captcha

README

Captcha

This module provides a simple captcha image generator.

Installation

go get github.com/cyberxnomad/captcha

Usage

example

package main

import (
	"fmt"
	"image/png"
	"os"

	"github.com/cyberxnomad/captcha"
)

func main() {
	c, err := captcha.New(
		// replace with your font file path
		captcha.WithFont("/path/to/font.ttf", 40),
		captcha.WithSize(150, 50),
		captcha.WithLength(4, 6),
		captcha.WithScale(0.8, 1.2),
		captcha.WithRotation(-30, 30),
		captcha.WithDistortion(1.2, 2),
		captcha.WithSpacing(0.7, 0.9),
		captcha.WithNoise(0.05),
		captcha.WithLines(4, 6),
	)
	if err != nil {
		panic(err)
	}

	f, err := os.Create("captcha.png")
	if err != nil {
		panic(err)
	}
	defer f.Close()

	img, code := c.Generate()
	fmt.Println(code)

	err = png.Encode(f, img)
	if err != nil {
		panic(err)
	}
}

output

code: wqufPK

image:

License

This project is licensed under the terms of the MIT license. See LICENSE for more details.

Documentation

Index

• type Captcha
  • func New(opts ...Option) (*Captcha, error)
  • func (c *Captcha) Generate() (image.Image, string)
• type CharSet
• type Option
  • func WithBackground(background color.Color) Option
  • func WithCharSet(charSet CharSet) Option
  • func WithDistortion(minDistortion, maxDistortion float64) Option
  • func WithFont(path string, size float64) Option
  • func WithForeground(foreground color.Color) Option
  • func WithLength(minLength, maxLength int) Option
  • func WithLines(minLines, maxLines int) Option
  • func WithNoise(level float64) Option
  • func WithRotation(minRotation, maxRotation float64) Option
  • func WithScale(minScale, maxScale float64) Option
  • func WithSize(width, height int) Option
  • func WithSpacing(minSpacing, maxSpacing float64) Option

Types

type Captcha

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

func New

func New(opts ...Option) (*Captcha, error)

func (*Captcha) Generate

func (c *Captcha) Generate() (image.Image, string)

Generate generates a captcha image and returns the image and the code

type CharSet

type CharSet = string

const (
	Lowercase                    CharSet = "abcdefghijklmnopqrstuvwxyz"
	Uppercase                    CharSet = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
	Alphabetic                   CharSet = Lowercase + Uppercase
	Numeric                      CharSet = "0123456789"
	Hex                          CharSet = Numeric + "abcdef"
	LowerNumeric                 CharSet = Lowercase + Numeric
	UpperNumeric                 CharSet = Uppercase + Numeric
	AlphaNumeric                 CharSet = Alphabetic + Numeric
	AlphaNumericWithoutConfusion CharSet = "ABCDEFGHKLMNPQRSTUVWXYZabcdefghkmnpqsuvwxyz23456789"
)

type Option

type Option func(*Captcha)

func WithBackground

func WithBackground(background color.Color) Option

WithBackground sets the background color of the captcha.

Default: color.White

func WithCharSet

func WithCharSet(charSet CharSet) Option

WithCharSet sets the character set used to generate the captcha.

Default: AlphaNumeric

func WithDistortion

func WithDistortion(minDistortion, maxDistortion float64) Option

WithDistortion sets the distortion factor of characters.

Default: 0.0, 0.0

func WithFont

func WithFont(path string, size float64) Option

WithFont sets the font used to generate the captcha.

Default: nil, 40

func WithForeground

func WithForeground(foreground color.Color) Option

WithForeground sets the foreground color of the captcha.

Default: color.Black

func WithLength

func WithLength(minLength, maxLength int) Option

WithLength sets the minimum and maximum length of the captcha.

Default: 4, 4

func WithLines

func WithLines(minLines, maxLines int) Option

WithLines sets the number of lines to draw on the captcha.

Default: 3, 7

func WithNoise

func WithNoise(level float64) Option

WithNoise sets the level of noise to add to the captcha.

Default: 0.1

func WithRotation

func WithRotation(minRotation, maxRotation float64) Option

WithRotation sets the rotation angle of characters.

Default: 0.0, 0.0

func WithScale

func WithScale(minScale, maxScale float64) Option

WithScale sets the scaling factor of characters.

Default: 1.0, 1.0

func WithSize

func WithSize(width, height int) Option

WithSize sets the size of the captcha image.

Default: 140x50

func WithSpacing

func WithSpacing(minSpacing, maxSpacing float64) Option

WithSpacing sets the spacing between characters.

Default: 1.0, 1.0