60 lines
1.5 KiB
PHP
60 lines
1.5 KiB
PHP
<?php
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session_start();
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// 生成验证码
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$code = '';
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$chars = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789';
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for ($i = 0; $i < 4; $i++) {
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$code .= $chars[rand(0, strlen($chars) - 1)];
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}
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$_SESSION['captcha'] = $code;
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// 创建图片
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$width = 100;
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$height = 40;
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$image = imagecreate($width, $height);
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// 颜色定义
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$bg_color = imagecolorallocate($image, 245, 245, 245);
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$text_color = imagecolorallocate($image, 50, 50, 50);
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$line_color = imagecolorallocate($image, 200, 200, 200);
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$noise_color = imagecolorallocate($image, 180, 180, 180);
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// 填充背景
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imagefill($image, 0, 0, $bg_color);
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// 添加干扰线
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for ($i = 0; $i < 5; $i++) {
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imageline($image, rand(0, $width), rand(0, $height), rand(0, $width), rand(0, $height), $line_color);
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}
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// 添加噪点
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for ($i = 0; $i < 50; $i++) {
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imagesetpixel($image, rand(0, $width), rand(0, $height), $noise_color);
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}
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// 添加验证码文字
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for ($i = 0; $i < 4; $i++) {
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$x = 15 + $i * 18;
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$y = rand(8, 15);
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$angle = rand(-15, 15);
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if (function_exists('imagettftext')) {
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// 如果支持TTF字体
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imagettftext($image, 16, $angle, $x, 25, $text_color, __DIR__ . '/arial.ttf', $code[$i]);
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} else {
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// 使用内置字体
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imagestring($image, 5, $x, $y, $code[$i], $text_color);
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}
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}
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// 输出图片
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header('Content-Type: image/png');
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header('Cache-Control: no-cache, no-store, must-revalidate');
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header('Pragma: no-cache');
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header('Expires: 0');
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imagepng($image);
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imagedestroy($image);
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?>
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