From 923ddc038a0cb10834f8cb3d0305ec104a8c2b36 Mon Sep 17 00:00:00 2001
From: Fay Carsons <faycarsons23@gmail.com>
Date: Thu, 14 Dec 2023 12:54:20 -0500
Subject: [PATCH 1/9] basic cairo prototype

---
 dune-project      |  2 +-
 examples/cairo.ml | 35 +++++++++++++++++++++++++++++++++++
 examples/dune     |  5 +++++
 3 files changed, 41 insertions(+), 1 deletion(-)
 create mode 100644 examples/cairo.ml

diff --git a/dune-project b/dune-project
index 0e71b62..e0b7929 100644
--- a/dune-project
+++ b/dune-project
@@ -17,6 +17,6 @@
  (name joy)
  (synopsis "Tiny creative coding library in OCaml")
  (description "Tiny creative coding library in OCaml")
- (depends ocaml dune graphics))
+ (depends ocaml dune graphics cairo2))
 
 ; See the complete stanza docs at https://dune.readthedocs.io/en/stable/dune-files.html#dune-project
diff --git a/examples/cairo.ml b/examples/cairo.ml
new file mode 100644
index 0000000..bbfd3f7
--- /dev/null
+++ b/examples/cairo.ml
@@ -0,0 +1,35 @@
+open Cairo
+
+type cairo_context = {
+  ctx: context; 
+  surface: Surface.t
+}
+
+let context : cairo_context option ref = ref None
+
+let draw () = 
+  match !context with 
+  | Some {ctx; surface} ->  
+    Cairo.set_line_width ctx 0.01;
+    Cairo.set_source_rgb ctx 0. 0. 0.;
+    Cairo.rectangle ctx 0.25 0.25 ~w: 0.5 ~h: 0.5;
+    Cairo.stroke ctx;
+
+    Cairo.set_source_rgb ctx 0. 0. 0.;
+    Cairo.arc ctx 0.5 0.5 ~r:0.25 ~a1: 0. ~a2: (2. *. Float.pi);
+    Cairo.stroke ctx;
+    Cairo.PNG.write surface "test2.png"
+  | None -> failwith "Context not found"
+
+let init ?size () = 
+  let w, h = match size with | Some s -> s | None -> (800., 800.) in
+  let surface = Cairo.Image.create Cairo.Image.ARGB32 ~w: (int_of_float w) ~h: (int_of_float h) in
+  let ctx = (Cairo.create surface) in
+  Cairo.scale ctx w h;
+  Cairo.set_source_rgb ctx 1. 1. 1.;
+  Cairo.paint ctx;
+  context := Some {ctx; surface};
+  draw ()
+
+let () = 
+  init ()
\ No newline at end of file
diff --git a/examples/dune b/examples/dune
index f8d4627..3087c6c 100644
--- a/examples/dune
+++ b/examples/dune
@@ -107,3 +107,8 @@
  (name circle_packing)
  (modules circle_packing)
  (libraries joy))
+
+(executable 
+ (name cairo)
+ (modules cairo)
+ (libraries cairo2))
\ No newline at end of file

From 880bbe3283035702473c262d92f469c29c3d3877 Mon Sep 17 00:00:00 2001
From: Fay Carsons <faycarsons23@gmail.com>
Date: Mon, 18 Dec 2023 14:14:43 -0500
Subject: [PATCH 2/9] Prototype functioning for all shapes but ellipse

---
 examples/cairo.ml | 210 +++++++++++++++++++++++++++++++++++++++-------
 examples/dune     |   4 +-
 joy.opam          |   1 +
 3 files changed, 185 insertions(+), 30 deletions(-)

diff --git a/examples/cairo.ml b/examples/cairo.ml
index bbfd3f7..de5bdb1 100644
--- a/examples/cairo.ml
+++ b/examples/cairo.ml
@@ -1,35 +1,189 @@
-open Cairo
+module Cairo = Cairo
 
+let tau = 2. *. Float.pi
+
+type point = { x : float; y : float }
+type circle = { c : point; radius : float }
+type rectangle = { c : point; width : float; height : float }
+type line = { a : point; b : point }
+type polygon = point list
+
+type shape =
+  | Circle of circle
+  | Rectangle of rectangle
+  | Line of line
+  | Polygon of polygon
+  | Complex of shape list
+
+(* Point arithmetic operators
+
+   let ( +~ ) {x = x1; y = y1} {x = x2; y = y2} = {x = x1 +. x2; y = y1 +. y2}
+   let ( *~ ) {x = x1; y = y1} {x = x2; y = y2} = {x = x1 *. x2; y = y1 *. y2}
+   let ( /~ ) {x = x1; y = y1} {x = x2; y = y2} = {x = x1 /. x2; y = y1 /. y2}
+   let ( -~ ) {x = x1; y = y1} {x = x2; y = y2} = {x = x1 -. x2; y = y1 -. y2}
+
+   let ( +! ) {x = x1; y = y1} scalar = {x = x1 +. scalar; y = y1 +. scalar}
+   let ( *! ) {x = x1; y = y1} scalar = {x = x1 *. scalar; y = y1 *. scalar}
+   let ( /! ) {x = x1; y = y1} scalar = {x = x1 /. scalar; y = y1 /. scalar} *)
+let ( -! ) { x = x1; y = y1 } scalar = { x = x1 -. scalar; y = y1 -. scalar }
+
+(* Global rendering context singleton definition and instantiation *)
 type cairo_context = {
-  ctx: context; 
-  surface: Surface.t
+  ctx : Cairo.context;
+  surface : Cairo.Surface.t;
+  size : point;
+  filename : string;
 }
 
