765914 - -moz-device-pixel-ratio misreported as 1.0 instead of 2.0 on Mac HiDPI display

Status: RESOLVED WORKSFORME

(Firefox :: Untriaged, defect)

Description

[Brion Vibber]

Attachment: ratio.html

User Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.7; rv:16.0) Gecko/16.0 Firefox/16.0a1
Build ID: 20120618030531

Steps to reproduce:

Media queries using -moz-device-pixel-ratio or min--moz-device-pixel-ratio report the -moz-device-pixel-ratio value as 1.0 when running on a HiDPI screen, which should report a ratio of 2.0 (MacBook Pro with Retina display).

(Note that this is on a nightly with layers acceleration disabled, as per notes on bug 674373.)

Run the attached HTML file with a little scripting to check media queries.


Actual results:

Firefox nightly shows output:
"-device-pixel-ratio is 1.0 or higher."

indicating that -moz-device-pixel-ratio is 1 or higher  but not higher than 1.5.


Expected results:

Safari and Chrome Canary build show expected output:
"-device-pixel-ratio is 1.0 or higher. 1.5 or higher. 2.0 or higher."

indicating that -webkit-device-pixel-ratio is 2 or higher but not higher than 3.

Comment 1

[David Baron :dbaron: (⌚️UTC-5, no longer working on Mozilla)]

Are we actually displaying at 2 CSS pixels per device pixel, and reporting 1, or are we displaying incorrectly too?

Comment 2

[Brion Vibber]

When I filed this, nightlies were running at high resolution when gfx acceleration was off, but changes to the painting code are running everything through low-resolution buffers now.

So hopefully once everything's fixed to knowingly do high-res rendering through the whole pipeline, that should fix this...

Comment 3

[Brion Vibber]

Sample file seems to work as expected using Jonathan Kew's test build from bug  674373 comment 116. Yay!

Comment 4

[Brion Vibber]

This now works as expected on nightly since bug 674373 landed.