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Re: Any official clarification on Text-only zoom and RWD?


From: Alastair Campbell
Date: Feb 25, 2016 4:51AM

Jonathan Avila wrote:

> On the desktop at least zooming in the browser changes the width of the
> window and increases the scale.

I'd be careful with the terminology, the browser does not 'change the width
of the window', although I think I know what you mean.

Think of zoom as basically increasing the CSS pixels, so if the browser
(inner) window is 1000px wide, and you zoom to 200%, the window will show
500px of the content.

If the site is responsive (or even just 'liquid', percentage based) and
there are media queries to adapt to the change, you will not get horizontal

> In theory a developer could use fixed font sizes at different break
points or do something that caused the text to change but not actually
reach 200% at 200 percent zoom.

Possible but unusual. A developer could specify that text is 20px when the
window is 1000px wide, and 10px when the window is 500px wide. However,
that would look odd to most people as devices use a relative (physical)
size for pixels anyway, so 16px on desktop (at the assumed viewing
distance) should look the same as 16px on a mobile [1].

Also, I think the wording of the current success criteria would still make
that a fail, if you zoom in and the text doesn't increase in size, that's a

As an aside on a mobile browser where you can pinch zoom (when not blocked
> by the site or forced by the browser ) the ability to resize text alone is
> restricted to certain browsers or sites that use the system fonts that
> support the text size settings on the platform. So g142 allows mobile
> sites to meet the success criteria on small screens where text resize alone
> migh be more difficult.

I agree that zooming and/or text sizing on mobile is a real problem [2].
There is more than one solution though, I used to have a feed-reader which
would allow you to pinch-zoom on a responsive layout past it's maximum,
without causing horizontal scrolling. It just kept everything in one column
and within the window-width.

> I totally support text resize without zoom and believe it is a user
> requirement and need.

I am still not convinced, it is one of my questions to the Low Vision Task
Force [3].

I understand when a site is not responsive zoom causes horizontal
scrolling, but if:
- The site is responsive, so you don't get horizontal scrolling.
- It doesn't reduce content or functionality when zoomed.
- You are on a desktop style browser (as far as zoom is concerned)

What does text-sizing help with that zoom doesn't?



1] https://alastairc.ac/2013/02/how-to-hold-your-ipad/
2] https://alastairc.ac/2015/10/zoom-for-fixed-and-responsive-sites/