Allow flatten render for the svg

Added a new option `flatten` to the `%SvgSettings{}`.
This will allow `<path d="<data>" />` to be rendered.

Benefits:

1. Smaller files / markup;
2. Prevent "spacing" glitch that appear between
the `rects` due to pixel density.

.gitignore

@@ -34,3 +34,4 @@ tags
 .projections.json
 
 .elixir_ls/
+.DS_Store

README.md

@@ -66,6 +66,7 @@ There are several options to change the appearance of svg or png:
 | background_opacity | nil or 0.0 <= x <= 1.0 | nil           | sets background opacity of svg      |
 | background_color   | string or {r, g, b}    | "#ffffff"     | sets background color of svg        |
 | qrcode_color       | string or {r, g, b}    | "#000000"     | sets color of QR                    |
+| flatten            | boolean                | false         | renders path data instead of rects  |                                     |
 | image              | {string, size} or nil  | nil           | puts the image to the center of svg |
 | structure          | :minify or :readable   | :minify       | minifies or makes readable svg file |
 ```

lib/qr_code/render/svg.ex

@@ -44,15 +44,15 @@ defmodule QRCode.Render.Svg do
     |> construct_svg(settings)
   end
 
-  defp construct_body(matrix, svg, %SvgSettings{scale: scale}) do
+  defp construct_body(matrix, svg, %SvgSettings{scale: scale, flatten: flatten}) do
     {rank_matrix, _} = Matrix.size(matrix)
 
     %{
       svg
       | body:
           matrix
           |> find_nonzero_element()
-          |> Enum.map(&create_rect(&1, scale)),
+          |> Enum.map(&create_body(&1, scale, flatten)),
         rank_matrix: rank_matrix
     }
   end
@@ -69,6 +69,7 @@ defmodule QRCode.Render.Svg do
            background_color: bg,
            image: image,
            qrcode_color: qc,
+           flatten: flatten,
            scale: scale,
            structure: structure
          }
@@ -79,12 +80,11 @@ defmodule QRCode.Render.Svg do
        xlink: xlink,
        width: rank_matrix * scale,
        height: rank_matrix * scale
-     }, [background_rect(bg, bg_tr), to_group(body, qc), put_image(image)]}
+     }, [background_rect(bg, bg_tr), body_type(body, qc, flatten), put_image(image)]}
     |> XmlBuilder.generate(format: format(structure))
   end
 
   # Helpers
-
   defp background_settings(color) do
     %{
       width: "100%",
@@ -93,10 +93,17 @@ defmodule QRCode.Render.Svg do
     }
   end
 
-  defp create_rect({x_pos, y_pos}, scale) do
+  defp body_type(body, qc, false), do: to_group(body, qc)
+  defp body_type(body, qc, true), do: to_path(body, qc)
+
+  defp create_body({x_pos, y_pos}, scale, false) do
     {:rect, %{width: scale, height: scale, x: scale * x_pos, y: scale * y_pos}, nil}
   end
 
+  defp create_body({x_pos, y_pos}, scale, true) do
+    ~s(M#{scale * x_pos} #{scale * y_pos}h#{scale}v#{scale}H#{scale * x_pos}z)
+  end
+
   defp background_rect(color, nil) do
     {:rect, background_settings(color), nil}
   end
@@ -115,6 +122,10 @@ defmodule QRCode.Render.Svg do
     {:g, %{fill: to_hex(color)}, body}
   end
 
+  defp to_path(body, color) do
+    {:path, %{fill: to_hex(color), d: body}, nil}
+  end
+
   defp put_image(nil), do: ""
 
   defp put_image({path_to_image, size}) when is_binary(path_to_image) and 0 < size do

lib/qr_code/render/svg_settings.ex

@@ -17,6 +17,7 @@ defmodule QRCode.Render.SvgSettings do
   @type background_opacity :: ExMaybe.t(float())
   @type background_color :: String.t() | tuple
   @type qrcode_color :: String.t() | tuple
+  @type flatten :: boolean()
   @type structure :: :minify | :readable
 
   @type t :: %__MODULE__{
@@ -25,6 +26,7 @@ defmodule QRCode.Render.SvgSettings do
           background_opacity: background_opacity,
           background_color: background_color,
           qrcode_color: qrcode_color,
+          flatten: flatten,
           structure: structure
         }
 
@@ -33,5 +35,6 @@ defmodule QRCode.Render.SvgSettings do
             background_opacity: nil,
             background_color: "#ffffff",
             qrcode_color: "#000000",
+            flatten: false,
             structure: :minify
 end