288 lines
14 KiB
Markdown
288 lines
14 KiB
Markdown
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<img src="logos/tcell.png" style="float: right"/>
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# Tcell
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_Tcell_ is a _Go_ package that provides a cell based view for text terminals, like _XTerm_.
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It was inspired by _termbox_, but includes many additional improvements.
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[](https://stand-with-ukraine.pp.ua)
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[](https://github.com/gdamore/tcell/actions/workflows/linux.yml)
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[](https://github.com/gdamore/tcell/actions/workflows/windows.yml)
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[](https://github.com/gdamore/tcell/blob/master/LICENSE)
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[](https://pkg.go.dev/github.com/gdamore/tcell/v2)
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[](https://discord.gg/urTTxDN)
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[](https://codecov.io/gh/gdamore/tcell)
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[](https://goreportcard.com/report/github.com/gdamore/tcell/v2)
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Please see [here](UKRAINE.md) for an important message for the people of Russia.
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NOTE: This is version 2 of _Tcell_. There are breaking changes relative to version 1.
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Version 1.x remains available using the import `github.com/gdamore/tcell`.
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## Tutorial
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A brief, and still somewhat rough, [tutorial](TUTORIAL.md) is available.
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## Examples
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- [proxima5](https://github.com/gdamore/proxima5) - space shooter ([video](https://youtu.be/jNxKTCmY_bQ))
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- [govisor](https://github.com/gdamore/govisor) - service management UI ([screenshot](http://2.bp.blogspot.com/--OsvnfzSNow/Vf7aqMw3zXI/AAAAAAAAARo/uOMtOvw4Sbg/s1600/Screen%2BShot%2B2015-09-20%2Bat%2B9.08.41%2BAM.png))
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- mouse demo - included mouse test ([screenshot](http://2.bp.blogspot.com/-fWvW5opT0es/VhIdItdKqJI/AAAAAAAAATE/7Ojc0L1SpB0/s1600/Screen%2BShot%2B2015-10-04%2Bat%2B11.47.13%2BPM.png))
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- [gomatrix](https://github.com/gdamore/gomatrix) - converted from Termbox
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- [micro](https://github.com/zyedidia/micro/) - lightweight text editor with syntax-highlighting and themes
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- [godu](https://github.com/viktomas/godu) - utility to discover large files/folders
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- [tview](https://github.com/rivo/tview/) - rich interactive widgets
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- [cview](https://code.rocketnine.space/tslocum/cview) - user interface toolkit (fork of _tview_)
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- [awsome gocui](https://github.com/awesome-gocui/gocui) - Go Console User Interface
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- [gomandelbrot](https://github.com/rgm3/gomandelbrot) - Mandelbrot!
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- [WTF](https://github.com/senorprogrammer/wtf) - personal information dashboard
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- [browsh](https://github.com/browsh-org/browsh) - modern web browser ([video](https://www.youtube.com/watch?v=HZq86XfBoRo))
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- [go-life](https://github.com/sachaos/go-life) - Conway's Game of Life
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- [gowid](https://github.com/gcla/gowid) - compositional widgets for terminal UIs, inspired by _urwid_
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- [termshark](https://termshark.io) - interface for _tshark_, inspired by Wireshark, built on _gowid_
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- [go-tetris](https://github.com/MichaelS11/go-tetris) - Go Tetris with AI option
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- [fzf](https://github.com/junegunn/fzf) - command-line fuzzy finder
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- [ascii-fluid](https://github.com/esimov/ascii-fluid) - fluid simulation controlled by webcam
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- [cbind](https://code.rocketnine.space/tslocum/cbind) - key event encoding, decoding and handling
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- [tpong](https://github.com/spinzed/tpong) - old-school Pong
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- [aerc](https://git.sr.ht/~sircmpwn/aerc) - email client
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- [tblogs](https://github.com/ezeoleaf/tblogs) - development blogs reader
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- [spinc](https://github.com/lallassu/spinc) - _irssi_ inspired chat application for Cisco Spark/WebEx
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- [gorss](https://github.com/lallassu/gorss) - RSS/Atom feed reader
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- [memoryalike](https://github.com/Bios-Marcel/memoryalike) - memorization game
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- [lf](https://github.com/gokcehan/lf) - file manager
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- [goful](https://github.com/anmitsu/goful) - CUI file manager
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- [gokeybr](https://github.com/bunyk/gokeybr) - deliberately practice your typing
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- [gonano](https://github.com/jbaramidze/gonano) - editor, mimics _nano_
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- [uchess](https://github.com/tmountain/uchess) - UCI chess client
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- [min](https://github.com/a-h/min) - Gemini browser
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- [ov](https://github.com/noborus/ov) - file pager
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- [tmux-wormhole](https://github.com/gcla/tmux-wormhole) - _tmux_ plugin to transfer files
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- [gruid-tcell](https://github.com/anaseto/gruid-tcell) - driver for the grid based UI and game framework
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- [aretext](https://github.com/aretext/aretext) - minimalist text editor with _vim_ key bindings
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- [sync](https://github.com/kyprifog/sync) - GitHub repo synchronization tool
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- [statusbar](https://github.com/kyprifog/statusbar) - statusbar motivation tool for tracking periodic tasks/goals
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- [todo](https://github.com/kyprifog/todo) - simple todo app
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- [gosnakego](https://github.com/liweiyi88/gosnakego) - a snake game
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- [gbb](https://github.com/sdemingo/gbb) - A classical bulletin board app for tildes or public unix servers
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- [lil](https://github.com/andrievsky/lil) - A simple and flexible interface for any service by implementing only list and get operations
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- [hero.go](https://github.com/barisbll/hero.go) - 2d monster shooter ([video](https://user-images.githubusercontent.com/40062673/277157369-240d7606-b471-4aa1-8c54-4379a513122b.mp4))
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## Pure Go Terminfo Database
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_Tcell_ includes a full parser and expander for terminfo capability strings,
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so that it can avoid hard coding escape strings for formatting. It also favors
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portability, and includes support for all POSIX systems.
