Adding color information to targets

[dominicbarnes]

I was needing to write a custom legend for my charts, and the only piece of information I was missing was color. Thus, I've added it as a part of the target object.

[masayuki0812]

Hi, Thank you for the PR, but I think there would be better way to get the color by id. How about color API that we can get the color by id? I think this is better because the color could change according to the situation (color can be change by data and updated by some API), and I think it's more flexible as a interface to colors. API would be like c3.color(id, data) and return the hex;

What do you think about this idea? If this is acceptable, I'll add this feature in the next version.

[dominicbarnes]

I don't think a c3.color method makes much sense, as you said there are lots of internal factors to consider. I'd be willing to change this and expose the color function directly, and then it will still reflect the internal state of the chart. (maybe chart.getTargetColor(targetId)?)

[masayuki0812]

Sorry, I meant chart.getTargetColor as you wrote. This method will be exposed like other APIs. By this API, you can get the color by id through the chart object generated by c3.generate().

[dominicbarnes]

I've made the change you suggested, let me know if there's anything else I can do.

[masayuki0812]

Thank you!
Could you change the name getTargetColor to color? This method can accept not only id but also an object that includes id, value and etc, so I think color would be more appropriate.

[masayuki0812]

I added this feature as color, so I'll close this PR. Thank you for your help.