-let context : cairo_context option ref = ref None
-
-let draw () = 
-  match !context with 
-  | Some {ctx; surface} ->  
-    Cairo.set_line_width ctx 0.01;
-    Cairo.set_source_rgb ctx 0. 0. 0.;
-    Cairo.rectangle ctx 0.25 0.25 ~w: 0.5 ~h: 0.5;
-    Cairo.stroke ctx;
-
-    Cairo.set_source_rgb ctx 0. 0. 0.;
-    Cairo.arc ctx 0.5 0.5 ~r:0.25 ~a1: 0. ~a2: (2. *. Float.pi);
-    Cairo.stroke ctx;
-    Cairo.PNG.write surface "test2.png"
-  | None -> failwith "Context not found"
-
-let init ?size () = 
-  let w, h = match size with | Some s -> s | None -> (800., 800.) in
-  let surface = Cairo.Image.create Cairo.Image.ARGB32 ~w: (int_of_float w) ~h: (int_of_float h) in
-  let ctx = (Cairo.create surface) in
+let context = ref None
+
+(* Error message *)
+let fail = "Context not initialized"
+
+
+(* Context initialization, render, and update fns *)
+let init_context ?line_width (w, h) filename = 
+  let surface =
+    Cairo.Image.create Cairo.Image.ARGB32 ~w: (int_of_float w)
+      ~h: (int_of_float h)
+  in
+  let ctx = Cairo.create surface in
   Cairo.scale ctx w h;
-  Cairo.set_source_rgb ctx 1. 1. 1.;
-  Cairo.paint ctx;
-  context := Some {ctx; surface};
+  Cairo.set_line_width ctx (match line_width with | Some n -> n | None -> 0.002);
+  context := Some { ctx; surface; size = {x = w; y = h}; filename }
+
+(* Renders context to PNG *)
+let write ctx = Cairo.PNG.write ctx.surface ctx.filename
+
+let get_dimensions () =
+  match !context with Some ctx -> ctx.size | None -> failwith fail
+
+let set_color color =
+  match !context with
+  | Some ctx ->
+      let r, g, b = color in
+      Cairo.set_source_rgb ctx.ctx r g b
+  | None -> failwith fail
+
+let background color =
+  match !context with
+  | Some ctx ->
+      let r, g, b = color in
+      Cairo.set_source_rgb ctx.ctx r g b;
+      Cairo.paint ctx.ctx
+  | None -> failwith fail
+
+let scale_point size point =
+  let { x; y } = point in
+  let x, y = (x /. size.x, y /. size.y) in
+  List.iter (fun n -> print_float n |> print_newline) [ x; y ];
+  (x, y)
+
+let draw_circle ctx (circle : circle) =
+  let x, y = scale_point ctx.size circle.c in
+  let radius = circle.radius /. min ctx.size.x ctx.size.y in
+  Cairo.arc ctx.ctx x y ~r:radius ~a1:0. ~a2:tau;
+  Cairo.stroke ctx.ctx
+
+let draw_rect ctx (rect : rectangle) =
+  let x, y =
+    scale_point ctx.size (rect.c -! ((rect.width +. rect.height) /. 4.))
+  in
+  let w = rect.width /. ctx.size.x in
+  let h = rect.height /. ctx.size.y in
+  Cairo.rectangle ctx.ctx x y ~w ~h;
+  Cairo.stroke ctx.ctx
+
+let draw_line ctx line =
+  let x1, y1 = scale_point ctx.size line.a in
+  let x2, y2 = scale_point ctx.size line.b in
+  Cairo.move_to ctx.ctx x1 y1;
+  Cairo.line_to ctx.ctx x2 y2;
+  Cairo.stroke ctx.ctx;
+  Cairo.move_to ctx.ctx 0. 0.
+
+(* Polygon helper fns and rendering fn *)
+let rec take n lst =
+  match (n, lst) with
+  | 0, _ -> ([], lst)
+  | _, [] -> ([], [])
+  | n, x :: xs ->
+      let taken, rest = take (n - 1) xs in
+      (x :: taken, rest)
+
+let rec partition n ?step lst =
+  match lst with
+  | [] -> []
+  | _ ->
+      let taken, _ = take n lst in
+      if List.length taken = n then
+        taken
+        ::
+        (match step with
+        | Some s -> partition n ~step:s (List.tl lst)
+        | None -> partition n ~step:0 (List.tl lst))
+      else []
+
+let draw_polygon ctx (polygon : polygon) =
+  let points = partition 2 ~step:1 (polygon @ [ List.hd polygon ]) in
+  List.iter
+    (fun pair ->
+      let pair = List.map (scale_point ctx.size) pair in
+      let (x1, y1), (x2, y2) = (List.nth pair 0, List.nth pair 1) in
+      Cairo.move_to ctx.ctx x1 y1;
+      Cairo.line_to ctx.ctx x2 y2)
+    points;
+  Cairo.move_to ctx.ctx 0. 0.;
+  Cairo.stroke ctx.ctx
+
+(* Root render fn *)
+let rec render_shape ctx shape =
+  let _ =
+    match shape with
+    | Circle circle -> draw_circle ctx circle
+    | Rectangle rectangle -> draw_rect ctx rectangle
+    | Line line -> draw_line ctx line
+    | Polygon polygon -> draw_polygon ctx polygon
+    | Complex complex -> List.iter (render_shape ctx) complex
+  in
+  write ctx
+
+(* Validates context before rendering *)
+let render shape =
+  match !context with
+  | Some ctx -> render_shape ctx shape
+  | None -> failwith fail
+
+(* 'sketch' functions - this is a prototype of what the user would be writing *)
+let draw () =
+  let { x = w; y = h } = get_dimensions () in
+  let c = { x = w /. 2.; y = h /. 2. } in
+  let circle = Circle { c; radius = 100. } in
+  let rect = Rectangle { c; width = w /. 4.; height = h /. 4. } in
+  let _cartesian_product l l' =
+    List.concat (List.map (fun e -> List.map (fun e' -> (e, e')) l') l)
+  in
+  let polygon =
+    Polygon (List.map (fun {x; y} -> {x = x +. 10.; y = y +. 10.})[ c; { x = c.x; y = c.y +. 100. }; { x = c.x +. 100.; y = c.y } ])
+  in
+
+  let axes =
+    Complex
+      [
+        Line { a = { x = w /. 2.; y = 0. }; b = { x = w /. 2.; y = h } };
+        Line { a = { x = 0.; y = h /. 2. }; b = { x = w; y = h /. 2. } };
+      ]
+  in
+  let complex = Complex [ circle; rect; polygon; axes ] in
+  render complex
+
+let init ?size ?filename () =
+  let size = match size with Some s -> s | None -> { x = 800.; y = 800. } in
+  let { x; y } = size in
+  let filename = match filename with Some s -> s | None -> "cairo.png" in
+  init_context (x, y) filename;
+  background (1., 1., 1.);
+  set_color (0., 0., 0.);
   draw ()
 
-let () = 
-  init ()
\ No newline at end of file
+let () = init ()
diff --git a/examples/dune b/examples/dune
index 3087c6c..2434364 100644
--- a/examples/dune
+++ b/examples/dune
@@ -108,7 +108,7 @@
  (modules circle_packing)
  (libraries joy))
 
-(executable 
+(executable
  (name cairo)
  (modules cairo)
- (libraries cairo2))
\ No newline at end of file
+ (libraries cairo2))
diff --git a/joy.opam b/joy.opam
index 6b4f63f..c5bfbd8 100644
--- a/joy.opam
+++ b/joy.opam
@@ -11,6 +11,7 @@ depends: [
   "ocaml"
   "dune" {>= "3.10"}
   "graphics"
+  "cairo2"
   "odoc" {with-doc}
 ]
 build: [

From 4f7e93e51d910f875249175645611618340d24d8 Mon Sep 17 00:00:00 2001
From: Fay Carsons <faycarsons23@gmail.com>
Date: Mon, 18 Dec 2023 14:30:10 -0500
Subject: [PATCH 3/9] dune fmt

---
 examples/cairo.ml | 16 +++++++++-------
 1 file changed, 9 insertions(+), 7 deletions(-)

diff --git a/examples/cairo.ml b/examples/cairo.ml
index de5bdb1..01bfda8 100644
--- a/examples/cairo.ml
+++ b/examples/cairo.ml
@@ -40,17 +40,16 @@ let context = ref None
 (* Error message *)
 let fail = "Context not initialized"
 
