`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`. ## Screen ```go // Reset the terminal to its default style, removing any active styles termenv.Reset() // 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() // Move the cursor to a given position termenv.MoveCursor(row, column) // Hide the cursor termenv.HideCursor() // Show the cursor termenv.ShowCursor() // 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) // 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) ``` ## 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() ``` ## 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)