Summary of API requirements suggested by AT developers

This document:: http://www.w3.org/WAI/UA/2002/04/api-reqs
Editor:: Ian Jacobs, W3C

Status of this Document

This document has been produced for the User Agent Guidelines Working Group (UAWG) to summarize responses from assistive technology developers to a request made a the 28 Mar 2002 teleconference. This summary is likely to change at any time, and represents no consensus. This summary is expected to help the UAWG refine the requirement in UAAG 1.0 pertaining to communication between a conforming user agent and other software such as assistive technologies.

1. Content/ui/event/api requirements

The following table organizes content requirements expressed by AT developers. The table indicates by @@ where these requirements are not met by the W3C XML Infoset Recommendation (see email on establishing minimal set of API requirements in terms of the Infoset, for both XML and HTML).

Note: A linear version of this table is also available.

Jill Thomas, ION Jost Eckhardt, AISquared Cathy Laws, IBM Content

All text
All attribute info items
All parent element info items

All text
All enabled elements
Attribute info items for some elements (e.g., frames)
(Navigation) ordered list of links, frames, form controls
Functional blocks of content (in UAAG 1.0 terms, "important elements")
Layout v. Data table

Retrieve and change all element content
Retrieve and change all attribute values

Rendering structure

None

Coordinates of rendered elements
Coordinates of rendered words
Coordinates of rendered characters
Mapping from screen coordinates to source element

For each rendered character, pixel location
Mapping from character pixel location to DOM text node and character offset

Style

None

Text foreground and background color, font family name, text size, font characteristics

Text display attributes

UI/Session variables

None

Content focus (fast access)
State of form controls

Selection (including selected non-text content).
Get viewports for embedded objets or applets. Note: This is generally done through the operating system, not the API used to access content.

Events/Change notification

None

Content focus
Selection
Form controls: radio buttons, check boxes, choices, text area
Download complete

Receive event notifications for mouse events, key events
Changes to elements/attributes

Programmatic control

None

Move rendered content into viewport
Move focus to enabled elements
Activate enabled elements

For both rendered elements and characters, simulate an event even if not for an enabled element (left or right mouse click)
Move focus to viewports with embedded objects or applets.
Select content (text and images).
Set focus

API requirements

Preserve document order
Provide alert when document object construction is complete.

Preserve document order

Content information and events must represent rendered content (after error correction).

2. Out of scope for UAAG 1.0

From Jost:

Meaningful description of an image. This is an authoring issue (and is recognized by WCAG 1.0). If provided, then presumably this information would be available through any API we would require.

From Catherine:

Be able to determine an element's structural "containing element" (e.g., form, table, frame, page, etc.). This semantic information is determined by specification, not by the API.

Last modified: $Date: 2002/05/10 19:54:35 $ by $Author: ijacobs $.