php 添加水印图片类

<?php
class Watermark {
    public function addTextWatermark($sourceImage, $text, $outputImage, $position = 'bottom-right', $opacity = 50) {
        // 获取图片资源
        $image = imagecreatefromjpeg($sourceImage);
        $width = imagesx($image);
        $height = imagesy($image);

        // 创建一个新的透明图层
        $watermark = imagecreatetruecolor($width, $height);
        $transparent = imagecolorallocatealpha($watermark, 0, 0, 0, 127);
        imagefill($watermark, 0, 0, $transparent);
        imagesavealpha($watermark, true);

        // 设置字体颜色和大小
        $textColor = imagecolorallocate($watermark, 255, 255, 255);
        $fontSize = 20;
        $fontFile = 'arial.ttf'; // 确保字体文件存在

        // 计算文字位置
        $textWidth = imagettfbbox($fontSize, 0, $fontFile, $text);
        $textWidth = $textWidth[2] - $textWidth[6];
        $textHeight = $textWidth / 2;

        switch ($position) {
            case 'top-left':
                $x = 10;
                $y = 10;
                break;
            case 'top-right':
                $x = $width - $textWidth - 10;
                $y = 10;
                break;
            case 'bottom-left':
                $x = 10;
                $y = $height - $textHeight - 10;
                break;
            case 'bottom-right':
            default:
                $x = $width - $textWidth - 10;
                $y = $height - $textHeight - 10;
                break;
        }

        // 添加文字水印
        imagettftext($watermark, $fontSize, 0, $x, $y, $textColor, $fontFile, $text);

        // 合并水印图层和原图
        imagecopymerge($image, $watermark, 0, 0, 0, 0, $width, $height, $opacity);

        // 输出图片
        imagejpeg($image, $outputImage);
        imagedestroy($image);
        imagedestroy($watermark);
    }
}

// 使用示例
$watermark = new Watermark();
$watermark->addTextWatermark('source.jpg', 'Copyright © 2023', 'output.jpg');
?>