NonVisual Desktop Access

from Wikipedia, the free encyclopedia
NonVisual Desktop Access
Basic data

Maintainer Michael Curran
developer NV Access and Community
Publishing year 2006
Current  version 2020.1
(May 7, 2020)
operating system Windows
programming language Python and C ++
category Screen reader
License GPL
German speaking Yes
www.nvaccess.org

NonVisual Desktop Access (NVDA) is a free, portable and open source screen reader that enables blind people to use computers with the Windows operating system .

The project was started in 2006 by Australian Michael Curran, who, like most volunteers, is blind himself. The majority of NVDA is programmed in Python , but a few parts are also programmed in C ++ . From version 2010.2 Beta1 onwards, the screen content is also read using display hooking . However, by default it uses accessibility frameworks such as Microsoft Active Accessibility (MSAA), the newer User Interface Automation or the Java Access Bridge (JAB). The project uses the GNU General Public License .

NVDA contains the integrated speech synthesizer eSpeak and also supports other speech synthesizers such as SAPI synthesizers. However, since version 2017.3, Windows OneCore voices are used by default. The output on Braille displays is officially possible from version 0.6p3.

history

Concerned about the high cost of commercial screen readers , Michael Curran began developing a Python -based screen reader with Microsoft SAPI as the interface for speech output in April 2006 . It provided support for Windows 2000 onwards and provided screen reading features such as basic support for some third-party software and web browsing . In late 2006, Curran called his project Nonvisual Desktop Access (NVDA) and released version 0.5 the following year. In the course of 2008 and 2009, several versions of version 0.6 were released with enhanced web browsing, support for more programs, braille display and improved support for more languages. To manage the further development of NVDA, Curran and James Teh founded NV access, a not-for-profit company, in 2007 .

NVDA's features and popularity continued to grow. 2009 brought support for 64-bit versions of Windows as well as greater program stability in 2010. Major code restructuring to support third-party modules and basic support for Windows 8 became available in 2011. During 2012, NVDA received improved support for Windows 8, the ability to perform automatic updates, extension manager to manage third-party extensions, improved support for entering East Asian text, and introduced touchscreen support, the first of its kind for screen readers from Third party providers for Windows. NVDA received support for Microsoft PowerPoint in 2013 and was updated in 2014 to support PowerPoint 2013; In the same year, NVDA also added improved WAI-ARIA support. Also in 2013, NV Access introduced a restructured method for checking screen texts and a function for managing profiles for applications. In 2014, access to Microsoft Office and other Office suites was improved.

The accessibility of math formulas can be a problem for the blind and visually impaired. In 2015, NVDA received support for MathML through MathPlayer , along with improved support for Mintty, an open source terminal emulation , the desktop client for Skype, and charts in Microsoft Excel . Also in 2015, NVDA was one of the first screen readers to support Windows 10 and experimentally added support for Microsoft Edge , which is now fully supported. In 2016, the ability to turn down the volume of other applications while NVDA was talking was introduced.

In 2019, NVDA was voted the world's most popular screen reader in a poll . However, this survey is not representative due to the lack of awareness and the concentration of the Anglo-American area. NVDA is particularly popular in developing countries because it is free to download and use, and it is so accessible to many blind and visually impaired people who otherwise would not have access to the Internet.

NVDA can be used with steganography- based software to provide a textual description of images.

technical features

NVDA is divided into several subsystems, including the event loop, add-on manager, application modules, event handler, and input and output handlers, as well as modules to support accessibility APIs such as Microsoft Active Accessibility. NVDA also has several proprietary graphical user interfaces developed by wxPython , such as: B. various setting dialogs and dialogs for setup and update management.

NVDA uses objects to represent items in an application, such as menu bars, status bars, and various foreground windows. Various information about an object, such as its name, value, and screen coordinates, is collected by NVDA through accessibility APIs that are exposed by an object, such as: B. by UIA (User Interface Automation). The information collected is processed by various subsystems, such as B. Speech Handler, and presented to the user in speech, Braille and on screen windows. NVDA also provides facilities for handling events such as keys pressed, name changes, and when an application gains or loses focus.

NVDA offers the possibility to examine the object hierarchy of an application and to implement possibilities to improve the accessibility of a program. It provides dedicated commands for moving through the object hierarchy within an application, as well as an interactive Python console for performing focus manipulations, monitoring objects for events, and testing code to improve the accessibility of an application packaged in an application module shall be.

Development model

From 2006 to 2013, the NVDA source code was managed through Bazaar , with NV Access switching to Git in 2013, citing development progress with Bazaar . The developers also took the opportunity to periodically change the release schedule to avoid delays in the release of an official version and to make the release timeframe predictable.

In addition to the official publications, so-called snapshot builds are also available for testing. Similar to the Linux kernel release process , NVDA snapshots are divided into beta and alpha branches, with special topic branches being created from time to time. NV Access describes the beta branch as a chance for users to get early access to new features, the alpha branch as very unstable code for possible inclusion in the upcoming version, and topic branches for the development of a major feature or in preparation for the official release (rc branch). Some third-party developers also maintain specific branches, including language-specific versions of NVDA or to offer a public preview of a feature that are in active development.

The current lead developers are Michael "Mick" Curran and Reef Turner with code and translation contributions from users and other developers around the world.

Extensions

Since version 2011.1, the range of functions of NVDA can be significantly expanded using so-called extensions . The numerous extensions are mostly developed by the community and made available on a special website . In addition to expanding the functionality and the menus, other applications that would otherwise not be barrier-free can be made accessible.

With the help of these extensions the following functions can be added:

  • New braille display and speech output drivers
  • Extension for remote maintenance functionality
  • Display of the symbols in the notification area
  • Description of pictures
  • Counting elements of the selected text
  • Extended Outlook functions
  • Improvements for Mozilla applications
  • Updater for extensions

Some of these enhancements (such as text recognition or screen privacy protection) have already been integrated into NVDA itself.

Web links

Individual evidence

  1. ↑ http://espeak.sourceforge.net/
  2. ↑ https://mediaaccess.org.au/latest_news/general/a-screen-reader-for-everyone-why-the-world-needs-nvda
  3. ↑ https://www.couriermail.com.au/technology/blindness-cant-cloud-inventors-vision/news-story/8c77189c959ad62f5e168eb2961b5dfb
  4. ↑ https://www.netz-barrierefrei.de/wordpress/erkenntnisse-aus-dem-webaim-screenreader-survey-2019/
  5. ↑ https://www.pro-retina.de/forum/zugang-zu-informationen-im-digitalen-zeitalter
  6. ^ Leonard de Ruijter: Braille framework . Retrieved May 8, 2020.
  7. ↑ http://www.nvaccess.org/files/nvda/snapshots/
  8. ↑ https://addons.nvda-project.org/index.de.html