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`termenv` lets you safely use advanced styling options on the terminal. It
gathers information about the terminal environment in terms of its ANSI & color
support and offers you convenient methods to colorize and style your output,
without you having to deal with all kinds of weird ANSI escape sequences and
color conversions.
## Features
- RGB/TrueColor support
- Detects the supported color range of your terminal
- Automatically converts colors to the best matching, available colors
- Terminal theme (light/dark) detection
- Chainable syntax
- Nested styles
## Installation
```bash
go get github.com/muesli/termenv
```
## Query Terminal Support
`termenv` can query the terminal it is running in, so you can safely use
advanced features, like RGB colors. `ColorProfile` returns the color profile
supported by the terminal:
```go
profile := termenv.ColorProfile()
```
This returns one of the supported color profiles:
- `termenv.Ascii` - no ANSI support detected, ASCII only
- `termenv.ANSI` - 16 color ANSI support
- `termenv.ANSI256` - Extended 256 color ANSI support
- `termenv.TrueColor` - RGB/TrueColor support
You can also query the terminal for its color scheme, so you know whether your
app is running in a light- or dark-themed environment:
```go
// Returns terminal's foreground color
color := termenv.ForegroundColor()
// Returns terminal's background color
color := termenv.BackgroundColor()
// Returns whether terminal uses a dark-ish background
darkTheme := termenv.HasDarkBackground()
```
## Colors
`termenv` supports multiple color profiles: ANSI (16 colors), ANSI Extended
(256 colors), and TrueColor (24-bit RGB). Colors will automatically be degraded
to the best matching available color in the desired profile:
`TrueColor` => `ANSI 256 Colors` => `ANSI 16 Colors` => `Ascii`
```go
s := termenv.String("Hello World")
// Retrieve color profile supported by terminal
p := termenv.ColorProfile()
// Supports hex values
// Will automatically degrade colors on terminals not supporting RGB
s.Foreground(p.Color("#abcdef"))
// but also supports ANSI colors (0-255)
s.Background(p.Color("69"))
// ...or the color.Color interface
s.Foreground(p.FromColor(color.RGBA{255, 128, 0, 255}))
// Combine fore- & background colors
s.Foreground(p.Color("#ffffff")).Background(p.Color("#0000ff"))
// Supports the fmt.Stringer interface
fmt.Println(s)
```
## Styles
You can use a chainable syntax to compose your own styles:
```go
s := termenv.String("foobar")
// Text styles
s.Bold()
s.Faint()
s.Italic()
s.CrossOut()
s.Underline()
s.Overline()
// Reverse swaps current fore- & background colors
s.Reverse()
// Blinking text
s.Blink()
// Combine multiple options
s.Bold().Underline()
```
## Template Helpers
```go
// load template helpers
f := termenv.TemplateFuncs(termenv.ColorProfile())
tpl := template.New("tpl").Funcs(f)
// apply bold style in a template
bold := `{{ Bold "Hello World" }}`
// examples for colorized templates
col := `{{ Color "#ff0000" "#0000ff" "Red on Blue" }}`
fg := `{{ Foreground "#ff0000" "Red Foreground" }}`
bg := `{{ Background "#0000ff" "Blue Background" }}`
// wrap styles
wrap := `{{ Bold (Underline "Hello World") }}`
// parse and render
tpl, err = tpl.Parse(bold)
var buf bytes.Buffer
tpl.Execute(&buf, nil)
fmt.Println(&buf)
```
Other available helper functions are: `Faint`, `Italic`, `CrossOut`,
`Underline`, `Overline`, `Reverse`, and `Blink`.
