How php generates an image Verification Code,

How php generates an image Verification Code,

This article describes how to generate an image verification code in php for your reference. The content is as follows:

First, a fixed number of characters are randomly extracted from the specified character set, and painted on the canvas in an irregular way. Then, some interference points and interference elements are added as appropriate, and the image is output, A brand new verification code is complete.

The front-end code is as follows:

<! DOCTYPE html> 
The php script file verification code is as follows:

<? Php session_start (); // enable session record verification code data vCode (4, 15); // set the number of characters in the verification code and the Image Base Width // Number of vCode characters, font size, function vCode ($ num = 4, $ size = 20, $ width = 0, $ height = 0 ){! $ Width & $ width = $ num * $ size x 4/5 + 15 ;! $ Height & $ height = $ size + 10; // set the verification code character set to $ str = "23456789 abcdefghijkmnpqrstuvwxyzABCDEFGHIJKLMNPQRSTUVW"; // Save the obtained Verification code $ code = ''; // randomly select the character for ($ I = 0; $ I <$ num; $ I ++) {$ code. = $ str [mt_rand (0, strlen ($ str)-1)];} // create a verification code canvas $ im = imagecreatetruecolor ($ width, $ height ); // background color $ back_color = imagecolorallocate ($ im, mt_rand (0,100), mt_rand (0,100), mt_rand (0,100); // text color $ text_color = imagecoloralloc Ate ($ im, mt_rand (100,255), mt_rand (100,255), mt_rand (100,255); imagefilledrectangle ($ im, 0, 0, $ width, $ height, $ back_color ); // draw interference lines 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 (30, $ width * 2), mt_rand (20, $ height * 2), mt_rand (0,360), mt_rand (0,360), $ font_color);} // draw interference points for ($ I = 0; $ I <50; $ 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);} // random rotation angle array $ array = array (5, 4, 3, 2, 1, 0,-1,-2,-3,-4,-5 ); // output verification code // imagefttext (image, size, angle, x, y, color, fontfile, text) @ imagefttext ($ im, $ size, array_rand ($ array), 12, $ Size + 6, $ text_color, 'c: \ WINDOWS \ Fonts \ simsun. ttc ', $ code); $ _ SESSION ["VerifyCode"] = $ code; // no-cache will access the server upon each request // max-age will access the server upon another 1 s request, and must-revalidate will access the server upon the first request, the server will not be accessed later // header ("Cache-Control: max-age = 1, s-maxage = 1, no-cache, must-revalidate "); header ("Cache-Control: no-cache"); header ("Content-type: image/png; charset = gb2312 "); // convert the image to png format imagepng ($ im); imagedestroy ($ im );}?>
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The above is all the content of this article. I hope it will help you learn php programming and learn how to compile php image verification code.
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