colour from hex; use From and Into traits

Cargo.toml

@@ -8,6 +8,7 @@ edition = "2018"
 
 [dependencies]
 env_logger = "0.8.3"
+hex = "^0.4.3"
 image = "0.23.14"
 log = "0.4.14"
 pixels = "0.3.0"

src/colour.rs

@@ -7,8 +7,16 @@ pub struct Colour {
     pub blue: u8,
 }
 
-impl Colour {
-    pub fn from(colours: Vec<u8>) -> Colour {
+impl From<&str> for Colour {
+    fn from(str: &str) -> Self {
+        let rgb = hex::decode(&str[str.len() - 6..]).unwrap();
+
+        Colour { red: rgb[0], green: rgb[1], blue: rgb[2] }
+    }
+}
+
+impl From<Vec<u8>> for Colour {
+    fn from(colours: Vec<u8>) -> Self {
         const ZERO: u8 = 0;
         Colour {
             red:   *colours.get(0).unwrap_or(&ZERO),
@@ -16,8 +24,10 @@ impl Colour {
             blue:  *colours.get(2).unwrap_or(&ZERO),
         }
     }
+}
 
-    pub fn to_vec(&self) -> Vec<u8> {
+impl Into<Vec<u8>> for Colour {
+    fn into(self) -> Vec<u8> {
         vec![self.red, self.green, self.blue]
     }
 }
@@ -26,6 +36,15 @@ impl Colour {
 mod test {
     use crate::Colour;
 
+    #[test]
+    fn test_colour_from_hex() {
+        assert_eq!(Colour::from("#ff00ff" ), Colour { red: 255, green: 0,   blue: 255 });
+        assert_eq!(Colour::from("0xffffff"), Colour { red: 255, green: 255, blue: 255 });
+        assert_eq!(Colour::from("ffffff"  ), Colour { red: 255, green: 255, blue: 255 });
+        assert_eq!(Colour::from("#010203" ), Colour { red: 1,   green: 2,   blue: 3   });
+        assert_eq!(Colour::from("0xa0b0c0"), Colour { red: 160, green: 176, blue: 192 });
+    }
+
     #[test]
     fn test_colour_from_intermediate() {
         let output = Colour::from(vec![64, 128, 192]);
@@ -35,7 +54,7 @@ mod test {
 
     #[test]
     fn test_colour_to_intermediate() {
-        let output = Colour { red: 64, green: 128, blue: 192 }.to_vec();
+        let output: Vec<u8> = Colour { red: 64, green: 128, blue: 192 }.into();
         let expected = vec![64, 128, 192];
         assert_eq!(output, expected);
     }