Add Spectrum's functionality

[trans]

Came across this project today: https://github.com/twoism-dev/Spectrum. It's a rather small set of functions for extracting color references from strings.

Seems like that could be a good addition to color gem, and can do it better since it can return actual Color objects.

So maybe something like:

Color.extract_names('I love the color red, blue is awful') => { "red"=>RGB [#ff0000], "blue"=>RGB [#ff00ff] }
Color.extract_css('I love the color #f00, #00f is awful') => { "#f00"=>RGB [#ff0000], "#00f"=>RGB [#ff00ff] }

Also, it would be cool to get the CSS name given the html string.

r = Color::CSS::Red
r.css_name  #=> "red"

Taking it one step further, maybe even return the closest matching name, if there is no exact match.

r = Color::RGB.from_html("#ff1111")
r.css_name  #=> "red"

[halostatue]

Sounds interesting. I don't have time to work on this at the moment (paying work, work on my wife's novel, and gem work on libraries that I consider more important/relevant) but your proposed API isn't a bad one. The only thing that I'd probably do differently is that I probably wouldn't have #css_name return an inexact match unless the user requested it (maybe #css_nearest_names—since it could theoretically return more than one).

If you want to work up a pull request, I'd be happy to consider it for inclusion.

[trans]

Cool. I don't have time at the moment either, but I'll try to get to it sooner rather then later.

[halostatue]

These methods are going to be hung off Color::RGB. The functionality is:

Color::RGB.by_hex('0ff') # => Color::RGB::Cyan
Color::RGB.by_hex('333') # => Color::RGB.from_hex('333')
Color::RGB.by_name('cyan') # => Color::RGB::Cyan
Color::RGB.by_name('cyanide') # => raise KeyError
Color::RGB.by_css('0ff') # => Color::RGB::Cyan
Color::RGB.by_css('333') # => Color::RGB.from_hex('333')
Color::RGB.by_css('cyan') # => Color::RGB::Cyan
Color::RGB.by_css('cyanide') # => raise ArgumentError

I've made it so that Color::CSS[name] calls Color::RGB.by_name(name) instead.

As far as #extract_names is concerned, here’s the test:

      assert_equal([ Color::RGB::BlanchedAlmond, Color::RGB::Cyan ],
                   Color::RGB.extract_colors('BlanchedAlmond is a nice shade, but #00ffff is not.'))