complexcaptcha v0.9.4
Project that aims for generating captcha image with various customization options - for Node.JS
Quick look
For simply generating and saving one captcha image:
import * as fs from "fs";
import ComplexCaptcha from "complexcaptcha";
//
// generating captcha
const data = ComplexCaptcha.Generate({
mimeType: "image/jpeg"
});
// saving to file
fs.writeFileSync(`./captcha__${data.solution}.jpeg`), data.buffer);
Current features
- Custom characters list (string)
- Custom font or fonts selected randomly for each character.
- Custom colors by creating palette of 3 colors (background, foreground, details) or providing array of palettes (random picking)
- Displacement of individual characters on y-axis
- Deformation of individual characters (scaling/skewing)
- Rotation of individual characters
- Pairing individual characters for overlaping
- Randomly picking characters for being impostors (characters that doesn't matter in answer/solution)
- Randomly picking font for each character.
- Ability to disable features for individual provided fonts
- Ability to disable characters for individual provided fonts
- Drawing fake captcha text in background with smaller font size (dummies)
- Drawing dirt on top of captcha (lines, xor linex/box/islands)
How to build
To build from typescript to javascript CommonJS module, just run command npm run build. You will find built code in dist directory. This command build whole module along with examples.
Examples
To run any of the examples located in examples folder:
- Run command npm run build for building whole module along with examples.
- Run command npm run example1 for running example1 program.
- Look at the output in output/example1 directory.
API
Registering custom font
If You want to use custom font/s, just call ComplexCaptcha.CanvasRegisterFont function with same arguments as in registerFont function in canvas module for Node.js. Read more details here: https://github.com/Automattic/node-canvas#registerfont
ComplexCaptcha.Generate
Static function ComplexCaptcha.Generate
generates captcha and returns object of GeneratedCaptcha
type. It takes one argument, object of GenerateOptions
type.
GeneratedCaptcha
Object of GeneratedCaptcha
type contains fields:
GeneratedCaptcha.Instructions
GenerateOptions
Object of GenerateOptions
type may contains fields:
GenerateOptions, Palette
GenerateOptions, FontInfo/FrontFontInfo
Object of FontInfo
/FrontFontInfo
type contains information about font used to render text:
GenerateOptions.CharDisplacementVOptions
Object of CharDisplacementVOptions
type contains information about how generator will displace vertically characters on image.
GenerateOptions.CharRotationOptions
Object of CharRotationOptions
type contains information about how generator will rotate characters on image.
GenerateOptions.CharDeformationOptions
Object of CharDeformationOptions
type contains information about how generator will deformate characters on image. First, a chance test will be performed, then the deformation type will be selected randomly (scaling on x or y axis, or skewing on x or y axis)
GenerateOptions.PairingOptions
Object of PairingOptions
type contains information about how generator will pair characters rendered on image.
Pairing is feature that randomly pair two characters into one unit, that will be rotated/deformated together and also both characters in pair will slightly overlapped for less readability and greater challange (can be customized).
GenerateOptions.ImpostorsOptions
Object of ImpostorsOptions
type contains information about fake characters will be placed among real ones. User is challanged to skip fake characters when rewriting captcha. Fake characters are marked by circle colored by palette.details, but modified to be semi-transparent.
GenerateOptions.DirtOptions
Object of DirtOptions
type contains information about drawings that will be put on top of whole image to make it less readable for cpu. Currently only xor box and line are avaliable and are selected randomly.
GenerateOptions.DummiesOptions
Object of DummiesOptions
type contains information about smaller text units that will be put behind real text to make whole captcha less readable for cpu.