851197 - (metro-hidpi) handle dynamic changes to scaling on Metro

Status: RESOLVED FIXED

(Core Graveyard :: Widget: WinRT, defect)

Description

[Jonathan Kew [:jfkthame]]

This is a followup to bug 816709, which provided basic support for HiDPI rendering on Metro, respecting the system's ResolutionScale property. However, as noted in bug 816709 comment 25, dynamic changes (toggling Metro's 'Make everything bigger' setting) while Firefox is open are not handled properly.

We should be able to fix this by handling the LogicalDpiChanged event (which FrameworkView already registers for), similarly to how changes to the "backing scale factor" are handled by the Cocoa widget code.

Comment 1

[Jonathan Kew [:jfkthame]]

Attachment: patch, handle dynamic resolution changes

With this patch, the browser responds properly to enabling/disabling the "Make everything bigger" option in Metro settings, toggling between the 100% and 140% scales (on my 13" machine, where the default is 100%; on an 11" FullHD screen, I assume it would toggle between 140% and 180%).

Comment 2

[Jonathan Kew [:jfkthame]]

Oh, one thought - do we need to consider plugins here? The Cocoa widgets version has some code to notify plugins of the change; do we need to do the same thing here?

Comment 3

[Jim Mathies [:jimm]]

(In reply to Jonathan Kew (:jfkthame) from comment #2)
> Oh, one thought - do we need to consider plugins here?

Nope!

Comment 4

[Jonathan Kew [:jfkthame]]

https://hg.mozilla.org/integration/mozilla-inbound/rev/ee2bba86031b

Comment 5

[Phil Ringnalda (:philor)]

https://hg.mozilla.org/mozilla-central/rev/ee2bba86031b