-
 (* Context initialization, render, and update fns *)
-let init_context ?line_width (w, h) filename = 
+let init_context ?line_width (w, h) filename =
   let surface =
-    Cairo.Image.create Cairo.Image.ARGB32 ~w: (int_of_float w)
-      ~h: (int_of_float h)
+    Cairo.Image.create Cairo.Image.ARGB32 ~w:(int_of_float w)
+      ~h:(int_of_float h)
   in
   let ctx = Cairo.create surface in
   Cairo.scale ctx w h;
-  Cairo.set_line_width ctx (match line_width with | Some n -> n | None -> 0.002);
-  context := Some { ctx; surface; size = {x = w; y = h}; filename }
+  Cairo.set_line_width ctx (match line_width with Some n -> n | None -> 0.002);
+  context := Some { ctx; surface; size = { x = w; y = h }; filename }
 
 (* Renders context to PNG *)
 let write ctx = Cairo.PNG.write ctx.surface ctx.filename
@@ -164,7 +163,10 @@ let draw () =
     List.concat (List.map (fun e -> List.map (fun e' -> (e, e')) l') l)
   in
   let polygon =
-    Polygon (List.map (fun {x; y} -> {x = x +. 10.; y = y +. 10.})[ c; { x = c.x; y = c.y +. 100. }; { x = c.x +. 100.; y = c.y } ])
+    Polygon
+      (List.map
+         (fun { x; y } -> { x = x +. 10.; y = y +. 10. })
+         [ c; { x = c.x; y = c.y +. 100. }; { x = c.x +. 100.; y = c.y } ])
   in
 
   let axes =

From 7787c8410e2e0dcf0a2f91c08fa62446ab340cd7 Mon Sep 17 00:00:00 2001
From: Fay Carsons <faycarsons23@gmail.com>
Date: Mon, 18 Dec 2023 14:33:11 -0500
Subject: [PATCH 4/9] cleanup and adding explanatory comments

---
 examples/cairo.ml | 11 +++++------
 1 file changed, 5 insertions(+), 6 deletions(-)

diff --git a/examples/cairo.ml b/examples/cairo.ml
index 01bfda8..339cb3d 100644
--- a/examples/cairo.ml
+++ b/examples/cairo.ml
@@ -60,8 +60,8 @@ let get_dimensions () =
 let set_color color =
   match !context with
   | Some ctx ->
-      let r, g, b = color in
-      Cairo.set_source_rgb ctx.ctx r g b
+      let r, g, b, a = color in
+      Cairo.set_source_rgba ctx.ctx r g b a
   | None -> failwith fail
 
 let background color =
@@ -72,12 +72,14 @@ let background color =
       Cairo.paint ctx.ctx
   | None -> failwith fail
 
+(* Scales points from 0 - image size to 0-1 *)
 let scale_point size point =
   let { x; y } = point in
   let x, y = (x /. size.x, y /. size.y) in
   List.iter (fun n -> print_float n |> print_newline) [ x; y ];
   (x, y)
 
+(* Shape rendering fns *)
 let draw_circle ctx (circle : circle) =
   let x, y = scale_point ctx.size circle.c in
   let radius = circle.radius /. min ctx.size.x ctx.size.y in
@@ -159,9 +161,6 @@ let draw () =
   let c = { x = w /. 2.; y = h /. 2. } in
   let circle = Circle { c; radius = 100. } in
   let rect = Rectangle { c; width = w /. 4.; height = h /. 4. } in
-  let _cartesian_product l l' =
-    List.concat (List.map (fun e -> List.map (fun e' -> (e, e')) l') l)
-  in
   let polygon =
     Polygon
       (List.map
@@ -185,7 +184,7 @@ let init ?size ?filename () =
   let filename = match filename with Some s -> s | None -> "cairo.png" in
   init_context (x, y) filename;
   background (1., 1., 1.);
-  set_color (0., 0., 0.);
+  set_color (0., 0., 0., 1.);
   draw ()
 
 let () = init ()

From bc7da1bfe7aede41bd31d628c33ea999322ca07b Mon Sep 17 00:00:00 2001
From: Fay Carsons <faycarsons23@gmail.com>
Date: Mon, 18 Dec 2023 15:06:10 -0500
Subject: [PATCH 5/9] removing debug statement

---
 examples/cairo.ml | 1 -
 1 file changed, 1 deletion(-)

diff --git a/examples/cairo.ml b/examples/cairo.ml
index 339cb3d..d3e5af8 100644
--- a/examples/cairo.ml
+++ b/examples/cairo.ml
@@ -76,7 +76,6 @@ let background color =
 let scale_point size point =
   let { x; y } = point in
   let x, y = (x /. size.x, y /. size.y) in
-  List.iter (fun n -> print_float n |> print_newline) [ x; y ];
   (x, y)
 
 (* Shape rendering fns *)

From a68a8d8e9082b87464d092c6d26a35c0f6871a5d Mon Sep 17 00:00:00 2001
From: Fay Carsons <faycarsons23@gmail.com>
Date: Mon, 18 Dec 2023 18:47:32 -0500
Subject: [PATCH 6/9] added implmentation for ellipses

---
 examples/cairo.ml | 80 +++++++++++++++++++++++++++++++++++------------
 1 file changed, 60 insertions(+), 20 deletions(-)

diff --git a/examples/cairo.ml b/examples/cairo.ml
index d3e5af8..4182fd8 100644
--- a/examples/cairo.ml
+++ b/examples/cairo.ml
@@ -4,27 +4,38 @@ let tau = 2. *. Float.pi
 
 type point = { x : float; y : float }
 type circle = { c : point; radius : float }
+type ellipse = { c : point; rx : float; ry : float }
 type rectangle = { c : point; width : float; height : float }
 type line = { a : point; b : point }
 type polygon = point list
 
 type shape =
   | Circle of circle
+  | Ellipse of ellipse
   | Rectangle of rectangle
   | Line of line
   | Polygon of polygon
   | Complex of shape list
 
 (* Point arithmetic operators
+    I think thesse would be useful, 
+    but also undeerstand not everyone likes the arithmetic operator 
+    symbol overload thing
 
    let ( +~ ) {x = x1; y = y1} {x = x2; y = y2} = {x = x1 +. x2; y = y1 +. y2}
    let ( *~ ) {x = x1; y = y1} {x = x2; y = y2} = {x = x1 *. x2; y = y1 *. y2}
-   let ( /~ ) {x = x1; y = y1} {x = x2; y = y2} = {x = x1 /. x2; y = y1 /. y2}
+
    let ( -~ ) {x = x1; y = y1} {x = x2; y = y2} = {x = x1 -. x2; y = y1 -. y2}
 
    let ( +! ) {x = x1; y = y1} scalar = {x = x1 +. scalar; y = y1 +. scalar}
    let ( *! ) {x = x1; y = y1} scalar = {x = x1 *. scalar; y = y1 *. scalar}
    let ( /! ) {x = x1; y = y1} scalar = {x = x1 /. scalar; y = y1 /. scalar} *)
+
+(* point + point arithmetic *)
+let ( /~ ) { x = x1; y = y1 } { x = x2; y = y2 } =
+  { x = x1 /. x2; y = y1 /. y2 }
+
+(* point + scalar arithmetic *)
 let ( -! ) { x = x1; y = y1 } scalar = { x = x1 -. scalar; y = y1 -. scalar }
 
 (* Global rendering context singleton definition and instantiation *)
@@ -79,18 +90,48 @@ let scale_point size point =
   (x, y)
 
