color

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 Go to latest Published: Apr 1, 2021 License: Apache-2.0 Imports: 8 Imported by: 0

Documentation

Overview

Package color is an ANSI color package to output colorized or SGR defined output to the standard output. The API can be used in several way, pick one that suits you.

Use simple and default helper functions with predefined foreground colors: 

color.Cyan("Prints text in cyan.")

// a newline will be appended automatically
color.Blue("Prints %s in blue.", "text")

// More default foreground colors..
color.Red("We have red")
color.Yellow("Yellow color too!")
color.Magenta("And many others ..")

// Hi-intensity colors
color.HiGreen("Bright green color.")
color.HiBlack("Bright black means gray..")
color.HiWhite("Shiny white color!")

However there are times where custom color mixes are required. Below are some examples to create custom color objects and use the print functions of each separate color object. 

// Create a new color object
c := color.New(color.FgCyan).Add(color.Underline)
c.Println("Prints cyan text with an underline.")

// Or just add them to New()
d := color.New(color.FgCyan, color.Bold)
d.Printf("This prints bold cyan %s\n", "too!.")

// Mix up foreground and background colors, create new mixes!
red := color.New(color.FgRed)

boldRed := red.Add(color.Bold)
boldRed.Println("This will print text in bold red.")

whiteBackground := red.Add(color.BgWhite)
whiteBackground.Println("Red text with White background.")

// Use your own io.Writer output
color.New(color.FgBlue).Fprintln(myWriter, "blue color!")

blue := color.New(color.FgBlue)
blue.Fprint(myWriter, "This will print text in blue.")

You can create PrintXxx functions to simplify even more: 

// Create a custom print function for convenient
red := color.New(color.FgRed).PrintfFunc()
red("warning")
red("error: %s", err)

// Mix up multiple attributes
notice := color.New(color.Bold, color.FgGreen).PrintlnFunc()
notice("don't forget this...")

You can also FprintXxx functions to pass your own io.Writer: 

blue := color.New(FgBlue).FprintfFunc()
blue(myWriter, "important notice: %s", stars)

// Mix up with multiple attributes
success := color.New(color.Bold, color.FgGreen).FprintlnFunc()
success(myWriter, don't forget this...")

Or create SprintXxx functions to mix strings with other non-colorized strings: 

yellow := New(FgYellow).SprintFunc()
red := New(FgRed).SprintFunc()

fmt.Printf("this is a %s and this is %s.\n", yellow("warning"), red("error"))

info := New(FgWhite, BgGreen).SprintFunc()
fmt.Printf("this %s rocks!\n", info("package"))

Windows support is enabled by default. All Print functions work as intended. However only for color.SprintXXX functions, user should use fmt.FprintXXX and set the output to color.Output: 

fmt.Fprintf(color.Output, "Windows support: %s", color.GreenString("PASS"))

info := New(FgWhite, BgGreen).SprintFunc()
fmt.Fprintf(color.Output, "this %s rocks!\n", info("package"))

Using with existing code is possible. Just use the Set() method to set the standard output to the given parameters. That way a rewrite of an existing code is not required. 

// Use handy standard colors.
color.Set(color.FgYellow)

fmt.Println("Existing text will be now in Yellow")
fmt.Printf("This one %s\n", "too")

color.Unset() // don't forget to unset

// You can mix up parameters
color.Set(color.FgMagenta, color.Bold)
defer color.Unset() // use it in your function

fmt.Println("All text will be now bold magenta.")

There might be a case where you want to disable color output (for example to pipe the standard output of your app to somewhere else). `Color` has support to disable colors both globally and for single color definition. For example suppose you have a CLI app and a `--no-color` bool flag. You can easily disable the color output with: 

var flagNoColor = flag.Bool("no-color", false, "Disable color output")

if *flagNoColor {
	color.NoColor = true // disables colorized output
}

It also has support for single color definitions (local). You can disable/enable color output on the fly: 

c := color.New(color.FgCyan)
c.Println("Prints cyan text")

c.DisableColor()
c.Println("This is printed without any color")

c.EnableColor()
c.Println("This prints again cyan...")

