Convert to parametric types.

[timholy]

DO NOT MERGE YET: waiting on JuliaMath/FixedPointNumbers.jl#2.

This implements #42. Tedious but hopefully well worth it. I also added lots of conversion tests, and this caught at least one missing method.

I'm pretty excited about what this will allow in Images!

[timholy]

OK, I do believe we can merge this.

This is (mildly) breaking. A few situations will likely trigger an error:

• A = Array(RGB, sz) change to A = Array(RGB{T}, sz) where T is a Fractional (FloatingPoint or FixedPoint) type (formerly it would hve been RGB{Float64}.
• Poorly-typed comprehensions. For example, rgb = [RGB(g, g, g) for g in gray] might need to change to rgb = [RGB{Float64}(g, g, g) etc], for example.

Here are the packages that depend on Color.jl, together with what I know about them:

• "Cairo" passes
• "Compose" has no independent tests
• "Gadfly" passes (remarkably!)
• "Images" fails, will take care of it myself
• "ImageView" passes
• "ProfileView" passes
• "PyPlot" has no tests
• "Winston" passes (I just submitted a PR to improve the tests)

I was intending to submit PRs or at least raise issues in most of these, but it looks like it may not be necessary. Perhaps a brief public service announcement on julia-users would make sense, though.

[dcjones]

This code makes me happy. I love that we're not forced to either make compromises or implement multiple versions of everything, as we would be in many other languages.

[kmsquire]

Did you lose the default value here?

[timholy]

I think it should be covered by the outer constructor?

[kmsquire]

Right, missed that.

[timholy]

Agreed, Julia is very nice that way.

Thanks for merging!

[timholy]

OK if I tag a new version in the next 24 hrs? I'll try to coordinate a new release of Images to go with it, since that's the one clearly-broken package.

[dcjones]

Gadfly tests look good, so it's fine with me.

[timholy]

OK. Since this is breaking, should we increment the minor version?

[kmsquire]

Might want to look closer at PyPlot. Even though there aren't any tests, it does use ColorValues extensively. Cc: @stevengj

[stevengj]

Probably PyPlot will now need to use convert(RGB{Float64}, c::ColorValue) instead of convert(RGB, c). I don't see any other obvious changes that are required, but I will update PyPlot as needed once this is merged.

[timholy]

Thanks, @stevengj

[stevengj]

Actually, it looks like it works as-is, because your fallback convert method is to the Float64 type.

[timholy]

That was the plan, glad to hear it actually worked.

[dcjones]

Tagged 0.3.0