue]))
+    }
+}
+
 impl Into<Vec<u8>> for Colour {
     fn into(self) -> Vec<u8> {
         vec![self.red, self.green, self.blue]
@@ -43,6 +51,13 @@ mod test {
         assert_eq!(Colour::from("0xa0b0c0"), Colour { red: 160, green: 176, blue: 192 });
     }
 
+    #[test]
+    fn test_colour_to_hex() {
+        assert_eq!(Colour { red: 255, green: 255, blue: 255 }.to_string(), "#ffffff");
+        assert_eq!(Colour { red: 0,   green: 0,   blue: 0   }.to_string(), "#000000");
+        assert_eq!(Colour { red: 0,   green: 128, blue: 64  }.to_string(), "#008040");
+    }
+
     #[test]
     fn test_colour_from_intermediate() {
         let output = Colour::from(vec![64, 128, 192]);