From 5f3d80185139a2b744f4f9bfb420c91baf56b186 Mon Sep 17 00:00:00 2001
From: genius <pelekhay@gmail.com>
Date: Sun, 31 May 2020 11:32:58 +0200
Subject: [PATCH 1/2] Fix pistons scaling of circles

---
 src/drawing/backend_impl/piston.rs | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/src/drawing/backend_impl/piston.rs b/src/drawing/backend_impl/piston.rs
index 4a579056..80e59cd6 100644
--- a/src/drawing/backend_impl/piston.rs
+++ b/src/drawing/backend_impl/piston.rs
@@ -150,7 +150,11 @@ impl<'a, 'b> DrawingBackend for PistonBackend<'a, 'b> {
         style: &S,
         fill: bool,
     ) -> Result<(), DrawingErrorKind<Self::ErrorType>> {
-        let rect = circle(center.0 as f64, center.1 as f64, radius as f64);
+        let rect = circle(
+            center.0 as f64 * self.scale,
+            center.1 as f64 * self.scale,
+            radius as f64 * self.scale,
+        );
         if fill {
             ellipse(
                 make_piston_rgba(&style.as_color()),

From 5244a9fdfe0e47b608dc25f5c7a18e3ba9149384 Mon Sep 17 00:00:00 2001
From: genius <pelekhay@gmail.com>
Date: Tue, 2 Jun 2020 10:37:43 +0200
Subject: [PATCH 2/2] refactored call to piston_window::circle into make_circle
 and added unit-test for it

---
 src/drawing/backend_impl/piston.rs | 24 +++++++++++++++++++-----
 1 file changed, 19 insertions(+), 5 deletions(-)

diff --git a/src/drawing/backend_impl/piston.rs b/src/drawing/backend_impl/piston.rs
index 80e59cd6..02605fcb 100644
--- a/src/drawing/backend_impl/piston.rs
+++ b/src/drawing/backend_impl/piston.rs
@@ -34,6 +34,14 @@ fn make_point_pair(a: BackendCoord, b: BackendCoord, scale: f64) -> [f64; 4] {
     ]
 }
 
+fn make_circle(center: BackendCoord, radius: u32, scale: f64) -> [f64; 4] {
+    circle(
+        center.0 as f64 * scale,
+        center.1 as f64 * scale,
+        radius as f64 * scale,
+    )
+}
+
 impl<'a, 'b> PistonBackend<'a, 'b> {
     pub fn new(size: (u32, u32), scale: f64, context: Context, graphics: &'b mut G2d<'a>) -> Self {
         Self {
@@ -150,11 +158,7 @@ impl<'a, 'b> DrawingBackend for PistonBackend<'a, 'b> {
         style: &S,
         fill: bool,
     ) -> Result<(), DrawingErrorKind<Self::ErrorType>> {
-        let rect = circle(
-            center.0 as f64 * self.scale,
-            center.1 as f64 * self.scale,
-            radius as f64 * self.scale,
-        );
+        let rect = make_circle(center, radius, self.scale);
         if fill {
             ellipse(
                 make_piston_rgba(&style.as_color()),
@@ -208,3 +212,13 @@ pub fn draw_piston_window<F: FnOnce(PistonBackend) -> Result<(), Box<dyn std::er
     }
     None
 }
+
+#[cfg(test)]
+mod test {
+    use super::*;
+    #[test]
+    fn test_make_circle() {
+        assert_eq!(make_circle((1, 1), 0, 1.0), [1.0, 1.0, 0.0, 0.0]);
+        assert_eq!(make_circle((1, 2), 3, 4.0), [-8.0, -4.0, 24.0, 24.0]);
+    }
+}