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106.3 Accessibility

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Demonstrate knowledge and awareness of accessibility technologies.

Objectives

  • Basic knowledge of visual settings and themes.
  • Basic knowledge of assistive technology.

Terms

High Contrast/Large Print Desktop Themes, Screen Reader, Braille Display, Screen Magnifier, On-Screen Keyboard, Sticky/Repeat keys, Slow/Bounce/Toggle keys, Mouse keys, Gestures, Voice recognition

Linux is for everyone

People have different physical needs: some cannot see well, some cannot see at all, some cannot use a mouse or a keyboard the usual way. Linux answers with three groups of tools:

  1. AccessX helps people who have trouble with a keyboard or mouse.
  2. Visual settings help people with low vision, for example by magnifying the screen.
  3. Assistive technologies such as text-to-speech read the screen aloud for people who cannot see it.

These options live both in the display manager (the login screen) and in the major desktops (GNOME, KDE Plasma, Xfce). In GNOME they are under Settings, Universal Access.

Visual settings and themes

For low vision, the desktop can change how everything looks:

  • High Contrast theme: strong colour contrast so shapes and text stand out.
  • Large Print / Large Text: bigger fonts across the interface.
  • Cursor Size: a larger mouse pointer that is easier to track.
  • Screen Magnifier (Zoom): enlarges part of the screen, following the pointer. GNOME calls it Zoom, KDE ships it as KMagnifier.

Assistive technology

For people who cannot rely on the screen or a normal keyboard:

  • Screen Reader: reads the interface aloud. Orca (GNOME) and Emacspeak are common ones; they read dialog boxes so you can answer by ear.
  • Braille Display: a hardware device that outputs the on-screen text as refreshable braille. A modern screen reader or text-to-speech is often more practical when it is available.
  • On-Screen Keyboard: a keyboard drawn on the screen, typed with a mouse or touch, for people who cannot use a physical one. GNOME has one built in; other desktops can add the onboard package.

Keyboard and mouse helpers (AccessX)

These make the keyboard and mouse easier for people with limited movement. They are part of the X keyboard extension and can also be toggled from the command line with xkbset. Several have an activation gesture, so they can be switched on without the mouse:

  • Sticky keys: press modifiers one at a time instead of together, so Shift then a gives a capital A. Turn on by pressing Shift five times.
  • Repeat keys: control whether, and how fast, a held-down key repeats.
  • Slow keys: ignore a key until it has been held for a moment, to avoid accidental taps. Turn on by holding Shift for eight seconds.
  • Bounce keys: ignore a second press of the same key that comes too quickly, to avoid double letters.
  • Toggle keys: play a sound when a lock key such as Caps Lock is switched on or off.
  • Mouse keys: move the pointer with the number-pad arrow keys instead of a mouse.
  • Gestures: trigger actions from touch or pointer movements.

GNOME's Universal Access also offers Visual Alerts (flash the screen instead of a beep), Simulate Secondary Click (hold the button for a right-click), and Hover Click (click by resting the pointer).

Voice recognition

Recent advances in voice recognition have made speaking to the computer one of the best ways for people with disabilities to control the operating system, both for dictation and for issuing commands.

Summary

This objective is about awareness. Linux groups accessibility into three ideas: AccessX for keyboard and mouse difficulties, visual settings for low vision, and assistive technology for people who cannot see the screen, all reachable from the display manager and from GNOME's Universal Access. For vision I know the High Contrast and Large Print themes and the Screen Magnifier (zoom). For assistive technology I know the Screen Reader (Orca, Emacspeak), the Braille Display, and the On-Screen Keyboard. For limited movement, AccessX (toggled in the desktop or with xkbset) gives Sticky, Repeat, Slow, Bounce, and Toggle keys, plus Mouse keys and Gestures. And voice recognition is now a strong way to drive the whole system hands-free.