Assistive Technologies: partial list of the files, terms, and utilities used
The following is a partial list of the files, terms, and utilities used:
• Sticky/repeat keys
StickyKeys
Allows users to lock modifier keys such as ctrl and shift. This enables them to complete keyboard tasks with just one finger that would normally require two or more fingers.
• Slow/bounce/toggle keys
SlowKeys
Configures the keyboard such that the user must hold a key down for a specified period of time before the keystroke is actually sent. This helps the user avoid sending accidental keystrokes.
BounceKeys and DelayKeys
Inserts a slight delay between keystrokes to prevent the keyboard from sending unintentional keystrokes.
ToggleKeys
Sounds an audible alert if either the caps lockkey or the num lock key is on
• Mouse keys
Enables key sequences to be used to move the mouse cursor on the screen and to send mouse clicks.
• High-contrast/large-print desktop themes
The last visibility accessibility option we’re going to look at here involves high-contrast, large-text desktop themes. In the Universal Access panel, enable the High Contrast and Large Text options under Seeing.
• Screen reader
One option available to visually impaired users is a screen reader, which “reads” the text displayed on the screen audibly for the user. Some screen readers can use your computer’s sound interface, whereas others require special speech synthesizer hardware. The Orca application is probably the most commonly used screen reader.
• Braille display
Visually impaired Linux users can also use Braille hardware devices. Several types of Braille displays and embossers are supported. To interface with these types of devices, the Linux system must be running the brltty daemon.
• Screen magnifier
A screen magnifier allows visually impaired users to magnify areas of the screen as if they were using a real magnifying glass. You can choose from a wide variety of screen magnifiers, including Orca, GNOME Magnifier, and KDE Magnifier. Of these, Orca is probably the most popular, primarily because it can function as both a screen reader and a screen magnifier.
• Onscreen keyboard
For physically impaired users who aren’t able to use a traditional keyboard, Linux provides the option of using an onscreen keyboard, which allows users to use any pointing device (such as a mouse) to select keys on a virtual keyboard.
• Gestures (used at login; for example, gdm)
GDM supports "Accessible Login" to allow users to log in to their desktop session even if they cannot easily use the screen, mouse, or keyboard in the usual way. This feature allows the user to launch assistive technologies at login time by means of special "gestures" from the standard keyboard and from a keyboard, pointing device, or switch device attached to the USB or PS/2 mouse port. It also allows the user to change the visual appearance of the login UI before logging in, for instance to use a higher-contrast color scheme for better visibility. GDM only supports accessibility with the Standard Greeter, so the "Greeter" parameter in gdm.conf must be set to the Standard Greeter "gdmlogin".
• Orca
Orca is a free and open source, flexible, extensible screen reader from the GNOME project for individuals who are blind or visually impaired.
• OK
Onscreen keyboard
Commonly used onscreen keyboard applications include GOK (GNOME Onscreen Keyboard) and GTkeyboard
• emacspeak
emacspeak :Screen reader, text-based terminal screens
LX0-104 Exam Objectives (J)
Showing posts with label x windows. Show all posts
Showing posts with label x windows. Show all posts
Thursday, December 8, 2016
X Windows: Braille Devices
X Windows
Assistive Technologies V
Braille Devices
Visually impaired Linux users can also use Braille hardware devices. Several types of Braille displays and embossers are supported. To interface with these types of devices, the Linux system must be running the brltty daemon.
The Orca utility mentioned earlier can be used to support Braille devices. Start Orca by searching for Orca and selecting its icon. Then select the Braille tab in the Orca preferences.
Configure the following Braille options, as appropriate for your preferences and for your Braille devices:
• Enable Braille Support: Configure Orca to use a Braille display.
• Enable Braille Monitor: Configure a Braille monitor on the regular display, which allows you to visually observe what’s happening on the Braille display device.
• Enable Contracted Braille: Use contracted Braille.
• Abbreviated Role Names: Abbreviate role names on the Braille display.
• Disable End of Line Symbol: Do not send the $l end-of-line characters to the Braille display.
• Verbosity: Controls the level of information to be sent to the Braille display.
• Selection Indicator: How selected text on the screen will be underlined on the Braille display.
• Hyperlink Indicator: How hypertext on the screen will be underlined on the Braille display.
Select OK to save your changes to the Orca Braille configuration
LX0-104 Exam Objectives (J)
Assistive Technologies V
Braille Devices
Visually impaired Linux users can also use Braille hardware devices. Several types of Braille displays and embossers are supported. To interface with these types of devices, the Linux system must be running the brltty daemon.
