2 files changed, 120 insertions, 8 deletions

diff --git a/src/app.rs b/src/app.rs
index bcc9c3a..13f8732 100644
--- a/src/app.rs
+++ b/src/app.rs
@@ -38,6 +38,12 @@ struct Grid {
     color: Color,
 }
 
+#[derive(Debug, Default, Copy, Clone)]
+struct Symmetry {
+    x: Option<u32>,
+    y: Option<u32>,
+}
+
 impl Grid {
     fn new() -> Self {
         Self {
@@ -99,6 +105,44 @@ impl<'ctx> AppState<'ctx> {
         self.grid.enabled = !self.grid.enabled;
     }
 
+    fn cycle_symmetry(&mut self) {
+        let Symmetry { x, y } = self.symmetry;
+        self.symmetry = match (x, y) {
+            (None, None) => Symmetry {
+                x: Some(self.width() / 2),
+                y: None,
+            },
+            (_, None) => Symmetry {
+                x: None,
+                y: Some(self.height() / 2),
+            },
+            (None, y) => Symmetry {
+                x: Some(self.width() / 2),
+                y,
+            },
+            (Some(_), Some(_)) => Symmetry { x: None, y: None },
+        }
+    }
+
+    fn apply_symmetry(&self, figure: &[MapPoint]) -> Vec<MapPoint> {
+        let Symmetry { x, y } = self.symmetry;
+        match (x, y) {
+            (None, None) => vec![],
+            (Some(line), None) => self.pixmap.mirror_figure(figure, line, Axis::X),
+            (None, Some(line)) => self.pixmap.mirror_figure(figure, line, Axis::Y),
+            (Some(x), Some(y)) => {
+                let along_x = self.pixmap.mirror_figure(figure, x, Axis::X);
+                let along_y = self.pixmap.mirror_figure(figure, y, Axis::Y);
+                let reflected = self.pixmap.reflect_figure(figure, (x, y).into());
+                along_x
+                    .into_iter()
+                    .chain(along_y)
+                    .chain(reflected)
+                    .collect()
+            }
+        }
+    }
+
     fn paint_point<P: Into<Point>>(
         &mut self,
         center: P,
@@ -106,21 +150,24 @@ impl<'ctx> AppState<'ctx> {
     ) -> Result<Vec<ModifyRecord>, ()> {
         let radius = self.brush_size as u32;
         let center = self.idx_at_coord(center).ok_or(())?;
-        let mut circle_modify_record = vec![];
-        for point in self.pixmap.get_circle(center, radius) {
+        let mut modify_record = vec![];
+        let circle = self.pixmap.get_circle(center, radius);
+        let sym_circle = self.apply_symmetry(&circle);
+        for point in circle.into_iter().chain(sym_circle) {
             let old_val = self.pixmap.set(point, val);
-            circle_modify_record.push(ModifyRecord::new(point, old_val, val));
+            modify_record.push(ModifyRecord::new(point, old_val, val));
         }
-        Ok(circle_modify_record)
+        Ok(modify_record)
     }
 
     fn paint_line<P: Into<Point>>(&mut self, start: P, end: P) -> Result<Vec<ModifyRecord>, ()> {
         let start = self.idx_at_coord(start).ok_or(())?;
         let end = self.idx_at_coord(end).ok_or(())?;
-        let line_coords = self.pixmap.get_line(start, end);
+        let line = self.pixmap.get_line(start, end);
+        let sym_line = self.apply_symmetry(&line);
         let mut line_modify_record = vec![];
         let val = self.active_color;
-        for point in line_coords {
+        for point in line.into_iter().chain(sym_line) {
             let circle_around_point = self.pixmap.get_circle(point, self.brush_size as u32);
             for c in circle_around_point {
                 let old_val = self.pixmap.set(c, val);
@@ -292,7 +339,6 @@ impl<'ctx> AppState<'ctx> {
         self.canvas.present();
 
         let mut event_pump = self.context.event_pump().unwrap();
-
         'running: loop {
             let mouse = event_pump.mouse_state();
             for event in event_pump.poll_iter() {
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 {