 (* Shape rendering fns *)
-let draw_circle ctx (circle : circle) =
-  let x, y = scale_point ctx.size circle.c in
-  let radius = circle.radius /. min ctx.size.x ctx.size.y in
+let draw_circle ctx ({ c; radius } : circle) =
+  let x, y = scale_point ctx.size c in
+  let radius = radius /. min ctx.size.x ctx.size.y in
   Cairo.arc ctx.ctx x y ~r:radius ~a1:0. ~a2:tau;
   Cairo.stroke ctx.ctx
 
-let draw_rect ctx (rect : rectangle) =
-  let x, y =
-    scale_point ctx.size (rect.c -! ((rect.width +. rect.height) /. 4.))
-  in
-  let w = rect.width /. ctx.size.x in
-  let h = rect.height /. ctx.size.y in
+(* Ellipse helper fn & rendering fn *)
+
+let calculate_control_points (size : point) ({ c; rx; ry } : ellipse) =
+  let { x; y } = c in
+  let { x = w; y = h } = size in
+  let half_height = ry /. 2. in
+  let width_two_thirds = rx *. (2. /. 3.) in
+  ( { x; y = y -. half_height } /~ size,
+    ( (x +. width_two_thirds) /. w,
+      (y -. half_height) /. h,
+      (x +. width_two_thirds) /. w,
+      (y +. half_height) /. h,
+      x /. w,
+      (y +. half_height) /. h ),
+    ( (x -. width_two_thirds) /. w,
+      (y +. half_height) /. h,
+      (x -. width_two_thirds) /. w,
+      (y -. half_height) /. h,
+      x /. w,
+      (y -. half_height) /. h ) )
+
+let draw_ellipse (ctx : cairo_context) (ellipse : ellipse) =
+  let start, curve_one, curve_two = calculate_control_points ctx.size ellipse in
+  Cairo.save ctx.ctx;
+  Cairo.move_to ctx.ctx start.x start.y;
+  let x1, y1, x2, y2, x3, y3 = curve_one in
+  Cairo.curve_to ctx.ctx x1 y1 x2 y2 x3 y3;
+  let x1, y1, x2, y2, x3, y3 = curve_two in
+  Cairo.curve_to ctx.ctx x1 y1 x2 y2 x3 y3;
+  Cairo.stroke ctx.ctx;
+  Cairo.restore ctx.ctx
+
+let draw_rect ctx ({ c; width; height } : rectangle) =
+  let x, y = scale_point ctx.size (c -! ((width +. height) /. 4.)) in
+  let w = width /. ctx.size.x in
+  let h = height /. ctx.size.y in
   Cairo.rectangle ctx.ctx x y ~w ~h;
   Cairo.stroke ctx.ctx
 
@@ -138,14 +179,13 @@ let draw_polygon ctx (polygon : polygon) =
 
 (* Root render fn *)
 let rec render_shape ctx shape =
-  let _ =
-    match shape with
-    | Circle circle -> draw_circle ctx circle
-    | Rectangle rectangle -> draw_rect ctx rectangle
-    | Line line -> draw_line ctx line
-    | Polygon polygon -> draw_polygon ctx polygon
-    | Complex complex -> List.iter (render_shape ctx) complex
-  in
+  (match shape with
+  | Circle circle -> draw_circle ctx circle
+  | Rectangle rectangle -> draw_rect ctx rectangle
+  | Ellipse ellipse -> draw_ellipse ctx ellipse
+  | Line line -> draw_line ctx line
+  | Polygon polygon -> draw_polygon ctx polygon
+  | Complex complex -> List.iter (render_shape ctx) complex);
   write ctx
 
 (* Validates context before rendering *)
@@ -160,13 +200,13 @@ let draw () =
   let c = { x = w /. 2.; y = h /. 2. } in
   let circle = Circle { c; radius = 100. } in
   let rect = Rectangle { c; width = w /. 4.; height = h /. 4. } in
+  let ellip = Ellipse { c; rx = 75.; ry = 50. } in
   let polygon =
     Polygon
       (List.map
          (fun { x; y } -> { x = x +. 10.; y = y +. 10. })
          [ c; { x = c.x; y = c.y +. 100. }; { x = c.x +. 100.; y = c.y } ])
   in
-
   let axes =
     Complex
       [
@@ -174,7 +214,7 @@ let draw () =
         Line { a = { x = 0.; y = h /. 2. }; b = { x = w; y = h /. 2. } };
       ]
   in
-  let complex = Complex [ circle; rect; polygon; axes ] in
+  let complex = Complex [ circle; rect; ellip; polygon; axes ] in
   render complex
 
 let init ?size ?filename () =

From ec3b82b3a5c13e473cfdeb50bcb3c56ce0777c35 Mon Sep 17 00:00:00 2001
From: Fay Carsons <faycarsons23@gmail.com>
Date: Mon, 18 Dec 2023 22:24:52 -0500
Subject: [PATCH 7/9] ellipse sclaing hacky fix, context singletont enforcement

---
 examples/cairo.ml | 108 ++++++++++++++++++++++++----------------------
 1 file changed, 56 insertions(+), 52 deletions(-)

diff --git a/examples/cairo.ml b/examples/cairo.ml
index 4182fd8..5fbd2fb 100644
--- a/examples/cairo.ml
+++ b/examples/cairo.ml
@@ -18,22 +18,21 @@ type shape =
   | Complex of shape list
 
 (* Point arithmetic operators
-    I think thesse would be useful, 
-    but also undeerstand not everyone likes the arithmetic operator 
-    symbol overload thing
+     I think thesse would be useful,
+     but also undeerstand not everyone likes the arithmetic operator
+     symbol overload thing
 
-   let ( +~ ) {x = x1; y = y1} {x = x2; y = y2} = {x = x1 +. x2; y = y1 +. y2}
-   let ( *~ ) {x = x1; y = y1} {x = x2; y = y2} = {x = x1 *. x2; y = y1 *. y2}
+   let ( /~ ) { x = x1; y = y1 } { x = x2; y = y2 } = { x = x1 /. x2; y = y1 /. y2 }
+    let ( +~ ) {x = x1; y = y1} {x = x2; y = y2} = {x = x1 +. x2; y = y1 +. y2}
+    let ( *~ ) {x = x1; y = y1} {x = x2; y = y2} = {x = x1 *. x2; y = y1 *. y2}
 
-   let ( -~ ) {x = x1; y = y1} {x = x2; y = y2} = {x = x1 -. x2; y = y1 -. y2}
+    let ( -~ ) {x = x1; y = y1} {x = x2; y = y2} = {x = x1 -. x2; y = y1 -. y2}
 
-   let ( +! ) {x = x1; y = y1} scalar = {x = x1 +. scalar; y = y1 +. scalar}
-   let ( *! ) {x = x1; y = y1} scalar = {x = x1 *. scalar; y = y1 *. scalar}
-   let ( /! ) {x = x1; y = y1} scalar = {x = x1 /. scalar; y = y1 /. scalar} *)
+    let ( +! ) {x = x1; y = y1} scalar = {x = x1 +. scalar; y = y1 +. scalar}
+    let ( *! ) {x = x1; y = y1} scalar = {x = x1 *. scalar; y = y1 *. scalar}
+    let ( /! ) {x = x1; y = y1} scalar = {x = x1 /. scalar; y = y1 /. scalar} *)
 
