add symmetry options

1 files changed, 67 insertions, 1 deletions

diff --git a/src/bitmap.rs b/src/bitmap.rs
index 8ff311b..726e0a2 100644
--- a/src/bitmap.rs
+++ b/src/bitmap.rs
@@ -1,6 +1,6 @@
 use std::{
     convert::{From, Into, TryFrom},
-    ops::Sub,
+    ops::{Add, Sub},
 };
 
 #[derive(Debug)]
@@ -50,6 +50,56 @@ impl TryFrom<(i64, i64)> for MapPoint {
     }
 }
 
+impl Add for MapPoint {
+    type Output = Self;
+    fn add(self, rhs: Self) -> Self::Output {
+        MapPoint {
+            x: self.x + rhs.x,
+            y: self.y + rhs.y,
+        }
+    }
+}
+
+impl Sub for MapPoint {
+    type Output = Self;
+    fn sub(self, rhs: Self) -> Self::Output {
+        MapPoint {
+            x: self.x - rhs.x,
+            y: self.y - rhs.y,
+        }
+    }
+}
+
+#[derive(Debug, Copy, Clone)]
+pub enum Axis {
+    X,
+    Y,
+}
+
+impl MapPoint {
+    #[inline]
+    pub fn scale(self, c: u32) -> MapPoint {
+        MapPoint {
+            x: self.x * c,
+            y: self.y * c,
+        }
+    }
+
+    #[inline]
+    pub fn mirror_about(self, line: u32, axis: Axis) -> MapPoint {
+        let MapPoint { x, y } = self;
+        match axis {
+            Axis::X => MapPoint { x, y: 2 * line - y },
+            Axis::Y => MapPoint { x: 2 * line - x, y },
+        }
+    }
+
+    #[inline]
+    pub fn reflect(self, around: MapPoint) -> MapPoint {
+        around.scale(2) - self
+    }
+}
+
 impl<T> Pixmap<T>
 where
     T: Copy + Clone + Default,
@@ -179,6 +229,22 @@ where
             .filter(|&pt| self.is_inside(pt))
             .collect()
     }
+
+    pub fn mirror_figure(&self, figure: &[MapPoint], line: u32, axis: Axis) -> Vec<MapPoint> {
+        figure
+            .iter()
+            .map(|pt| pt.mirror_about(line, axis))
+            .filter(|&pt| self.is_inside(pt))
+            .collect()
+    }
+
+    pub fn reflect_figure(&self, figure: &[MapPoint], around: MapPoint) -> Vec<MapPoint> {
+        figure
+            .iter()
+            .map(|pt| pt.reflect(around))
+            .filter(|&pt| self.is_inside(pt))
+            .collect()
+    }
 }
 
 fn abs_difference<T: Sub<Output = T> + Ord>(x: T, y: T) -> T {