compose-pnm-files-multi-page

#!/usr/bin/ruby -w

pngtopnm = "pngtopnm"
pnmtopng = "pnmtopng"

page_glob_template = 'poster-inline-breaks-%02d-00*.pnm'
complete_page_template_pnm = 'poster-complete-%02d.pnm'
complete_page_template_png = 'poster-complete-%02d.png'

png_files = Dir['poster-inline-breaks-*-00*.png']
png_files.sort!

page_numbers = png_files.collect { |e| e.gsub(/poster-inline-breaks-(\d\d)-.*/,'\1') }.sort.uniq

puts "There seem to be #{page_numbers.length} pages of poster..."

widths  = Array.new( page_numbers.length )
heights = Array.new( page_numbers.length, 0 )

# Calculate the final dimensions of each poster:

png_files.each do |png_file|
  png_width, png_height = `png-find-grid-revised/png-size #{png_file}`.chomp.split(/x/).collect { |e| Integer(e) }
  png_file =~ /^poster-inline-breaks-(\d+)-/
  page = Integer($1)
  if widths[page]
    if png_width != widths[page]
      raise "BUG: Not all the same width!"
    end
  else
    widths[page] = png_width
  end
  heights[page] += png_height
end

puts "Poster pages will have dimensions:"
widths.each_index do |i|
  puts sprintf( "%02d: %d x %d", i, widths[i], heights[i] )
end

# Now create the huge PNM files, by stripping the headings from each
# and concatenating:

pages_started = Array.new( page_numbers.length, false )

png_files.each do |png_file|

  png_file =~ /^poster-inline-breaks-(\d+)-/
  page_string = $1
  page = Integer(page_string)

  output_filename = sprintf(complete_page_template_pnm,page);

  unless pages_started[page]
    puts "Starting new page: #{page}"
    # Output the heading and indicated we've started:
    output_filename = sprintf(complete_page_template_pnm,page)
    open( output_filename, "w" ) do |o|
      o.puts("P5")
      o.puts("#{widths[page]} #{heights[page]}")
      o.puts("255")
    end
    pages_started[page] = true
  end

  puts "  Adding strip: #{png_file}"
  open( output_filename, "a" ) do |o|
    Kernel.open( "|-", "r" ) do |f|
      if f
        f.gets # Read the P5
        f.gets # Read the width and height
        f.gets # Read the 255
        o.write(f.read)
      else
        begin
          exec( pngtopnm, png_file )
        rescue
          raise "Couldn't exec #{command}: #{$!}\n"
        end
      end
    end
  end

end

## This takes ages and is basically pointless since we almost
## always want to work with a reduced size version instead.
#
# page_numbers.each_index do |i|
#   puts "Creating PNG version of page #{i}:"
#   pnm = sprintf( complete_page_template_pnm, i )
#   png = sprintf( complete_page_template_png, i )
#   system "#{pnmtopng} #{pnm} > #{png}"
# end