oily_png ruby gem installation error

Question

I'm getting an error upon installing of oily_png gems. Ruby is already installed my system. I'm on Windows 7 - 64 bit.

C:\Users\jitendra>gem install oily_png
Fetching: oily_png-1.0.2.gem (100%)
ERROR:  Error installing oily_png:
        The 'oily_png' native gem requires installed build tools.

Please update your PATH to include build tools or download the DevKit
from 'http://rubyinstaller.org/downloads' and follow the instructions
at 'http://github.com/oneclick/rubyinstaller/wiki/Development-Kit'

Answer 1

OilyPNG is written in C and therefore has to be compiled. You need to have a compiler installed and set up properly so that Ruby/Rubygems can find it in order to install the gem.

It is possible to release a gem with a Windows binary, so that compilation is not needed on Windows machines. Unfortunately, because I don't have a Windows machine nor do I have Windows development experience, I am not able to to this. (Pull requests are accepted though :)

My advice is to follow the advice Rubygems gave you:

Please update your PATH to include build tools or download the DevKit from 'http://rubyinstaller.org/downloads' and follow the instructions at 'http://github.com/oneclick/rubyinstaller/wiki/Development-Kit'