1473501 - Improve the way Gecko selects images based on srcset values (don't just round up, when rounding up is a huge jump)

Status: NEW

(Core :: Layout: Images, Video, and HTML Frames, enhancement, P3)

Description

[Karl Dubost💡 :karlcow]

I'm opening this issue because in a couple of cases, we get an image which is slightly blurry in Firefox while Chrome seems to get a higher resolution image.


1. Load URL on a phone.
2. Scroll down to image.
3. Compare to mobile Chrome.


We have at least two issues already with this behavior.

https://webcompat.com/issues/12774 
https://webcompat.com/issues/16836


There's a good discussion and analysis in 
https://webcompat.com/issues/12774#issuecomment-339094641

comparing what chrome and firefox do.

Comment 1

[Daniel Holbert [:dholbert]]

(In reply to Karl Dubost :karlcow (away from 2018-07-10 to 2018-07-25) from comment #0)
> I'm opening this issue because in a couple of cases, we get an image which
> is slightly blurry in Firefox while Chrome seems to get a higher resolution
> image.

That's an accurate description of the latter NatGeo webcompat issue that you linked.

However: I think the former webcompat issue ( https://webcompat.com/issues/12774 ) is substantially different -- there, Firefox was getting a *higher-res* (i.e. larger/wider) image as compared to Chrome.

(Also, a big part of the main issue there was that the website was lying about the image resolutions. I don't think that's the case with this NatGeo scenario.)

So there may be different problems... Unfortunately I can't investigate the NatGeo issue because I'm getting just-fine image resolutions on my (Google Pixel 2) mobile device -- no blurriness/low-qualitiness visible.

Comment 2

[Daniel Holbert [:dholbert]]

Correction: per updates on the NatGeo webcompat issue, it's hitting the same sort of issue as in https://webcompat.com/issues/12774 after all.

The general webcompat issue here is that *Firefox* is picking a higher-resolution image than Chrome is. We round up when deciding between sources, whereas Chrome rounds to the nearest (possibly picking an image whose "###w" specifier is lower than the screen resolution). Or something like that.

And this is particularly problematic (for us) when rounding up is a large jump whereas rounding down would be a small jump.

Comment 3

[Firefox Bug Husbandry Bot]

Migrating Webcompat whiteboard priorities to project flags. See bug 1547409.

Comment 4

[Firefox Bug Husbandry Bot]

See bug 1547409. Migrating whiteboard priority tags to program flags.