/Access all areas/ Zoom!
05/08/2009 | Filed under Develop > Access all areas
Nomensa’s Alastair Campbell examines what increasingly common browser zoom features mean for accessible layouts
The landscape for accessible layouts is changing, with browsers altering their display methods and the guidelines for layouts updated in the new version of the Web Content Accessibility Guidelines (WCAG 2).
A strict reading of the original guidelines would make you think every unit on the page (for fonts and layout) had to be ‘relative’ (that is, Percentage or Em) so they can flex to fit different font sizes and resolutions. In practice, making everything flexible can be counterproductive: for example, areas with fixed content, such as images, don’t need to flex. A couple of years ago, I outlined various options for doing accessible layouts, but things have changed since then.
Browsers have followed Opera’s lead and are changing from being able to increase text size to full zoom. All the recent browsers now have full zoom, which increases the size of layouts, images and text. The only exception is Safari, but that will soon implement it too. You could naturally think that it’s over, we don’t need to worry about relative sizes any more, but, unfortunately, it isn’t that simple. The browsers all implement this zoom feature in various different ways.
Opera has two modes, standard and ‘fit to width’, which is like applying max-width: 100 per cent. Internet Explorer 7 simply scales everything up, which tends to cause horizontal scrolling quickly. Firefox 3 is a fairly standard zoom, but it does respect CSS statements like min and max width well, while Internet Explorer 8 will use an adaptive zoom, which will act in a similar vein to the Opera style system. So what does this mean for accessibility?
The main audiences that zoom affects are those with mild to moderate visual impairments. It’s going to have an impact on those people who either don’t like or can’t read tiny text, but don’t need a screen magnifier to increase the size of everything. With this audience in mind, it does mean there’s a practical limit on how much zoom people are likely to apply – which WCAG 2 has set at 200 per cent.
Dealing with text-zoom was a straightforward concept that meant you needed to leave a horizontal buffer and make sure areas could expand vertically. Putting a pixel height on things containing text is likely to cut off that text for some people. With full-page zoom, the issue becomes horizontal scrolling (for IE7), and what happens when the ‘fit to width’ option in Opera is switched on. For people with an 800px wide screen, IE7’s zooming is not very helpful, though it is on wider screens. Also, don’t forget a lot of people are still using the zoomless IE6, whether it’s due to preference, ignorance or the fact that they’re stuck on a corporate network.
The best way of working out if your layout is accessible is to test it. It should survive (that is, still be usable and readable) when people increase the size by up to 200 per cent. If you test your site at extremes of browser size (for example, 800px and 1600px wide), at normal and 200 per cent, you’ll have effectively covered a good range of usage.
Alastair Campbell is director of user experience at digital agency Nomensa. From a usability background, Alastair embraced technical web standards seven years ago.
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Comments
Earl Savino / 27/08/2009 / 14:00
That's nice!
Any serious suggestions on "how to adjust"?