The Orca utility mentioned earlier can be used to support Braille devices. Start Orca by searching for Orca and selecting its icon. Then select the Braille tab in the Orca preferences.
Configure the following Braille options, as appropriate for your preferences and for your Braille devices:
• Enable Braille Support: Configure Orca to use a Braille display.
• Enable Braille Monitor: Configure a Braille monitor on the regular display, which allows you to visually observe what’s happening on the Braille display device.
• Enable Contracted Braille: Use contracted Braille.
• Abbreviated Role Names: Abbreviate role names on the Braille display.
• Disable End of Line Symbol: Do not send the $l end-of-line characters to the Braille display.
• Verbosity: Controls the level of information to be sent to the Braille display.
• Selection Indicator: How selected text on the screen will be underlined on the Braille display.
• Hyperlink Indicator: How hypertext on the screen will be underlined on the Braille display.
Select OK to save your changes to the Orca Braille configuration
LX0-104 Exam Objectives (J)
X Windows: Screen Magnifiers
X Windows
Assistive Technologies IV
Screen Magnifiers
A screen magnifier allows visually impaired users to magnify areas of the screen as if they were using a real magnifying glass. You can choose from a wide variety of screen magnifiers, including Orca, GNOME Magnifier, and KDE Magnifier.
Of these, Orca is probably the most popular, primarily because it can function as both a screen reader and a screen magnifier.
You can start Orca from the shell prompt by entering orca –e magnifier.To configure a screen magnifier, do the following:
1. Access the Universal Access panel and select Zoom.
2. Configure the following magnification options:
• Magnification: The level of magnification to be used
• Magnifier position: The size and color of the magnifier’s cursor
• Crosshairs Settings: The magnifier’s area-targeting cursor
• Color Effects Settings: The color of the magnified region
3. When you’re done, select Close
LX0-104 Exam Objectives (J)
Assistive Technologies IV
Screen Magnifiers
A screen magnifier allows visually impaired users to magnify areas of the screen as if they were using a real magnifying glass. You can choose from a wide variety of screen magnifiers, including Orca, GNOME Magnifier, and KDE Magnifier.
Of these, Orca is probably the most popular, primarily because it can function as both a screen reader and a screen magnifier.
You can start Orca from the shell prompt by entering orca –e magnifier.To configure a screen magnifier, do the following:
1. Access the Universal Access panel and select Zoom.
2. Configure the following magnification options:
• Magnification: The level of magnification to be used
• Magnifier position: The size and color of the magnifier’s cursor
• Crosshairs Settings: The magnifier’s area-targeting cursor
• Color Effects Settings: The color of the magnified region
3. When you’re done, select Close
LX0-104 Exam Objectives (J)
X Windows: Screen Readers
X Windows
Assistive Technologies III
Screen Readers
One option available to visually impaired users is a screen reader, which “reads” the text displayed on the screen audibly for the user. Some screen readers can use your computer’s sound interface, whereas others require special speech synthesizer hardware.
The Orca application is probably the most commonly used screen reader. Unlike many other screen readers, Orca can read text from the GNOME desktop. Many other screen readers, such as emacspeak, only work with text-based terminal screens.
To configure a screen reader, open Universal Access and then click Screen Reader.
LX0-104 Exam Objectives (J)
Assistive Technologies III
Screen Readers
One option available to visually impaired users is a screen reader, which “reads” the text displayed on the screen audibly for the user. Some screen readers can use your computer’s sound interface, whereas others require special speech synthesizer hardware.
The Orca application is probably the most commonly used screen reader. Unlike many other screen readers, Orca can read text from the GNOME desktop. Many other screen readers, such as emacspeak, only work with text-based terminal screens.
To configure a screen reader, open Universal Access and then click Screen Reader.
LX0-104 Exam Objectives (J)
X Windows: High-Contrast, Large-Text Desktop Themes
X Windows
Assistive Technologies II
High-Contrast, Large-Text Desktop Themes
The last visibility accessibility option we’re going to look at here involves high-contrast, large-text
desktop themes. In the Universal Access panel, enable the High Contrast and Large Text options
under Seeing. These options were shown earlier in Figure 7-11.
Let’s practice working with Accessibility Settings in the following exercise.
