php图片缩放比例

<?php
// 打开原始图像
$image = imagecreatefromjpeg('original.jpg');

// 获取原始图像的宽度和高度
$width = imagesx($image);
$height = imagesy($image);

// 设置目标宽度
$targetWidth = 300;

// 计算目标高度以保持宽高比
$targetHeight = ($height / $width) * $targetWidth;

// 创建一个新的图像资源
$newImage = imagecreatetruecolor($targetWidth, $targetHeight);

// 进行图像缩放
imagecopyresampled($newImage, $image, 0, 0, 0, 0, $targetWidth, $targetHeight, $width, $height);

// 保存新的图像
imagejpeg($newImage, 'resized.jpg');

// 释放内存
imagedestroy($image);
imagedestroy($newImage);
?>

imagecopyresampled($newImage, $image, 0, 0, 0, 0, $targetWidth, $targetHeight, $width, $height);

$newImage = imagecreatetruecolor($targetWidth, $targetHeight);
$backgroundColor = imagecolorallocate($newImage, 255, 255, 255);
imagefill($newImage, 0, 0, $backgroundColor);