UI for managing the zoom level in high DPI environments
Sylvain Pasche
Hi,
Some operating systems allow you to scale the fonts and user interface
globally by a given percent value. For instance all versions of Windows
since XP let you adjust that OS zoom level in order to make everything
larger [1]. That's particularly handy when you have a high DPI monitor,
look at it from a large distance or just prefer bigger text.
For the moment if you configure Windows to use a OS zoom level of 150%,
Firefox will still show everything at 100%. There was a discussion on
mozilla.dev.platform [2] about the backend change that would make
Firefox match the OS zoom level for any OS zoom value. This would be the
right thing to do (on Windows at least) because all "DPI-aware"
applications (such as IE) do that. As of now, it only works if you set
the OS zoom level to 200% or set the layout.css.dpi pref to 192.
Now there's a potential annoyance when you view web pages at a zoom
level higher than 100%: images can look blurry and the layout may not
exactly match what the designer created. Because of this, I think the
user should have ways to:
1) Switch to a zoom level of 100% for a specific page
2) Have an option to browse at 100% zoom level by default for users who
prefer smaller text over blurry images (note that "zoom text only" is
another way to avoid these blurry images).
What IE did to solve 1) is to show a dropdown menu in the status bar
with a list of zoom levels.
Some proposals how Firefox could address the issue (they may not be
mutually exclusive):
a) Do something like IE, maybe only when the OS zoom level is not 100%.
b) In the View > Zoom menu:
b.i) Provide two kinds of zoom reset if the default zoom level is not
100%: one to reset to the default zoom level and one to reset to 100%.
b.ii) Show the list of zoom scales in that menu (instead of having
them in the status bar drop down).
For 2), I guess there could be a preference in the Options>Content tab
for setting the default zoom level to 100% (that could be visible only
if the OS zoom (and consequently the default Firefox zoom level) is > 100%).
What do you think?
This is not directly related to the zoom UI, but for the best possible
high DPI user experience, high resolution theme image should be used.
This image [3] shows how Firefox looks with a 150% OS zoom level (with a
modification to scale the UI smoothly). You can notice that the theme
images look a bit blurry.
Sylvain
[2]
http://groups.google.com/group/mozilla.dev.platform/browse_thread/thread/7d6822e96dc10705