I spoke briefly to Alex about this at GUADEC, he believed it might work to just export the icons at 180 instead of 90 in Inkscape, so I wanted to test that.

The result is available here: https://cloud.gnome.org/public.php?service=files&t=3191b5cd394734e43afd3cea956149a0 (too big to attach to bugzilla I believe).

I've named these user-bookmarks@2x.png etc. similar to how qt5 and osx names their icons and placed those in their respective folders next to the regular sizes. Is this naming and placement correct?

Some icons exported a bit weird, such as the emotes in 32 and 48, and the folder icons in 48. Other icons just had bitmaps pasted into the svg source for 16 and 24, so they ended up blurry due to that. However, this should work to at least test this approach with and then we can revisit the few icons that currently look weird.

I think alex' idea was to put these icons into separate 48x48@2/ directories, and add those to the index.theme with some metadata. Lets wait for alex to come back from vacation. Thanks for the icons, anyway !

Should be easy to tweak the theme to just do that. Is he back before ui-freeze?

He's back next week, I think. In any case, we need gtk patches to make use of these icons when appropriate.

Here with folder names like 48x48@2x etc.
https://cloud.gnome.org/public.php?service=files&t=ab22f0963bc810fc11ff19e4bbceb657

Created attachment 251594 [details]
modified render-icon-theme.py

Here are the crude modifications to render-icon-theme.py. Needs to accommodate rendering the regular ones and the *@2x folders but that is way above my level of programming :)

And here are the stock icons for gtk @2x
https://cloud.gnome.org/public.php?service=files&t=f09e1faf657175d062e62819db676163

Created attachment 251618 [details]
bash script for outputting the stock icons @2x

The only thing I would do about hidpi would be to render hidef at 512px instead of 256px, but I really don't feel rendering lowres icons @2 is worth the price.

Created attachment 252281 [details] [review]
Render icons at 2x for HiDPI displays

Created attachment 252283 [details]
Example with re-rendered icons

Created attachment 252284 [details]
Example with just letting gtk+ pick larger icons

I just attached example screenshots at scale 2, with gtk3-demo showing 24x24 toolbar icons either with 24x24@2 re-rendered svgs or just picking the old 48x48 icons. IMHO the old 48x48 icons look better, so maybe its a bad idea to do this.

Sizes 16 and 24 have natural double sized icons at 32 and 48. 22 is not really used. For 48 at scale 2 we're probably ok with the 256 icons scaled down to 96x96. Unsure about size 32, it will currently pick the 256x256 icons and scale them down to 64x64, not sure if thats good enough.

I think maybe we should leave things as is and instead only add Scale=2 directories if we find any particular icon that needs to be custom-drawn for scale 2.

I agree we get better results in using higher detail variants than double-resolution rendering lowers size assets. Closing as wontfix