Adobe Flash Professional CS3 - Manual (Page 487)

FLASH CS3
User Guide
481
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.
See also
“Using Flash to enter accessibility information for screen readers” on page 356
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 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 intel-
ligent 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 reference.
Note: Avoid invisible buttons in accessible SWF files, because screen readers do not recognize these buttons. (Invisible
buttons are buttons for which you define only a hit area, the clickable region, for the button.)
Many SWF files have a rapid succession of information, and screen readers frequently cannot keep up with this pace.
Provide controls for the SWF file, letting the user use buttons to navigate through the file at their own pace, and
letting them pause the process if necessary.