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2011-02-25

The Need

Today I started putting together a little image gallery for my sideburns and I really wanted a way to easily scale a directory of images to a specific height, save the result in a directory and then repeat the process and save in yet another directory.

The Solution

There is probably an easy way to do what I want using GIMP, but I thought it would be better if I wrote a script to handle this for me. Technically, the script that I wrote is just a fancy wrapper for the imagemagick convert command.

Enter the Ruby

#!/usr/bin/env ruby

#create a function to end the script with a message
def exit_help(message=nil)
  #did a message get passed in?
  if !message.nil?
    #print the message
    puts message
  end
  #print the 'help'
  puts "--Help--
#{$0} path/to/image/directory thumbnail_height image_height  
  "
  exit()
end

#make a function to create a dir if it doesn't exist
def check_dir(dir)
  if !File.directory?( dir )
  Dir.mkdir(dir)
  end
end

#make a function to run a set command
def do_command(comm)
  puts comm
  system(comm)
end

#set some variable  based on the input from the user
start_dir = ARGV[0]
thumb_height = ARGV[1].to_i
image_height = ARGV[2].to_i

#if any of the vars aren't set, the user didn't input enough info
if start_dir.nil? or thumb_height==0 or image_height==0
  exit_help()
end

#does the start dir exist?
if !File.directory?( start_dir )
  exit_help( "#{start_dir} does not exist" )
end

# define the output dirs
gallery_dir = File.join(start_dir,'gallery')
thumb_dir = File.join(start_dir,'gallery_thumbs')

# make the dirs if they don't exist
check_dir(gallery_dir)
check_dir(thumb_dir)

#loop through the files in the start_dir
start_dir_files = File.join(start_dir,"*.{png,jpg}")
Dir.glob(start_dir_files)  do |file|
  #what is the name of the file?
  fname = File.basename(file)
  #what is the path of the new gallery file?
  gfile = File.join(gallery_dir,fname)
  #what is the path of the new thumbnail file?
  tfile = File.join(thumb_dir,fname)
  #what imagemagick commands will resize the images? 
  c1 = "convert -resize x#{image_height} #{file} #{gfile}"
  c2 = "convert -resize x#{thumb_height} #{file} #{tfile}"
  #run the commands
  do_command( c1 )
  do_command( c2 )
end

What It Do?

I'll tell you what it do! When run, the script requires three arguments: 1. The name of the directory containing the images 2. the height of the thumbnail image 3. the height of the gallery image

The end result will be a directory named "gallery" and a directory named "gallery_thumbs" in the images directory. Gallery will contain the images resized to the gallery height specifications. I'll leave it to you to figure out what images are in the "gallery_thumbs" directory.

My Take Away

Originally, I had planned on using the exec() function to run my convert commands but exec() replaces the calling script with the command being called. This means that as soon as I ran exec(), my code would quit running. Oh well, system() works just fine for my needs.

my resized images using Ruby and Imagemagick from jezra.net
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