std/terminal

Source Edit

This module contains a few procedures to control the terminal (also called console). On UNIX, the implementation simply uses ANSI escape sequences and does not depend on any other module, on Windows it uses the Windows API. Changing the style is permanent even after program termination! Use the code exitprocs.addExitProc(resetAttributes) to restore the defaults. Similarly, if you hide the cursor, make sure to unhide it with showCursor before quitting.

Progress bar

Basic progress bar example:

Example: cmd: -r:off

import std/terminal
import std/[os, strutils]

for i in 0..100:
  stdout.styledWriteLine(fgRed, "0% ", fgWhite, '#'.repeat i, if i > 50: fgGreen else: fgYellow, "\t", $i , "%")
  sleep 42
  cursorUp 1
  eraseLine()

stdout.resetAttributes()

Playing with colorful and styled text

Procs like styledWriteLine, styledEcho etc. have a temporary effect on text parameters. Style parameters only affect the text parameter right after them. After being called, these procs will reset the default style of the terminal. While setBackGroundColor, setForeGroundColor etc. have a lasting influence on the terminal, you can use resetAttributes to reset the default style of the terminal.

Example: cmd: -r:off

import std/terminal
stdout.styledWriteLine({styleBright, styleBlink, styleUnderscore}, "styled text ")
stdout.styledWriteLine(fgRed, "red text ")
stdout.styledWriteLine(fgWhite, bgRed, "white text in red background")
stdout.styledWriteLine(" ordinary text without style ")

stdout.setBackGroundColor(bgCyan, true)
stdout.setForeGroundColor(fgBlue)
stdout.write("blue text in cyan background")
stdout.resetAttributes()

# You can specify multiple text parameters. Style parameters
# only affect the text parameter right after them.
styledEcho styleBright, fgGreen, "[PASS]", resetStyle, fgGreen, " Yay!"

stdout.styledWriteLine(fgRed, "red text ", styleBright, "bold red", fgDefault, " bold text")

Imports

macros, strformat, strutils, colors, winlean, winlean, os, os

Types

BackgroundColor = enum
  bgBlack = 40,             ## black
  bgRed,                    ## red
  bgGreen,                  ## green
  bgYellow,                 ## yellow
  bgBlue,                   ## blue
  bgMagenta,                ## magenta
  bgCyan,                   ## cyan
  bgWhite,                  ## white
  bg8Bit,                   ## 256-color (not supported, see `enableTrueColors` instead.)
  bgDefault                  ## default terminal background color

Terminal's background colors. Source Edit

ForegroundColor = enum
  fgBlack = 30,             ## black
  fgRed,                    ## red
  fgGreen,                  ## green
  fgYellow,                 ## yellow
  fgBlue,                   ## blue
  fgMagenta,                ## magenta
  fgCyan,                   ## cyan
  fgWhite,                  ## white
  fg8Bit,                   ## 256-color (not supported, see `enableTrueColors` instead.)
  fgDefault                  ## default terminal foreground color

Terminal's foreground colors. Source Edit

Style = enum
  styleBright = 1,          ## bright text
  styleDim,                 ## dim text
  styleItalic,              ## italic (or reverse on terminals not supporting)
  styleUnderscore,          ## underscored text
  styleBlink,               ## blinking/bold text
  styleBlinkRapid,          ## rapid blinking/bold text (not widely supported)
  styleReverse,             ## reverse
  styleHidden,              ## hidden text
  styleStrikethrough         ## strikethrough

Different styles for text output. Source Edit

TerminalCmd = enum
  resetStyle,               ## reset attributes
  fgColor,                  ## set foreground's true color
  bgColor                    ## set background's true color

commands that can be expressed as arguments Source Edit

Consts

ansiResetCode = "\e[0m"

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Procs

proc ansiBackgroundColorCode(color: Color): string {....raises: [ValueError],
    tags: [], forbids: [].}

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proc ansiForegroundColorCode(color: Color): string {....raises: [ValueError],
    tags: [], forbids: [].}

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proc ansiForegroundColorCode(fg: ForegroundColor; bright = false): string {.
    ...raises: [ValueError], tags: [], forbids: [].}

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proc ansiStyleCode(style: int): string {....raises: [ValueError], tags: [],
    forbids: [].}

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proc cursorBackward(f: File; count = 1) {....raises: [OSError], tags: [RootEffect],
    forbids: [].}

Moves the cursor backward by count columns.

Example: cmd: -r:off

stdout.cursorBackward(2)
write(stdout, "Hello World!") # anything written at that location will be erased/replaced with this

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proc cursorDown(f: File; count = 1) {....raises: [OSError], tags: [RootEffect],
                                      forbids: [].}

Moves the cursor down by count rows.

Example: cmd: -r:off

stdout.cursorDown(2)
write(stdout, "Hello World!") # anything written at that location will be erased/replaced with this

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proc cursorForward(f: File; count = 1) {....raises: [OSError], tags: [RootEffect],
    forbids: [].}

Moves the cursor forward by count columns.

Example: cmd: -r:off

stdout.cursorForward(2)
write(stdout, "Hello World!") # anything written at that location will be erased/replaced with this

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proc cursorUp(f: File; count = 1) {....raises: [OSError], tags: [RootEffect],
                                    forbids: [].}

Moves the cursor up by count rows.

Example: cmd: -r:off

stdout.cursorUp(2)
write(stdout, "Hello World!") # anything written at that location will be erased/replaced with this

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proc disableTrueColors() {....raises: [], tags: [RootEffect, ReadEnvEffect],
                           forbids: [].}

Disables true color. Source Edit

proc enableTrueColors() {....raises: [], tags: [RootEffect, ReadEnvEffect],
                          forbids: [].}

Enables true color. Source Edit

proc eraseLine(f: File) {....raises: [OSError], tags: [RootEffect], forbids: [].}

Erases the entire current line.

Example: cmd: -r:off

write(stdout, "never mind")
stdout.eraseLine() # nothing will be printed on the screen

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proc eraseScreen(f: File) {....raises: [OSError], tags: [RootEffect], forbids: [].}

Erases the screen with the background colour and moves the cursor to home. Source Edit

proc getch(): char {....raises: [], tags: [], forbids: [].}

Reads a single character from the terminal, blocking until it is entered. The character is not printed to the terminal. Source Edit

proc hideCursor(f: File) {....raises: [OSError], tags: [RootEffect], forbids: [].}

Hides the cursor. Source Edit

proc isatty(f: File): bool {....raises: [], tags: [], forbids: [].}

Returns true if f is associated with a terminal device. Source Edit

proc isTrueColorSupported(): bool {....raises: [], tags: [RootEffect], forbids: [].}

Returns true if a terminal supports true color. Source Edit

proc readPasswordFromStdin(prompt = "password: "): string {....raises: [IOError],
    tags: [ReadIOEffect, WriteIOEffect], forbids: [].}

Reads a password from stdin without printing it. Source Edit

proc readPasswordFromStdin(prompt: string; password: var string): bool {.
    ...tags: [ReadIOEffect, WriteIOEffect], raises: [IOError], forbids: [].}

Reads a password from stdin without printing it. password must not be nil! Returns false if the end of the file has been reached, true otherwise. Source Edit

proc resetAttributes() {.noconv, ...raises: [], tags: [RootEffect], forbids: [].}

Resets all attributes on stdout. It is advisable to register this as a quit proc with exitprocs.addExitProc(resetAttributes). Source Edit

proc resetAttributes(f: File) {....raises: [], tags: [RootEffect], forbids: [].}

Resets all attributes. Source Edit

proc setBackgroundColor(f: File; bg: BackgroundColor; bright = false) {.
    ...raises: [], tags: [RootEffect], forbids: [].}

Sets the terminal's background color. Source Edit

proc setBackgroundColor(f: File; color: Color) {....raises: [IOError, ValueError],
    tags: [RootEffect, WriteIOEffect], forbids: [].}