 (* point + point arithmetic *)
-let ( /~ ) { x = x1; y = y1 } { x = x2; y = y2 } =
-  { x = x1 /. x2; y = y1 /. y2 }
 
 (* point + scalar arithmetic *)
 let ( -! ) { x = x1; y = y1 } scalar = { x = x1 -. scalar; y = y1 -. scalar }
@@ -47,27 +46,31 @@ type cairo_context = {
 }
 
 let context = ref None
-
-(* Error message *)
 let fail = "Context not initialized"
 
 (* Context initialization, render, and update fns *)
-let init_context ?line_width (w, h) filename =
+let init_context ?line_width (x, y) filename =
+  (* Fail if context has already been instantiated *)
+  if Option.is_some !context then
+    failwith "Context cannot be initialized twice!";
+
   let surface =
-    Cairo.Image.create Cairo.Image.ARGB32 ~w:(int_of_float w)
-      ~h:(int_of_float h)
+    Cairo.Image.create Cairo.Image.ARGB32 ~w:(int_of_float x)
+      ~h:(int_of_float y)
   in
   let ctx = Cairo.create surface in
-  Cairo.scale ctx w h;
+  Cairo.scale ctx x y;
   Cairo.set_line_width ctx (match line_width with Some n -> n | None -> 0.002);
-  context := Some { ctx; surface; size = { x = w; y = h }; filename }
+  context := Some { ctx; surface; size = { x; y }; filename }
 
 (* Renders context to PNG *)
 let write ctx = Cairo.PNG.write ctx.surface ctx.filename
 
+(* gets surface size in range 0..pixels *)
 let get_dimensions () =
   match !context with Some ctx -> ctx.size | None -> failwith fail
 
+(* sets global color *)
 let set_color color =
   match !context with
   | Some ctx ->
@@ -75,6 +78,7 @@ let set_color color =
       Cairo.set_source_rgba ctx.ctx r g b a
   | None -> failwith fail
 
+(* sets background color *)
 let background color =
   match !context with
   | Some ctx ->
@@ -83,7 +87,7 @@ let background color =
       Cairo.paint ctx.ctx
   | None -> failwith fail
 
-(* Scales points from 0 - image size to 0-1 *)
+(* Scales points from 0-image size to 0-1 on both axes *)
 let scale_point size point =
   let { x; y } = point in
   let x, y = (x /. size.x, y /. size.y) in
@@ -96,38 +100,6 @@ let draw_circle ctx ({ c; radius } : circle) =
   Cairo.arc ctx.ctx x y ~r:radius ~a1:0. ~a2:tau;
   Cairo.stroke ctx.ctx
 
-(* Ellipse helper fn & rendering fn *)
-
-let calculate_control_points (size : point) ({ c; rx; ry } : ellipse) =
-  let { x; y } = c in
-  let { x = w; y = h } = size in
-  let half_height = ry /. 2. in
-  let width_two_thirds = rx *. (2. /. 3.) in
-  ( { x; y = y -. half_height } /~ size,
-    ( (x +. width_two_thirds) /. w,
-      (y -. half_height) /. h,
-      (x +. width_two_thirds) /. w,
-      (y +. half_height) /. h,
-      x /. w,
-      (y +. half_height) /. h ),
-    ( (x -. width_two_thirds) /. w,
-      (y +. half_height) /. h,
-      (x -. width_two_thirds) /. w,
-      (y -. half_height) /. h,
-      x /. w,
-      (y -. half_height) /. h ) )
-
-let draw_ellipse (ctx : cairo_context) (ellipse : ellipse) =
-  let start, curve_one, curve_two = calculate_control_points ctx.size ellipse in
-  Cairo.save ctx.ctx;
-  Cairo.move_to ctx.ctx start.x start.y;
-  let x1, y1, x2, y2, x3, y3 = curve_one in
-  Cairo.curve_to ctx.ctx x1 y1 x2 y2 x3 y3;
-  let x1, y1, x2, y2, x3, y3 = curve_two in
-  Cairo.curve_to ctx.ctx x1 y1 x2 y2 x3 y3;
-  Cairo.stroke ctx.ctx;
-  Cairo.restore ctx.ctx
-
 let draw_rect ctx ({ c; width; height } : rectangle) =
   let x, y = scale_point ctx.size (c -! ((width +. height) /. 4.)) in
   let w = width /. ctx.size.x in
@@ -143,6 +115,38 @@ let draw_line ctx line =
   Cairo.stroke ctx.ctx;
   Cairo.move_to ctx.ctx 0. 0.
 
+(* Ellipse helper fn & rendering fn 
+   currently just multiplying radii by 2 to offset scaling issue 
+   feels hacky *)
+let calculate_control_points (size : point) ({ c; rx; ry } : ellipse) =
+  let x, y = scale_point size c in
+  let half_height = ry /. size.y in
+  let width_two_thirds = rx /. size.x *. (2. /. 3.) *. 2. in
+  ( { x; y = y -. half_height },
+    ( x +. width_two_thirds,
+      y -. half_height,
+      x +. width_two_thirds,
+      y +. half_height,
+      x,
+      y +. half_height ),
+    ( x -. width_two_thirds,
+      y +. half_height,
+      x -. width_two_thirds,
+      y -. half_height,
+      x,
+      y -. half_height ) )
+
+let draw_ellipse (ctx : cairo_context) (ellipse : ellipse) =
+  let start, curve_one, curve_two = calculate_control_points ctx.size ellipse in
+  Cairo.save ctx.ctx;
+  Cairo.move_to ctx.ctx start.x start.y;
+  let x1, y1, x2, y2, x3, y3 = curve_one in
+  Cairo.curve_to ctx.ctx x1 y1 x2 y2 x3 y3;
+  let x1, y1, x2, y2, x3, y3 = curve_two in
+  Cairo.curve_to ctx.ctx x1 y1 x2 y2 x3 y3;
+  Cairo.stroke ctx.ctx;
+  Cairo.restore ctx.ctx
+
 (* Polygon helper fns and rendering fn *)
 let rec take n lst =
   match (n, lst) with
@@ -200,7 +204,7 @@ let draw () =
   let c = { x = w /. 2.; y = h /. 2. } in
   let circle = Circle { c; radius = 100. } in
   let rect = Rectangle { c; width = w /. 4.; height = h /. 4. } in
-  let ellip = Ellipse { c; rx = 75.; ry = 50. } in
+  let ellip = Ellipse { c; rx = 100.; ry = 90. } in
   let polygon =
     Polygon
       (List.map

From 89c095175e971d0dfae8ea36ce4222fc2f6a8f87 Mon Sep 17 00:00:00 2001
From: Fay Carsons <faycarsons23@gmail.com>
Date: Wed, 20 Dec 2023 20:00:50 -0500
Subject: [PATCH 8/9] refactored ellipse representation, added constructor fns

