php生成缩略图等比例

<?php
// 原始图片路径
$originalImage = 'path/to/original/image.jpg';
// 缩略图路径
$thumbnailPath = 'path/to/thumbnail/image.jpg';
// 目标宽度
$targetWidth = 200;
// 目标高度
$targetHeight = 200;

// 获取原始图片信息
$imageInfo = getimagesize($originalImage);
$imageType = $imageInfo[2];

// 根据图片类型创建图像资源
switch ($imageType) {
    case IMAGETYPE_JPEG:
        $originalImageResource = imagecreatefromjpeg($originalImage);
        break;
    case IMAGETYPE_PNG:
        $originalImageResource = imagecreatefrompng($originalImage);
        break;
    case IMAGETYPE_GIF:
        $originalImageResource = imagecreatefromgif($originalImage);
        break;
    default:
        die('Unsupported image type');
}

// 计算缩略图的宽度和高度
list($originalWidth, $originalHeight) = getimagesize($originalImage);
$ratio = min($targetWidth / $originalWidth, $targetHeight / $originalHeight);
$newWidth = intval($originalWidth * $ratio);
$newHeight = intval($originalHeight * $ratio);

// 创建缩略图资源
$thumbnailResource = imagecreatetruecolor($newWidth, $newHeight);

// 复制并调整原始图像到缩略图资源
imagecopyresampled($thumbnailResource, $originalImageResource, 0, 0, 0, 0, $newWidth, $newHeight, $originalWidth, $originalHeight);

// 保存缩略图
switch ($imageType) {
    case IMAGETYPE_JPEG:
        imagejpeg($thumbnailResource, $thumbnailPath);
        break;
    case IMAGETYPE_PNG:
        imagepng($thumbnailResource, $thumbnailPath);
        break;
    case IMAGETYPE_GIF:
        imagegif($thumbnailResource, $thumbnailPath);
        break;
}

// 释放图像资源
imagedestroy($originalImageResource);
imagedestroy($thumbnailResource);

echo '缩略图生成成功！';
?>

imagejpeg($thumbnailResource, $thumbnailPath, 90); // 设置图像质量为90%