Re: [WSG] Accessibility - display: none v.s. left: -9999px
On 15 Feb 2007, at 02:06:11, Michael MD wrote: Do any screen readers support some kind of metadata or semantic markup that could be used to embed such content in the page? No, because screen readers never actually see the markup - they're designed to work with Windows applications that support MSAA (Microsoft Active Accessibility), not just browsers. (After all, a user who paid all that money for Jaws would probably be pretty annoyed if all it could do was read web pages, but not email or Excel spreadsheets.) So what happens is that the application does whatever it does (e.g. a browser parses and renders the page, Excel parses a file and builds a visual representation of a spreadsheet) and then exposes the contents of its display to the screen reader via the MSAA API. The screen reader then queries the application via that API to find out what is being displayed, and reads it out. This is presumably why display: none and visibility: hidden don't work, but margin-left: -px does - in the first two cases, the element is never made a part of whatever internal representation of the render tree IE builds for its display (this is not the same as the DOM, by the way), whereas in the last case it _is_ included in the internal representation, but when that representation is actually drawn on the screen, it is in a position where Window's built-in clipping to window boundaries means it is never seen. So any attempt to include markup just for screen readers is doomed to failure - screen readers don't use markup. Please note that I'm not claiming to be an expert on this particular topic, but I think this explanation covers what actually happens. There's more info on MSAA (primarily aimed at application developers) at http://msdn.microsoft.com/library/default.asp?url=/library/en-us/ msaa/msaastart_9w2t.asp and you can get some idea of the range of applications other than web browsers (from Access to WinZip :-) that Jaws is used with from the dropdown list on the FAQ page: http://www.freedomscientific.com/fs_support/Specific_Product.cfm? ProdID=1 Regards, Nick. -- Nick Fitzsimons http://www.nickfitz.co.uk/ *** List Guidelines: http://webstandardsgroup.org/mail/guidelines.cfm Unsubscribe: http://webstandardsgroup.org/join/unsubscribe.cfm Help: [EMAIL PROTECTED] ***
Re: [WSG] Accessibility - display: none v.s. left: -9999px
Nick Fitzsimons wrote: So any attempt to include markup just for screen readers is doomed to failure - screen readers don't use markup. Do screen readers reveal cover-ups ? Example: http://www.gunlaug.no/contents/wd_chaos_14.html Georg -- http://www.gunlaug.no *** List Guidelines: http://webstandardsgroup.org/mail/guidelines.cfm Unsubscribe: http://webstandardsgroup.org/join/unsubscribe.cfm Help: [EMAIL PROTECTED] ***
Re: [WSG] Accessibility - display: none v.s. left: -9999px
Michael MD wrote: Do any screen readers support some kind of metadata or semantic markup that could be used to embed such content in the page? Such stuff 'exists' only ethereally. In their wisdom, screen reader developers have by and wide chosen not to bother implementing any of the manifold techniques for distinguishing audio from video in web formats. Standards-aware designers are, somewhat righteously, resentful of this lack of attention that we could well use, but the reasoning behind these make sense: hardly anyone uses these functions, and as far as they probably see it, the developers' priorities lie in making the vast majority of sites (designed with no great concern for the visually-impaired) work as best they can. The tragedy is that normally designers can encourage the development community by carefully putting in place the hooks for future implementation of such features - but in the case of visibility:hidden, this would mean wrecking our design in the present. ...It's a mess! Regards, Barney *** List Guidelines: http://webstandardsgroup.org/mail/guidelines.cfm Unsubscribe: http://webstandardsgroup.org/join/unsubscribe.cfm Help: [EMAIL PROTECTED] ***
Re: [WSG] Accessibility - display: none v.s. left: -9999px
On 14 Feb 2007, at 15:48:00, Gunlaug Sørtun wrote: Nick Fitzsimons wrote: So any attempt to include markup just for screen readers is doomed to failure - screen readers don't use markup. Do screen readers reveal cover-ups ? Example: http://www.gunlaug.no/contents/wd_chaos_14.html I don't know. It's entirely dependent on two factors: first is how Internet Explorer creates its internal representation used to render the display (just to reiterate, this is not the same as the DOM), and how it exposes that representation via the MSAA API. Then the other factor kicks in: how well the screen reader deals with the information it gets from those APIs. So the best people to ask would be the developers from the IE Team and at the screen reader vendors :-) Cheers, Nick. -- Nick Fitzsimons http://www.nickfitz.co.uk/ *** List Guidelines: http://webstandardsgroup.org/mail/guidelines.cfm Unsubscribe: http://webstandardsgroup.org/join/unsubscribe.cfm Help: [EMAIL PROTECTED] ***
Re: [WSG] Accessibility - display: none v.s. left: -9999px
