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:
<?php session_start (); header ( 'Content-type: image/png' ); //创建图片 $im = imagecreate($x=130,$y=45 ); $bg = imagecolorallocate($im,rand(50,200),rand(0,155),rand(0,155)); //第一次对 imagecolorallocate() 的调用会给基于调色板的图像填充背景色 $fontColor = imageColorAllocate ( $im, 255, 255, 255 ); //字体颜色 $fontstyle = 'rock.ttf'; //字体样式，这个可以从c:windowsFonts文件夹下找到，我把它放到和authcode.php文件同一个目录，这里可以替换其他的字体样式 //产生随机字符 for($i = 0; $i < 4; $i ++) { $randAsciiNumArray = array (rand(48,57),rand(65,90)); $randAsciiNum = $randAsciiNumArray [rand ( 0, 1 )]; $randStr = chr ( $randAsciiNum ); imagettftext($im,30,rand(0,20)-rand(0,25),5+$i*30,rand(30,35),$fontColor,$fontstyle,$randStr); $authcode .= $randStr; } $_SESSION['authcode'] = $randFourStr;//用户和用户输入的验证码做比较 //干扰线 for ($i=0;$i<8;$i++){ $lineColor = imagecolorallocate($im,rand(0,255),rand(0,255),rand(0,255)); imageline ($im,rand(0,$x),0,rand(0,$x),$y,$lineColor); } //干扰点 for ($i=0;$i<250;$i++){ imagesetpixel($im,rand(0,$x),rand(0,$y),$fontColor); } imagepng($im); imagedestroy($im); ?>
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 & $int); }
显示验证码页面index.php,实例代码如下:
<?php session_start(); if(isset($_REQUEST['Submit'])){ // code for check server side validation if(emptyempty($_SESSION['6_letters_code'] ) || strcasecmp($_SESSION['6_letters_code'], $_POST['6_letters_code']) != 0) { $msg="您输入的验证码有误，请重新输入!"; }else{ echo "您输入的是正确的!"; // Captcha verification is Correct. Final Code Execute here! } } ?> <style type="text/css"> .table{ font-family:Arial, Helvetica, sans-serif; font-size:12px; color:#333; background-color:#E4E4E4; } .table td{ background-color:#F8F8F8; } </style> <form action="" method="post" > <table cellpadding="5" cellspacing="1"> <?php if(isset($msg)){?> <tr> <td colspan="2" valign="top"><?php echo $msg;?></td> </tr> <?php } ?> <tr> <td valign="top"> 验证码Demo:</td> <td><img src="captcha_code_file.php?rand=<?php echo rand(0,20);?>" ><br> <label for='message'>请输入验证码:</label> <br> <input type="text"> <br> 如果看不到，请 <a href='javascript： refreshCaptcha();'>点我</a> 刷新一下! </p></td> </tr> <tr> <td>&nbsp;</td> <td><input type="submit" value="Submit"></td> </tr> </table> </form> <script type='text/javascript'> //定义的刷新请求 function refreshCaptcha() { var img = document.images['captchaimg']; img.src = img.src.substring(0,img.src.lastIndexOf("?"))+"?rand="+Math.random()*1000; } </script>
例3,带有雪花背景的验证码,代码如下: