PHP -从图片创建缩略图，没有白/黑条(并保持比例)

<?php
// 原始图片路径
$sourceImagePath = 'path/to/source/image.jpg';

// 创建缩略图的宽度和高度
$thumbnailWidth = 200;
$thumbnailHeight = 200;

// 获取原始图片的宽度和高度
list($sourceWidth, $sourceHeight) = getimagesize($sourceImagePath);

// 计算缩略图的宽度和高度，保持比例
if ($sourceWidth > $sourceHeight) {
    $thumbnailWidth = $thumbnailWidth;
    $thumbnailHeight = intval($sourceHeight / $sourceWidth * $thumbnailWidth);
} else {
    $thumbnailHeight = $thumbnailHeight;
    $thumbnailWidth = intval($sourceWidth / $sourceHeight * $thumbnailHeight);
}

// 创建一个空白的缩略图
$thumbnailImage = imagecreatetruecolor($thumbnailWidth, $thumbnailHeight);

// 根据原始图片创建缩略图
$sourceImage = imagecreatefromjpeg($sourceImagePath);
imagecopyresampled($thumbnailImage, $sourceImage, 0, 0, 0, 0, $thumbnailWidth, $thumbnailHeight, $sourceWidth, $sourceHeight);

// 输出缩略图到浏览器或保存到文件
header('Content-Type: image/jpeg');
imagejpeg($thumbnailImage);

// 释放内存
imagedestroy($thumbnailImage);
imagedestroy($sourceImage);
?>