Adobe Flash Professional CC 2014 v.13.0 - Manual (Page 850)

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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 applications if the content changes at runtime.
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.
Note: Do not type a description in the Description field of the Accessibility panel for instances (such as text) that the screen reader reads
aloud.
Using color
You must make decisions about using colors in an accessible file. You must not rely only on color to communicate particular information or
directives to users. A color-blind user cannot operate a page if it asks to click on the blue area to launch a new page or the red area to hear
music. Offer text equivalents on the page or in an alternate version to make your site accessible. Also, check that significant contrast exists
between foreground and background colors to enhance readability. If you place light gray text on a white background, users cannot easily read it.
Similarly, small text is difficult for many visitors to read. Using high-contrast and large or resizable text benefits most users, even those without
impairments.
Ordering, tabbing, and the keyboard
Reading order and tabbing are important considerations for making accessible Flash Professional websites. When you design an interface, the
order that it appears on the page might not match the order in which the screen reader describes each instance. You can control and test reading
order, as well as control tabbing in the SWF file.
Controlling reading order
The default reading order is not predictable and does not always match the placement of your assets or the visual layout of the page. Keeping the
layout simple can help create a logical reading order without using ActionScript. However, you have more control over reading order if you use
ActionScript and test the reading order in your SWF files.
Important: Do not miss ordering a single instance in your SWF file, or the reading order reverts to the default (and unpredictable) reading order.
Controlling tabbing and content
Visitors who rely on screen readers to describe a site’s content typically use tabbing and keyboard controls to navigate the operating system and
web pages, because using the mouse is not useful when the screen cannot be seen. Use the tabIndex and tabEnabled properties with the movie
clip, button, text field, or component instances to offer intelligent tabbing control in accessible SWF files. In addition to tabbing, you can use any
key-press actions to navigate through the SWF file, but you must communicate that information using the Accessibility panel. Use the Key class in
ActionScript to add key-press scripts to the SWF file. Select the object for which you want to use the key-press script, and add the shortcut key in
the Shortcut field on the Accessibility panel. Add keyboard shortcuts to essential and frequently used buttons in your SWF file.
Note: In ActionScript 3.0, tabIndex and tabEnabled are properties of the InteractiveObject class. In ActionScript 2.0, they do not require a class
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