Individuals with visual impairments have needs ranging from those with low vision who can benefit from the application of text enlargement, to blind individuals who may need full text-to-speech or Braille display for the representation of characters or graphics depicted on the computer screen. A program that provides speech output of information on the screen is usually called a screen reader. No such program yet exists for workstations using X Windows. As another goal of the DACX Project, members of the graphical user access subcommittee have been developing a set of software "hooks" that make it much easier to create screen readers for the GUI of X Windows. These hooks allow a screen reader program to be notified whenever a portion of the application interface is created (for example when a window appears), modified (as when a menu button is highlighted) or deleted (as when a pop-up window closes). To date, these hooks have been defined and reviewed by the X Consortium for incorporation into the libraries of the upcoming version of X Windows (X11R6).
In addition to these hooks, other new and existing parts of the X Window System can be used to improve screen reader access. For example, the XTest extension already supports remapping user input. A screen reader program could use this extension to convert user keyboard input into mouse input. This feature helps support "mouse-less" operations of X applications--necessary for blind users, who cannot operate the mouse.
DACX Members are currently designing a new communication protocol which will allow the information from the software hooks to be transmitted to screen reader programs. This protocol will also allow the screen reader to query about a part of the interface, such as finding out the fonts or colors that are used. Likewise, it can be used to change portions of the interface, such as moving the location of a scrollbar.
During beta testing for the next release of X in early 1994, DACX members will be working closely with members of the X Consortium to ensure that the new hooks and protocol, as well as the existing XTest extension, are sufficient for screen reader access. Hopefully this will lead to the successful development and commercial readiness of very powerful screen readers for X very soon after X11R6 is released.