Red Hat Bugzilla – Bug 1282134
[SKIA] disabled skia causes scaled-down images to look awful
Last modified: 2016-01-04 09:08:45 EST
Created attachment 1094294 [details]
Screenshot from URL mentioned above, rendered with Fedora's Firefox v42
Description of problem:
skia is explicitly disabled in Fedora's firefox package. One noticeable effect is that scaled-down images look pixelated. If there is text in the image, it can be unreadable. I'm not sure why skia is disabled; the changelog mentions fixes to get skia working on arm platforms around v37, but nothing since then. Skia is enabled in binary builds from Mozilla. With skia enabled, scaled-down images get anti-aliased and look better.
Version-Release number of selected component (if applicable):
Steps to Reproduce:
1. Visit http://rheneas.eng.buffalo.edu/~andrew/ff-scaling.html in Fedora's Firefox.
3. Note that text is hard to read
4. Build without skia disabled or use a binary build from mozilla
5. Visit http://rheneas.eng.buffalo.edu/~andrew/ff-scaling.html
7. Note that text is small but readable.
While scaled-down text images are not the most common thing, they often result from page-spanning images viewed on a low resolution display (or in a small browser window) like https://spins.fedoraproject.org/kde/
Please re-enable skia.
Created attachment 1094295 [details]
screenshot of same page, rendered with Mozilla's Firefox v42
With Mozilla's Firefox, the text is readable down to 6px (especially if the scaling is due to a low-res display, which would make the text bigger). Fedora's Firefox looks similarly readable at 11px.
Yes, I can reproduce it. Although the Skia backend is still disabled in Firefox (https://bugzilla.mozilla.org/show_bug.cgi?id=1038800) looks like the Skia is used for a final layer composition and affect the scaling here.
Enabled in Rawhide.
(In reply to Martin Stransky from comment #2)
> Yes, I can reproduce it. Although the Skia backend is still disabled in
> Firefox (https://bugzilla.mozilla.org/show_bug.cgi?id=1038800) looks like
> the Skia is used for a final layer composition and affect the scaling here.
Mozilla absolutely ships linux builds with skia enabled in the buildconfig (they do not --disable-skia) although they may not be enabling it for everything it can do (the prefs in https://bugzilla.mozilla.org/show_bug.cgi?id=740200#c44). This bug is just requesting enabling the buildconfig option, which would match upstream.