Index.php:
<form name="form" method="post" action="">
<label><strong>Enter Captcha:</strong></label><br />
<input type="text" name="captcha" />
<p><br />
<img src="captcha.php?rand=<?php echo rand(); ?>" id='captcha_image'>
</p>
<p>Can't read the image?
<a href='javascript: refreshCaptcha();'>click here</a>
to refresh</p>
<input type="submit" name="submit" value="Submit">
</form>
<script>
//Refresh Captcha
function refreshCaptcha(){
var img = document.images['captcha_image'];
img.src = img.src.substring(
0,img.src.lastIndexOf("?")
)+"?rand="+Math.random()*1000;
}
</script>
Index.php Header
<?php
session_start();
$status = '';
if ( isset($_POST['captcha']) && ($_POST['captcha']!="") ){
// Validation: Checking entered captcha code with the generated captcha code
if(strcasecmp($_SESSION['captcha'], $_POST['captcha']) != 0){
// Note: the captcha code is compared case insensitively.
// if you want case sensitive match, check above with strcmp()
$status = "<p style='color:#FFFFFF; font-size:20px'>
<span style='background-color:#FF0000;'>Entered captcha code does not match!
Kindly try again.</span></p>";
}else{
$status = "<p style='color:#FFFFFF; font-size:20px'>
<span style='background-color:#46ab4a;'>Your captcha code is match.</span>
</p>";
}
}
echo $status;
?>
Captcha.php
<?php
session_start();
//You can customize your captcha settings here
$captcha_code = '';
$captcha_image_height = 50;
$captcha_image_width = 130;
$total_characters_on_image = 6;
//The characters that can be used in the CAPTCHA code.
//avoid all confusing characters and numbers (For example: l, 1 and i)
$possible_captcha_letters = 'bcdfghjkmnpqrstvwxyz23456789';
$captcha_font = 'monofont.ttf';
$random_captcha_dots = 50;
$random_captcha_lines = 25;
$captcha_text_color = "0x142864";
$captcha_noise_color = "0x142864";
$count = 0;
while ($count < $total_characters_on_image) {
$captcha_code .= substr(
$possible_captcha_letters,
mt_rand(0, strlen($possible_captcha_letters)-1),
1);
$count++;
}
$captcha_font_size = $captcha_image_height * 0.65;
$captcha_image = @imagecreate(
$captcha_image_width,
$captcha_image_height
);
/* setting the background, text and noise colours here */
$background_color = imagecolorallocate(
$captcha_image,
255,
255,
255
);
$array_text_color = hextorgb($captcha_text_color);
$captcha_text_color = imagecolorallocate(
$captcha_image,
$array_text_color['red'],
$array_text_color['green'],
$array_text_color['blue']
);
$array_noise_color = hextorgb($captcha_noise_color);
$image_noise_color = imagecolorallocate(
$captcha_image,
$array_noise_color['red'],
$array_noise_color['green'],
$array_noise_color['blue']
);
/* Generate random dots in background of the captcha image */
for( $count=0; $count<$random_captcha_dots; $count++ ) {
imagefilledellipse(
$captcha_image,
mt_rand(0,$captcha_image_width),
mt_rand(0,$captcha_image_height),
2,
3,
$image_noise_color
);
}
/* Generate random lines in background of the captcha image */
for( $count=0; $count<$random_captcha_lines; $count++ ) {
imageline(
$captcha_image,
mt_rand(0,$captcha_image_width),
mt_rand(0,$captcha_image_height),
mt_rand(0,$captcha_image_width),
mt_rand(0,$captcha_image_height),
$image_noise_color
);
}
/* Create a text box and add 6 captcha letters code in it */
$text_box = imagettfbbox(
$captcha_font_size,
0,
$captcha_font,
$captcha_code
);
$x = ($captcha_image_width - $text_box[4])/2;
$y = ($captcha_image_height - $text_box[5])/2;
imagettftext(
$captcha_image,
$captcha_font_size,
0,
$x,
$y,
$captcha_text_color,
$captcha_font,
$captcha_code
);
/* Show captcha image in the html page */
// defining the image type to be shown in browser widow
header('Content-Type: image/jpeg');
imagejpeg($captcha_image); //showing the image
imagedestroy($captcha_image); //destroying the image instance
$_SESSION['captcha'] = $captcha_code;
function hextorgb ($hexstring){
$integar = hexdec($hexstring);
return array("red" => 0xFF & ($integar >> 0x10),
"green" => 0xFF & ($integar >> 0x8),
"blue" => 0xFF & $integar);
}
?>