color

package
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 Go to latest Published: Mar 3, 2016 License: GPL-3.0, MIT Imports: 6 Imported by: 0

README

Color GoDoc Build Status

Color lets you use colorized outputs in terms of ANSI Escape Codes in Go (Golang). It has support for Windows too! The API can be used in several ways, pick one that suits you.

Color

Install

go get github.com/fatih/color

Examples

Standard colors
// Print with default helper functions
color.Cyan("Prints text in cyan.")

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

// These are using the default foreground colors
color.Red("We have red")
color.Magenta("And many others ..")
Mix and reuse colors
// 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.")
Custom print functions (PrintFunc)
// Create a custom print function for convenience
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...")
Insert into noncolor strings (SprintFunc)
// Create SprintXxx functions to mix strings with other non-colorized strings:
yellow := color.New(color.FgYellow).SprintFunc()
red := color.New(color.FgRed).SprintFunc()
fmt.Printf("This is a %s and this is %s.\n", yellow("warning"), red("error"))

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

// Use helper functions
fmt.Printf("This", color.RedString("warning"), "should be not neglected.")
fmt.Printf(color.GreenString("Info:"), "an important message." )

// Windows supported too! Just don't forget to change the output to color.Output
fmt.Fprintf(color.Output, "Windows support: %s", color.GreenString("PASS"))
Plug into existing code
// Use handy standard colors
color.Set(color.FgYellow)

fmt.Println("Existing text will now be 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 now be bold magenta.")
Disable color

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...")

Todo

  • Save/Return previous values
  • Evaluate fmt.Formatter interface

Credits

License

The MIT License (MIT) - see LICENSE.md for more details

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 ..")

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.")

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...")

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 works 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 = !isatty.IsTerminal(os.Stdout.Fd())

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.

View Source 
var Output = ansicolor.NewAnsiColorWriter(os.Stdout)

Output defines the standard output of the print functions. By default os.Stdout is used.

Functions

func Black 

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

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

func Blue 

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

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

func Cyan 

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

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

func Green 

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

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

func Magenta 

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

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

func Red 

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

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

func Yellow 

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

Yellow is an 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 an 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 (
	BgBlack Attribute = iota + 40
	BgRed
	BgGreen
	BgYellow
	BgBlue
	BgMagenta
	BgCyan
	BgWhite
)

Background 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 conjuction with DisableColor(). Otherwise this method has no side effects.

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) 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 conjuction with color.Output, example: 

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

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 conjuction with color.Output.

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 conjuction with color.Output.

Source Files

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