Index

Constants

This section is empty.

Variables

View Source 
var (
	// NoColor defines if the output is colorized or not. It's dynamically set to
	// false or true based on the stdout's file descriptor referring to a terminal
	// or not. This is a global option and affects all colors. For more control
	// over each color block use the methods DisableColor() individually.
	NoColor = os.Getenv("TERM") == "dumb" ||
		(!isatty.IsTerminal(os.Stdout.Fd()) && !isatty.IsCygwinTerminal(os.Stdout.Fd()))

	// Output defines the standard output of the print functions. By default
	// os.Stdout is used.
	Output = colorable.NewColorableStdout()

	// Error defines a color supporting writer for os.Stderr.
	Error = colorable.NewColorableStderr()
)

Functions

func Black 

func Black(format string, a ...interface{})

Black is a convenient helper function to print with black foreground. A newline is appended to format by default.

func BlackString 

func BlackString(format string, a ...interface{}) string

BlackString is a convenient helper function to return a string with black foreground.

func Blue 

func Blue(format string, a ...interface{})

Blue is a convenient helper function to print with blue foreground. A newline is appended to format by default.

func BlueString 

func BlueString(format string, a ...interface{}) string

BlueString is a convenient helper function to return a string with blue foreground.

func Cyan 

func Cyan(format string, a ...interface{})

Cyan is a convenient helper function to print with cyan foreground. A newline is appended to format by default.

func CyanString 

func CyanString(format string, a ...interface{}) string

CyanString is a convenient helper function to return a string with cyan foreground.

func Green 

func Green(format string, a ...interface{})

Green is a convenient helper function to print with green foreground. A newline is appended to format by default.

func GreenString 

func GreenString(format string, a ...interface{}) string

GreenString is a convenient helper function to return a string with green foreground.

func HiBlack 

func HiBlack(format string, a ...interface{})

HiBlack is a convenient helper function to print with hi-intensity black foreground. A newline is appended to format by default.

func HiBlackString 

func HiBlackString(format string, a ...interface{}) string

HiBlackString is a convenient helper function to return a string with hi-intensity black foreground.

func HiBlue 

func HiBlue(format string, a ...interface{})

HiBlue is a convenient helper function to print with hi-intensity blue foreground. A newline is appended to format by default.

func HiBlueString 

func HiBlueString(format string, a ...interface{}) string

HiBlueString is a convenient helper function to return a string with hi-intensity blue foreground.

func HiCyan 

func HiCyan(format string, a ...interface{})

HiCyan is a convenient helper function to print with hi-intensity cyan foreground. A newline is appended to format by default.

func HiCyanString 

func HiCyanString(format string, a ...interface{}) string

HiCyanString is a convenient helper function to return a string with hi-intensity cyan foreground.

func HiGreen 

func HiGreen(format string, a ...interface{})

HiGreen is a convenient helper function to print with hi-intensity green foreground. A newline is appended to format by default.

func HiGreenString 

func HiGreenString(format string, a ...interface{}) string

HiGreenString is a convenient helper function to return a string with hi-intensity green foreground.

func HiMagenta 

func HiMagenta(format string, a ...interface{})

HiMagenta is a convenient helper function to print with hi-intensity magenta foreground. A newline is appended to format by default.

func HiMagentaString 

func HiMagentaString(format string, a ...interface{}) string

HiMagentaString is a convenient helper function to return a string with hi-intensity magenta foreground.

func HiRed 

func HiRed(format string, a ...interface{})

HiRed is a convenient helper function to print with hi-intensity red foreground. A newline is appended to format by default.

func HiRedString 

func HiRedString(format string, a ...interface{}) string

HiRedString is a convenient helper function to return a string with hi-intensity red foreground.

func HiWhite 

func HiWhite(format string, a ...interface{})

HiWhite is a convenient helper function to print with hi-intensity white foreground. A newline is appended to format by default.

func HiWhiteString 

func HiWhiteString(format string, a ...interface{}) string

HiWhiteString is a convenient helper function to return a string with hi-intensity white foreground.

func HiYellow 

func HiYellow(format string, a ...interface{})

