- From: Jeanne Spellman <jeanne@w3.org>
- Date: Thu, 16 Jan 2014 13:42:08 -0500
- To: UAWG <w3c-wai-ua@w3.org>
The User Agent Accessibility Guidelines Working Group (UAWG) was asked by the Protocols and Formats Working Group (PFWG) to review the Resource Priorities FPWD. We would like to make the following comments: 1) In the code example in 1.2 Optimizing download priority during network contention (and other code examples) there are images with no alternative text. Please change them to show best practices. (E.g. <img id="Logo" src=".../images/Logo.png" alt="XYZ organization"/> ) 2) In sections 1.2 and 4.2, please make it clear that text alternatives for lazyload resources should be displayed at initial load and not wait for the lazyload, since some assistive technologies like screenreaders take a snapshot of the page at load time, so a delayed load of the alternative text (including @alt, @longdesc and caption files) would result in that information being lost unless the screenreader reloaded the page. 3) In sections 4.2 The lazyload attribute (and 4.3 and 4.4): When the lazyload attribute is applied to an iframe (for example), will it also be applied to the child elements in that frame? How would a video in the iframe be handled? Similar to comment #2, our concern is that it may not be picked up by screenreaders loading the page. Please keep in mind that screenreaders are also used by sighted people with reading disabilities who are going to want to look at videos and images. 4) In section 4.3 The @postpone attribute: The IF condition does not appear to accommodate linear browsers, such as a screenreader, which reads the page without scrolling. It is possible that the screenreader would not change the User Agent's interpretation of the document's viewport, and the material would not be downloaded or read to the user. 5) In section 4.3 @postpone: If there were text material in a postponed iframe (or other resource), would that material be available to text search? Search of postponed iframe (or other resource) need to make explicit to author that if a user searches for a string at the top of a page (which includes an iframe) the search will not find content in the iframe because it has not yet been loaded. 6) We recommend that it be explicitly stated in the introduction that user agents give the user the ability to disable @lazyload and @postpone to accommodate assistive technology that may block any content that is not available on pageload. 7) In Section 4.4 the "resource-priorities" CSS attribute: a) lazy-load in CSS and @lazyload in HTML are spelled differently. This adds to the cognitive load and increases errors b) It needs to be explicitly stated that the CSS lazy-load and postpone need to be able to override by a user stylesheet. 8) in Section 4.3 Postpone: It should explicitly state that print overrides postponed. @postpone uses the term @postpone uses the term "User Agent's interpretation of the Document's viewport", if user loads a page and hits PRINT, then the viewport changes to the entire document, and all resources need to be downloaded, for the printing viewport. If you would like to discuss any of these issues further, we would like to be available for email exchange, a joint phone call, or individuals working together. We hope our comments are helpful. Regards, Jim Allan, Co-Chair Kelly Ford, Co-Chair Jeanne Spellman, Staff Contact on behalf of the UAWG
Received on Thursday, 16 January 2014 18:42:32 UTC