Image.invert()

src/image.rs

@@ -4,6 +4,10 @@ pub struct Image {
 }
 
 impl Image {
+    pub fn invert(&mut self) {
+        self.pixels = self.pixels.iter().map(|pixel| 1 - pixel).collect();
+    }
+
     /// flip image vertically
     pub fn flip(&mut self) {
         let mut pixels = Vec::with_capacity(64);
@@ -159,6 +163,14 @@ mod test {
         assert_eq!(output, expected);
     }
 
+    #[test]
+    fn invert() {
+        let mut output = crate::mock::image::chequers_1();
+        output.invert();
+        let expected = crate::mock::image::chequers_2();
+        assert_eq!(output, expected);
+    }
+
     #[test]
     fn flip() {
         let mut image = crate::mock::image::asymmetrical();