HiYellow is a convenient helper function to print with hi-intensity yellow foreground. A newline is appended to format by default.

func HiYellowString 

func HiYellowString(format string, a ...interface{}) string

HiYellowString is a convenient helper function to return a string with hi-intensity yellow foreground.

func Magenta 

func Magenta(format string, a ...interface{})

Magenta is a convenient helper function to print with magenta foreground. A newline is appended to format by default.

func MagentaString 

func MagentaString(format string, a ...interface{}) string

MagentaString is a convenient helper function to return a string with magenta foreground.

func Red 

func Red(format string, a ...interface{})

Red is a convenient helper function to print with red foreground. A newline is appended to format by default.

func RedString 

func RedString(format string, a ...interface{}) string

RedString is a convenient helper function to return a string with red foreground.

func Unset 

func Unset()

Unset resets all escape attributes and clears the output. Usually should be called after Set().

func White 

func White(format string, a ...interface{})

White is a convenient helper function to print with white foreground. A newline is appended to format by default.

func WhiteString 

func WhiteString(format string, a ...interface{}) string

WhiteString is a convenient helper function to return a string with white foreground.

func Yellow 

func Yellow(format string, a ...interface{})

Yellow is a convenient helper function to print with yellow foreground. A newline is appended to format by default.

func YellowString 

func YellowString(format string, a ...interface{}) string

YellowString is a convenient helper function to return a string with yellow foreground.

Types

type Attribute 

type Attribute int

Attribute defines a single SGR Code 

const (
	Reset Attribute = iota
	Bold
	Faint
	Italic
	Underline
	BlinkSlow
	BlinkRapid
	ReverseVideo
	Concealed
	CrossedOut
)

Base attributes 

const (
	FgBlack Attribute = iota + 30
	FgRed
	FgGreen
	FgYellow
	FgBlue
	FgMagenta
	FgCyan
	FgWhite
)

Foreground text colors 

const (
	FgHiBlack Attribute = iota + 90
	FgHiRed
	FgHiGreen
	FgHiYellow
	FgHiBlue
	FgHiMagenta
	FgHiCyan
	FgHiWhite
)

Foreground Hi-Intensity text colors 

const (
	BgBlack Attribute = iota + 40
	BgRed
	BgGreen
	BgYellow
	BgBlue
	BgMagenta
	BgCyan
	BgWhite
)

Background text colors 

const (
	BgHiBlack Attribute = iota + 100
	BgHiRed
	BgHiGreen
	BgHiYellow
	BgHiBlue
	BgHiMagenta
	BgHiCyan
	BgHiWhite
)

Background Hi-Intensity text colors

type Color 

type Color struct {
	// contains filtered or unexported fields
}

Color defines a custom color object which is defined by SGR parameters.

func New 

func New(value ...Attribute) *Color

New returns a newly created color object.

func Set 

func Set(p ...Attribute) *Color

Set sets the given parameters immediately. It will change the color of output with the given SGR parameters until color.Unset() is called.

func (*Color) Add 

func (c *Color) Add(value ...Attribute) *Color

Add is used to chain SGR parameters. Use as many as parameters to combine and create custom color objects. Example: Add(color.FgRed, color.Underline).

func (*Color) DisableColor 

func (c *Color) DisableColor()

DisableColor disables the color output. Useful to not change any existing code and still being able to output. Can be used for flags like "--no-color". To enable back use EnableColor() method.

func (*Color) EnableColor 

func (c *Color) EnableColor()

EnableColor enables the color output. Use it in conjunction with DisableColor(). Otherwise this method has no side effects.

func (*Color) Equals 

func (c *Color) Equals(c2 *Color) bool

Equals returns a boolean value indicating whether two colors are equal.

func (*Color) Fprint 

func (c *Color) Fprint(w io.Writer, a ...interface{}) (n int, err error)

Fprint formats using the default formats for its operands and writes to w. Spaces are added between operands when neither is a string. It returns the number of bytes written and any write error encountered. On Windows, users should wrap w with colorable.NewColorable() if w is of type *os.File.

func (*Color) FprintFunc 

func (c *Color) FprintFunc() func(w io.Writer, a ...interface{})

