image rotation

src/image.rs

@@ -29,6 +29,21 @@ impl Image {
 
         self.pixels = pixels;
     }
+
+    /// rotate image 90° clockwise
+    fn rotate(&mut self) {
+        let mut pixels = Vec::with_capacity(64);
+
+        // start from bottom-left corner, work upward in that column,
+        // then work on the next column to the right
+        for x in 0..8 {
+            for y in (0..8).rev() {
+                pixels.push(self.pixels[(y * 8) + x]);
+            }
+        }
+
+        self.pixels = pixels;
+    }
 }
 
 impl From<String> for Image {
@@ -163,7 +178,7 @@ mod test {
     }
 
     #[test]
-    fn test_mirror() {
+    fn mirror() {
         let mut image = crate::mock::image::asymmetrical();
         image.mirror();
 
@@ -180,4 +195,23 @@ mod test {
 
         assert_eq!(image, mirrored);
     }
+
+    #[test]
+    fn rotate() {
+        let mut image = crate::mock::image::asymmetrical();
+        image.rotate();
+
+        let rotated = Image { pixels: vec![
+            0,0,0,1,1,0,0,0,
+            0,0,1,0,0,1,0,0,
+            0,1,0,0,0,0,0,0,
+            1,0,0,0,0,0,0,0,
+            0,0,0,0,0,0,0,0,
+            0,0,0,0,0,0,0,0,
+            0,0,0,0,0,0,0,0,
+            0,0,0,0,0,0,0,0,
+        ]};
+
+        assert_eq!(image, rotated);
+    }
 }