Converting SVG content from Highcharts into PNGs to be embedded into a PDF. Eventually I settled on using prawn-svg (thanks, Matt!). But I thought this solution was interesting enough to retain.

svg_to_png.rb

@pngs = {}
timestamp = Time.now.to_i
Dir.mkdir("#{Rails.root}/tmp/rmagick") unless File.exists?("#{Rails.root}/tmp/rmagick")
Dir.mkdir("#{Rails.root}/tmp/rmagick/reports") unless File.exists?("#{Rails.root}/tmp/rmagick/reports")
Dir.mkdir("#{Rails.root}/tmp/rmagick/reports/#{timestamp}") unless File.exists?("#{Rails.root}/tmp/rmagick/reports/#{timestamp}")
params[:svgs].each do |key,svg|
  string = '<?xml version="1.0" encoding="UTF-8" standalone="no"?>'+URI.unescape(svg)
  string.gsub!("'lucida grande', 'lucida sans unicode', verdana, arial, helvetica, sans-serif",'') # classes_observed_by_grade_level
  string.gsub!(/clip-path="url\(#highcharts-[0-9]*\)"/,'clip-path="none"') # classes_observed_by_grade_level
  string.gsub!(' opacity="1"','') # classes_observed_by_grade_level
  string.gsub!('translate(0,0) rotate(270 24.03125 156)','translate(0,0) rotate(270 -130 156)') # classes_observed_by_grade_level
  string.gsub!('scale(-1,1) scale(1 1)', 'scale(1,-1)') # content_and_materials, training_attendance
  img = Magick::Image::from_blob(string)  { self.format = 'SVG'; }.first
  img.format = 'JPG'
  path = "#{Rails.root}/tmp/rmagick/reports/#{timestamp}/#{key}.jpg"
  img.write(path)
  @pngs[key] = path # , :type => 'image/png',:disposition => 'inline'
end