- From: Charles McCathieNevile <charles@w3.org>
- Date: Tue, 1 Jan 2002 17:47:07 -0500 (EST)
- To: Rowan Smith <rowan@absolutely.co.nz>
- cc: <w3c-wai-gl@w3.org>
Hi Rowan, well, users who are themselves relying on speech output often get that from software that reads the content as presented on the screen, rather than using software that provides a true audio interface. So anything affecting visual presentation will affect the presentation for many screen reader users. But the major problems will in fact be for visual users - if the screen is magnified, 4 or 5 times, or if the font size is set in the region of 30 or 40 pt, or if the window size is changed between 320x240 and 1200x800 is there any problem? (In X window systems setting the screen size at 320x240 or a bit smaller is an easy way of getting effective screen magnification, when it is rendered on a large screen. Cheers Charles On Wed, 2 Jan 2002, Rowan Smith wrote: Hi Charles I'm using layers as a means of positioning blocks that make up elements of a page (which contain text), rather than as a means of controlling the text directly. Changes to text size etc should still fit within the blocks. The page in question degrades logically in the absence of styles, so I guess my question was about maintaining the visual integrity (ie layout) of an accessible page. Given that my (intended) use of px was to preserve visual appearance, I was wondering if that got in the way of users who don't rely on the visual but I can't think why it should. Cheers Rowan -----Original Message----- From: Charles McCathieNevile [mailto:charles@w3.org] Sent: Wednesday, 2 January 2002 2:46 a.m. To: Rowan Smith Cc: w3c-wai-gl@w3.org Subject: Re: ems versus pixels Well, the accessibility downside depends on what you are soing with your layers. If you are going to have text positioning determined by them, and people changing text sizes or window sizes to suit their needs is going to make a big mess, then the accessibility downside is that the design (not just using pixels, which is really a fairly small part) isn't going to work. In this case I would suggest changing the design to start with, to one where it does work to specify sizes in em units. If you are trying to put a pretty border around the edge of a page, or place a picture that doesn't scale properly anyway, then there is probably no real problem that could be solved by switching to em units. As I undertstand it the techniques document, where you have obviously looked, is a FAQ, and raising further issues on it means that there is a need for some more material there. Cheers Charles On Tue, 1 Jan 2002, Rowan Smith wrote: Hi there WAI Priority 3 guidelines (WCAG Checkpoint 3.4) recommend using relative units rather than absolute. The Techniques document suggests that using ems rather than pixels as a unit is a way of doing this even when using absolute positioning. OK, I can understand that for text specifications like font sizes and line heights, but does it apply to positioning layers on a page using CSS? Is there an accessibility downside of positioning layers (div tags) by using px? Thanks Rowan -- Charles McCathieNevile http://www.w3.org/People/Charles phone: +61 409 134 136 W3C Web Accessibility Initiative http://www.w3.org/WAI fax: +1 617 258 5999 Location: 21 Mitchell street FOOTSCRAY Vic 3011, Australia (or W3C INRIA, Route des Lucioles, BP 93, 06902 Sophia Antipolis Cedex, France) -- Charles McCathieNevile http://www.w3.org/People/Charles phone: +61 409 134 136 W3C Web Accessibility Initiative http://www.w3.org/WAI fax: +1 617 258 5999 Location: 21 Mitchell street FOOTSCRAY Vic 3011, Australia (or W3C INRIA, Route des Lucioles, BP 93, 06902 Sophia Antipolis Cedex, France)
Received on Tuesday, 1 January 2002 17:47:10 UTC