Add SVG options to render using paths.

README.md

@@ -92,6 +92,9 @@ shape_rendering - SVG Attribute: auto | optimizeSpeed | crispEdges | geometricPr
                   (defaults crispEdges)
 standalone      - whether to make this a full SVG file, or only an svg to embed in other svg
                   (default true)
+use_path        - Use <path> to render SVG rather than <rect> to significantly reduce size
+                  and quality. This will become the default in future versions.
+                  (default false)
 ```
 Example
 ```ruby

lib/rqrcode/export/svg.rb

@@ -1,23 +1,151 @@
 # frozen_string_literal: true
 
 # This class creates a SVG files.
-# Code from: https://github.com/samvincent/rqrcode-rails3
+# Initial code from: https://github.com/samvincent/rqrcode-rails3
 module RQRCode
   module Export
     module SVG
+      class BaseOutputSVG
+        attr_reader :result
+
+        def initialize(qrcode)
+          @qrcode = qrcode
+          @result = []
+        end
+      end
+
+      class Path < BaseOutputSVG
+        def build(module_size, offset, color)
+          modules_array = @qrcode.modules
+          matrix_width = matrix_height = modules_array.length + 1
+          empty_row = [Array.new(matrix_width - 1, false)]
+          edge_matrix = Array.new(matrix_height) { Array.new(matrix_width) }
+
+          (empty_row + modules_array + empty_row).each_cons(2).with_index do |row_pair, row_index|
+            first_row, second_row = row_pair
+
+            # horizontal edges
+            first_row.zip(second_row).each_with_index do |cell_pair, column_index|
+              edge = case cell_pair
+              when [true, false] then Edge.new column_index + 1, row_index, :left
+              when [false, true] then Edge.new column_index, row_index, :right
+              end
+
+              (edge_matrix[edge.start_y][edge.start_x] ||= []) << edge if edge
+            end
+
+            # vertical edges
+            ([false] + second_row + [false]).each_cons(2).each_with_index do |cell_pair, column_index|
+              edge = case cell_pair
+              when [true, false] then Edge.new column_index, row_index, :down
+              when [false, true] then Edge.new column_index, row_index + 1, :up
+              end
+
+              (edge_matrix[edge.start_y][edge.start_x] ||= []) << edge if edge
+            end
+          end
+
+          edge_count = edge_matrix.flatten.compact.count
+          path = []
+
+          while edge_count > 0
+            edge_loop = []
+            next_matrix_cell = edge_matrix.find(&:any?).find { |cell| cell&.any? }
+            edge = next_matrix_cell.first
+
+            while edge
+              edge_loop << edge
+              matrix_cell = edge_matrix[edge.start_y][edge.start_x]
+              matrix_cell.delete edge
+              edge_matrix[edge.start_y][edge.start_x] = nil if matrix_cell.empty?
+              edge_count -= 1
+
+              # try to find an edge continuing the current edge
+              edge = edge_matrix[edge.end_y][edge.end_x]&.first
+            end
+
+            first_edge = edge_loop.first
+            edge_loop_string = SVG_PATH_COMMANDS[:move]
+            edge_loop_string += "#{first_edge.start_x} #{first_edge.start_y}"
+
+            edge_loop.chunk(&:direction).to_a[0...-1].each do |direction, edges|
+              edge_loop_string << "#{SVG_PATH_COMMANDS[direction]}#{edges.length}"
+            end
+            edge_loop_string << SVG_PATH_COMMANDS[:close]
+
+            path << edge_loop_string
+          end
+
+          @result << %{<path d="#{path.join}" style="fill:##{color}" transform="translate(#{offset},#{offset}) scale(#{module_size})"/>}
+        end
+      end
+
+      class Rect < BaseOutputSVG
+        def build(module_size, offset, color)
+          @qrcode.modules.each_index do |c|
+            tmp = []
+            @qrcode.modules.each_index do |r|
+              y = c * module_size + offset
+              x = r * module_size + offset
+
+              next unless @qrcode.checked?(c, r)
+              tmp << %(<rect width="#{module_size}" height="#{module_size}" x="#{x}" y="#{y}" style="fill:##{color}"/>)
+            end
+
+            @result << tmp.join
+          end
+        end
+      end
+
+      class Edge < Struct.new(:start_x, :start_y, :direction)
+        def end_x
+          case direction
+          when :right then start_x + 1
+          when :left then start_x - 1
+          else start_x
+          end
+        end
+
+        def end_y
+          case direction
+          when :down then start_y + 1
+          when :up then start_y - 1
+          else start_y
+          end
+        end
+      end
+
+      SVG_PATH_COMMANDS = {
+        move: "M",
+        up: "v-",
+        down: "v",
+        left: "h-",
+        right: "h",
+        close: "z"
+      }
+
       #
       # Render the SVG from the Qrcode.
       #
       # Options:
-      # offset - Padding around the QR Code (e.g. 10)
-      # fill - Background color (e.g "ffffff" or :white)
-      # color - Foreground color for the code (e.g. "000000" or :black)
-      # module_size - The Pixel size of each module (e.g. 11)
-      # shape_rendering - Defaults to crispEdges
-      # standalone - wether to make this a full SVG file, or only svg to embed
-      #              in other svg.
+      # offset          - Padding around the QR Code in pixels
+      #                   (default 0)
+      # fill            - Background color e.g "ffffff"
+      #                   (default none)
+      # color           - Foreground color e.g "000"
+      #                   (default "000")
+      # module_size     - The Pixel size of each module
+      #                   (defaults 11)
+      # shape_rendering - SVG Attribute: auto | optimizeSpeed | crispEdges | geometricPrecision
+      #                   (defaults crispEdges)
+      # standalone      - Whether to make this a full SVG file, or only an svg to embed in other svg
+      #                   (default true)
+      # use_path        - Use <path> to render SVG rather than <rect> to significantly reduce size
+      #                   and quality. This will become the default in future versions.
+      #                   (default false)
       #
       def as_svg(options = {})
+        use_path = options[:use_path]
         offset = options[:offset].to_i || 0
         color = options[:color] || "000"
         shape_rendering = options[:shape_rendering] || "crispEdges"
@@ -31,29 +159,19 @@ def as_svg(options = {})
         open_tag = %(<svg version="1.1" xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:ev="http://www.w3.org/2001/xml-events" width="#{dimension}" height="#{dimension}" shape-rendering="#{shape_rendering}">)
         close_tag = "</svg>"
 
-        result = []
-        @qrcode.modules.each_index do |c|
-          tmp = []
-          @qrcode.modules.each_index do |r|
-            y = c * module_size + offset
-            x = r * module_size + offset
-
-            next unless @qrcode.checked?(c, r)
-            tmp << %(<rect width="#{module_size}" height="#{module_size}" x="#{x}" y="#{y}" style="fill:##{color}"/>)
-          end
-          result << tmp.join
-        end
+        output_tag = (use_path ? Path : Rect).new(@qrcode)
+        output_tag.build(module_size, offset, color)
 
         if options[:fill]
-          result.unshift %(<rect width="#{dimension}" height="#{dimension}" x="0" y="0" style="fill:##{options[:fill]}"/>)
+          output_tag.result.unshift %(<rect width="#{dimension}" height="#{dimension}" x="0" y="0" style="fill:##{options[:fill]}"/>)
         end
 
         if standalone
-          result.unshift(xml_tag, open_tag)
-          result << close_tag
+          output_tag.result.unshift(xml_tag, open_tag)
+          output_tag.result << close_tag
         end
 
-        result.join("\n")
+        output_tag.result.join
       end
     end
   end