LX0-104 Exam Objectives (J)
Assistive Technologies II
High-Contrast, Large-Text Desktop Themes
The last visibility accessibility option we’re going to look at here involves high-contrast, large-text
desktop themes. In the Universal Access panel, enable the High Contrast and Large Text options
under Seeing. These options were shown earlier in Figure 7-11.
Let’s practice working with Accessibility Settings in the following exercise.
LX0-104 Exam Objectives (J)
X Windows: Keyboard Accessibility
X Windows
Assistive Technologies I
Keyboard Accessibility
These settings are designed to enable physically impaired users to use
a traditional keyboard. You can configure the following:
1) StickyKeys Allows users to lock modifier keys such as ctrl and
shift. This enables them to complete keyboard tasks with just one
finger that would normally require two or more fingers.
2) MouseKeys Enables key sequences to be used to move the mouse cursor
on the screen and to send mouse clicks.
3) SlowKeys Configures the keyboard such that the user must hold a key
down for a specified period of time before the keystroke is actually
sent. This helps the user avoid sending accidental keystrokes.
4) ToggleKeys Sounds an audible alert if either the caps lock key or
the num lock key is on.
5) RepeatKeys Configures the keyboard to allow the user extra time to
release a pressed key before sending multiple keystrokes.
6) BounceKeys and DelayKeys Inserts a slight delay between keystrokes
to prevent the keyboard from sending unintentional keystrokes.
To configure AccessX settings, access Universal Access and select the
option to configure keyboard preferences. For example, on a Fedora
system, you would select Typing Assist (AccessX) under Typing.
LX0-104 Exam Objectives (J)
Assistive Technologies I
Keyboard Accessibility
These settings are designed to enable physically impaired users to use
a traditional keyboard. You can configure the following:
1) StickyKeys Allows users to lock modifier keys such as ctrl and
shift. This enables them to complete keyboard tasks with just one
finger that would normally require two or more fingers.
2) MouseKeys Enables key sequences to be used to move the mouse cursor
on the screen and to send mouse clicks.
3) SlowKeys Configures the keyboard such that the user must hold a key
down for a specified period of time before the keystroke is actually
sent. This helps the user avoid sending accidental keystrokes.
4) ToggleKeys Sounds an audible alert if either the caps lock key or
the num lock key is on.
5) RepeatKeys Configures the keyboard to allow the user extra time to
release a pressed key before sending multiple keystrokes.
6) BounceKeys and DelayKeys Inserts a slight delay between keystrokes
to prevent the keyboard from sending unintentional keystrokes.
To configure AccessX settings, access Universal Access and select the
option to configure keyboard preferences. For example, on a Fedora
system, you would select Typing Assist (AccessX) under Typing.
LX0-104 Exam Objectives (J)
Configuring the Display Manager The following is a partial list of the files, terms, and utilities used
X Windows
Configuring the Display Manager
The following is a partial list of the files, terms, and utilities used:
• lightdm
The LightDM display manager
•/etc/lightdm/
The LightDM display manager is configured using several different files:
• /usr/share/lightdm/lightdm.conf.d
• /etc/lightdm/lightdm.conf.d
• /etc/lightdm/lightdm.conf
LX0-104 Exam Objectives (I)
Configuring the Display Manager
The following is a partial list of the files, terms, and utilities used:
• lightdm
The LightDM display manager
•/etc/lightdm/
The LightDM display manager is configured using several different files:
• /usr/share/lightdm/lightdm.conf.d
• /etc/lightdm/lightdm.conf.d
• /etc/lightdm/lightdm.conf
LX0-104 Exam Objectives (I)
X Windows: Configuring the Display Manager
X Windows
Configuring the Display Manager
You can configure your display manager by editing the appropriate
configuration file:
• xdm /etc/X11/xdm/xdm-config
• LightDM The LightDM display manager is configured using several
different files:
• /usr/share/lightdm/lightdm.conf.d
• /etc/lightdm/lightdm.conf.d
• /etc/lightdm/lightdm.conf
• kdm The KDE display manager is actually based on xdm and usually
uses the xdm configuration files. However, some distributions store
your kdm settings in /etc/kde/kdm or /etc/X11/ kdm instead. In this
situation, you will use the kdmrc file in either of these directories
to make most configuration changes.
• gdm /etc/X11/gdm
We are going to focus on configuring the LightDM display manager in
this chapter.
When working with the LightDM display manager, it’s important to
remember that all of its configuration files are combined together to
configure LightDM. The key is the fact the files are applied in the
order shown previously.
