- //首先开启session
- session_start();
- //定义前台显示验证码长&宽
- $image_width = 120;
- $image_height = 40;
- $characters_on_image = 6;
- $font = './monofont.ttf';
- //The characters that can be used in the CAPTCHA code.
- //avoid confusing characters (l 1 and i for example)
- $possible_letters = '23456789bcdfghjkmnpqrstvwxyz';
- $random_dots = 10;
- $random_lines = 30;
- $captcha_text_color="0x142864";
- $captcha_noice_color = "0x142864";
- //定义要生成验证码的字符串
- $code = '';
- $i = 0;
- while ($i < $characters_on_image) {
- $code .= substr($possible_letters, mt_rand(0, strlen($possible_letters)-1), 1);
- $i++;
- }
- $font_size = $image_height * 0.75;
- $image = @imagecreate($image_width, $image_height);
- /* setting the background, text and noise colours here */
- $background_color = imagecolorallocate($image, 255, 255, 255);
- $arr_text_color = hexrgb($captcha_text_color);
- $text_color = imagecolorallocate($image, $arr_text_color['red'],
- $arr_text_color['green'], $arr_text_color['blue']);
- $arr_noice_color = hexrgb($captcha_noice_color);
- $image_noise_color = imagecolorallocate($image, $arr_noice_color['red'],
- $arr_noice_color['green'], $arr_noice_color['blue']);
- /* generating the dots randomly in background */
- for( $i=0; $i<$random_dots; $i++ ) {
- imagefilledellipse($image, mt_rand(0,$image_width),
- mt_rand(0,$image_height), 2, 3, $image_noise_color);
- }
- /* generating lines randomly in background of image */
- for( $i=0; $i<$random_lines; $i++ ) {
- imageline($image, mt_rand(0,$image_width), mt_rand(0,$image_height),
- mt_rand(0,$image_width), mt_rand(0,$image_height), $image_noise_color);
- }
- /* create a text box and add 6 letters code in it */
- $textbox = imagettfbbox($font_size, 0, $font, $code);
- $x = ($image_width - $textbox[4])/2;
- $y = ($image_height - $textbox[5])/2;
- imagettftext($image, $font_size, 0, $x, $y, $text_color, $font , $code);
- /* Show captcha image in the page html page */
- header('Content-Type: image/jpeg');// defining the image type to be shown in browser widow
- imagejpeg($image);//showing the image
- imagedestroy($image);//destroying the image instance
- //设置session,做验证
- $_SESSION['6_letters_code'] = $code;
- function hexrgb ($hexstr)
- {
- $int = hexdec($hexstr);
- return array("red" => 0xFF & ($int >> 0x10),
- "green" => 0xFF & ($int >> 0x8),
- "blue" => 0xFF & $int);
- }
- //该片段来自于http://www.codesnippet.cn/detail/041120136897.html
来源: http://www.codesnippet.cn/detail/041120136897.html