本文实例讲述了PHP实现生成带背景的图形验证码功能。分享给大家供大家参考,具体如下:
以前我们利用php生成的都是无背景或同一色彩背景的验证码了,但这种验证容易给机器识别了,这里就来介绍一些生成带背景的图形验证码实例.
1、产生一张png的图片,
2、为图片设置背景色,
3、设置字体颜色和样式,
4、产生4位数的随机的验证码,
5、把产生的每个字符调整旋转角度和位置画到png图片上,
6、加入噪点和干扰线防止注册机器分析原图片来恶意注册,
7、输出图片,
8、释放图片所占内存
authcode.php文件,代码如下:
例2,新建一个PHP文件captcha_code_file.php,代码如下:
//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 & $int); }
显示验证码页面index.php,实例代码如下:
例3,带有雪花背景的验证码,代码如下:
//检验校验码 if(isset($HTTP_POST_VARS["sub"])): if($HTTP_POST_VARS["number"] != $HTTP_SESSION_VARS[login_check_number] || emptyempty($HTTP_POST_VARS["number"])){ echo "校验码不正确!" ; }else{ echo"验证码通过!"; } endif; show_source('test.php'); //以上本页的源码 //以下是生成验证码的源码 show_source('YanZhengMa.php'); ?>
希望本文所述对大家PHP程序设计有所帮助。
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