验证码扭曲php

<?php
session_start();

// 生成随机字符串
function generateRandomString($length = 6) {
    $characters = '0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ';
    $charactersLength = strlen($characters);
    $randomString = '';
    for ($i = 0; $i < $length; $i++) {
        $randomString .= $characters[rand(0, $charactersLength - 1)];
    }
    return $randomString;
}

// 生成扭曲验证码
function generateCaptcha($text) {
    $width = 150;
    $height = 50;
    $image = imagecreatetruecolor($width, $height);
    $backgroundColor = imagecolorallocate($image, 255, 255, 255);
    imagefill($image, 0, 0, $backgroundColor);

    $textColor = imagecolorallocate($image, 0, 0, 0);
    $font = 'arial.ttf'; // 确保字体文件存在

    // 扭曲图像
    for ($x = 0; $x < $width; $x++) {
        for ($y = 0; $y < $height; $y++) {
            $newX = $x + 10 * sin($y / 10);
            $newY = $y + 10 * cos($x / 10);
            imagesetpixel($image, $newX, $newY, imagecolorallocate($image, rand(200, 255), rand(200, 255), rand(200, 255)));
        }
    }

    // 添加文字
    imagettftext($image, 20, 10, 30, 30, $textColor, $font, $text);

    header('Content-type: image/png');
    imagepng($image);
    imagedestroy($image);
}

// 生成并保存验证码
$captchaText = generateRandomString();
$_SESSION['captcha'] = $captchaText;
generateCaptcha($captchaText);
?>