Provide a way to limit the maximum screen resolution

[mavaddat]

From jekyll-cloudinary created by nhoizey: nhoizey#28

For example, 2x images should be enough on most websites, even on devices with 3x screens.

Use a <picture> with a dpr-based media query to limit the maximum screen resolution served.

[mavaddat]

There are definitely diminishing returns, and accelerating costs, with DPRs > 2... are you seeing bad effects on real pages? Small 3x viewports downloading resources meant for 5K displays or something?

I love the “browser knows best” attitude of srcset, but if this is a case where browsers are making bad decisions, I suppose that’s why we have <picture>. Maybe file bugs with browsers, too, though?

Chrome goes some way towards mitigating these diminishing returns by picking the closest resource, rather than the smallest-resource-that's-bigger, when DPR ≥ 2. But there are definitely cases on hi-DPR screens when you might want to aim even lower.

(Back in the day I had a too-clever-by-half idea about this. A hard limit like 2x is probably better.)

[mavaddat]

I've seen browsers download really heavy images on mobiles, and I think it is not necessary most of the time. We now have 4x screens on some phablets.

Unfortunately, we can't really expect Jekyll users to implement client hints like save-data, so I thought it would be nice to add a way to reduce the bandwidth waste for all visitors.

I don't think browsers should decide this themselves.

I like you square root formula, but I think sticking to a simple limit of 2x should be enough… ;-)

Anyway, I plan to make it a settings option.