First create a file in your theme named: fcaptcha.php
fcaptcha.php
<?php
session_start();
$permitted_chars = 'ABCDEFGHJKLMNPQRSTUVWXYZ';
function generate_string($input, $strength = 10) {
$input_length = strlen($input);
$random_string = '';
for($i = 0; $i < $strength; $i++) {
$random_character = $input[mt_rand(0, $input_length - 1)];
$random_string .= $random_character;
}
return $random_string;
}
$image = imagecreatetruecolor(200, 50);
imageantialias($image, true);
$colors = [];
$red = rand(125, 175);
$green = rand(125, 175);
$blue = rand(125, 175);
for ( $i = 0; $i < 5; $i++ ) {
$colors[] = imagecolorallocate($image, $red - 20*$i, $green - 20*$i, $blue - 20*$i);
}
imagefill($image, 0, 0, $colors[0]);
$black = imagecolorallocate($image, 0, 0, 0);
$white = imagecolorallocate($image, 255, 255, 255);
$textcolors = [$black, $white];
$string_length = 6;
$captcha_string = generate_string($permitted_chars, $string_length);
$_SESSION['captcha_text'] = $captcha_string;
imagestring($image, 18, 10, 12, $captcha_string, $textcolors[rand(0, 1)]);
imagepng($image);
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After that, in functions.php file put the below code to start session:
if ( ! session_id() ) {
session_start();
}
And add below lines to functions.php to localize some data:
wp_enqueue_script('jsScript', get_template_directory_uri() . '/js/script.js', array('jquery'), false, true);
$translation_array = array( 'templateUrl' => get_stylesheet_directory_uri() );
wp_localize_script( 'jsScript', 'globalJSObject', $translation_array );
script.js
$('<img/>').attr({ src: globalJSObject.templateUrl+'/fcaptcha.php', id: 'captcha_image'}).appendTo('.solution_captcha');
See the class name of solution_captcha, it can be anything but you will need to put that class in your ACF captcha field.