FprintFunc returns a new function that prints the passed arguments as colorized with color.Fprint().

func (*Color) Fprintf 

func (c *Color) Fprintf(w io.Writer, format string, a ...interface{}) (n int, err error)

Fprintf formats according to a format specifier and writes to w. It returns the number of bytes written and any write error encountered. On Windows, users should wrap w with colorable.NewColorable() if w is of type *os.File.

func (*Color) FprintfFunc 

func (c *Color) FprintfFunc() func(w io.Writer, format string, a ...interface{})

FprintfFunc returns a new function that prints the passed arguments as colorized with color.Fprintf().

func (*Color) Fprintln 

func (c *Color) Fprintln(w io.Writer, a ...interface{}) (n int, err error)

Fprintln formats using the default formats for its operands and writes to w. Spaces are always added between operands and a newline is appended. On Windows, users should wrap w with colorable.NewColorable() if w is of type *os.File.

func (*Color) FprintlnFunc 

func (c *Color) FprintlnFunc() func(w io.Writer, a ...interface{})

FprintlnFunc returns a new function that prints the passed arguments as colorized with color.Fprintln().

func (*Color) Print 

func (c *Color) Print(a ...interface{}) (n int, err error)

Print formats using the default formats for its operands and writes to standard output. Spaces are added between operands when neither is a string. It returns the number of bytes written and any write error encountered. This is the standard fmt.Print() method wrapped with the given color.

func (*Color) PrintFunc 

func (c *Color) PrintFunc() func(a ...interface{})

PrintFunc returns a new function that prints the passed arguments as colorized with color.Print().

func (*Color) Printf 

func (c *Color) Printf(format string, a ...interface{}) (n int, err error)

Printf formats according to a format specifier and writes to standard output. It returns the number of bytes written and any write error encountered. This is the standard fmt.Printf() method wrapped with the given color.

func (*Color) PrintfFunc 

func (c *Color) PrintfFunc() func(format string, a ...interface{})

PrintfFunc returns a new function that prints the passed arguments as colorized with color.Printf().

func (*Color) Println 

func (c *Color) Println(a ...interface{}) (n int, err error)

Println formats using the default formats for its operands and writes to standard output. Spaces are always added between operands and a newline is appended. It returns the number of bytes written and any write error encountered. This is the standard fmt.Print() method wrapped with the given color.

func (*Color) PrintlnFunc 

func (c *Color) PrintlnFunc() func(a ...interface{})

PrintlnFunc returns a new function that prints the passed arguments as colorized with color.Println().

func (*Color) Set 

func (c *Color) Set() *Color

Set sets the SGR sequence.

func (*Color) Sprint 

func (c *Color) Sprint(a ...interface{}) string

Sprint is just like Print, but returns a string instead of printing it.

func (*Color) SprintFunc 

func (c *Color) SprintFunc() func(a ...interface{}) string

SprintFunc returns a new function that returns colorized strings for the given arguments with fmt.Sprint(). Useful to put into or mix into other string. Windows users should use this in conjunction with color.Output, example: 

put := New(FgYellow).SprintFunc()
fmt.Fprintf(color.Output, "This is a %s", put("warning"))

func (*Color) Sprintf 

func (c *Color) Sprintf(format string, a ...interface{}) string

Sprintf is just like Printf, but returns a string instead of printing it.

func (*Color) SprintfFunc 

func (c *Color) SprintfFunc() func(format string, a ...interface{}) string

SprintfFunc returns a new function that returns colorized strings for the given arguments with fmt.Sprintf(). Useful to put into or mix into other string. Windows users should use this in conjunction with color.Output.

func (*Color) Sprintln 

func (c *Color) Sprintln(a ...interface{}) string

Sprintln is just like Println, but returns a string instead of printing it.

func (*Color) SprintlnFunc 

func (c *Color) SprintlnFunc() func(a ...interface{}) string

SprintlnFunc returns a new function that returns colorized strings for the given arguments with fmt.Sprintln(). Useful to put into or mix into other string. Windows users should use this in conjunction with color.Output.

Source Files

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