Added traits: from and display to all color struct

[bresilla]

For each colorstruct (Color, Lab, RGB...) traits 'From' and 'Diplay' are coded. Those are very important when you want simply comvert from one color to another with standard Rust things: let new_color = Lab::from(&Color) or let new_color: Lab = somme_color.into()

In addidtion another delta_e was added: cir94, which is faster than ciede2000 bu more accurate than cie76.

Lastly, a function nearest was added that is 5 lines, but, with your premission in the future, i want to add functionality to extract colors fom image, and this function is needed. It simply finds the index and distance from nearest color from a group of colors

[sharkdp]

Thank you for your contribution!

All of these changes sound great, but I would prefer if we could split them into multiple PRs.

i want to add functionality to extract colors fom image, and this function is needed.

This sounds like a useful functionality, but I'm not sure it would really fit into this library. Wouldn't it require new dependencies?

[bresilla]

Yes sure. I think that delta_e changes can be ingnored for the moment. I can try later as anther PR for that (an loading colors from images - which requires only image lib).

The changes in lib file are that have the traits From and Display added. I don't know if you want this as two PR's (one for each)? Is that what you mean to split in multiple PR'S?

[sharkdp]

I don't know if you want this as two PR's (one for each)? Is that what you mean to split in multiple PR'S?

No. I Display and From is fine in one PR, but it would be great to split out the other things (nearest and new distance function)

[bresilla]

Sure thing. I'll do that.

PS: I am building a tool that uses extensively pastel, and along the way, if i see that some functions are better in pastel, I'll make a PR :)

[sharkdp]

PS: I am building a tool that uses extensively pastel, and along the way, if i see that some functions are better in pastel, I'll make a PR :)

Sounds great. Definitely interested to hear more :smile:

[bresilla]

You already have in the main function the print_XXX_string(), which in all cases is a formated version something like hsl({:.0},{space}{:.1}%,{space}{:.1}%). Do you think that the display funciton we should have more like hsl({}, {}, {}), so its more like raw numbers. SO when people want to use:

let new_color = Color::from(&RGBA{ r:100, g:100, b:100, alpha: 1.0} )

then this println!("{}", new_color.to_hsl_string()) would print better formmated version like:

hsl(0, 1.0, 0.5)

while this println!("{}", new_color) would print a rawer version:

hsl(0.0000, 1.0000, 0.5253)

So, if you use the function you build it, then you get a prettier format, but if you don't specify, the Display trait will print it a bit more accurate but less pretty.

[sharkdp]

So, if you use the function you build it, then you get a prettier format, but if you don't specify, the Display trait will print it a bit more accurate but less pretty.

Yes, I think that's a good idea. Just do the "bare minimum" work in the Display trait. It's meant for debugging, not for pretty-printing (to my knowledge).

[sharkdp]

Could you please also add an entry to the "unreleased" section in CHANGELOG.md? The format for entries is:

- Description what has been changed, see #123 (@user)

where #123 links to the bug ticket and/or the PR and user is your username.

[bresilla]

Could you please also add an entry to the "unreleased" section in CHANGELOG.md? The format for entries is:

Done. :)

So, if you use the function you build it, then you get a prettier format, but if you don't specify, the Display trait will print it a bit more accurate but less pretty.

Well, there is the Debug trait too but that is automatically implemented i believe, in the other hand the Display makes possible that any struct that implements can have to_string() which is very useful for others that want to use this library.

[sharkdp]

Thank you!