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 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.
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/
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.
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 ++. The tab contains the following options:
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.
selects a font for displaying documents.
selects a font to use for the text that is displayed on the desktop background only.
selects a font for the text that is displayed in the title bar area of windows.
selects a font to use for editing documents.
To specify how to render fonts on the desktop select either:
,
,
or .
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 tool. Some applications allow this default font to be customized.
If you have difficulties with the desktop contrast, you can change the contrast.
To change change the contrast theme, select +++. The tab contains several high- and low-contrast themes.
To customize the desktop background, select +++.
Set the to .
Set the to “Solid Color”.
Select a background color that suits your needs.
Ensure that the option is selected in the tabbed section of the dialog.
In the gedit text editor, ensure that the option is selected in the tabbed section of the dialog.
If you have problems with the desktop print size, you can select the theme. To configure the large-print desktop, click on +++ and select .
Click on the 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.
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.
The following sections describe how to modify the behavior of the mouse to suit your needs.
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 + and select the mouse orientation. When you select this option, the system swaps the functions of the left and the right mouse button.
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 ++ and specify the . Double-click on the light bulb to the right of 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.
If you have dificulties with the behaviour of the pointer, you can change the speed and sensitivity of the pointer. To configure the speed and sensitivity of the pointer, select +++.
Use the 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 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.
Use the tool to configure the keyboard accessibility options. To open the tool, choose ++. Accessibility options can be enabled by selecting the tab.
The GNOME On-Screen Keyboard (GOK) 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.
You must enable assistive technology services before you are able to use many of the available tools.
Choose ++.
Select and press and .
Log back in. Assistive technology services are now activated.
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:
Do not enable the Full-Screen mode in the application.
Give focus to the application window.
Press F10 to maximize the application.
Visual limitations range from low vision to blindness. Users with visual disabilities encounter problems when seeing text or images on a computer screen and when performing tasks that require hand-eye coordination, like moving a computer mouse. Text size and color can make a big difference in legibility for people with low vision.
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.
For a text-only guided setup, open a dialog with
Alt+F2,
enter Orca text-setup and press
Enter.
The first time Orca is launched you will be presented with a list of
languages from which to choose. Enter the ID number of your language
(for example, 7 for American English) and press
Enter.
When you run Orca for the first time, it will automatically enter setup
mode. If you want to run setup at some later point, you can pass the
setup option to Orca the next time you run it.
Furthermore, while Orca is running you can press Ins+Space to
bring up Orca's configuration GUI. Finally, Orca provides a text setup
utility that you can start by passing the --text-setup
option to Orca. All of these options will create a
~/.orca/user-settings.py file that holds your
Control Center and will also enable the accessibility infrastructure.
You need to log out and log back in for the new setting to take effect.
Start Orca by typing orca in a terminal session window. You can do so from a virtual console window if you do not yet have access to the GUI. With the GUI installed you can also press Alt+F2 to bring up the dialog and then type the command orca (followed by any optional parameters) and press Enter. Orca will automatically enter text setup mode if you run it from a virtual console window or if your GUI environment is not yet set up for accessibility.
To quit Orca press Ins+Q (or CapsLock+Q in laptop layout mode). A dialog will appear.
The braille page allows you to customize various aspects of braille usage.
The first control on the braille page is the check box. This check box toggles whether or not Orca will make use of a braille display.
Orca's braille monitor provides an on-screen representation of what takes place on the braille display. This feature is mostly for demonstration purposes, but is also useful for Orca developers who do not have access to a braille display.
The check box determines the manner in which role names are displayed and can be used to help conserve real estate on the braille display.
When checked, this feature tells Orca to not present the
$1 string at the end of a line.
The radio button group determines the amount of information that will be, in certain situations, converted to braille.
The magnifier page allows you to enable/disable magnification and specify how magnification is performed.
The first control on the magnifier page is the check box. This check box toggles whether or not Orca will provide magnification. This option, along with the ability to enable speech and to enable braille support, allows Orca to be tailored to meet the needs of a wide variety of users.
Two zoomer GUI controls determine magnification characteristics: , which sets magnification power and , which sets the location and size of the magnifier window.