Add 'compare' or 'difference' subcommand

[sharkdp]

Which computes contrast, color difference, etc.

in the interactive version, we could show a-colored text on a b-colored background. Also, show two color panels (like in pastel color) directly next to each other.

[JuanPotato]

I was in the process of writing this feature, but I'm not sure what else to add in for text. I also wanted to ask if there was a way to print styled text at a specific location. I can see Canvas has draw_text but that only draws unstyled text at a certain location. The paint subcommand uses the paint function in Brush but that doesn't accept a position.

[sharkdp]

Awesome, thank you for looking into this.

As for more information, I think we should also display the CIEDE2000 color difference. Other interesting quantities could be ΔL(ightness) or ΔH(ue).

For both the contrast ratio and the color difference, we could also provide a little context as to what these values represent (e.g.: "not noticeable" or "high" for the difference).

For more information on contrast ratios, see: https://www.w3.org/TR/2008/REC-WCAG20-20081211/#contrast-ratiodef

I guess there is no way (yet) to draw colorized text, no.

[bresilla]

Hi @JuanPotato

Do you mind sharing what you've worked about this so far, so i can have a look at it and check if i can implement this?? (cos in your screenshots seem you've already have something working...)

Thank you.

P.S. I checked if you've got t in your public repos but couldn't find it.

[JuanPotato]

https://github.com/JuanPotato/pastel/tree/compare

Did you look at this branch?

[bresilla]

@JuanPotato Thank you.

No I have not. But now whenever have some free time in coming weeks I'll give it a go...

What i am thinking is that: the logic that does "the sorting" (command: sort-by) already holds the logic of comparison of colors based on brightness, luminance, hue and chroma, so I'll take that logic/code and use with your code that you implemented for cli entry (command: compare) and other components.

I didn't go enough into the source code of pastel, but i think this can be done. But maybe i am wrong into thinking this, so I'll see.

Thank you again :)