PHP generates graphics verification code with background

Cases

1, produce a picture of PNG
2. Set the background color for the picture
3. Set font color and style
4, generate a 4-digit random verification code
5, the resulting each character adjusted rotation angle and position to the PNG picture
6, add noise and interference line to prevent the registration machine analysis of the original picture to malicious registration
7. Output picture
8, free up the image of memory
authcode.php file

Code

The code is as follows

Copy Code

<?php Session_Start (); Header (' content-type:image/png '); Create a picture $im = Imagecreate ($x =130, $y = 45); $BG = Imagecolorallocate ($im, Rand (50,200), Rand (0,155), Rand (0,155)); The first call to Imagecolorallocate () fills the background color with the palette-based image $fontColor = Imagecolorallocate ($im, 255, 255, 255); Font Color $fontstyle = ' Rock.ttf '; Font style, this can be found from the C:windowsfonts folder, I put it in the same directory as the authcode.php file, where you can replace other font styles Generate random characters for ($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 ' = $randFourStr;//user and user input validation code comparison Jamming line For ($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, $lineColor); } Jamming Point For ($i =0 $i <250; $i + +) { Imagesetpixel ($im, rand (0, $x), rand (0, $y), $fontColor); } Imagepng ($im); Imagedestroy ($im); ?>

Example 2

• Create a new PHP file captcha_code_file.php

The code is as follows

Copy Code

Open Session First Session_Start (); Define foreground display verification code length & width $image _width = 120; $image _height = 40; $characters _on_image = 6; $font = './monofont.ttf '; The characters that can is 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"; To define the string to generate the verification code $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, $code); /* Show CAPTCHA image in the page HTML page */ Header (' content-type:image/jpeg ');//Defining the image Type to is shown in browser widow Imagejpeg ($image);//showing the image Imagedestroy ($image);//destroying the image instance Set session, do validation $_session[' 6_letters_code ' = $code; function Hexrgb ($HEXSTR) { $int = Hexdec ($HEXSTR); Return Array ("Red" => 0xFF & ($int >> 0x10), "Green" => 0xFF & ($int >> 0x8), "Blue" => 0xFF & $int); } Show authentication code page index.php <?php Session_Start (); if (Isset ($_request[' Submit ')) { Code for check server side validation if (Empty ($_session[' 6_letters_code ')) | | STRCASECMP ($_session[' 6_letters_code '], $_post[' 6_letters_code '])!= 0) { $msg = "The authentication code you entered is wrong, please re-enter!"; }else{ echo "you entered the correct!"; Captcha verification is correct. Final Code Execute here! } } ?> <style type= "Text/css" > . table{ Font-family:arial, Helvetica, Sans-serif; font-size:12px; Color: #333; Background-color: #E4E4E4; } . Table td{ <a href= "http://www.111cn.net" >coinstar money point</a> background-color: #F8F8F8; } </style> <form action= "" method= "Post" Name= "Form1" Id= "Form1" > <table width= "border=" 0 "align=" center "cellpadding=" 5 "cellspacing=" 1 "> <?php if (isset ($msg)) {?> <tr> &LT;TD colspan= "2" align= "center" valign= "Top" ><?php echo $msg;? ></td> </tr> <?php}?> <tr> &LT;TD align= ' right ' valign= ' top ' > Verification Code demo:</td> <td> "id= ' captchaimg ' onclick=" Refreshcaptcha (); "><br> <label for= ' message ' > Please enter the verification code:</label> <br> <input id= "6_letters_code" name= "6_letters_code" type= "text" > <br> If you do not see it, please <a href= ' Javascript:refreshcaptcha (); ' > Point I </a> Refresh! </p></td> </tr> <tr> <td>&amp;nbsp;</td> <td><input name= "Submit" type= "Submit" onclick= "return Validate ();" value= "Submit" ></td> </tr> </table> </form> <script type= ' Text/javascript ' > The refresh request defined function Refreshcaptcha () { var img = document.images[' captchaimg ']; IMG.SRC = img.src.substring (0,img.src.lastindexof ("?")) + "? rand=" +math.random () *1000; } </script>

Example 3

Validation code with a snowflake background

The code is as follows

Copy Code

<?session_start ();? > <form method=post action= "" > <input type=text name=number maxlength=4> <input type= "Submit" Name= "Sub" > </FORM> ? Check-Check Code if (Isset ($HTTP _post_vars["Sub"]): if ($HTTP _post_vars["number"]!= $HTTP _session_vars[login_check_number] | | empty ($HTTP _post_vars["number"]) { echo "Check code is incorrect!"; }else{ echo "Verification code passed! "; } endif Show_source (' test.php '); Above this page's source code The following is the source code to generate the verification code Show_source (' yanzhengma.php '); ?> <?php Session_Start (); Session_register ("Login_check_number"); Last night saw the verification code effect on the Chianren, just consider it, using PHP's GD library to complete a similar function First genetic the background, and then put the generated verification into the stacking $img _height=120; First define the length and width of the picture $img _width=40; if ($HTTP _get_vars["act"]== "init") { Srand (Microtime () * 100000); After//php420, Srand is not necessary. For ($Tmpa =0 $Tmpa <4; $Tmpa + +) { $nmsg. =dechex (rand (0,15)); }//by Sports98 $HTTP _session_vars[login_check_number] = $nmsg; $HTTP _session_vars[login_check_number] = Strval (Mt_rand ("1111", "9999")); Generates a 4-bit random number and puts it in session Who can make the supplement, can generate letters and numbers at the same time?? ----finished by Sports98. $aimg = Imagecreate ($img _height, $img _width); Generate pictures Imagecolorallocate ($aimg, 255,255,255); Picture background, imagecolorallocate the 1th time to define color PHP is considered to be the background $black = Imagecolorallocate ($aimg, 0,0,0); Define the required Black Imagerectangle ($aimg, 0,0, $img _height-1, $img _width-1, $black);//A black rectangle to surround the picture The following is the creation of a snowflake background, in fact, is to generate some symbols on the picture For ($i =1 $i <=100; $i + +) {//test with 100 first         imagestring ($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));        /ha, see it, in fact, is not a snowflake, is the generation of * No. In order for them to look "cluttered, 5-color, 6", they have to have their position, color, or even size randomly counted at 1 1, and rand () or mt_rand can do it.    } With the background generated, it's time to put the generated random numbers up. The reason is similar to above, random number 1 1 places, at the same time let their position, size, color are used into random number ~ ~ In order to distinguish it from the background, the color here is not more than 200, the above is not less than 200 For ($i =0 $i <strlen ($HTTP _session_vars[login_check_number]); $i + +) { Imagestring ($aimg, Mt_rand (3,5), $i * $img _height/4+mt_rand (1,10), Mt_rand (1, $img _width/2), $HTTP _session_vars[login _check_number][$i],imagecolorallocate ($aimg, Mt_rand (0,100), Mt_rand (0,150), Mt_rand (0,200)); } Header ("Content-type:image/png"); Tell the browser that the following data is a picture, not a text display Imagepng ($AIMG); Generate PNG format ... The effect is quite like a matter of ... Imagedestroy ($AIMG); } ?>