The default LightDM configuration is stored in the configuration files in
/usr/share/lightdm /lightdm.conf.d/
These files are generated by the system and should not be edited directly.
Instead, you should create override files containing the changes you want to make in
/etc/lightdm /lightdm.conf.d/
(Alternatively, you can also enter them into the
/etc/lightdm/lightdm.conf file.)
If there are identical settings in more than one file, the setting in the last file processed
is applied and the others are overridden. For example, suppose you
wanted to override the default session type (configured in
/usr/share/lightdm/lightdm.conf.d/50-ubuntu.conf); you could make a
file named /etc/lightdm/lightdm.conf.d/50-myconfig.conf and enter the
appropriate configuration settings.
LightDM uses the concept of a greeter, which is basically a user
interface for interacting with LightDM. For example, the Ubuntu
distribution uses the Unity greeter by default. You can customize the
way LightDM works and which greeter it uses using the LightDM
configuration files, including the following:
You can change which greeter LightDM uses. To do this, create the
appropriate file in
/etc/lightdm/lightdm.conf.d/
and specify the name of a greeter file (which has a .desktop extension) that you want to
use in
/usr/share/xgreeters
Use the following syntax:
[SeatDefaults]
greeter-session=file_name
You can disable guest logins. By default, LightDM allows you to log in
to the system as a guest user. For security reasons, you may want to
disable this functionality. To do this, create the appropriate file in
/etc/lightdm/lightdm.conf.d/
and enter the following lines:
[SeatDefaults]
allow-guest=false
You can hide the user list. Many LightDM greeters display a list of
possible user accounts by default. Again, for security reasons, you
may want to disable this functionality. Create the appropriate file in
/etc/lightdm/lightdm.conf.d/
and enter the following lines:
[SeatDefaults]
greeter-hide-users=true
You can configure LightDM to allow manual logins. By default, the
Unity greeter doesn’t allow you to manually enter a username when
logging in to the system. You can reconfigure Unity to allow this by
creating the appropriate file in
/etc/lightdm/lightdm.conf.d/
and enter the following lines:
[SeatDefaults]
greeter-show-manual-login=true
You can change the default session type used by LightDM by manually
specifying a session file.
These files have a .desktop extension and are located in
/usr/share/xsessions.
Again, create the appropriate file in
/etc/lightdm/lightdm.conf.d/
and enter the following lines:
[SeatDefaults]
user-session=file_name
LX0-104 Exam Objectives (I)
Configuring the Display Manager
You can configure your display manager by editing the appropriate
configuration file:
• xdm /etc/X11/xdm/xdm-config
• LightDM The LightDM display manager is configured using several
different files:
• /usr/share/lightdm/lightdm.conf.d
• /etc/lightdm/lightdm.conf.d
• /etc/lightdm/lightdm.conf
• kdm The KDE display manager is actually based on xdm and usually
uses the xdm configuration files. However, some distributions store
your kdm settings in /etc/kde/kdm or /etc/X11/ kdm instead. In this
situation, you will use the kdmrc file in either of these directories
to make most configuration changes.
• gdm /etc/X11/gdm
We are going to focus on configuring the LightDM display manager in
this chapter.
When working with the LightDM display manager, it’s important to
remember that all of its configuration files are combined together to
configure LightDM. The key is the fact the files are applied in the
order shown previously.
The default LightDM configuration is stored in the configuration files in
/usr/share/lightdm /lightdm.conf.d/
These files are generated by the system and should not be edited directly.
Instead, you should create override files containing the changes you want to make in
/etc/lightdm /lightdm.conf.d/
(Alternatively, you can also enter them into the
/etc/lightdm/lightdm.conf file.)
If there are identical settings in more than one file, the setting in the last file processed
is applied and the others are overridden. For example, suppose you
wanted to override the default session type (configured in
/usr/share/lightdm/lightdm.conf.d/50-ubuntu.conf); you could make a
file named /etc/lightdm/lightdm.conf.d/50-myconfig.conf and enter the
appropriate configuration settings.
