Summary of several methods for generating graphics verification code in PHP

Let's check our PHP first to see if we've opened the GD library.

The code is as follows	Copy Code
<?php if (extension_loaded (' GD ')) { Echo ' You can use gd<br> '; foreach (Gd_info () as $cate => $value) echo "$cate: $value <br>"; }else Echo ' You did not install GD extension '; ?>

If there is return information on the correct can be used frequently

Example 1

The code is as follows

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<?php /** * Vcode (M,n,x,y) m number display size is n edge wide x Edge high Y * Self rewrite record session $code */ Session_Start (); Vcode (4, 15); 4 digits with a display size of 15 function Vcode ($num = 4, $size = $width = 0, $height = 0) { ! $width && $width = $num * $size * 4/5 + 5; ! $height && $height = $size + 10; Removed 0 1 O l etc $str = "23456789abcdefghijkmnpqrstuvwxyzABCDEFGHIJKLMNPQRSTUVW"; $code = '; for ($i = 0; $i < $num; $i + +) { $code. = $str [Mt_rand (0, strlen ($str)-1)]; } Drawing images $im = Imagecreatetruecolor ($width, $height); Define the color you want to use $back _color = Imagecolorallocate ($im, 235, 236, 237); $boer _color = Imagecolorallocate ($im, 118, 151, 199); $text _color = imagecolorallocate ($im, Mt_rand (0), Mt_rand (0,), Mt_rand (0, 120)); Draw background Imagefilledrectangle ($im, 0, 0, $width, $height, $back _color); Draw a border Imagerectangle ($im, 0, 0, $width-1, $height-1, $boer _color); Draw Interference Line for ($i = 0; $i < 5; $i + +) { $font _color = imagecolorallocate ($im, Mt_rand (0, 255), Mt_rand (0, 255), Mt_rand (0, 255)); Imagearc ($im, Mt_rand (-$width, $width), Mt_rand (-$height, $height), Mt_rand ($width * 2), Mt_rand ($height * 2), M T_rand (0, 360), Mt_rand (0, 360), $font _color); } Draw the jamming point for ($i = 0; $i < $i + +) { $font _color = imagecolorallocate ($im, Mt_rand (0, 255), Mt_rand (0, 255), Mt_rand (0, 255)); Imagesetpixel ($im, Mt_rand (0, $width), Mt_rand (0, $height), $font _color); } Picture Verification Code @imagefttext ($im, $size, 0, 5, $size + 3, $text _color, ' C:\WINDOWS\FONTS\SIMSUN.TTC ', $code); $_session["Verifycode"]= $code; Header ("cache-control:max-age=1, s-maxage=1, No-cache, must-revalidate"); Header ("content-type:image/png;charset=gb2312"); Imagepng ($im); Imagedestroy ($im); } ?>

Example 2

The use of PHP, combined with session and the GD Library expansion development of a build verification code example (recommended by the consortium), can be easily used in projects. And the style is beautiful//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);
}

Recommended by the personal recommendation of the second generation of verification Code program code, you can try to reference the comparison Oh, the last one is the standard generated by the consortium is also the use of the PHP GD library.