On 14 Feb 2007, at 14:49:43, Nick Fitzsimons wrote: On 15 Feb 2007, at 02:06:11, Michael MD wrote: Do any screen readers support some kind of metadata or semantic markup that could be used to embed such content in the page? No, because screen readers never actually see the markup - they're designed to work with Windows applications that support MSAA (Microsoft Active Accessibility), not just browsers. To follow myself up with some hard facts: The page at http://msdn.microsoft.com/workshop/browser/accessibility/ overview/invisible.asp states that: With Internet Explorer 6 and later, the pvarState parameter of the IAccessible::get_accState property receives STATE_SYSTEM_OFFSCREEN when the object is invisible because of scrolling and receives STATE_SYSTEM_INVISIBLE when the object is invisible because its IHTMLStyle::visibility property is set to hidden, or its IHTMLStyle::display property is set to none. This means that using offscreen positioning is seen by the browser as making an object invisible by scrolling - but as Windows (or at least IE) doesn't support the concept of scrolling to a negative position, it can't be seen. Screen readers apparently treat STATE_SYSTEM_OFFSCREEN as meaning that the content of the object should still be spoken - fairly obviously, as otherwise a wide or tall page would only have its visible region spoken. However, said screen readers treat STATE_SYSTEM_INVISIBLE as meaning that the content of the object should not be spoken. Thus display:none and visibility:hidden prevent the content from being spoken. More info is available at http://msdn.microsoft.com/library/default.asp?url=/workshop/browser/ accessibility/accessibility_node_entry.asp and in particular the article at https://msdn.microsoft.com/workshop/browser/accessibility/overview/ overview.asp is definitely enlightening. Cheers, Nick. -- Nick Fitzsimons http://www.nickfitz.co.uk/ *** List Guidelines: http://webstandardsgroup.org/mail/guidelines.cfm Unsubscribe: http://webstandardsgroup.org/join/unsubscribe.cfm Help: [EMAIL PROTECTED] ***
Re: [WSG] Accessibility - display: none v.s. left: -9999px
On 14 Feb 2007, at 16:44:22, Nick Fitzsimons wrote: To follow myself up with some hard facts: OK, I've written up what is hopefully a factual and detailed account of exactly what's going on with the display:none, visibility:hidden and left:-px techniques, explaining what the interaction between the browser and the screen reader is. It's at http://www.nickfitz.co.uk/2007/02/14/why-left-px-is-better-for- accessibility-than-display-none/ HTH, Nick. -- Nick Fitzsimons http://www.nickfitz.co.uk/ *** List Guidelines: http://webstandardsgroup.org/mail/guidelines.cfm Unsubscribe: http://webstandardsgroup.org/join/unsubscribe.cfm Help: [EMAIL PROTECTED] ***
Re: [WSG] Accessibility - display: none v.s. left: -9999px
The tests documented here http://www.access-matters.com/screen-reader-test-results/ confirm that either negative text indent or absolute positioning off screen is the best way to go - if you need to have content heard but not seen. And best not style with 'visibility: hidden;' or 'display:none;' as the content will not be heard in the majority of cases. Kind regards, Brad Pollard http://www.fatpublisher.com.au - Original Message - From: Gav [EMAIL PROTECTED] To: wsg@webstandardsgroup.org Sent: Monday, February 12, 2007 6:31 PM Subject: RE: [WSG] Accessibility - display: none v.s. left: -px -Original Message- From: listdad@webstandardsgroup.org [mailto:[EMAIL PROTECTED] On Behalf Of Blake Sent: Monday, 12 February 2007 5:20 PM To: wsg@webstandardsgroup.org Subject: [WSG] Accessibility - display: none v.s. left: -px Which is more accessible to screen readers and the like? display: none; or position: absolute; left: -px; I think I've read that screen readers will read content that is positioned off-screen, but will not read content that is set to display: none. Yep, correct on both counts. Gav... -- Australian Web Designer - http://www.blakehaswell.com/ *** List Guidelines: http://webstandardsgroup.org/mail/guidelines.cfm Unsubscribe: http://webstandardsgroup.org/join/unsubscribe.cfm Help: [EMAIL PROTECTED] *** -- No virus found in this incoming message. Checked by AVG Free Edition. Version: 7.1.411 / Virus Database: 268.17.35/680 - Release Date: 2/10/2007 *** List Guidelines: http://webstandardsgroup.org/mail/guidelines.cfm Unsubscribe: http://webstandardsgroup.org/join/unsubscribe.cfm Help: [EMAIL PROTECTED] *** *** List Guidelines: http://webstandardsgroup.org/mail/guidelines.cfm Unsubscribe: http://webstandardsgroup.org/join/unsubscribe.cfm Help: [EMAIL PROTECTED] ***
Re: [WSG] Accessibility - display: none v.s. left: -9999px
Hi guys Which is more accessible to screen readers and the like? display: none; or position: absolute; left: -px; I think I've read that screen readers will read content that is positioned off-screen, but will not read content that is set to display: none. You need to keep in mind that some users will have CSS on, but images will be turned off. That means that if your text is positioned off screen, and images are off, nothing will be displayed. It's really important to remember this when you're using Images as text for headings and navigation. Users who might do this are people in rural and regional areas, who have a poor Internet connection, or even some users of mobile devices. So... what's the workaround for this?? Try not to use images for text in essential elements such as headings, navigation and content. Lisa *** List Guidelines: http://webstandardsgroup.org/mail/guidelines.cfm Unsubscribe: http://webstandardsgroup.org/join/unsubscribe.cfm Help: [EMAIL PROTECTED] ***
RE: [WSG] Accessibility - display: none v.s. left: -9999px
-Original Message- From: listdad@webstandardsgroup.org [mailto:[EMAIL PROTECTED] On Behalf Of Blake Sent: Monday, 12 February 2007 5:20 PM To: wsg@webstandardsgroup.org Subject: [WSG] Accessibility - display: none v.s. left: -px Which is more accessible to screen readers and the like? display: none; or position: absolute; left: -px; I think I've read that screen readers will read content that is positioned off-screen, but will not read content that is set to display: none. Yep, correct on both counts. Gav... -- Australian Web Designer - http://www.blakehaswell.com/ *** List Guidelines: http://webstandardsgroup.org/mail/guidelines.cfm Unsubscribe: http://webstandardsgroup.org/join/unsubscribe.cfm Help: [EMAIL PROTECTED] *** -- No virus found in this incoming message. Checked by AVG Free Edition. Version: 7.1.411 / Virus Database: 268.17.35/680 - Release Date: 2/10/2007 *** List Guidelines: http://webstandardsgroup.org/mail/guidelines.cfm Unsubscribe: http://webstandardsgroup.org/join/unsubscribe.cfm Help: [EMAIL PROTECTED] ***
