Accessibility Issues in Flash
Flash is generally based on a time-line with content that changes over time. Screen readers present information in a linear format. This presents the basis of most accessibility issues with Flash content. Much of the content that is created in Flash cannot be made natively accessible to screen readers.
Flash uses MSAA (Microsoft Active Accessibility) to deliver information about Flash movies to the screen reader. The flash player creates a list of objects that are on the screen and lists them in the MSAA "data tree". The screen reader reads this list. As changes are made to the screen, this "data tree" is updated and the screen reader returns to the top of the list and starts reading again. This experience makes it extremely challenging to make certain Flash content (any changing content on the screen) accessible to screen readers.
If flash content is non-essential to the meaning of the page then the flash object can be tabbed through or bypassed by assistive technology. If the content conveys information or responds to user input, assistive technology must be able to access the information and functionality.
Can Flash be accessible?
Flash is able to deliver content in a number of ways - through graphics, video, audio, text. This flexibility gives Flash the ability to address certain accessibility issues with online content. Here are a few of the ways Flash can increase accessibility:
- Multiple ways of presentation: Flash can provide content in multiple ways.
- Engaging: The multimedia nature of Flash can take a page otherwise presented in static html and offer an engaging interaction between user and content - an important benefit with learning applications and users with learning or cognitive disabilities.
- Scalability: Flash is vector based, as such Flash content can be easily scaled without losing visual quality and often times without increasing file size. This provides an easy way to enlarge content for users with low vision.
- Self-voicing: Flash can provide information in an audio format - either representing or augmenting content already on the screen. This could provide an alternative to a screen-reader.
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