Chapter 4. Assistive Technologies

Contents

4.1. Enabling Assistive Technologies
4.2. General Accessibility Features
4.3. Mobility Impairments
4.4. Orca

Abstract

The GNOME user interface includes many accessibility features and assistive technologies. All applications in the GNOME Desktop have specially designed accessibility features. Thanks to the many customization tools users with physical disabilities can use all features of the GNOME Desktop.

This chapter describes several assistive technology applications designed to meet the needs of users with physical disabilities like low vision or impaired motor skills.

4.1. Enabling Assistive Technologies

You must enable assistive technology services before you are able to use many of the available Accessibility tools.

  1. Choose Computer+Control Center+Personal+Assistive Technologies.

  2. Select Enable assistive technologies and press Close and Log Out.

  3. Log back in. Assistive technology services are now activated.

4.2. General Accessibility Features

A number of technologies can be of assistance to people with different types of disabilities. These are covered in this section.

For a more detailed guide, see: http://library.gnome.org/users/gnome-access-guide/

4.2.1. Desktop Appearance Enhancement

There are several ways to customize the appearance of the GNOME desktop. Themes are the most effective way to change the appearance of the desktop in a consistent manner. You can also customize different applications and the desktop to get the display settings that you need, in addition or as an alternative to themes. For details, see Chapter 3, Customizing Your Settings.

4.2.1.1. Font Settings of the Desktop

If you have difficulties with the default font type and size on the desktop and desktop background, you can customize the font settings to suit your needs.

To change the font, select Computer+Control Center+Look and Feel+Appearance. The Fonts tab contains the following options:

Application Font

Application Font selects a default font for the text that is displayed on the desktop, including the text displayed on the windows and dialogs associated with GNOME-compliant applications.

Document Font

Document Font selects a font for displaying documents.

Desktop Font

Desktop selects a font to use for the text that is displayed on the desktop background only.

Window Title Font

Window Title Font selects a font for the text that is displayed in the title bar area of windows.

Fixed Width Font

Fixed Width Font selects a font to use for editing documents.

Rendering

To specify how to render fonts on the desktop select either:

  • Monochrome,

  • Best Shapes,

  • Best Contrast

  • or Subpixel Smoothing.

If you use large fonts, you may need to change the size of panes in some applications, such as the file manager and Help browser.

By default, GNOME applications use the default font specified in the Appearance tool. Some applications allow this default font to be customized.

4.2.1.2. Desktop Contrast

If you have difficulties with the desktop contrast, you can change the contrast.

To change change the contrast theme, select Computer+Control Center+Look and Feel+Appearance. The Theme tab contains several high- and low-contrast themes.

To change the desktop background to a solid color, select Computer+Control Center+Look and Feel+Appearance+Background.

  • Choose a color background from the wallpapers available.

  • Set the Colors to Solid Color.

  • Select a background color that suits your needs.

4.2.1.3. A Large-Print Desktop

If you have problems with the desktop print size, you can select the Large Print theme. To configure the large-print desktop, click Computer+Control Center+Look and Feel+Appearance+Theme and select Large Print.

Click on the Apply Font to increase the size of the font that is used on the desktop and on window frames.

If you use applications that use panes, like the file manager and help browser, you may need to change the size of panes to accommodate the large print. See the online help for the appropriate application for more information.

4.3. Mobility Impairments

Mobility impairments can have many causes. Poor muscle control or weakness can make using standard keyboards and mouse devices difficult. For instance, some people are unable to type two keys simultaneously, others hit multiple keys or bounce keys when pressing or releasing them. People who are able to use only one hand often have difficulties with some keyboard and mouse tasks.

4.3.1. Mouse Behavior

The following sections describe how to modify the behavior of the mouse to suit your needs.

4.3.1.1. Mouse for Left-Handed Use

If you have difficulties using the right-handed mouse, you can change the mouse setting to left-handed. To configure the mouse for left-handed use, select Computer+Control Center+Hardware+Mouse+ General and select the Left-handed mouse orientation. When you select this option, the system swaps the functions of the left and the right mouse button.

