Port to WebExtensions

[acmiyaguchi]

This addon is awesome and has been valuable to my mixed dpi setup. However, this addon has been marked as 'legacy' in about:addons on recent builds of Firefox 55 nightly due to the transition to WebExtensions in FF57. In particular, it looks like legacy addons will no longer be supported mid-June on nightly and developer channels.

This MDN comparison between the SDK and WebExtensions seems like a good starting place to look.

[gerv]

@ertug: ping? Can you confirm whether or not you plan to update this great add-on?

[ertug]

Thank you! I'd want to but I didn't have the time. I will try to look into it.

[ertug]

I had a look at the WebExtensions API and noticed that the API for setting layout.css.devPixelsPerPx is missing. I found a bug about it that also mentions AutoHiDPI:
https://bugzilla.mozilla.org/show_bug.cgi?id=1373607

[alexbel]

@ertug looks like layout.css.devPixelsPerPx is back in Firefox 57.0

[gerv]

@alexbel No one ever said the pref was missing. But WebExtensions can't alter arbitrary preferences.

[mcanonic]

Without this extension my second monitor is useless. Firefox was the only one app able to auto-adapt to screen with different density. Too bad.

[kalliste]

Setting layout.css.devPixelsPerPx to -1 seems to make it do the right thing for me in Firefox 57

[mcanonic]

I tried but the firefox does not change its aspect on my two monitors. Did you set something else? Did you keep this parameter as "string"?

[gerv]

What "-1" seems to do is to cause Firefox to calculate a good value for this pref every time it restarts. I don't think it's possible to get Firefox to render at a different perpx value on two monitors simultaneously.

[kalliste]

On Firefox 57 on Mac it is readjusting for me each time I move between the retina display and the external monitor, without restarting the browser. This was working with the value set as -1 and is now still working with the value reset to default and showing as -1.0

[mcanonic]

Thanks, it seems that this does not work on Linux. Has anyone tried this on Linux?

[kalliste]

It looks like this may work if you have Wayland and install a (still experimental) Wayland build of Firefox. You should be using Wayland already if you happen to be on a fresh install of Ubuntu 17.10 and you can install Wayland Firefox using Flatpak https://firefox-flatpak.mojefedora.cz/

[grahamperrin]

… WebExtensions can't alter arbitrary preferences.

Mozilla bug 1363856 - [tracker] Implement WebExtensions API to give access to specific preferences

[gigitux]

Have you found a workaround to run firefox on monitor with different dpi?

[mcanonic]

NO, I have bought a new monitor 4k.
In the meanwhile I used firefox in just one (of the two) monitor and I have set the layout.css.depixelperpx field in about:config to 3 (or 4). You can also play with the firefox zoom. These solutions work only if you decide ONE SINGLE monitor to be dedicated to firefox. I'm still wondering why firefox did not implement an "auto-zoom" feature.

[gigitux]

Thanks for your answer! :D
"In the meanwhile I used firefox in just one (of the two) monitor"
Same here!

[kalliste]

@gigitux @mcanonic when I set layout.css.devPixelsPerPx to -1 it seems to do the right thing for me. What is yours set to?

[mcanonic]

My first set was 2, then I set it to 1 for my external monitor. The "-1" does not scale: when I move the firefox wondow from one monitor to the other, I get bad results.

[notartom]

For what it's worth I wrote a WebExtension that does the same thing: https://addons.mozilla.org/en-US/firefox/addon/ffreszoom / https://github.com/notartom/ffreszoom

[rubo77]

Did you try the extension on Waterfox?