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
代码如下 | 复制代码 |
<?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 | 复制代码 |
//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 & $int); } 显示验证码页面index.php <?php |
例3
带有雪花背景的验证码
代码如下 | 复制代码 |
<?session_start();?> <FORM METHOD=POST ACTION=""> <input type=text name=number maxlength=4><img src="YanZhengMa.php?act=init"> <INPUT TYPE="submit" name="sub"> </FORM> <? //检验校验码 if(isset($HTTP_POST_VARS["sub"])): if($HTTP_POST_VARS["number"] != $HTTP_SESSION_VARS[login_check_number] || empty($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
//昨晚看到了chianren上的验证码效果,就考虑了一下,用PHP的GD库完成了类似功能 $HTTP_SESSION_VARS[login_check_number] = $nmsg; //$HTTP_SESSION_VARS[login_check_number] = strval(mt_rand("1111","9999")); //生成4位的随机数,放入session中
$aimg = imageCreate($img_height,$img_width); //生成图片 ImageRectangle($aimg,0,0,$img_height-1,$img_width-1,$black);//先成一黑色的矩形把图片包围 //下面该生成雪花背景了,其实就是在图片上生成一些符号 imageString($aimg,1,mt_rand(1,$img_height),mt_rand(1,$img_width),"*",imageColorAllocate($aimg,mt_rand(200,255),mt_rand(200,255),mt_rand(200,255))); //上面生成了背景,现在就该把已经生成的随机数放上来了。道理和上面差不多,随机数1个1个地放,同时让他们的位置、大小、颜色都用成随机数~~ ?> |