---
 examples/cairo.ml | 154 ++++++++++++++++-------------
 temp.ml           | 240 ++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 329 insertions(+), 65 deletions(-)
 create mode 100644 temp.ml

diff --git a/examples/cairo.ml b/examples/cairo.ml
index 5fbd2fb..1cb3eb9 100644
--- a/examples/cairo.ml
+++ b/examples/cairo.ml
@@ -4,41 +4,28 @@ let tau = 2. *. Float.pi
 
 type point = { x : float; y : float }
 type circle = { c : point; radius : float }
-type ellipse = { c : point; rx : float; ry : float }
-type rectangle = { c : point; width : float; height : float }
+
+type ellipse = {
+  start : point;
+  curve_one : float * float * float * float * float * float;
+  curve_two : float * float * float * float * float * float;
+}
+
 type line = { a : point; b : point }
 type polygon = point list
 
 type shape =
   | Circle of circle
   | Ellipse of ellipse
-  | Rectangle of rectangle
   | Line of line
   | Polygon of polygon
   | Complex of shape list
 
-(* Point arithmetic operators
-     I think thesse would be useful,
-     but also undeerstand not everyone likes the arithmetic operator
-     symbol overload thing
-
-   let ( /~ ) { x = x1; y = y1 } { x = x2; y = y2 } = { x = x1 /. x2; y = y1 /. y2 }
-    let ( +~ ) {x = x1; y = y1} {x = x2; y = y2} = {x = x1 +. x2; y = y1 +. y2}
-    let ( *~ ) {x = x1; y = y1} {x = x2; y = y2} = {x = x1 *. x2; y = y1 *. y2}
-
-    let ( -~ ) {x = x1; y = y1} {x = x2; y = y2} = {x = x1 -. x2; y = y1 -. y2}
-
-    let ( +! ) {x = x1; y = y1} scalar = {x = x1 +. scalar; y = y1 +. scalar}
-    let ( *! ) {x = x1; y = y1} scalar = {x = x1 *. scalar; y = y1 *. scalar}
-    let ( /! ) {x = x1; y = y1} scalar = {x = x1 /. scalar; y = y1 /. scalar} *)
-
-(* point + point arithmetic *)
-
 (* point + scalar arithmetic *)
 let ( -! ) { x = x1; y = y1 } scalar = { x = x1 -. scalar; y = y1 -. scalar }
 
 (* Global rendering context singleton definition and instantiation *)
-type cairo_context = {
+type joy_context = {
   ctx : Cairo.context;
   surface : Cairo.Surface.t;
   size : point;
@@ -46,9 +33,14 @@ type cairo_context = {
 }
 
 let context = ref None
-let fail = "Context not initialized"
+let fail () = failwith "Context not initialized"
 
 (* Context initialization, render, and update fns *)
+(* Currently, function signature does not match the canvas
+   backend function signature, which is a problem.
+
+   Having the end-user call 'set_filename', 'set_size', and
+   'set_line_width' isn't particularly satisfying either though *)
 let init_context ?line_width (x, y) filename =
   (* Fail if context has already been instantiated *)
   if Option.is_some !context then
@@ -67,8 +59,8 @@ let init_context ?line_width (x, y) filename =
 let write ctx = Cairo.PNG.write ctx.surface ctx.filename
 
 (* gets surface size in range 0..pixels *)
-let get_dimensions () =
-  match !context with Some ctx -> ctx.size | None -> failwith fail
+let get_window_size () =
+  match !context with Some ctx -> ctx.size | None -> fail ()
 
 (* sets global color *)
 let set_color color =
@@ -76,7 +68,7 @@ let set_color color =
   | Some ctx ->
       let r, g, b, a = color in
       Cairo.set_source_rgba ctx.ctx r g b a
-  | None -> failwith fail
+  | None -> fail ()
 
 (* sets background color *)
 let background color =
@@ -85,7 +77,7 @@ let background color =
       let r, g, b = color in
       Cairo.set_source_rgb ctx.ctx r g b;
       Cairo.paint ctx.ctx
-  | None -> failwith fail
+  | None -> fail ()
 
 (* Scales points from 0-image size to 0-1 on both axes *)
 let scale_point size point =
@@ -94,18 +86,41 @@ let scale_point size point =
   (x, y)
 
 (* Shape rendering fns *)
+
+(* Circle *)
+let circle ?point radius =
+  match point with
+  | Some c -> Circle { c; radius }
+  | None -> Circle { c = { x = 0.; y = 0. }; radius }
+
 let draw_circle ctx ({ c; radius } : circle) =
   let x, y = scale_point ctx.size c in
   let radius = radius /. min ctx.size.x ctx.size.y in
   Cairo.arc ctx.ctx x y ~r:radius ~a1:0. ~a2:tau;
   Cairo.stroke ctx.ctx
 
-let draw_rect ctx ({ c; width; height } : rectangle) =
-  let x, y = scale_point ctx.size (c -! ((width +. height) /. 4.)) in
-  let w = width /. ctx.size.x in
-  let h = height /. ctx.size.y in
-  Cairo.rectangle ctx.ctx x y ~w ~h;
-  Cairo.stroke ctx.ctx
+(* Rectangle *)
+let make_rectangle c width height =
+  let width, height = (width *. 2., height *. 2.) in
+  let { x; y } = c -! ((width +. height) /. 4.) in
+  Polygon
+    [
+      { x; y };
+      { x; y = y +. height };
+      { x = x +. width; y = y +. height };
+      { x = x +. width; y };
+    ]
+
+let rectangle ?point width height =
+  match point with
+  | Some c -> make_rectangle c width height
+  | None -> make_rectangle { x = 0.; y = 0. } width height
+
+(* Line *)
+let line ?point b =
+  match point with
+  | Some a -> Line { a; b }
+  | None -> Line { a = { x = 0.; y = 0. }; b }
 
 let draw_line ctx line =
   let x1, y1 = scale_point ctx.size line.a in
@@ -115,29 +130,36 @@ let draw_line ctx line =
   Cairo.stroke ctx.ctx;
   Cairo.move_to ctx.ctx 0. 0.
 
-(* Ellipse helper fn & rendering fn 
-   currently just multiplying radii by 2 to offset scaling issue 
+(* Ellipse helper fn & rendering fn
+
+   currently just multiplying radii by 2 to offset scaling issue
    feels hacky *)
-let calculate_control_points (size : point) ({ c; rx; ry } : ellipse) =
+let ellipse ?point rx ry =
+  let c = match point with Some p -> p | None -> { x = 0.; y = 0. } in
+  let size = get_window_size () in
   let x, y = scale_point size c in
   let half_height = ry /. size.y in
   let width_two_thirds = rx /. size.x *. (2. /. 3.) *. 2. in
-  ( { x; y = y -. half_height },
-    ( x +. width_two_thirds,
-      y -. half_height,
-      x +. width_two_thirds,
-      y +. half_height,
-      x,
-      y +. half_height ),
-    ( x -. width_two_thirds,
-      y +. half_height,
-      x -. width_two_thirds,
-      y -. half_height,
-      x,
-      y -. half_height ) )
-
-let draw_ellipse (ctx : cairo_context) (ellipse : ellipse) =
-  let start, curve_one, curve_two = calculate_control_points ctx.size ellipse in
+  Ellipse
+    {
+      start = { x; y = y -. half_height };
+      curve_one =
+        ( x +. width_two_thirds,
+          y -. half_height,
+          x +. width_two_thirds,
+          y +. half_height,
+          x,
+          y +. half_height );
+      curve_two =
+        ( x -. width_two_thirds,
+          y +. half_height,
+          x -. width_two_thirds,
+          y -. half_height,
+          x,
+          y -. half_height );
+    }
+
+let draw_ellipse (ctx : joy_context) { start; curve_one; curve_two } =
   Cairo.save ctx.ctx;
   Cairo.move_to ctx.ctx start.x start.y;
   let x1, y1, x2, y2, x3, y3 = curve_one in
@@ -148,6 +170,8 @@ let draw_ellipse (ctx : cairo_context) (ellipse : ellipse) =
   Cairo.restore ctx.ctx
 
