feat(ruby): QR/Barcode merge placeholders in SVG templates

Add data-kb-placeholder qr/barcode support with rqrcode and barby.
Scale QR to fit placeholder box (viewBox + meet) and barcode by height
with natural width. Declare barby and rqrcode runtime dependencies.

Made-with: Cursor

ruby/lib/libptouch/cli/label_print.rb

@@ -2,9 +2,13 @@
 
 require "json"
 require "optparse"
+require "rqrcode"
 require "rexml/document"
 require "tempfile"
 require "yaml"
+require "barby"
+require "barby/barcode/code_128"
+require "barby/outputter/svg_outputter"
 
 require "libptouch"
 
@@ -289,12 +293,155 @@ module Libptouch
 
           replace_text_element_content(el, data[key].to_s)
         end
+        replace_code_placeholders(doc, data)
         out = +""
         formatter = REXML::Formatters::Default.new
         formatter.write(doc, out)
         out
       end
 
+      def replace_code_placeholders(doc, data)
+        doc.elements.each("//*[@data-field][@data-kb-placeholder]") do |el|
+          key = el.attributes["data-field"].to_s
+          next unless data.key?(key)
+
+          kind = el.attributes["data-kb-placeholder"].to_s.downcase
+          next unless %w[qr barcode].include?(kind)
+
+          x, y, width, height = read_box(el)
+          next if width <= 0 || height <= 0
+
+          raw_value = data[key].to_s
+          next if raw_value.empty?
+
+          replacement = build_code_svg_element(
+            kind: kind,
+            value: raw_value,
+            x: x,
+            y: y,
+            width: width,
+            height: height
+          )
+          el.parent&.insert_after(el, replacement)
+          el.parent&.delete(el)
+        end
+      end
+
+      def read_box(el)
+        x = el.attributes["x"].to_s.to_f
+        y = el.attributes["y"].to_s.to_f
+        width = el.attributes["width"].to_s.to_f
+        height = el.attributes["height"].to_s.to_f
+        [x, y, width, height]
+      end
+
+      def build_code_svg_element(kind:, value:, x:, y:, width:, height:)
+        svg_fragment =
+          if kind == "qr"
+            render_qr_svg(value)
+          else
+            render_barcode_svg(value)
+          end
+        fragment_doc = REXML::Document.new(strip_xml_declaration(svg_fragment))
+        svg_root = fragment_doc.root
+        svg_root = wrap_non_svg_root(svg_root) unless svg_root&.name == "svg"
+
+        if kind == "qr"
+          apply_qr_svg_box(svg_root, x: x, y: y, width: width, height: height)
+        else
+          apply_barcode_svg_box(svg_root, x: x, y: y, height: height)
+        end
+        svg_root
+      end
+
+      def apply_qr_svg_box(svg_root, x:, y:, width:, height:)
+        nat_w, nat_h = svg_natural_dimensions(svg_root)
+        if nat_w <= 0 || nat_h <= 0
+          nat_w = parse_length_attr(svg_root.attributes["width"])
+          nat_h = parse_length_attr(svg_root.attributes["height"])
+        end
+        raise ArgumentError, "QR SVG has no usable dimensions" if nat_w <= 0 || nat_h <= 0
+
+        svg_root.attributes["viewBox"] = "0 0 #{nat_w} #{nat_h}"
+        svg_root.attributes["x"] = x.to_s
+        svg_root.attributes["y"] = y.to_s
+        svg_root.attributes["width"] = width.to_s
+        svg_root.attributes["height"] = height.to_s
+        svg_root.attributes["preserveAspectRatio"] = "xMidYMid meet"
+      end
+
+      def apply_barcode_svg_box(svg_root, x:, y:, height:)
+        nat_w, nat_h = svg_natural_dimensions(svg_root)
+        if nat_w <= 0 || nat_h <= 0
+          nat_w = parse_length_attr(svg_root.attributes["width"])
+          nat_h = parse_length_attr(svg_root.attributes["height"])
+        end
+        raise ArgumentError, "barcode SVG has no usable dimensions" if nat_w <= 0 || nat_h <= 0
+
+        scale = height / nat_h
+        out_w = nat_w * scale
+        out_h = nat_h * scale
+
+        svg_root.attributes["viewBox"] = "0 0 #{nat_w} #{nat_h}"
+        svg_root.attributes["x"] = x.to_s
+        svg_root.attributes["y"] = y.to_s
+        svg_root.attributes["width"] = out_w.to_s
+        svg_root.attributes["height"] = out_h.to_s
+        svg_root.attributes["preserveAspectRatio"] = "xMidYMid meet"
+      end
+
+      def strip_xml_declaration(s)
+        s.to_s.sub(/\A<\?xml[^>]*\?>\s*/m, "")
+      end
+
+      def svg_natural_dimensions(svg_root)
+        vb = svg_root.attributes["viewBox"].to_s.strip
+        if (m = /\A\s*([-\d.eE+]+)\s+([-\d.eE+]+)\s+([-\d.eE+]+)\s+([-\d.eE+]+)\s*\z/.match(vb))
+          return [m[3].to_f, m[4].to_f]
+        end
+
+        [parse_length_attr(svg_root.attributes["width"]),
+         parse_length_attr(svg_root.attributes["height"])]
+      end
+
+      def parse_length_attr(str)
+        s = str.to_s.strip
+        return 0.0 if s.empty?
+
+        s = s.delete_suffix("px").strip
+        Float(s)
+      rescue ArgumentError
+        0.0
+      end
+
+      def render_qr_svg(value)
+        qrcode = RQRCode::QRCode.new(value)
+        qrcode.as_svg(
+          standalone: true,
+          use_path: true,
+          module_size: 1,
+          offset: 0,
+          color: "000",
+          shape_rendering: "crispEdges"
+        )
+      end
+
+      def render_barcode_svg(value)
+        barcode = Barby::Code128B.new(value)
+        Barby::SvgOutputter.new(barcode).to_svg(
+          xdim: 2,
+          height: 64,
+          margin: 0
+        )
+      end
+
+      def wrap_non_svg_root(root)
+        svg = REXML::Element.new("svg")
+        svg.add_namespace("http://www.w3.org/2000/svg")
+        svg.add_element(root)
+        svg
+      end
+
       def replace_text_element_content(text_element, value)
         # Remove all child nodes first so mixed content (<tspan>, text nodes, etc.)
         # gets replaced consistently by merge data.