LightDM uses the concept of a greeter, which is basically a user
interface for interacting with LightDM. For example, the Ubuntu
distribution uses the Unity greeter by default. You can customize the
way LightDM works and which greeter it uses using the LightDM
configuration files, including the following:
You can change which greeter LightDM uses. To do this, create the
appropriate file in
/etc/lightdm/lightdm.conf.d/
and specify the name of a greeter file (which has a .desktop extension) that you want to
use in
/usr/share/xgreeters
Use the following syntax:
[SeatDefaults]
greeter-session=file_name
You can disable guest logins. By default, LightDM allows you to log in
to the system as a guest user. For security reasons, you may want to
disable this functionality. To do this, create the appropriate file in
/etc/lightdm/lightdm.conf.d/
and enter the following lines:
[SeatDefaults]
allow-guest=false
You can hide the user list. Many LightDM greeters display a list of
possible user accounts by default. Again, for security reasons, you
may want to disable this functionality. Create the appropriate file in
/etc/lightdm/lightdm.conf.d/
and enter the following lines:
[SeatDefaults]
greeter-hide-users=true
You can configure LightDM to allow manual logins. By default, the
Unity greeter doesn’t allow you to manually enter a username when
logging in to the system. You can reconfigure Unity to allow this by
creating the appropriate file in
/etc/lightdm/lightdm.conf.d/
and enter the following lines:
[SeatDefaults]
greeter-show-manual-login=true
You can change the default session type used by LightDM by manually
specifying a session file.
These files have a .desktop extension and are located in
/usr/share/xsessions.
Again, create the appropriate file in
/etc/lightdm/lightdm.conf.d/
and enter the following lines:
[SeatDefaults]
user-session=file_name
LX0-104 Exam Objectives (I)
X Windows: Configure the display manager load at start up
X Windows
Configure the display manager load at start up
Because the display manager is managed using an init script, you can
control whether or not the display manager is loaded when the system
boots using the chkconfig command.
For example, to configure the xdm
display manager to not load at boot, enter
chkconfig xdm off.
You can verify that it is disabled by entering
chkconfig xdm –l
at the shell prompt. Here is an example:
ws1:/ # chkconfig xdm off
ws1:/ # chkconfig xdm –l
xdm 0:off 1:off 2:off 3:off 4:off 5:off 6:off
Alternatively, to configure the display to automatically load at
system start, you would enter
chkconfig xdm on.
Again, enter
chkconfig xdm –l
to verify that the display manager is configured to start
automatically at runlevel 5, as shown here:
ws1:/ # chkconfig xdm on
ws1:/ # chkconfig xdm –l
xdm 0:off 1:off 2:off 3:off 4:off 5:on 6:off
LX0-104 Exam Objectives (I)
Configure the display manager load at start up
Because the display manager is managed using an init script, you can
control whether or not the display manager is loaded when the system
boots using the chkconfig command.
For example, to configure the xdm
display manager to not load at boot, enter
chkconfig xdm off.
You can verify that it is disabled by entering
chkconfig xdm –l
at the shell prompt. Here is an example:
ws1:/ # chkconfig xdm off
ws1:/ # chkconfig xdm –l
xdm 0:off 1:off 2:off 3:off 4:off 5:off 6:off
Alternatively, to configure the display to automatically load at
system start, you would enter
chkconfig xdm on.
Again, enter
chkconfig xdm –l
to verify that the display manager is configured to start
automatically at runlevel 5, as shown here:
ws1:/ # chkconfig xdm on
ws1:/ # chkconfig xdm –l
xdm 0:off 1:off 2:off 3:off 4:off 5:on 6:off
LX0-104 Exam Objectives (I)
X Windows: enable or disable the display manager
X Windows
Enabling or Disabling the Display Manager
You can enable or disable the display manager using an init script.
Which one depends on the Linux distribution you’re using. On many
Linux distributions, such as openSUSE, the display manager is
managed by the xdm init script located in the /etc/init.d directory.
Other distributions may use the GNOME display manager (gdm) or the KDE
display manager (kdm). To manually manage the display manager, enter
/etc/init.d/init_script stop or start
at the shell prompt.
You can also use rcxdm stop or start to accomplish the same thing.
LX0-104 Exam Objectives (I)
Enabling or Disabling the Display Manager
You can enable or disable the display manager using an init script.
Which one depends on the Linux distribution you’re using. On many
Linux distributions, such as openSUSE, the display manager is
managed by the xdm init script located in the /etc/init.d directory.
Other distributions may use the GNOME display manager (gdm) or the KDE
display manager (kdm). To manually manage the display manager, enter
/etc/init.d/init_script stop or start
at the shell prompt.
You can also use rcxdm stop or start to accomplish the same thing.
LX0-104 Exam Objectives (I)
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