WCAG 2.2、Web内容可访问性标准与您
Firmly rooted goalposts are a necessary condition for a fair playing field—Calvinball 只有当你碰巧是卡尔文的时候才好玩. 当它来临时
to making software accessible so all users have a level playing field for work or study, 公司和开发者同样有必要
所有人都在朝着一个商定的标准努力.
Fortunately, that is largely the case now in the Western world. 但并非总是如此. 例如，2007年，我所在的伊利诺伊州通过了它的
自己的数码无障碍法律, 伊利诺伊州信息技术无障碍法案(IITAA), which was much more demanding than federal guidelines set by Section 508. It created a scramble to upgrade government and public education IT systems to a standard that most vendors were completely unprepared to meet.
Instead of a patchwork of accessibility standards for California, 伊利诺斯州, 欧洲, 还有其他地方, the current standard is set by a broad cross-section of experts from the industry and published by the World Wide Web Consortium (W3C) as the 无障碍网页指引(WCAG).
WCAG benefits vendors by setting uniform endzones to strategize toward and also benefits legislatures, 因为他们不再需要召唤
experts but periodically need to update their existing accessibility laws to conform to the latest version of WCAG. WCAG的最新版本是2.于10月2日被正式收养. 5 after 3 years of publicly reviewable version-controlled revisions. 幸运的是，WCAG 2.2完全向后兼容WCAG 2.1、 变化 非常少, especially compared to the substantial 变化 necessitated by the enormous amount of lessons learned in internet technology between earlier versions adopted in 2008 (coinciding with the initial release of HTML5 and amid peak Myspace) and 2018 (with Web 3.0 usability challenges, such as real-time interactively updating websites, being the norm).
去WCAG 2.2 conformance, there are two changed guidelines that demand special attention. The first is one that video platforms often have a hard time not tripping over: three additional success criteria standards for the navigable operation of websites. The first two criteria require that any user interface component be visible to the user and anyone watching the screen; the third sets clear size and contrast standards for indicating focus. 这是教育视频平台关注的问题, since video players in course webpages are almost always embedded via confining iFrames. 例如, the platform may make it possible for teachers to add annotations to their video that are implemented using an HTML element on top of the video. If a teacher adds an annotation near the bottom of the video screen and a user tabs onto an element that opens a dialog over the video, that dialog must not be obscured by the annotation element while the dialog has keyboard focus. 这在测试中很容易被忽略, since the annotation isn’t part of the video player as designed, but something that the teacher can add and position as they choose. 视频测验界面和其他弹出窗口也是如此.
第二个改变的准则是2.5, Input Modalities, which likely requires an update to your video player. 成功标准二.5.7 states that any element that can be repositioned using a drag-and-drop mechanism must also\ have a means of repositioning the element that only requires single clicks. Closed captions are often displayed in a container element on top of the video screen, and many players allow the user to reposition the captions by dragging and dropping them. This is very useful for educational videos that may consistently show slides in which there’s important text at the bottom, 默认情况下显示标题的位置, 也许还有顶部的装饰图案.
A user who doesn’t use a mouse or lacks the dexterity to hold down the mouse button needs to be able to reposition the captions as well—
for example, by tabbing onto a labeled control button in the caption container and pressing Enter. That would create a new tab index of labeled drop zones where the caption container could be repositioned to the original location to cancel the reposition interface.
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