如何使用PHP生成高質量縮略圖：保持圖片清晰度的技巧

<?php

 // 原始圖片路徑
$source_image = 'path/to/image.jpg';

// 縮略圖路徑
$thumbnail_image = 'path/to/thumbnail.jpg';

// 縮略圖尺寸
$thumbnail_width = 200;
$thumbnail_height = 200;

// 創建一個圖像資源對象
$source_resource = imagecreatefromjpeg($source_image);

// 獲取原始圖片的寬度和高度
$source_width = imagesx($source_resource);
$source_height = imagesy($source_resource);

// 計算縮略圖的寬度和高度
if ($source_width > $source_height) {
    $thumbnail_width = $thumbnail_width;
    $thumbnail_height = intval($source_height / $source_width * $thumbnail_width);
} else {
    $thumbnail_height = $thumbnail_height;
    $thumbnail_width = intval($source_width / $source_height * $thumbnail_height);
}

// 創建一個新的圖像資源對象，用於生成縮略圖
$thumbnail_resource = imagecreatetruecolor($thumbnail_width, $thumbnail_height);

imagecopyresampled($thumbnail_resource, $source_resource, 0, 0, 0, 0, $thumbnail_width, $thumbnail_height, $source_width, $source_height);

// 保存縮略圖
imagejpeg($thumbnail_resource, $thumbnail_image, 90);

// 釋放資源
imagedestroy($source_resource);
imagedestroy($thumbnail_resource);
?>