Adobe Flash Professional CS3 - Manual (Page 486)

FLASH CS3
User Guide
480
Many nations have specified guidelines to follow to create accessible web sites, or follow guidelines established by
other organizations. For more information on accessibility and web standards, see the World Wide Web Consortium
(W3C) Web Accessibility Initiative website. These standards and guidelines describe what factors you must address
when you create accessible HTML websites, and some of this information applies to Flash.
Exposing SWF file structure and navigation
Because of the visual nature of some SWF files, the layout and navigation of the page can be complex and difficult
for screen readers to translate. An overall description of the SWF file is important to communicate information
about its structure and how to navigate through the site’s structure. You can provide this description by clicking the
Stage and entering a description into the Accessibility panel. You can also create a separate area of the site to provide
this description or overview.
Note: If you enter a description for the main SWF file, this description is read each time the SWF file refreshes. You can
avoid this redundancy by creating a separate informational page.
Inform the user about any navigational elements that change in the SWF file. Perhaps an extra button is added, or
the text on the face of a button changes, and this change is read aloud by the screen reader. Flash Player 7 and later
supports updating these properties by using ActionScript. You can update the accessibility information in your appli-
cations if the content changes at runtime.
See also
“Creating accessibility with ActionScript” on page 363
Controlling descriptions and repetition
Designers and developers can assign descriptions for the animations, images, and graphics in a SWF file. Provide
names for graphics so the screen reader can interpret them. If a graphic or animation does not communicate vital
information to the SWF file (perhaps it is decorative or repetitive), or you outlined the element in the overall SWF
file description, do not provide a separate description for that element. Providing unnecessary descriptions can be
confusing to users who use screen readers.
Note: If you divide text or use images for text in your SWF files, provide either a name or description for these elements.
If you have several nested movie clips that serve a single purpose or convey one idea, ensure that you do the
following:
• Group these elements in your SWF file.
• Provide a description for the parent movie clip.
• Make all the child movie clips inaccessible.
This is extremely important, or the screen reader tries to describe all the irrelevant nested movie clips, which will
confuse the user, and might cause the user to leave your website. Make this decision whenever you have more than
one object, such as many movie clips, in a SWF file. If the overall message is best conveyed using a single description,
provide a description on one of the objects, and make all the other objects inaccessible to the screen reader.
Looping SWF files and applications cause screen readers to constantly refresh because the screen reader detects new
content on the page. Because the reader thinks the content is updated, it returns to the top of the web page and starts
rereading the content. Make inaccessible to screen readers any looping or refreshing objects that do not have to be
reread.