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The database is also flexible & extensible, and can be modified by either running
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a program to build the entire database, or an entry for just a single terminal.
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## More Portable
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_Tcell_ is portable to a wide variety of systems, and is pure Go, without
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any need for CGO.
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_Tcell_ is believed to work with mainstream systems officially supported by golang.
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## No Async IO
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_Tcell_ is able to operate without requiring `SIGIO` signals (unlike _termbox_),
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or asynchronous I/O, and can instead use standard Go file objects and Go routines.
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This means it should be safe, especially for
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use with programs that use exec, or otherwise need to manipulate the tty streams.
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This model is also much closer to idiomatic Go, leading to fewer surprises.
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## Rich Unicode & non-Unicode support
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_Tcell_ includes enhanced support for Unicode, including wide characters and
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combining characters, provided your terminal can support them.
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Note that
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Windows terminals generally don't support the full Unicode repertoire.
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It will also convert to and from Unicode locales, so that the program
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can work with UTF-8 internally, and get reasonable output in other locales.
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_Tcell_ tries hard to convert to native characters on both input and output.
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On output _Tcell_ even makes use of the alternate character set to facilitate
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drawing certain characters.
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## More Function Keys
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_Tcell_ also has richer support for a larger number of special keys that some
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terminals can send.
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## Better Color Handling
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_Tcell_ will respect your terminal's color space as specified within your terminfo entries.
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For example attempts to emit color sequences on VT100 terminals
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won't result in unintended consequences.
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In legacy Windows mode, _Tcell_ supports 16 colors, bold, dim, and reverse,
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instead of just termbox's 8 colors with reverse. (Note that there is some
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conflation with bold/dim and colors.)
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Modern Windows 10 can benefit from much richer colors however.
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_Tcell_ maps 16 colors down to 8, for terminals that need it.
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(The upper 8 colors are just brighter versions of the lower 8.)
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## Better Mouse Support
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_Tcell_ supports enhanced mouse tracking mode, so your application can receive
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regular mouse motion events, and wheel events, if your terminal supports it.
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(Note: The Windows 10 Terminal application suffers from a flaw in this regard,
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and does not support mouse interaction. The stock Windows 10 console host
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fired up with cmd.exe or PowerShell works fine however.)
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## _Termbox_ Compatibility
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A compatibility layer for _termbox_ is provided in the `compat` directory.
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To use it, try importing `github.com/gdamore/tcell/termbox` instead.
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Most _termbox-go_ programs will probably work without further modification.
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## Working With Unicode
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Internally _Tcell_ uses UTF-8, just like Go.
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However, _Tcell_ understands how to
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convert to and from other character sets, using the capabilities of
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the `golang.org/x/text/encoding packages`.
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Your application must supply
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them, as the full set of the most common ones bloats the program by about 2 MB.
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If you're lazy, and want them all anyway, see the `encoding` sub-directory.
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## Wide & Combining Characters
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The `SetContent()` API takes a primary rune, and an optional list of combining runes.
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If any of the runes is a wide (East Asian) rune occupying two cells,
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then the library will skip output from the following cell. Care must be
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taken in the application to avoid explicitly attempting to set content in the
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next cell, otherwise the results are undefined. (Normally the wide character
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is displayed, and the other character is not; do not depend on that behavior.)
