Dasher is an

input method An input method (or input method editor, commonly abbreviated IME) is an operating system component or program that enables users to generate characters not natively available on their input devices by using sequences of characters (or mouse oper ...

and

computer accessibility Computer accessibility refers to the accessibility of a computer system to all people, regardless of disability type or severity of impairment. The term ''accessibility'' is most often used in reference to specialized hardware or software, or a co ...

tool which enables users to compose text without using a keyboard, by entering text on a screen with a

pointing device A pointing device is a human interface device that allows a User (computing)#End-user, user to input Three-dimensional space, spatial (i.e., continuous and multi-dimensional) data to a computer. Graphical user interfaces (GUI) and Computer- ...

such as a

mouse A mouse (: mice) is a small rodent. Characteristically, mice are known to have a pointed snout, small rounded ears, a body-length scaly tail, and a high breeding rate. The best known mouse species is the common house mouse (''Mus musculus'' ...

touch screen A touchscreen (or touch screen) is a type of electronic visual display, display that can detect touch input from a user. It consists of both an input device (a touch panel) and an output device (a visual display). The touch panel is typically l ...

, or mice operated by the foot or head. Such instruments could serve as prosthetic devices for disabled people who cannot use standard keyboards, or where the use of one is impractical. Dasher is

free and open-source software Free and open-source software (FOSS) is software available under a license that grants users the right to use, modify, and distribute the software modified or not to everyone free of charge. FOSS is an inclusive umbrella term encompassing free ...

, subject to the requirements of the

GNU General Public License The GNU General Public Licenses (GNU GPL or simply GPL) are a series of widely used free software licenses, or ''copyleft'' licenses, that guarantee end users the freedom to run, study, share, or modify the software. The GPL was the first ...

(GPL), version 2. Dasher is available for operating systems with

GTK+ GTK (formerly GIMP ToolKit and GTK+) is a free software cross-platform widget toolkit for creating graphical user interfaces (GUIs). It is licensed under the terms of the GNU Lesser General Public License, allowing both free and proprietary s ...

support, i.e.

Linux Linux ( ) is a family of open source Unix-like operating systems based on the Linux kernel, an kernel (operating system), operating system kernel first released on September 17, 1991, by Linus Torvalds. Linux is typically package manager, pac ...

BSD The Berkeley Software Distribution (BSD), also known as Berkeley Unix or BSD Unix, is a discontinued Unix operating system developed and distributed by the Computer Systems Research Group (CSRG) at the University of California, Berkeley, beginni ...

s and other

Unix-like A Unix-like (sometimes referred to as UN*X, *nix or *NIX) operating system is one that behaves in a manner similar to a Unix system, although not necessarily conforming to or being certified to any version of the Single UNIX Specification. A Uni ...

including

macOS macOS, previously OS X and originally Mac OS X, is a Unix, Unix-based operating system developed and marketed by Apple Inc., Apple since 2001. It is the current operating system for Apple's Mac (computer), Mac computers. With ...

Windows Windows is a Product lining, product line of Proprietary software, proprietary graphical user interface, graphical operating systems developed and marketed by Microsoft. It is grouped into families and subfamilies that cater to particular sec ...

Pocket PC A Pocket PC (P/PC, PPC) is a class of personal digital assistant (PDA) that runs the Windows Mobile operating system, which is based on Windows Embedded Compact, Windows CE/Windows Embedded Compact, and that has some of the abilities of modern ...

iOS Ios, Io or Nio (, ; ; locally Nios, Νιός) is a Greek island in the Cyclades group in the Aegean Sea. Ios is a hilly island with cliffs down to the sea on most sides. It is situated halfway between Naxos and Santorini. It is about long an ...

and Android. Dasher was invented by David J. C. MacKay and developed by David Ward and other members of MacKay's Cambridge research group. The Dasher project is supported by the Gatsby Charitable Foundation and by the EU aegis-project. Dasher's code is currently maintained by the ACE Centre, and is being relicensed to the

MIT License The MIT License is a permissive software license originating at the Massachusetts Institute of Technology (MIT) in the late 1980s. As a permissive license, it puts very few restrictions on reuse and therefore has high license compatibility. Unl ...

Design

For whatever the writer intends to write, they select a letter from ones displayed on a screen by using a pointer, whereupon the system uses a

probabilistic Probability is a branch of mathematics and statistics concerning events and numerical descriptions of how likely they are to occur. The probability of an event is a number between 0 and 1; the larger the probability, the more likely an e ...

predictive

model A model is an informative representation of an object, person, or system. The term originally denoted the plans of a building in late 16th-century English, and derived via French and Italian ultimately from Latin , . Models can be divided in ...

to anticipate the likely character combinations for the next piece of text, and accord these higher priority by displaying them more prominently than less likely letter combinations. This saves the user effort and time as they proceed to choose the next letter from those offered. The process of composing text in this way has been likened to an

arcade game An arcade game or coin-op game is a coin-operated entertainment machine typically installed in public businesses such as restaurants, bars and amusement arcades. Most arcade games are presented as primarily game of skill, games of skill and in ...

, as users zoom through characters that fly across the screen and select them in order to compose text. The system learns from experience which letter combinations are the most popular, and changes its display protocol over time to reflect this.

Features

The Dasher package contains various architecture-independent data files: * alphabet descriptions for over 150 languages * letter colours settings * training files in all supported languages

References

External links

Original website

New website
* {{GitHub, dasher-project User interfaces User interface techniques Pointing-device text input Disability software Free software programmed in C Free software programmed in C++ Free software programmed in Java (programming language) GNOME Accessibility Cross-platform free software Free and open-source Android software