#! /usr/bin/ruby
# == Synopsis
# Ruby script to animate a directory of images.
# Requires gifsicle and convert (ImageMagick)
# 
# == Usage
#   ruby animate.rb [ -h | --help ] [ -c | --clobber ] dir output.gif [ type ]
#
# dir::
#   Directory will be expanded internally.
# type:: 
#   Filetype of input images (default .png)
# clobber::
#   Overwrite an existing output file.
#
# == Author 
# Matt Foster <mattfoster@clara.co.uk>
#
# == Bugs
# Probably.
# Should take a glob instead of a directory as an argument.
# 
# == Copyright
# Copyright (c) 2006 Matt Foster
# Licensed under the same terms as Ruby.

require 'optparse'
require 'rdoc/usage'

DELAY = 100           # Delay time between frames 1/100 s.
COLS  = 256           # Colours in animation.
DISP  = true          # Debug switch.
clobber = false
TYPE  = '.png'        # Default image type.

def progTest(prog)
  out = %x{which #{prog}}
  if out.length == 0
    $stderr.puts "Missing program #{prog}"
    false
  else
    true
  end
end

if __FILE__ == $0
  opts = OptionParser.new

  opts.on("-h", "--help") { RDoc::usage }
  opts.on("-c", "--clobber") { clobber = true }
  opts.parse!(ARGV) rescue RDoc::usage('usage')

  dir  = ARGV.shift || nil
  out  = ARGV.shift || nil
  type = ARGV.shift || TYPE
  type = '.' + type unless type[0...1] == '.'

  # Test for programs we need to continue
  if progTest('convert') == false || progTest('gifsicle') == false
    puts 'gifsicle lives at: http://www.lcdf.org/gifsicle/'
    puts 'ImageMagick lives at: http://www.imagemagick.org/'
    exit
  end

  if dir == nil || out == nil
    RDoc::usage('usage')
    exit
  end
  
  if File.exist?(out)
    if clobber
      begin 
        File.unlink(out)
      rescue
        $stderr.puts "Problem removing old output file" + $!
      end
    else
      puts "File #{out} exists"
      exit
    end
  end
  
  dir  = File.expand_path(dir)
  
  files = Dir["#{dir}/*#{type}"]

  if DISP
    puts "Processing #{files.length} #{type} files in #{dir}"
  end
  
  files.each do |file|
    # Convert to gif
    print '.' if DISP
    system("convert -trim #{file} #{File.basename(file, type)}.gif")
  end
  print("\n") if DISP

  gifs = Dir["#{dir}/*.gif"]
 
  # Animate with gifsicle
  system("gifsicle --colors #{COLS} -O2 --delay #{DELAY} #{gifs.join(' ')} > #{out}.tmp")

  begin
    gifs.each {|f| File.unlink(f)}
    File.rename("#{out}.tmp", out)
  rescue Errno::EEXIST
    $stderr.puts "Output file aready exists" + $!
  rescue 
    $stderr.puts "Problem unlinking/renaming files" + $!
  end
  
  puts 'Completed' if DISP
end