[导入]Produce GIF or PNG barcode images from a Ruby on Rails application using RMagick and Gbarcode
On Mac OS X, you can use the Locomotive RMagick bundle (http://locomotive.raaum.org/bundles/index.html) if you install the gbarcode gem into it first, for instance:
% export GEM_HOME=/Applications/Locomotive2/Bundles/rmagickRailsMar2007_i386.locobundle/framework/lib/ruby/gems/1.8/
% gem install gbarcode
To use it, save this code as barcode_controller.rb in the apps/controllers directory of your Rails application. Generate the barcodes using a URL like this:
http://localhost:3000/barcode/get_barcode_image?string=foo
This example uses the BARCODE_128 encoding; you can use different barcode encodings by adjusting the code. To produce PNG images, make sure you have have the PNG libraries installed on your system, and that your ImageMagick is compiled with PNG support, and then change 'image/gif' to 'image/png' and im.format = "GIF" to im.format = "PNG".
# $RAILS_ROOT/apps/controllers/barcode_controller.rb
class BarcodeController < ApplicationController
def get_barcode_image
string_to_encode = params[:string]
barcode_image = BarcodeGenerator.get_barcode_image(string_to_encode)
send_data(barcode_image, :type => 'image/gif',
:disposition => 'inline')
end
end
# $RAILS_ROOT/app/helpers/barcode_generator.rb
#
# note: this will not work without rmagick (Ruby ImageMagick interface) and gbarcode (GNU barcode)
# gems installed. rmagick needs ImageMagick plus dependencies.
class BarcodeGenerator
# 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