 (* Polygon helper fns and rendering fn *)
+let polygon points = Polygon points
+
 let rec take n lst =
   match (n, lst) with
   | 0, _ -> ([], lst)
@@ -181,11 +205,13 @@ let draw_polygon ctx (polygon : polygon) =
   Cairo.move_to ctx.ctx 0. 0.;
   Cairo.stroke ctx.ctx
 
+(* Complex *)
+let complex shapes = Complex shapes
+
 (* Root render fn *)
 let rec render_shape ctx shape =
   (match shape with
   | Circle circle -> draw_circle ctx circle
-  | Rectangle rectangle -> draw_rect ctx rectangle
   | Ellipse ellipse -> draw_ellipse ctx ellipse
   | Line line -> draw_line ctx line
   | Polygon polygon -> draw_polygon ctx polygon
@@ -194,34 +220,32 @@ let rec render_shape ctx shape =
 
 (* Validates context before rendering *)
 let render shape =
-  match !context with
-  | Some ctx -> render_shape ctx shape
-  | None -> failwith fail
+  match !context with Some ctx -> render_shape ctx shape | None -> fail ()
 
 (* 'sketch' functions - this is a prototype of what the user would be writing *)
 let draw () =
-  let { x = w; y = h } = get_dimensions () in
+  let { x = w; y = h } = get_window_size () in
   let c = { x = w /. 2.; y = h /. 2. } in
-  let circle = Circle { c; radius = 100. } in
-  let rect = Rectangle { c; width = w /. 4.; height = h /. 4. } in
-  let ellip = Ellipse { c; rx = 100.; ry = 90. } in
+  let circle = circle ~point:c 100. in
+  let rect = rectangle ~point:c (w /. 4.) (h /. 4.) in
+  let ellip = ellipse ~point:c 100. 75. in
   let polygon =
-    Polygon
+    polygon
       (List.map
          (fun { x; y } -> { x = x +. 10.; y = y +. 10. })
          [ c; { x = c.x; y = c.y +. 100. }; { x = c.x +. 100.; y = c.y } ])
   in
   let axes =
-    Complex
+    complex
       [
-        Line { a = { x = w /. 2.; y = 0. }; b = { x = w /. 2.; y = h } };
-        Line { a = { x = 0.; y = h /. 2. }; b = { x = w; y = h /. 2. } };
+        line ~point:{ x = w /. 2.; y = 0. } { x = w /. 2.; y = h };
+        line ~point:{ x = 0.; y = h /. 2. } { x = w; y = h /. 2. };
       ]
   in
   let complex = Complex [ circle; rect; ellip; polygon; axes ] in
   render complex
 
-let init ?size ?filename () =
+let setup ?size ?filename () =
   let size = match size with Some s -> s | None -> { x = 800.; y = 800. } in
   let { x; y } = size in
   let filename = match filename with Some s -> s | None -> "cairo.png" in
@@ -230,4 +254,4 @@ let init ?size ?filename () =
   set_color (0., 0., 0., 1.);
   draw ()
 
