255 lines
12 KiB
Markdown
255 lines
12 KiB
Markdown
## tcell <img src=tcell.png align=right>
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This is a fork of [tcell](https://github.com/gdamore/tcell) with the patches from [zyedidia](https://github.com/zyedidia/tcell).
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[](https://travis-ci.org/gdamore/tcell)
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[](https://ci.appveyor.com/project/gdamore/tcell)
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[](https://github.com/gdamore/tcell/blob/master/LICENSE)
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[](https://gitter.im/gdamore/tcell)
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[](https://godoc.org/github.com/gdamore/tcell)
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[](http://goreportcard.com/report/gdamore/tcell)
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[](https://codecov.io/gh/gdamore/tcell)
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Package tcell provides a cell based view for text terminals, like xterm.
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It was inspired by termbox, but differs from termbox in some important
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ways. It also adds substantial functionality beyond termbox.
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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 - [screenshot](http://2.bp.blogspot.com/-fWvW5opT0es/VhIdItdKqJI/AAAAAAAAATE/7Ojc0L1SpB0/s1600/Screen%2BShot%2B2015-10-04%2Bat%2B11.47.13%2BPM.png) - included mouse test
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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) - simple golang utility helping to discover large files/folders.
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* [tview](https://github.com/rivo/tview) - rich interactive widgets for terminal UIs
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* [tui-go](https://github.com/marcusolsson/tui-go) - UI library for terminal apps
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* [gomandelbrot](https://github.com/rgm3/gomandelbrot) - Mandelbrot!
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## Pure Go Terminfo Database
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First, it 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 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 wider variety of systems. Tcell is believed
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to work with all of the systems officially supported by golang with
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the exception of nacl (which lacks any kind of a terminal interface).
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(Plan9 is not supported by Tcell, but it is experimental status only
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in golang.) For all of these systems *except Solaris/illumos*, Tcell
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is pure Go, with no need for CGO.
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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
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objects and Go routines. This means it should be safe, especially for
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use with programs that use exec, or otherwise need to manipulate the
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tty streams. This model is also much closer to idiomatic Go, leading
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to fewer surprises.
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## Richer 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. 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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We try hard to convert to native characters on both input and output, and
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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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It 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
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entries, so that 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 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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Tcell maps 16 colors down to 8, for terminals that need it. (The upper
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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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## Termbox Compatibility
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A compatibility layer for termbox is provided in the compat
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directory. To use it, try importing "maunium.net/go/tcell/termbox"
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instead. Most termbox-go programs will probably work without further
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modification.
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## Working With Unicode
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Internally Tcell uses UTF-8, just like Go. 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. Your application must supply
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them, as the full set of the most common ones bloats the program by about
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2MB. If you're lazy, and want them all anyway, see the encoding
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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
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runes. 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, but 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 wide character
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is displayed, and the other character is not; do not depend on that behavior.)
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Experience has shown that the vanilla Windows 8 console application does not
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support any of these characters properly, but at least some options like
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ConEmu do support Wide characters at least.
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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 let me
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know; it wouldn't be hard to add that if there is need.
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## 24-bit Color
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Tcell _supports true color_! (That is, if your terminal can support it,
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Tcell can accurately display 24-bit color.)
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To use 24-bit color, you need to use a terminal that supports it. Modern
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xterm and similar teminal emulators can support this. As terminfo lacks any
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way to describe this capability, we fabricate the capability for
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terminals with names ending in *-truecolor. The stock distribution ships
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with a database that defines xterm-truecolor. To try it out, set your
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TERM variable to xterm-truecolor.
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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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If you find this undesirable, you can either use a TERM variable
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that lacks the TRUECOLOR setting, or set TCELL_TRUECOLOR=disable in your
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environment.
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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 relevent for Windows users.)
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The Terminfo implementation operates with two forms of database. The first
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is the built-in go database, which contains a number of real database entries
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that are compiled into the program directly. This should minimize calling
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out to database file searches.
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The second is in the form of JSON files, that contain the same information,
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which can be located either by the $TCELLDB environment file, $HOME/.tcelldb,
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or is located in the Go source directory as database.json.
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These files (both the Go and the JSON files) can be generated using the
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mkinfo.go program. If you need to regnerate the entire set for some reason,
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run the mkdatabase.sh file. The generation uses the infocmp(1) program on
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the system to collect the necessary information.
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The mkinfo.go program can also be used to generate specific database entries
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for named terminals, in case your favorite terminal is missing. (If you
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find that this is the case, please let me know and I'll try to add it!)
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Tcell requires that the terminal support the 'cup' mode of cursor addressing.
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Terminals without absolute cursor addressability 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. As of this writing 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. As a particular datum, MacOS X Terminal
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does not support Mouse events at all (as of MacOS 10.10, aka Yosemite.) The
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excellent iTerm application is fully supported, as is vanilla XTerm.
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Mouse tracking with live tracking also varies widely. Current XTerm
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implementations, as well as current Screen and iTerm2, and Windows
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consoles, all support this quite nicely. On other platforms you might
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find that only mouse click and release events are reported, with
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no intervening motion events. It really depends on your terminal.
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## Testablity
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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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For mainstream systems with a suitably well defined system call interface
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to tty settings, everything works using pure Go.
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For the remainder (right now means only Solaris/illumos) we use POSIX function
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calls to manage termios, which implies that CGO is required on those platforms.
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### Windows
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Windows console mode applications are supported. Unfortunately mintty
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and other cygwin style applications are not supported.
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Modern console applications like ConEmu, as well as the Windows 10
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console itself, support all the good features (resize, mouse tracking, etc.)
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I haven't figured out how to cleanly resolve the dichotomy between cygwin
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style termios and the Windows Console API; it seems that perhaps nobody else
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has either. If anyone has suggestions, let me know! Really, if you're
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using a Windows application, you should use the native Windows console or a
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fully compatible console implementation.
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### Plan9 and Native Client (Nacl)
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The nacl and plan9 platforms won't work, but compilation stubs are supplied
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for folks that want to include parts of this in software targetting 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 either of these,
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please let me know. PRs are especially welcome.
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### Commercial Support
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This software is absolutely free, but if you want to obtain commercial
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support (giving prioritized access to the developer, etc. on an hourly
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rate), please drop a line to info@staysail.tech
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I also welcome donations at Patreon, if you just want to feel good about
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defraying development costs: https://www.patreon.com/gedamore
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