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Older terminal applications (especially on systems like Windows 8) lack support
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for advanced Unicode, and thus may not fare well.
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## Colors
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_Tcell_ assumes the ANSI/XTerm color model, including the 256 color map that
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XTerm uses when it supports 256 colors. The terminfo guidance will be
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honored, with respect to the number of colors supported. Also, only
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terminals which expose ANSI style `setaf` and `setab` will support color;
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if you have a color terminal that only has `setf` and `setb`, please submit
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a ticket.
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## 24-bit Color
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_Tcell_ _supports 24-bit color!_ (That is, if your terminal can support it.)
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NOTE: Technically the approach of using 24-bit RGB values for color is more
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accurately described as "direct color", but most people use the term "true color".
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We follow the (inaccurate) common convention.
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There are a few ways you can enable (or disable) true color.
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- For many terminals, we can detect it automatically if your terminal
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includes the `RGB` or `Tc` capabilities (or rather it did when the database
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was updated.)
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- You can force this one by setting the `COLORTERM` environment variable to
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`24-bit`, `truecolor` or `24bit`. This is the same method used
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by most other terminal applications that support 24-bit color.
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- If you set your `TERM` environment variable to a value with the suffix `-truecolor`
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then 24-bit color compatible with XTerm and ECMA-48 will be assumed.
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(This feature is deprecated.
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It is recommended to use one of other methods listed above.)
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- You can disable 24-bit color by setting `TCELL_TRUECOLOR=disable` in your
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environment.
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When using TrueColor, programs will display the colors that the programmer
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intended, overriding any "`themes`" you may have set in your terminal
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emulator. (For some cases, accurate color fidelity is more important
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than respecting themes. For other cases, such as typical text apps that
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only use a few colors, its more desirable to respect the themes that
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the user has established.)
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## Performance
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Reasonable attempts have been made to minimize sending data to terminals,
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avoiding repeated sequences or drawing the same cell on refresh updates.
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## Terminfo
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(Not relevant for Windows users.)
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The Terminfo implementation operates with a built-in database.
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This should satisfy most users. However, it can also (on systems
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with ncurses installed), dynamically parse the output from `infocmp`
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for terminals it does not already know about.
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See the `terminfo/` directory for more information about generating
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new entries for the built-in database.
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_Tcell_ requires that the terminal support the `cup` mode of cursor addressing.
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Ancient terminals without the ability to position the cursor directly
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are not supported.
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This is unlikely to be a problem; such terminals have not been mass-produced
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since the early 1970s.
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## Mouse Support
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Mouse support is detected via the `kmous` terminfo variable, however,
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enablement/disablement and decoding mouse events is done using hard coded
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sequences based on the XTerm X11 model. All popular
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terminals with mouse tracking support this model. (Full terminfo support
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is not possible as terminfo sequences are not defined.)
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On Windows, the mouse works normally.
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Mouse wheel buttons on various terminals are known to work, but the support
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in terminal emulators, as well as support for various buttons and
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live mouse tracking, varies widely.
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Modern _xterm_, macOS _Terminal_, and _iTerm_ all work well.
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## Bracketed Paste
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Terminals that appear to support the XTerm mouse model also can support
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bracketed paste, for applications that opt-in. See `EnablePaste()` for details.
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## Testability
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There is a `SimulationScreen`, that can be used to simulate a real screen
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for automated testing. The supplied tests do this. The simulation contains
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event delivery, screen resizing support, and capabilities to inject events
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and examine "`physical`" screen contents.
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## Platforms
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### POSIX (Linux, FreeBSD, macOS, Solaris, etc.)
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Everything works using pure Go on mainstream platforms. Some more esoteric
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platforms (e.g., AIX) may need to be added. Pull requests are welcome!
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### Windows
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Windows console mode applications are supported.
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Modern console applications like ConEmu and the Windows 10 terminal,
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support all the good features (resize, mouse tracking, etc.)
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### WASM
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WASM is supported, but needs additional setup detailed in [README-wasm](README-wasm.md).
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### Plan9 and others
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These platforms won't work, but compilation stubs are supplied
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for folks that want to include parts of this in software for those
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platforms. The Simulation screen works, but as _Tcell_ doesn't know how to
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allocate a real screen object on those platforms, `NewScreen()` will fail.
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If anyone has wisdom about how to improve support for these,
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please let me know. PRs are especially welcome.
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### Commercial Support
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_Tcell_ is absolutely free, but if you want to obtain commercial, professional support, there are options.
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- [TideLift](https://tidelift.com/) subscriptions include support for _Tcell_, as well as many other open source packages.
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- [Staysail Systems Inc.](mailto:info@staysail.tech) offers direct support, and custom development around _Tcell_ on an hourly basis.
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