Cristian Fogel [:cfogel] Reporter
	Description • 6 years ago

[Affected versions]:
- 64.0a1, 63.0b13, 

[Affected platforms]:
- win10x64, macOS 10.13, Ubuntu 16.04

[Steps to reproduce]:
1. Launch Firefox;
2. Navigate to about:preferences#general
3. Enable the CTRL+Tab cycles through tabs in recently used order;
4. Open pages like youtube, reddit each in another tab;
5. Press CTRL+TAB a couple of times;

[Expected result]:
- tab previews are displayed properly;

[Actual result]:
- favicons are blurry

[Regression range]:
- pre Bug 1383217, the icons where smaller and this was not an issue;
- issue is noticeable after the above mentioned update when the icons in previews are increased in size;

[Additional notes]:
- attached screen recording with the issue;
- have tried with fresh profiles as well;
- dpi settings set at 100%;

	Marco Bonardo [:mak]
	Comment 1 • 6 years ago

So, apparently the problem here is that, since we are at 100% dpi the tab fetches a 16x16 px. Ctrl+tab just reuses the tab image, though it shows it at a 42px (I think? ctrlTab-favicon has width and height at 42px). Anyway the fact it's upscaling the image, that only works if the original image was an ico or an svg, if it's a png it will look bad.
I can't reproduce this bug because I'm at 125% dpi, so the tab uses the 32px image and here we do the same, that image scales better.

The only solutions I may think of are:
1. use the history favicon through Places if history is not disabled (we're not yet able to store icons in PB mode, that needs fixing) and hopefully the hidpi image will downscale nicely, or we could store a 2x icon regardless.
2. don't upscale icons, just show them at their original size, with a min-width.
3. make the tab also store a larger icon and allow a way to pick that up.

	Dão Gottwald [:dao]
	Comment 2 • 6 years ago

(In reply to Marco Bonardo [::mak] from comment #1)
> So, apparently the problem here is that, since we are at 100% dpi the tab
> fetches a 16x16 px. Ctrl+tab just reuses the tab image, though it shows it
> at a 42px (I think? ctrlTab-favicon has width and height at 42px).

That includes 5px padding on each side, so the actual image size is 32*32px.

I believe these favicons are rendered pretty much the same as those in about:newtab which was the intent of bug 1383217.

	Marco Bonardo [:mak]
	Comment 3 • 6 years ago

The difference is that, IIRC, the newTab page uses the favicons service, that likely has larger icons available.

	Dão Gottwald [:dao]
	Comment 4 • 6 years ago

I'm at 100% DPI and I seem to be getting the same favicons in the Ctrl-Tab panel and about:newtab... Some are high-res such as these for treeherder.mozilla.org and mail.google.com.

	Marco Bonardo [:mak]
	Comment 5 • 6 years ago

it depends on what the dpi was when the favicon was fetched and stored.
Also, the report is missing a couple examples, this happens for example on reddit or youtube.

	Liz Henry (:lizzard) (relman/hg->git project)
	Comment 6 • 6 years ago

Marking fix-optional for 64. We could still take a patch in 65.