Re: [mediaqueries4] zoom-ratio as a media feature

Le 09/10/2013 02:06, Alex Bell a écrit :
> Hello,
>
> Current developer efforts to reliably measure user zoom are basically
> a shambles. There are dozens of different techniques, none of which
> are truly comprehensive cross-browser. The most encyclopedic of all
> approaches, the maniacally detailed 'detect-zoom' has been badly
> broken on the desktop by recent changes to FF18 and Chrome 27. FF 18+
> now change the 'devicePixelRatio' value on manual zoom (cmd/ctrl ±),
> arguably distorting the meaning of the word 'device'. On Chrome,
> webkitTextSizeAdjust was deprecated on the desktop, the only
> bulletproof method. For the whole convoluted story see:
>
> https://github.com/tombigel/detect-zoom
>
> One of the things that seems to trip up all discussion of this is that
> some code bases tie zoom to resolution, while others do not.
> Everybody's doing it their own way. This is an area that is just
> screaming for standardization.
>
> I realize I am probably wading into a few long-standing debates here,
> but IMHO user zoom should be queryable through window.matchMedia. The
> property could be called 'zoom-ratio', to make it absolutely clear
> that it's a ratio, and it should accept min/max prefixes. I propose
> that this be added to Media Queries Level 4.
>
> If I'm late to the discussion, or just totally wrong, I would really
> appreciate a nice clear explanation of why this is impossible, or a
> bad idea.

Hi,

Before we can discuss whether this is a good idea or if there is a 
better solution, please provide a well-defined proposal.

What exactly is "user zoom"? If it’s a ratio, between what and what? 
Note that there are many related concepts here: initial and actual 
viewport, device pixels and CSS px, etc.

http://dev.w3.org/csswg/css-device-adapt/#initial-viewport
http://dev.w3.org/csswg/css-device-adapt/#actual-viewport

-- 
Simon Sapin