This is a fork of https://github.com/dchest/captcha Original by Dmitry Chestnykh
import "github.com/ZiRo/captcha"
Package captcha implements generation and verification of image CAPTCHAs.
A captcha solution is the sequence of digits 0-9 and letters a-z, A-Z with a defined length.
The captcha is a PNG-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 only requires font files. See github.com/ZiRo-/captcha/fontgen for details on how to get them. So, before you start generating captchas, you have to load a font:
fn := libgocaptcha.LoadFontFromFile("Ubuntu-Mono.gob)
if fn == nil {
log.Fatalf("Couldn't load font file")
}
libgocaptcha.AddFont("font", fn)
libgocaptcha.SetCharacterRange(libgocaptcha.MODULE_UPPER)To make captchas one-time, the package includes a memory storage that stores captcha ids, their solutions, and expiration time. Used captchas are removed from the store immediately after calling Verify or VerifyString, while unused captchas (user loaded a page with captcha, but didn't submit the form) are collected automatically after the predefined expiration time. Developers can also provide custom store (for example, which saves captcha ids and solutions in database) by implementing Store interface and registering the object with SetCustomStore.
Captchas are created by calling New, which returns the captcha id. Their representations, though, are created on-the-fly by calling WriteImage. Created representations are not stored anywhere, but subsequent calls to these functions with the same id will write the same captcha solution. Reload function will create a new different solution for the provided captcha, allowing users to "reload" captcha if they can't solve the displayed one without reloading the whole page. Verify and VerifyString are used to verify that the given solution is the right one for the given captcha id.
Server provides an http.Handler which can serve image and audio representations of captchas automatically from the URL. It can also be used to reload captchas. Refer to Server function documentation for details, or take a look at the example in github.com/ZiRo-/captcha/capexample
See https://github.com/ZiRo-/captcha/tree/master/libgocaptcha/C_bindings
