From 24e11362a00dd63dbf4d345a046439525beca05a Mon Sep 17 00:00:00 2001
From: Max Bradbury <max@tinybird.info>
Date: Mon, 20 Jul 2020 14:42:33 +0100
Subject: [PATCH] flipping/mirroring images

---
 src/image.rs | 66 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 src/mock.rs  | 13 +++++++++++
 2 files changed, 79 insertions(+)

diff --git a/src/image.rs b/src/image.rs
index c55a843..1dc7a93 100644
--- a/src/image.rs
+++ b/src/image.rs
@@ -3,6 +3,34 @@ pub struct Image {
     pub pixels: Vec<u8>, // 64 for SD, 256 for HD
 }
 
+impl Image {
+    /// flip image vertically
+    fn flip(&mut self) {
+        let mut pixels = Vec::with_capacity(64);
+
+        for row in self.pixels.chunks(8).rev() {
+            for pixel in row {
+                pixels.push(*pixel);
+            }
+        }
+
+        self.pixels = pixels;
+    }
+
+    /// mirror image horizontally
+    fn mirror(&mut self) {
+        let mut pixels = Vec::with_capacity(64);
+
+        for row in self.pixels.chunks(8) {
+            for i in (0..8).rev() {
+                pixels.push(row[i]);
+            }
+        }
+
+        self.pixels = pixels;
+    }
+}
+
 impl From<String> for Image {
     fn from(string: String) -> Image {
         let string = string.replace("NaN", "0");
@@ -114,4 +142,42 @@ mod test {
         
         assert_eq!(output, expected);
     }
+
+    #[test]
+    fn flip() {
+        let mut image = crate::mock::image::asymmetrical();
+        image.flip();
+
+        let flipped = Image { pixels: vec![
+            0,0,0,1,0,0,0,0,
+            0,0,1,0,0,0,0,0,
+            0,1,0,0,0,0,0,0,
+            1,0,0,0,0,0,0,0,
+            1,0,0,0,0,0,0,0,
+            0,1,0,0,0,0,0,0,
+            0,0,0,0,0,0,0,0,
+            0,0,0,0,0,0,0,0,
+        ]};
+
+        assert_eq!(image, flipped);
+    }
+
+    #[test]
+    fn test_mirror() {
+        let mut image = crate::mock::image::asymmetrical();
+        image.mirror();
+
+        let mirrored = Image { pixels: vec![
+            0,0,0,0,0,0,0,0,
+            0,0,0,0,0,0,0,0,
+            0,0,0,0,0,0,1,0,
+            0,0,0,0,0,0,0,1,
+            0,0,0,0,0,0,0,1,
+            0,0,0,0,0,0,1,0,
+            0,0,0,0,0,1,0,0,
+            0,0,0,0,1,0,0,0,
+        ]};
+
+        assert_eq!(image, mirrored);
+    }
 }
diff --git a/src/mock.rs b/src/mock.rs
index fa67b2e..f5379c5 100644
--- a/src/mock.rs
+++ b/src/mock.rs
@@ -24,6 +24,19 @@ pub mod image {
         }
     }
 
+    pub fn asymmetrical() -> Image {
+        Image { pixels: vec![
+            0,0,0,0,0,0,0,0,
+            0,0,0,0,0,0,0,0,
+            0,1,0,0,0,0,0,0,
+            1,0,0,0,0,0,0,0,
+            1,0,0,0,0,0,0,0,
+            0,1,0,0,0,0,0,0,
+            0,0,1,0,0,0,0,0,
+            0,0,0,1,0,0,0,0,
+        ]}
+    }
+
     pub fn animation_frames() -> Vec<Image> {
         vec![
             Image {