libcaptcha

Libcaptcha

Highly customizable captcha making library.

Features

• TTF font support
• UTF-8 support, you can use any glyph
• An easy API (I suppose)
• Zero dependencies
• Entirely written in C

How to install

It is as simple as

./bootstrap
./configure
make
make install

How to use

First of all we need some text, and this text should be placed using some random values. Don't warry, preset functions make all those random stuff by itself.

Here is example how to use lc_preset_text() :

  lc_bmp * text = lc_preset_text( // returns single channel lc_bmp*
    "path_to_font.ttf",           // path to font file
    "HELLOWORLD",                 // our text
    38,                           // minimum font size
    50,                           // maximum font size (if zero, all glyphs will be 38)
    1,                            // 1 - rotate characters, 0 - off
    10,                           // horizontal random offset
    10);                          // vertical random offset

There's some simply functions that make noise and square captchas.

  lc_bmp * bmp = lc_preset_square(
    text,                         // is our font object with text
    1,                            // spacing
    2);                           // square size (2 is very small)

Lets save our image into a png file:

 lc_save_png("helloworld.png", bmp);

Don't forget to free() memory:

  lc_free(bmp);
  lc_free(text);

Also you can make some noisy pattern instead of squares, its usage is simple:

  lc_bmp * noise = lc_preset_noise(text);

That's it.

Advanced Use

Check out examples

Get familiar with general concept. example1.c

How to make a random sized glyphs. example2.c

Apply random positions for glyphs. example3.c

Get familiar with patterns made from png images. example4.c

Patterns, patterns everywhere. example5.c

Some crazy stuff. example6.c

Don't forget to use lc_free() to free all the stuff libcaptcha returns to you.

I've noticed that it is very easy to get lost sometimes, just use valgrind.

License

GPLv2