PHP Verification code making ideas and implementation methods, PHP verification code making Ideas _php tutorial

How to make PHP verification code and how to make PHP verification code

First, the production of ideas

Because registration code is often used to prevent malicious machine registration, here I publish a PNG image verification code basic image, simple thinking Analysis:

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. Adjust the rotation angle and position of each character produced to the PNG image.
6, add noise and interference line to prevent the registration machine analysis of the original image to malicious registration
7. Output image
8. Release the memory of the image

Second, the realization method

authcode.php file

<?php session_start ();    Header (' content-type:image/png ');    Create 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 color palette-based image with the background color $fontColor = imagecolorallocate ($im, 255, 255, 255);          Font Color $fontstyle = ' Rock.ttf ';         Font style, this can be found from the C:\windows\Fonts\ folder, I put it in the same directory as the authcode.php file, here can replace the other font style//generate random characters for ($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 ' = $randFourStr;//The user and user entered the verification code to do the comparison//interference line for ($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, $lineColor);    }//Interference point for ($i =0; $i <250; $i + +) {Imagesetpixel ($im, rand (0, $x), rand (0, $y), $fontColor);    } imagepng ($im);        Imagedestroy ($im); ?>

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The above is the PHP verification code making ideas and implementation methods, I hope that everyone's learning has helped.

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