Package captcha implements generation and verification of image CAPTCHAs.

A captcha solution is the sequence of digits 0-9 with the defined length.

An image representation is a PNG-encoded or JPEG-encoded image with the solution printed on it in such a way that makes it hard for computers to solve it using OCR.

This package doesn't require external files or libraries to generate captcha representations; it is self-contained.

Package code refer from dchest/captcha

Advantages:

1. High-Performance：Generation captcha use goroutine channel, get captcha ready in advance by channel
2. Change panic to error, avoid runtime panic
3. Not inline store interface, can use any store method such as Redis, Memcache, Memory and so on after get captcha image
4. Use uuid instead of original random id avoid conflict
5. Add Context to control generate captcha goroutine, can stop generate programming active

go get github.com/xkeyideal/captcha

NewCaptchaPool(width, height, wordLength, poolsize, parallelNum, imageType int)

Creates a new captcha pool

1. width, height: image's width and height
2. wordLength: generate words' length
3. poolsize: buffer size
4. parallelNum: goroutine number
5. imageType: PNG or JPEG

func (p *CaptchaPool) Stop()

Stop CaptchaPool active

    type CaptchaBody struct {
    	Id   string
    	Data *bytes.Buffer
    	Val  []byte
    }
    
    CaptchaPool = pool.NewCaptchaPool(240, 80, 6, 10, 1, 2)
    
    captchaBody := CaptchaPool.GetImage()
	
	CaptchaPool.Stop()
    

See detail in file captcha.go

Golang context can't control goroutine channel will deadlock by using sync.WaitGroup to wait all goroutine return and close channels.