Module: QRCode

Defined in:
lib/prawn/qrcode.rb

Overview

:title: Prawn/QRCode

:main: This is an extension for Prawn::Document to simplify rendering QR Codes. The module registers itself as Prawn extension upon loading.

Author

Jens Hausherr ([email protected])

Copyright

Copyright © 2011 Jens Hausherr

License

Apache License, Version 2.0

Constant Summary collapse

DEFAULT_DOTSIZE =

The default size for QR Code modules is 1/72 in

1

Instance Method Summary collapse

Instance Method Details

Prints a QR Code to the PDF document. The QR Code creation happens on the fly.

content

The string to render as content of the QR Code

*options

Named optional parameters

:level

Error correction level to use. One of: (:l,:m,:h,:q), Defaults to :m

:extent

Size of QR Code given in pt (1 pt == 1/72 in)

:pos

Two-element array containing the position at which the QR-Code should be rendered. Defaults to [0,cursor]

:dot

Size of QR Code module/dot. Calculated from extent or defaulting to 1pt

:stroke

boolean value whether to draw bounds around the QR Code.

          Defaults to true.
+:align+:: Optional alignment within the current bounding box. Valid values are :left, :right, and :center. If set
          This option overrides the horizontal positioning specified in :pos. Defaults to nil.



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# File 'lib/prawn/qrcode.rb', line 48

def print_qr_code(content, *options)
  opt = options.extract_options!
  qr_version = 0
  level = opt[:level] || :m
  extent = opt[:extent]
  dot_size = opt[:dot] || DEFAULT_DOTSIZE
  begin
    qr_version +=1
    qr_code = RQRCode::QRCode.new(content, :size=>qr_version, :level=>level)

    dot_size = extent/(8+qr_code.modules.length) if extent
    render_qr_code(qr_code, :dot=>dot_size, :pos=>opt[:pos], :stroke=>opt[:stroke], :align=>opt[:align])
  rescue RQRCode::QRCodeRunTimeError
    if qr_version <40
      retry
    else
      raise
    end
  end
end

#render_qr_code(qr_code, *options) ⇒ Object

Renders a prepared QR Code (RQRCode::QRCode) object.

qr_code

The QR Code (an RQRCode::QRCode) to render

*options

Named optional parameters

:extent

Size of QR Code given in pt (1 pt == 1/72 in)

:pos

Two-element array containing the position at which the QR-Code should be rendered. Defaults to [0,cursor]

:dot

Size of QR Code module/dot. Calculated from extent or defaulting to 1pt

:stroke

boolean value whether to draw bounds around the QR Code. Defaults to true.

:align

Optional alignment within the current bounding box. Valid values are :left, :right, and :center. If set

This option overrides the horizontal positioning specified in :pos. Defaults to nil.



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# File 'lib/prawn/qrcode.rb', line 80

def render_qr_code(qr_code, *options)
  opt = options.extract_options!
  dot = opt[:dot] || DEFAULT_DOTSIZE
  extent= opt[:extent] || (8+qr_code.modules.length) * dot
  stroke = (opt.has_key?(:stroke) && opt[:stroke].nil?) || opt[:stroke]
  pos = opt[:pos] ||[0, cursor]

  align = opt[:align]
  case(align)
  when :center
    pos[0] = (@bounding_box.right / 2) - (extent / 2) 
  when :right
    pos[0] = @bounding_box.right - extent
  when :left
    pos[0] = 0;
  end

  bounding_box pos, :width => extent, :height => extent do |box|
    if stroke
      stroke_bounds
    end

    pos_y = 4*dot +qr_code.modules.length * dot

    qr_code.modules.each_index do |row|
      pos_x = 4*dot
      dark_col = 0
      qr_code.modules.each_index do |col|
        move_to [pos_x, pos_y]
        if qr_code.dark?(row, col)
          dark_col = dark_col+1
        else
          if (dark_col>0)
            fill { rectangle([pos_x - dark_col*dot, pos_y], dot*dark_col, dot) }
            dark_col = 0
          end
        end
        pos_x = pos_x + dot
      end
      if (dark_col > 0)
        fill { rectangle([pos_x - dark_col*dot, pos_y], dot*dark_col, dot) }
      end
      pos_y = pos_y - dot
    end
  end
end