New function Script.arc/7 to add arcs to current path

Author: GPrimola

lib/scenic/script.ex

@@ -202,6 +202,7 @@ defmodule Scenic.Script do
   @op_sector 0x2F
   @op_circle 0x30
   @op_ellipse 0x31
+  @op_arc 0x32
 
   @op_push_state 0x40
   @op_pop_state 0x41
@@ -829,6 +830,33 @@ defmodule Scenic.Script do
     [{:ellipse, {radius0, radius1}} | ops]
   end
 
+  @doc """
+  Adds a new **circle arc** shaped segment to the path.
+
+  This adds to the current path. It does not fill or stroke anything.
+
+  ## Parameters
+
+    - cx, cy: The coordinates of the arc's center.
+    - r: the radius of the arc.
+    - a0, a1: the angles which the arc is drawn from angle a0 to a1, in radians.
+    - dir: s the direction of the arc sweep:
+      - `1` for counter clockwise sweep;
+      - `2` for clockwise sweep.
+  """
+  @spec arc(
+          ops :: t(),
+          cx :: number,
+          cy :: number,
+          r :: number,
+          a0 :: number,
+          a1 :: number,
+          dir :: integer
+        ) :: ops :: t()
+  def arc(ops, cx, cy, r, a0, a1, dir) do
+    [{:arc, {cx, cy, r, a0, a1, dir}} | ops]
+  end
+
   @doc """
   Add a triangle to the current path.
 
@@ -1538,6 +1566,23 @@ defmodule Scenic.Script do
     ]
   end
 
+  defp serialize_op({:arc, {cx, cy, r, a0, a1, dir}}) do
+    [
+      <<
+        @op_arc::16-big,
+        0::16
+      >>,
+      <<
+        cx::float-32-big,
+        cy::float-32-big,
+        r::float-32-big,
+        a0::float-32-big,
+        a1::float-32-big,
+        dir::32-big
+      >>
+    ]
+  end
+
   defp serialize_op({:bezier_to, {cp1x, cp1y, cp2x, cp2y, x, y}}) do
     [
       <<
@@ -2261,6 +2306,20 @@ defmodule Scenic.Script do
     {{:arc_to, {x1, y1, x2, y2, radius}}, bin}
   end
 
+  defp deserialize_op(<<
+         @op_arc::16-big,
+         0::16,
+         cx::float-32-big,
+         cy::float-32-big,
+         r::float-32-big,
+         a0::float-32-big,
+         a1::float-32-big,
+         dir::32-big,
+         bin::binary
+       >>) do
+    {{:arc, {cx, cy, r, a0, a1, dir}}, bin}
+  end
+
   defp deserialize_op(<<
          @op_bezier_to::16-big,
          0::16,

test/scenic/script_test.exs

@@ -351,6 +351,12 @@ defmodule Scenic.ScriptTest do
     assert expected == Script.serialize(expected) |> Script.deserialize()
   end
 
+  test "arc works" do
+    expected = [{:arc, {0.0, 0.0, 5.0, 0.0, 6.0, 1}}]
+    assert Script.arc([], 0, 0, 5, 0, 6, 1) == expected
+    assert expected == Script.serialize(expected) |> Script.deserialize()
+  end
+
   # --------------------------------------------------------
   # transform commands