Created
February 21, 2018 10:13
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Barby::Outputter to generate "proper" EAN-13 barcodes, with guard lines and code written below
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| class EAN13Outputter < Barby::RmagickOutputter | |
| attr_writer :font_size | |
| def to_image(opts = {}) | |
| with_options opts do | |
| canvas = Magick::Image.new(full_width, full_height) | |
| bars = Magick::Draw.new | |
| x1 = margin + offset_width | |
| y1 = margin + (offset_height / 2) | |
| guard_positions = [] | |
| booleans_with_guard.each do |(bar, guard)| | |
| if bar | |
| x2 = x1+(xdim-1) | |
| y2 = y1+(height-1) | |
| if guard.present? | |
| y2 += guard_height | |
| guard_positions << x1 | |
| end | |
| bars.rectangle(x1, y1, x2, y2) | |
| end | |
| x1 += xdim | |
| end | |
| bars.draw(canvas) | |
| draw_data(canvas, guard_positions) | |
| canvas | |
| end | |
| end | |
| def draw_data(canvas, guard_positions) | |
| draw_data_part(canvas, barcode.to_s[0, 1], margin, margin * 2.5) | |
| draw_data_part(canvas, barcode.to_s[1, 6], guard_positions[1], guard_positions[2]) | |
| draw_data_part(canvas, barcode.to_s[7, 6], guard_positions[3], guard_positions[4]) | |
| end | |
| def draw_data_part(canvas, part, start_x, end_x) | |
| text_width = text.get_type_metrics(part).width | |
| available_width = end_x - start_x | |
| centered_x = (available_width / 2) - (text_width / 2) | |
| text.annotate(canvas, 0, 0, start_x + centered_x, offset_height, part) | |
| end | |
| def booleans_with_guard | |
| raise "This doesn't look like an EAN-13 barcode" unless booleans.length == 95 | |
| guards = [ | |
| 0, 2, # left guard | |
| 46, 48, # center guard | |
| 92, 94 # right guard | |
| ] | |
| booleans.map.with_index do |boolean, index| | |
| [boolean, guards.index(index).try(:+, 1)] | |
| end | |
| end | |
| def text | |
| @magick_text_draw ||= begin | |
| result = Magick::Draw.new | |
| result.font_family = 'arial' | |
| result.pointsize = @font_size | |
| result.gravity = Magick::SouthWestGravity | |
| result | |
| end | |
| end | |
| def font_size | |
| @font_size || 22 | |
| end | |
| def character_height | |
| @character_height ||= text.get_type_metrics("M").height | |
| end | |
| def guard_height | |
| height * 0.15 | |
| end | |
| def offset_width | |
| @offset_width ||= text.get_type_metrics("M").width | |
| end | |
| def offset_height | |
| @offset_height ||= (character_height / 2) | |
| end | |
| def full_height | |
| super + guard_height + (offset_height * 2) | |
| end | |
| def full_width | |
| super + (offset_width * 2) | |
| end | |
| end |
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