[Bug 28029] Mouse coordinates represented in CSS pixels do not account for retina displays with window.devicePixelRatio > 1.

https://www.w3.org/Bugs/Public/show_bug.cgi?id=28029

--- Comment #4 from Jukka Jylänki <jujjyl@gmail.com> ---
I would be very cautious to state that this is not currently a big deal, since
already now only one quarter of the pixels on the screen are representable by
the DOM events on high DPI displays, and Macbook Pro retina displays came out
already in 2012.

I believe this issue also exists for all touch events
http://www.w3.org/TR/touch-events/#touch-interface , and currently the majority
of mobile devices out there have a window.devicePixelRatio greater than one.
For example, Google Nexus 4 has a devicePixelRatio of 2, and iPhone 6 Plus has
a devicePixelRatio of 3.

Also like Boris Gjenero mentions, this issue causes precision and stuttering to
pointer lock and relative mouse movement.

In my opinion, this is definitely a critical P1 bug. Most web APIs do not
properly handle high DPI, and the invention of hardware-independent pixels was
not done with a good understanding or design of its wide-spanning implications
on the different web APIs. This is a surface area of bugs that keeps popping up
in different places, here's a small example of recent issues to illustrate:

https://github.com/KhronosGroup/WebGL/issues/587
https://www.khronos.org/webgl/public-mailing-list/archives/1406/msg00019.html
https://bugzilla.mozilla.org/show_bug.cgi?id=1021547
https://bugzilla.mozilla.org/show_bug.cgi?id=1024493

And the common underlying issue in all of these is that the web APIs were not
designed to account for window.devicePixelRatio > 1.

My point is that everything is already broken now, and not just in a few years.
I would like to plea that this issue is taken seriously in W3, and even
further, I would like to see that non-high DPI APIs would get aggressively
documented as being broken and deprecated in the future.

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Received on Sunday, 15 February 2015 10:06:33 UTC