gbarcode生成条形码的代码
# Uses subprocesses because
? # 1. ImageMagick/RMagick leaks memory,
? #??? and doesn't work in a long-running process. The fork makes it safe.
? # 2. The output from the Gbarcode and ImageMagick is often longer than the pipe buffer,
? #??? so we have to empty the buffer from another subprocess
? def BarcodeGenerator.get_barcode_image(barcode_string)
??? return BarcodeGenerator.get_subprocess_output do
????? barcode_generator = BarcodeGenerator.new
????? $stdout.write(barcode_generator.get_barcode_image(barcode_string))
??? end
? end
? def initialize
??? # we do the imports here to protect long-running processes (like mongrel) from ImageMagick's memory leaks
??? require 'RMagick'
??? require 'gbarcode'
? end
? def get_barcode_image(string_to_encode)
??? if string_to_encode.nil?
????? string_to_encode = "No string specified"
??? end
??? string_to_encode = remove_rails_file_extension(string_to_encode)
??? eps_barcode = get_barcode_eps(string_to_encode)
??? gif_barcode = convert_eps_to_gif(eps_barcode)
??? return gif_barcode
? end
? def remove_rails_file_extension(string_to_encode)
??? if string_to_encode[-4..-1] == ".png"
????? string_to_encode = string_to_encode[0..-5]
??? end
??? return string_to_encode
? end
? def get_barcode_eps(string_to_encode)
??? barcode_object = Gbarcode.barcode_create(string_to_encode)
??? Gbarcode.barcode_encode(barcode_object, Gbarcode::BARCODE_128)
??? return BarcodeGenerator.get_subprocess_output do
????? Gbarcode.barcode_print(barcode_object, $stdout, Gbarcode::BARCODE_OUT_EPS)
??? end
? end
? def convert_eps_to_gif(eps_image)
??? base64_eps_image = Base64.encode64(eps_image)
??? im = Magick::Image::read_inline(base64_eps_image).first
??? im.format = "GIF"
??? return BarcodeGenerator.get_subprocess_output do
????? im.write($stdout)
??? end
? end
? # execute a block's code in a subprocess, returning any output
? def BarcodeGenerator.get_subprocess_output()
??? data = ""
??? IO.popen('-', 'r+') do |child_filehandle|
????? if child_filehandle
??????? begin
????????? data = child_filehandle.read
??????? ensure
????????? child_filehandle.close_write
??????? end
????? else
??????? yield
????? end
??? end
??? return data
? end
end
注：1. $stdout是rails的标准输出通道
??? 2. ImageMagick安装的时候一定要配置ghostscript fonts路径，如：./configure --with-gs-font-dir=/usr/share/ghostscript/8.70/Resource/Font ，否则gbarcode生成的条形码文件是.ep或.eps格式的，ImageMagick不能操作，正确配置
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