From c91cea12a15b34fd39933738df7291fa92b824b3 Mon Sep 17 00:00:00 2001
From: Kaustubh Maske Patil <37668193+nikochiko@users.noreply.github.com>
Date: Fri, 26 Jan 2024 20:10:44 +0530
Subject: [PATCH] Fix #92: centering for rectangle shape (#93)

---
 examples/dune         |  5 +++++
 examples/rectangle.ml |  7 ++-----
 examples/square.ml    | 10 ++++++++++
 lib/shape.ml          | 13 +++++++------
 4 files changed, 24 insertions(+), 11 deletions(-)
 create mode 100644 examples/square.ml

diff --git a/examples/dune b/examples/dune
index ca6ebee..1c42610 100644
--- a/examples/dune
+++ b/examples/dune
@@ -83,6 +83,11 @@
  (modules rectangle_canvas)
  (libraries joy))
 
+(executable
+ (name square)
+ (modules square)
+ (libraries joy))
+
 (executable
  (name star)
  (modules star)
diff --git a/examples/rectangle.ml b/examples/rectangle.ml
index 32707ba..282a2b4 100644
--- a/examples/rectangle.ml
+++ b/examples/rectangle.ml
@@ -1,12 +1,9 @@
 open Joy
 
-let size = 100
-
 let () =
   init ();
   background (255, 255, 255, 255);
-  (* creating a rectangle from points *)
-  let rect = rectangle size size in
   set_color (0, 0, 0);
-  render rect;
+  let r = rectangle 100 200 in
+  show [r];
   write ~filename:"rectangle.png" ()
diff --git a/examples/square.ml b/examples/square.ml
new file mode 100644
index 0000000..d367be0
--- /dev/null
+++ b/examples/square.ml
@@ -0,0 +1,10 @@
+open Joy
+
+let () =
+  init ();
+  background (255, 255, 255, 255);
+  let square = rectangle 100 100 in
+  set_color (0, 0, 0);
+  show [square];
+  write ~filename:"square.png" ()
+
diff --git a/lib/shape.ml b/lib/shape.ml
index 348b9b9..b47b594 100644
--- a/lib/shape.ml
+++ b/lib/shape.ml
@@ -30,14 +30,15 @@ let center = { x = 0.; y = 0. }
 let circle ?(c = center) r = Circle { c; radius = float_of_int r }
 
 let rectangle ?(c = center) width height =
-  let width, height = (float_of_int width, float_of_int height) in
-  let { x; y } = c -! ((width +. height) /. 4.) in
+  let w, h = (float_of_int width, float_of_int height) in
+  let x1 = c.x -. (w /. 2.) in
+  let y1 = c.x -. (h /. 2.) in
   Polygon
     [
-      { x; y };
-      { x; y = y +. height };
-      { x = x +. width; y = y +. height };
-      { x = x +. width; y };
+      { x = x1; y = y1 };
+      { x = x1; y = y1 +. h };
+      { x = x1 +. w; y = y1 +. h };
+      { x = x1 +. w; y = y1 };
     ]
 
 let ellipse ?(c = center) rx ry =