<?php
if(!isset($_SESSION)){ session_start(); } //檢查SESSION是否啟動
$_SESSION['check_word'] = ''; //設置存放檢查碼的SESSION
//設置定義為圖片
header("Content-type: image/PNG");
/*
imgcode($nums,$width,$high)
設置產生驗證碼圖示的參數
$nums 生成驗證碼個數
$width 圖片寬
$high 圖片高
*/
imgcode(5,120,30);
//imgcode的function
function imgcode($nums,$width,$high) {
//去除了數字0和1 字母小寫O和L，為了避免辨識不清楚
$str = "23456789abcdefghijkmnpqrstuvwxyzABCDEFGHIJKLMOPQRSTUBWXYZ";
$code = '';
for ($i = 0; $i < $nums; $i++) {
$code .= $str[mt_rand(0, strlen($str)-1)];
}
$_SESSION['check_word'] = $code;
//建立圖示，設置寬度及高度與顏色等等條件
$image = imagecreate($width, $high);
$black = imagecolorallocate($image, mt_rand(0, 200), mt_rand(0, 200), mt_rand(0, 200));
$border_color = imagecolorallocate($image, 21, 106, 235);
$background_color = imagecolorallocate($image, 235, 236, 237);
//建立圖示背景
imagefilledrectangle($image, 0, 0, $width, $high, $background_color);
//建立圖示邊框
imagerectangle($image, 0, 0, $width-1, $high-1, $border_color);
//在圖示布上隨機產生大量躁點
for ($i = 0; $i < 80; $i++) {
imagesetpixel($image, rand(0, $width), rand(0, $high), $black);
}
$strx = rand(3, 8);
for ($i = 0; $i < $nums; $i++) {
$strpos = rand(1, 6);
imagestring($image, 5, $strx, $strpos, substr($code, $i, 1), $black);
$strx += rand(10, 30);
}
imagepng($image);
imagedestroy($image);
}
?>