Sets the terminal's background true color. Source Edit

proc setCursorPos(f: File; x, y: int) {....raises: [OSError], tags: [RootEffect],
                                        forbids: [].}

Sets the terminal's cursor to the (x,y) position. (0,0) is the upper left of the screen. Source Edit

proc setCursorXPos(f: File; x: int) {....raises: [OSError], tags: [RootEffect],
                                      forbids: [].}

Sets the terminal's cursor to the x position. The y position is not changed. Source Edit

proc setCursorYPos(f: File; y: int) {....raises: [OSError], tags: [RootEffect],
                                      forbids: [].}

Sets the terminal's cursor to the y position. The x position is not changed. .. warning:: This is not supported on UNIX! Source Edit

proc setForegroundColor(f: File; color: Color) {....raises: [IOError, ValueError],
    tags: [RootEffect, WriteIOEffect], forbids: [].}

Sets the terminal's foreground true color. Source Edit

proc setForegroundColor(f: File; fg: ForegroundColor; bright = false) {.
    ...raises: [], tags: [RootEffect], forbids: [].}

Sets the terminal's foreground color. Source Edit

proc setStyle(f: File; style: set[Style]) {....raises: [], tags: [RootEffect],
    forbids: [].}

Sets the terminal style. Source Edit

proc showCursor(f: File) {....raises: [OSError], tags: [RootEffect], forbids: [].}

Shows the cursor. Source Edit

proc terminalHeight(): int {....raises: [], tags: [], forbids: [].}

Returns the terminal height in rows. Source Edit

proc terminalHeightIoctl(handles: openArray[Handle]): int {....raises: [],
    tags: [], forbids: [].}

Source Edit

proc terminalSize(): tuple[w, h: int] {....raises: [], tags: [], forbids: [].}

Returns the terminal width and height as a tuple. Internally calls terminalWidth and terminalHeight, so the same assumptions apply. Source Edit

proc terminalWidth(): int {....raises: [], tags: [], forbids: [].}

Returns the terminal width in columns. Source Edit

proc terminalWidthIoctl(handles: openArray[Handle]): int {....raises: [], tags: [],
    forbids: [].}

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proc writeStyled(txt: string; style: set[Style] = {styleBright}) {.
    ...raises: [IOError], tags: [RootEffect, WriteIOEffect], forbids: [].}

Writes the text txt in a given style to stdout. Source Edit

Macros

macro styledWrite(f: File; m: varargs[typed]): untyped

Similar to write, but treating terminal style arguments specially. When some argument is Style, set[Style], ForegroundColor, BackgroundColor or TerminalCmd then it is not sent directly to f, but instead corresponding terminal style proc is called.

Example: cmd: -r:off

stdout.styledWrite(fgRed, "red text ")
stdout.styledWrite(fgGreen, "green text")

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Templates

template ansiBackgroundColorCode(color: static[Color]): string

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template ansiForegroundColorCode(color: static[Color]): string

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template ansiForegroundColorCode(fg: static[ForegroundColor];
                                 bright: static[bool] = false): string

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template ansiStyleCode(style: static[Style]): string

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template ansiStyleCode(style: Style): string

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template cursorBackward(count = 1)

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template cursorDown(count = 1)

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template cursorForward(count = 1)

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template cursorUp(count = 1)

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template eraseLine()

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template eraseScreen()

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template hideCursor()

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template setBackgroundColor(bg: BackgroundColor; bright = false)

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template setBackgroundColor(color: Color)

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template setCursorPos(x, y: int)

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template setCursorXPos(x: int)

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template setCursorYPos(x: int)

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template setForegroundColor(color: Color)

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template setForegroundColor(fg: ForegroundColor; bright = false)

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template setStyle(style: set[Style])

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template showCursor()

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template styledEcho(args: varargs[untyped])

Echoes styles arguments to stdout using styledWriteLine. Source Edit

template styledWriteLine(f: File; args: varargs[untyped])

Calls styledWrite and appends a newline at the end.

Example:

proc error(msg: string) =
  styledWriteLine(stderr, fgRed, "Error: ", resetStyle, msg)

Source Edit