## Positioning
```go
// Move the cursor to a given position
termenv.MoveCursor(row, column)
// Save the cursor position
termenv.SaveCursorPosition()
// Restore a saved cursor position
termenv.RestoreCursorPosition()
// Move the cursor up a given number of lines
termenv.CursorUp(n)
// Move the cursor down a given number of lines
termenv.CursorDown(n)
// Move the cursor up a given number of lines
termenv.CursorForward(n)
// Move the cursor backwards a given number of cells
termenv.CursorBack(n)
// Move the cursor down a given number of lines and place it at the beginning
// of the line
termenv.CursorNextLine(n)
// Move the cursor up a given number of lines and place it at the beginning of
// the line
termenv.CursorPrevLine(n)
```
## Screen
```go
// Reset the terminal to its default style, removing any active styles
termenv.Reset()
// RestoreScreen restores a previously saved screen state
termenv.RestoreScreen()
// SaveScreen saves the screen state
termenv.SaveScreen()
// Switch to the altscreen. The former view can be restored with ExitAltScreen()
termenv.AltScreen()
// Exit the altscreen and return to the former terminal view
termenv.ExitAltScreen()
// Clear the visible portion of the terminal
termenv.ClearScreen()
// Clear the current line
termenv.ClearLine()
// Clear a given number of lines
termenv.ClearLines(n)
// Set the scrolling region of the terminal
termenv.ChangeScrollingRegion(top, bottom)
// Insert the given number of lines at the top of the scrollable region, pushing
// lines below down
termenv.InsertLines(n)
// Delete the given number of lines, pulling any lines in the scrollable region
// below up
termenv.DeleteLines(n)
```
## Session
```go
// SetWindowTitle sets the terminal window title
termenv.SetWindowTitle(title)
// SetForegroundColor sets the default foreground color
termenv.SetForegroundColor(color)
// SetBackgroundColor sets the default background color
termenv.SetBackgroundColor(color)
// SetCursorColor sets the cursor color
termenv.SetCursorColor(color)
// Hide the cursor
termenv.HideCursor()
// Show the cursor
termenv.ShowCursor()
```
## Mouse
```go
// Enable X10 mouse mode, only button press events are sent
termenv.EnableMousePress()
// Disable X10 mouse mode
termenv.DisableMousePress()
// Enable Mouse Tracking mode
termenv.EnableMouse()
// Disable Mouse Tracking mode
termenv.DisableMouse()
// Enable Hilite Mouse Tracking mode
termenv.EnableMouseHilite()
// Disable Hilite Mouse Tracking mode
termenv.DisableMouseHilite()
// Enable Cell Motion Mouse Tracking mode
termenv.EnableMouseCellMotion()
// Disable Cell Motion Mouse Tracking mode
termenv.DisableMouseCellMotion()
// Enable All Motion Mouse mode
termenv.EnableMouseAllMotion()
// Disable All Motion Mouse mode
termenv.DisableMouseAllMotion()
```
## Optional Feature Support
| Terminal | Alt Screen | Query Color Scheme | Query Cursor Position | Set Window Title | Change Cursor Color | Change Default Foreground Setting | Change Default Background Setting |
| ---------------- | :--------: | :----------------: | :-------------------: | :--------------: | :-----------------: | :-------------------------------: | :-------------------------------: |
| alacritty | ✅ | ✅ | ✅ | ✅ | ✅ | ✅ | ✅ |
| foot | ✅ | ✅ | ✅ | ✅ | ✅ | ✅ | ✅ |
| kitty | ✅ | ✅ | ✅ | ✅ | ✅ | ✅ | ✅ |
| Konsole | ✅ | ✅ | ✅ | ✅ | ❌ | ✅ | ✅ |
| rxvt | ✅ | ❌ | ✅ | ✅ | ✅ | ✅ | ✅ |
| screen | ✅ | ⛔[^mux] | ✅ | ✅ | ❌ | ❌ | ✅ |
| st | ✅ | ✅ | ✅ | ✅ | ✅ | ✅ | ✅ |
| tmux | ✅ | ⛔[^mux] | ✅ | ✅ | ✅ | ✅ | ✅ |
| vte-based[^vte] | ✅ | ✅ | ✅ | ✅ | ✅ | ✅ | ❌ |
| wezterm | ✅ | ✅ | ✅ | ✅ | ✅ | ✅ | ✅ |
| xterm | ✅ | ✅ | ✅ | ✅ | ❌ | ❌ | ❌ |
| Linux Console | ✅ | ❌ | ✅ | ⛔ | ❌ | ❌ | ❌ |
| Apple Terminal | ✅ | ✅ | ✅ | ✅ | ❌ | ✅ | ✅ |
| iTerm | ✅ | ✅ | ✅ | ✅ | ❌ | ❌ | ❌ |
| Power Shell | ✅ | ❔ | ❔ | ❔ | ❔ | ❔ | ❔ |
| Windows Terminal | ✅ | ❌ | ✅ | ✅ | ✅ | ✅ | ✅ |
[^vte]: This covers all vte-based terminals, including Gnome Terminal, guake, Pantheon Terminal, Terminator, Tilix, XFCE Terminal.
[^mux]: Unavailable as multiplexers (like tmux or screen) can be connected to multiple terminals (with different color settings) at the same time.
You can help improve this list! Check out [how to](ansi_compat.md) and open an issue or pull request.
### Color Support
- 24-bit (RGB): alacritty, foot, iTerm, kitty, Konsole, st, tmux, vte-based, wezterm, Windows Terminal
- 8-bit (256): rxvt, screen, xterm, Apple Terminal
- 4-bit (16): Linux Console
## Platform Support
`termenv` works on Unix systems (like Linux, macOS, or BSD) and Windows. While
terminal applications on Unix support ANSI styling out-of-the-box, on Windows
you need to enable ANSI processing in your application first:
```go
mode, err := termenv.EnableWindowsANSIConsole()
if err != nil {
panic(err)
}
defer termenv.RestoreWindowsConsole(mode)
```
## Color Chart
You can find the source code used to create this chart in `termenv`'s examples.
## Related Projects
- [reflow](https://github.com/muesli/reflow) - ANSI-aware text operations
- [Glow](https://github.com/charmbracelet/glow) - a markdown renderer for
the command-line, which uses `termenv`
## License
[MIT](https://github.com/muesli/termenv/raw/master/LICENSE)
## Feedback
Got some feedback or suggestions? Please open an issue or drop me a note!
* [Twitter](https://twitter.com/mueslix)
* [The Fediverse](https://mastodon.social/@fribbledom)