-let () = init ()
+let () = setup ()
diff --git a/temp.ml b/temp.ml
new file mode 100644
index 0000000..9927b1d
--- /dev/null
+++ b/temp.ml
@@ -0,0 +1,240 @@
+(* JS deps *)
+module Html = Js_of_ocaml.Dom_html
+module Dom = Js_of_ocaml.Dom
+module Js = Js_of_ocaml.Js
+module G = Graphics_js
+
+type point = { x : float; y : float }
+
+let ( -! ) point scalar = { x = point.x -. scalar; y = point.y -. scalar }
+
+type circle = { c : point; radius : float }
+
+type ellipse = {
+  start : point;
+  curve_one : float * float * float * float * float * float;
+  curve_two : float * float * float * float * float * float;
+}
+
+type line = { a : point; b : point }
+type polygon = point list
+
+type shape =
+  | Circle of circle
+  | Ellipse of ellipse
+  | Line of line
+  | Polygon of polygon
+  | Complex of shape list
+
+(* JS type conversion helpers *)
+let str = Js.string
+let bl = Js.bool
+
+(* aliases for globals *)
+let doc = Html.document
+let window = Html.window
+
+(* Context *)
+type joy_context = {
+  context : Html.canvasRenderingContext2D Js.t;
+  canvas : Html.canvasElement Js.t;
+}
+
+let context : joy_context option ref = ref None
+let fail () = window##alert (str "Context not initialized!")
+
+let init_context canvas =
+  if Option.is_some !context then
+    window##alert (str "Context cannot be initialized twice!")
+  else (
+    G.open_canvas canvas;
+    Dom.appendChild doc##.body canvas;
+    let ctx = canvas##getContext Html._2d_ in
+    context := Some { context = ctx; canvas })
+
+let get_window_size () =
+  let w = float_of_int window##.innerWidth in
+  let h = float_of_int window##.innerHeight in
+  (w, h)
+
+let maximize_canvas () =
+  match !context with
+  | Some ctx ->
+      let w, h = get_window_size () in
+      ctx.canvas##.width := int_of_float w;
+      ctx.canvas##.height := int_of_float h
+  | None -> fail ()
+
+let create_canvas () =
+  let w, h = get_window_size () in
+  let canvas = Html.createCanvas doc in
+  canvas##.width := int_of_float w;
+  canvas##.height := int_of_float h;
+  canvas
+
+let color_str (r, g, b) =
+  str (Printf.sprintf "rgb(%f, %f, %f)" (r *. 255.) (g *. 255.) (b *. 255.))
+
+(* Sets global color *)
+let set_color color =
+  match !context with
+  | Some { context; canvas = _canvas } ->
+      let color_string = color_str color in
+      context##.fillStyle := color_string
+  | None -> fail ()
+
+(* sets background color *)
+let background color =
+  match !context with
+  | Some { context; canvas = _canvas } ->
+      let w, h = get_window_size () in
+      let _color_string = color_str color in
+      context##.fillStyle := str "white";
+      context##fillRect 0. 0. w h
+  | None -> fail ()
+
+let circle ?point radius =
+  match point with
+  | Some c -> Circle { c; radius }
+  | None -> Circle { c = { x = 0.; y = 0. }; radius }
+
+let draw_circle ctx { c; radius } =
+  let { x; y } = c in
+  ctx##beginPath;
+  ctx##arc x y radius 0. (2. *. Float.pi) (bl false);
+  ctx##stroke
+
+(* Rectangle *)
+
+let line ?point b =
+  match point with
+  | Some a -> Line { a; b }
+  | None -> Line { a = { x = 0.; y = 0. }; b }
+
+let draw_line ctx { a = { x = x1; y = y1 }; b = { x = x2; y = y2 } } =
+  ctx##moveTo x1 y1;
+  ctx##lineTo x2 y2;
+  ctx##stroke;
+  ctx##moveTo 0. 0.
+
+(* Ellipse constructor fn & rendering fn
+   currently just multiplying radii by 2 to offset scaling issue
+   feels hacky *)
+let ellipse ?point rx ry =
+  let { x; y } = match point with Some p -> p | None -> { x = 0.; y = 0. } in
+  let rx, ry = (rx *. 2., ry *. 2.) in
+  let half_height = ry /. 2. in
+  let width_two_thirds = rx *. (2. /. 3.) in
+  Ellipse
+    {
+      start = { x; y = y -. half_height };
+      curve_one =
+        ( x +. width_two_thirds,
+          y -. half_height,
+          x +. width_two_thirds,
+          y +. half_height,
+          x,
+          y +. half_height );
+      curve_two =
+        ( x -. width_two_thirds,
+          y +. half_height,
+          x -. width_two_thirds,
+          y -. half_height,
+          x,
+          y -. half_height );
+    }
+
+let draw_ellipse ctx (ellipse : ellipse) =
+  let { start; curve_one; curve_two } = ellipse in
+  ctx##moveTo start.x start.y;
+  let x1, y1, x2, y2, x3, y3 = curve_one in
+  ctx##bezierCurveTo x1 y1 x2 y2 x3 y3;
+  let x1, y1, x2, y2, x3, y3 = curve_two in
+  ctx##bezierCurveTo x1 y1 x2 y2 x3 y3;
+  ctx##stroke;
+  ctx##moveTo 0. 0.
+
+(* Polygon helper fns and rendering fn *)
+let polygon points = Polygon points
+
+let rec take n lst =
+  match (n, lst) with
+  | 0, _ -> ([], lst)
+  | _, [] -> ([], [])
+  | n, x :: xs ->
+      let taken, rest = take (n - 1) xs in
+      (x :: taken, rest)
+
+let rec partition n ?step lst =
+  match lst with
+  | [] -> []
+  | _ ->
+      let taken, _ = take n lst in
+      if List.length taken = n then
+        taken
+        ::
+        (match step with
+        | Some s -> partition n ~step:s (List.tl lst)
+        | None -> partition n ~step:0 (List.tl lst))
+      else []
+
+let draw_polygon ctx (polygon : polygon) =
+  let points = partition 2 ~step:1 (polygon @ [ List.hd polygon ]) in
+  List.iter
+    (fun pair ->
+      let { x = x1; y = y1 }, { x = x2; y = y2 } =
+        (List.nth pair 0, List.nth pair 1)
+      in
+      ctx##moveTo x1 y1;
+      ctx##lineTo x2 y2)
+    points;
+  ctx##stroke;
+  ctx##moveTo 0. 0.
+
+let complex shapes = Complex shapes
+
+let rec render_shape ctx shape =
+  match shape with
+  | Circle circle -> draw_circle ctx circle
+  | Ellipse ellipse -> draw_ellipse ctx ellipse
+  | Line line -> draw_line ctx line
+  | Polygon polygon -> draw_polygon ctx polygon
+  | Complex complex -> List.iter (render_shape ctx) complex
+
+let render shape =
+  match !context with
+  | Some ctx -> render_shape ctx.context shape
+  | None -> fail ()
+
+let draw () =
+  let w, h = get_window_size () in
+  let c = { x = w /. 2.; y = h /. 2. } in
+  background (1., 1., 1.);
+  set_color (0., 0., 0.);
+  let circle = circle ~point:c 100. in
+  let rect = rectangle ~point:c 100. 100. in
+  let ellip = ellipse ~point:c 100. 75. in
+  let polygon =
+    polygon
+      (List.map
+         (fun { x; y } -> { x = x +. 10.; y = y +. 10. })
+         [ c; { x = c.x; y = c.y +. 100. }; { x = c.x +. 100.; y = c.y } ])
+  in
+  let axes =
+    complex
+      [
+        line ~point:{ x = w /. 2.; y = 0. } { x = w /. 2.; y = h };
+        line ~point:{ x = 0.; y = h /. 2. } { x = w; y = h /. 2. };
+      ]
+  in
+  let complex = complex [ rect; ellip; circle; polygon; axes ] in
+  render complex
+
+let onload _ =
+  let canvas = create_canvas () in
+  init_context canvas;
+  maximize_canvas ();
+  draw ();
+  Js._true
+
+let _ = window##.onload := Html.handler onload

From 35225f8ab9f5808600d80a9c8602d7938ca6bb8c Mon Sep 17 00:00:00 2001
From: Fay Carsons <faycarsons23@gmail.com>
Date: Wed, 20 Dec 2023 20:31:49 -0500
Subject: [PATCH 9/9] Created exception type for context errors, need help w
 custom printer

---
 examples/cairo.ml | 25 +++++++++++++++++--------
 1 file changed, 17 insertions(+), 8 deletions(-)

diff --git a/examples/cairo.ml b/examples/cairo.ml
index 1cb3eb9..01d5c3c 100644
--- a/examples/cairo.ml
+++ b/examples/cairo.ml
@@ -33,7 +33,16 @@ type joy_context = {
 }
 
 let context = ref None
-let fail () = failwith "Context not initialized"
+
+exception Context of string 
+(* Not working, could use help fixing *)
+let () = 
+  Printexc.register_printer (fun e -> match e with 
+    | Context err -> Some ("Context: " ^ err)
+    | _ -> None
+)
+
+let fail () = raise (Context "not initialized")
 
 (* Context initialization, render, and update fns *)
 (* Currently, function signature does not match the canvas
@@ -44,7 +53,7 @@ let fail () = failwith "Context not initialized"
 let init_context ?line_width (x, y) filename =
   (* Fail if context has already been instantiated *)
   if Option.is_some !context then
-    failwith "Context cannot be initialized twice!";
+    raise (Context "Cannot initialize context twice");
 
   let surface =
     Cairo.Image.create Cairo.Image.ARGB32 ~w:(int_of_float x)
@@ -53,7 +62,7 @@ let init_context ?line_width (x, y) filename =
   let ctx = Cairo.create surface in
   Cairo.scale ctx x y;
   Cairo.set_line_width ctx (match line_width with Some n -> n | None -> 0.002);
-  context := Some { ctx; surface; size = { x; y }; filename }
+  context := Some { ctx; surface; size = { x; y }; filename } 
 
 (* Renders context to PNG *)
 let write ctx = Cairo.PNG.write ctx.surface ctx.filename
@@ -245,13 +254,13 @@ let draw () =
   let complex = Complex [ circle; rect; ellip; polygon; axes ] in
   render complex
 
-let setup ?size ?filename () =
-  let size = match size with Some s -> s | None -> { x = 800.; y = 800. } in
-  let { x; y } = size in
-  let filename = match filename with Some s -> s | None -> "cairo.png" in
+let setup () =
+  let x, y = (800., 800.) in
+  let filename = "cairo.png" in
   init_context (x, y) filename;
   background (1., 1., 1.);
   set_color (0., 0., 0., 1.);
   draw ()
 
-let () = setup ()
+let _ = setup ()
+