Flash and Accessibility

问题:

As a web developer, a number of the projects I work on fall under government umbrellas and hence are subject to 508 Accessibility laws, and sometimes W3C accessibility guidelines. To what extent can Flash be used while still meeting these requirements?

For using javascript, the mantra is "Degrade gracefully" by providing the same content and function, just on different pages, or in a less interactive/dynamic way. This allows non-javascript browsers/users still use the site, as well as allowing search engine bots to access all of the content. Users of screen reading software, such as JAWS and Orca also are still able to fully use the site.

With flash, is there a similar way to gracefully fall back for non-flash users? If not, how accessible is flash-based content to search engine bots? And also, how do screen readers handle flash-based content?

回答1:

I'm visually impaired to the point where I use magnification tools and TTS for convenience but not as a necessity. I can tell you that Flash just doesn't work with the majority of accessibility tools out there. I believe JAWS (the market leader for Windows but not overwhelmingly dominant by any means) says it has Flash support, but most Flash developers don't seem to put in the work necessary to allow JAWS to grok the textual content of the Flash movie. And many visually impaired users just don't even have flash installed because for 95%+ of the time it's simply useless to them.

Another consideration is that the built-in Text-to-speech that Mac OS X provides also can't do anything with most Flash movies.

IMO 'degrading' or offering a link to an HTML version of your content is probably the only practical means of ensuring your site is accessible. If you are starting from scratch I would strongly consider JavaScript / JQuery over Flash if at all possible.

回答2:

I'm a totally blind user of Jaws and the short answer is it depends. For example on YouTube I can access the mute and play/pause buttons. Things such as sliders however don’t work. I don’t think Flash will determine how accessible your site is if coded properly nearly as much as the content itself will. For example, if you need to play videos, is there enough narration so that a blind individual can follow the video? If you are displaying charts, is there a textual description of that data? I agree with the poster who said to use JavaScript / JQuery if possible, but for things such as videos that need Flash you can make it accessible enough to do things like mute the video, stop the video, etc.

回答3:

Flash can be made accessible to visually impaired, but it takes some time and effort. It's not automaticly a no-go area. It's still important to check if the different browsers play along with flash in this way, as Alxp notes.

There is one additional problem with flash: it steals the keyboard shortcuts. With a piece of flash on the page, many standard browser keyboard controls stop functioning. These shortcuts are very important to people with mouse-problems, and people who prefer the keyboard for any other reason.

回答4:

If you're using Flash for things like navigation, then I would beg you on bended knee to use HTML and CSS instead. They degrade more gracefully, not just for people using site readers, but also to people who:

• Are on slower connections (like tethered phones)
• Have Flash turned off
• Are on a computer where Flash isn't installed, and they don't have admin rights
• Their version of Flash is terribly outdated, and they can't/won't update.

However, if you're creating something like a game, where Flash is vital, there are a few tips I have for the hearing impaired:

• If you use bells or sounds in your game to indicate a game event, add an option to turn this into a visual bell.

An example of this would be in the game Plants vs. Zombies. I played it with the sound off for months (I usually had music playing in the background). I didn't realize that some zombies were announced by sounds several seconds before they appeared. This made the game harder for me.

• If you have audio instructions, please put them in text as well. This goes for videos as well! A text-over is better than a text file next to the game/video, as it can be difficult to pair up the visual with the audio.