RQRCode插件使用

  def config
    {
      level: :m, # 容错级别
      mode: :mode_8bit_byte # 使用模型
    }
  end

  def png_config
    {
      file:              false,
      resize_gte_to:     false,
      resize_exactly_to: false,
      fill:              'white',
      color:             'black',
      border_modules:    1 # 白边宽度
    }
  end

  # 生成二维码的Base64字符串
  # data:image/png;base64,
  def as_encode64_png(str, with_logo = true, png_ops = {})
    rq     = RQRCode::QRCode.new(str.to_s, config)
    rq_png = rq.as_png(png_config.merge(png_ops))
    rq_png = draw_logo(rq_png.to_blob) if with_logo
    Base64.encode64(rq_png.to_s)
  end

  def draw_logo(rq_str)
    er_img = MiniMagick::Image.read(rq_str)
    er_img.colorspace('sRGB')
    logo_img   = MiniMagick::Image.read(File.open(LOGO_PATH).read.to_s)

    res          = er_img.composite(logo_img) do |logo|
      logo.compose('Over')
      logo.geometry("+<左边距>+<上边距>")
    end

    res.to_blob
  end