4.3.1.2. Double-Click Behavior

If you have difficulties double-clicking, you can increase the period of time that the system between the first and the second click of a double-click. For example, if the double-click timeout setting is 0.4 seconds, you must perform the second click of a double-click within 0.4 seconds of the first click. If the second click occurs more than 0.4 seconds after the first click, the system interprets the two clicks as two single clicks.

To configure the double-click timeout setting , select Computer+Control Center+Hardware+Mouse+ General and specify the Double-Click Timeout. Double-click the light bulb beneath the slider to test the setting. If you perform the two clicks of the double-click within the specified period, the light bulb energizes fully to display a yellow glow around the bulb. If you do not double-click within the timeout specified, the light bulb does not energize fully. You should increase the timeout setting and try again. When the light bulb energizes, the timeout setting is suitable for your needs.

4.3.1.3. Mouse Speed and Sensitivity

If you have difficulties with the behavior of the pointer, you can change the speed and sensitivity of the pointer. To configure the speed and sensitivity of the pointer, select Computer+ Control Center+Hardware+Mouse+ General.

Use the Acceleration slider to specify the mouse pointer speed when moving the mouse. Moving the slider to the right will increase speed and moving it to the left will decrease speed.

Use the Sensitivity slider to specify how responsive the pointer is to movements of the mouse. Moving the slider to the right will increase sensitivity and moving it to the left will decrease sensitivity.

Use the slider in the Drag and Drop section to modify the distance that you must move an item with the pointer before the action is interpreted as a drag and drop action.

If you select a low acceleration setting, the pointer moves at a speed similar to the speed at which you are physically moving the mouse or other pointer device. This means that you need to physically move the mouse larger distances to cover the screen area. If you select a high setting, the pointer moves at a faster speed than the speed at which you physically move the mouse. This means that you need to physically move the mouse smaller distances to cover the screen area.

4.3.1.4. Accessible Mouse

Use the Mouse Preferences tool to configure the mouse accessibility options. To open the Mouse Preferences tool, choose Computer+Control Center+Hardware+Mouse. Accessibility options can be enabled by selecting the Accessibility tab.

4.3.1.5. Accessible Keyboard

Use the Keyboard tool to configure the keyboard accessibility options. To open it, choose Computer+Control Center+Hardware+Keyboard. Accessibility options can be enabled by selecting the Accessibility tab.

4.3.2. GNOME On-Screen Keyboard

The GNOME On-Screen Keyboard displays virtual keyboards on your desktop. You can use the standard pointer or an alternative pointing device to operate the virtual keyboards. GOK displays the following types of keyboards:

  • Composer Keyboards enable you to compose text. To type alphanumeric characters, select the characters on the composer keyboard.

  • Dynamic Keyboards reflect the applications that are currently running on the desktop. For example, On-Screen Keyboard generates dynamic keyboards that contain keys to represent the applications that are running on your desktop or the menus that are contained in an application.

To start the On-Screen Keyboard, choose Computer+More Applications+Tools+On-Screen Keyboard.

[Note]

In order to use the GNOME On-Screen Keyboard, the Assistive Technologies need to be enabled as described under Section 4.1, “Enabling Assistive Technologies”.

If you are an On-Screen Keyboard user, you cannot use any application in Full-Screen mode because the application window obscures the On-Screen Keyboard display.

To resize the window for use with the On-Screen Keyboard application, perform the following steps:

  1. Do not enable the Full-Screen mode in the application.

  2. Give focus to the application window.

  3. Press F10 to maximize the application.

4.4. Orca

Orca is a flexible, extensible, and powerful assistive technology for people with visual impairments. Using various combinations of speech synthesis, braille and magnification, the Orca Screen Reader and Orca Magnifier application enable users with limited or no vision to use the GNOME desktop and associated applications. The screen reader also supports Braille.

Start Orca by choosing Computer+More Applications+Tools+Orca. When you run Orca for the first time, it will automatically enter setup mode where you can configure it according to your needs. The setup allows you to enable features like speech and braille support, word or key echoes and screen magnifier.