Convert pdf size

update_pdf_size.rb

require 'combine_pdf'
#require 'prawn'

def crop(page, x1, y1, x2, y2)
  size = page.page_size
  x1_new = size[0] - x1
  y1_new = size[1] - y1
  x2_new = size[2] + x2
  y2_new = size[3] + y2
  page.mediabox = [x1_new, y1_new, x2_new, y2_new]
  page.cropbox  = [x1_new, y1_new, x2_new, y2_new]
end

pdf2 = CombinePDF.load('./sample.pdf')

puts pdf2.pages[0].page_size
pdf2.pages.each do |page|
  crop(page, 40, 40, 40, 40)
end
puts pdf2.pages[0].page_size
pdf2.save('converted2.pdf')