[whatwg] Processing the zoom level - MS extensions to window.screen
Charles Pritchard
chuck at jumis.com
Tue Dec 14 10:22:07 PST 2010
On 11/24/2010 1:12 AM, Robert O'Callahan wrote:
> On Wed, Nov 24, 2010 at 9:09 PM, Charles Pritchard <chuck at jumis.com
> <mailto:chuck at jumis.com>> wrote:
>
> On 11/21/2010 4:12 PM, Robert O'Callahan wrote:
>> On Sun, Nov 21, 2010 at 9:59 AM, Charles Pritchard
>> <chuck at jumis.com <mailto:chuck at jumis.com>> wrote:
>>
>> Rob: Mobile deployments using dpiPixelRatio (as has been
>> adopted by Moz and Webkit) and target-DpiDensity work well on
>> the mobile, they are not hooked to zoom on the desktop,
>>
>>
>> It is in Firefox.
> I just tested in 4b7, and it's not changing dpiPixelRatio.
>
>
> Try this:
> <style>
> div { display:none; }
> @media screen and (min--moz-device-pixel-ratio: 1.5) {
> .in { display:block; }
> }
> @media screen and (max--moz-device-pixel-ratio: 0.66666666) {
> .out { display:block; }
> }
> </style>
> <div class="in">Zoomed in by a factor of at least 1.5</div>
> <div class="out">Zoomed out by a factor of at least 1.5</div>
>
> Try zooming in a lot and zooming out a lot. It works for me.
I've started working to get this behavior supported in webkit.
Currently, nobody is touching the devicePixelRatio [mislabeled
dpiPixelRatio in my prior e-mails],
outside of the mobile device atmosphere. As such, the CSS
device-pixel-ratio and window.devicePixelRatio
should be considered two different things. An unfortunate naming overlap.
I'd hoped for a cleaner resolution to the issue.
This represents my existing understanding of the consequences of
Mozilla's don't-make-it-easy policy:
var mozObfuscatedRatio = 0;
if(window.devicePixelRatio != 1) mozObfuscatedRatio =
window.devicePixelRatio;
else if(window.mozDevicePixelRatio != 1) mozObfuscatedRatio =
window.mozDevicePixelRatio;
else while(mozObfuscatedRatio < 10) {
mozObfuscatedRatio += .1;
if (false === matchMedia('(min--moz-device-pixel-ratio:
'+(mozObfuscatedRatio)+')').matches ) {
mozObfuscatedRatio -= .1; break;
}
}
The numbers should be tuned for typical zoom steps.
This doesn't feel like a win for anybody.
We couldn't even begin to talk about normalizing
window.innerWidth/window.outerWidth .
Mozilla's practice of normalizing all metrics to CSS units makes a lot
of sense.
Obfuscating access to device-pixel-ratio does not.
-Charles
In response to fiddling with ImageData: looks like a related
conversation took place in 2008:
http://lists.whatwg.org/pipermail/whatwg-whatwg.org/2008-February/013923.html
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