Changing mac folder icon with Ruby? - ruby

Question

Is it possible to change the icon of a Mac folder using a set of Ruby commands? I believe that OSX requires a .icon file to be present within the modified folder, perhaps there is a specific way of converting a jpg or png to the .icon criteria?
-- Edit (Working solution. Requires ImageMagick and OSXUtils)
* note, for my application I intended to set folder icons. It is entirely possible this could work for files as well.
def set_icon image, folder
# Convert to absolute paths and setup
image = File.expand_path image
folder = File.expand_path folder
dim = 512
thumb = folder + '/'+ 'thumb.png' # PNG supports transparency
icon = folder + '/'+ 'icon.icns'
# Convert original to thumbnail
system "convert '#{ image }' -quiet -thumbnail '#{dim}x#{dim}>' \
-background none -gravity center -extent #{dim}x#{dim} '#{ thumb }'"
# Set icon format. Causes 'libpng warning: Ignoring attempt to set cHRM RGB triangle with zero area'
system "sips -s format icns '#{ thumb }' --out '#{ icon }'"
# Set the icon
system "seticon -d '#{ icon }' '#{ folder }'"
# Cleanup
FileUtils.rm thumb
FileUtils.rm icon
end

Answer 1

It's been years since I played with them, but .icon files' format were documented by Apple's documentation and Wikepedia.
If I remember right, the name has a trailing "\r" to make it harder to type, but that's easily handled from code.
You should be able to use the normal File.rename method to move an .icon file into a folder, and the Finder should do the right thing.
Looking at your code, I'd do some things differently:
require 'fileutils'
def set_icon image, folder
# Convert to absolute paths and setup
image = File.expand_path image
folder = File.expand_path folder
temp = File.join(folder, 'temp2' + File.extname(image))
# Copy image
FileUtils.cp(image, temp)
# Take an image and make the image its own icon
system "sips -Z 512 -i #{ temp }"
# Extract the icon to its own resource file
system "DeRez -only icns #{ temp } > tmpicns.rsrc"
# Append a resource to the folder you want to icon-ize
system "Rez tmpicns.rsrc -o $'#{ folder }/Icon\r'"
# Use the resource to set the icon.
system "SetFile -a C #{ folder }"
end
Rather than rely on sprintf or % ("format") to build the strings, instead use simple interpolation. sprintf strings are great when you need to force column widths and coerce values into a different representation, but they're overkill when you're inserting a single value that isn't formatted.
sips has this option, which looks promising, but it's not documented well in the man page:
-i
--addIcon
Add a Finder icon to image file.
Also, Stack Overflow's sibling site "Ask Different" has "Why setting image as its own icon with sips result a blurred icon? Are there any alternatives?", "How do I set an icon for a directory via the CLI? and "Changing a file or folder icon using the Terminal" which look useful.