php - PHP 根据最大​​宽度或重量按比例调整图像大小

Question

有任何 php 脚本可以用最大宽度或高度按比例调整图像大小？

例如：我上传图片，这个原始尺寸是 w:500 h:1000。但是，我想调整这个最大高度是宽度和高度是 500...脚本调整图像的大小为 w: 250 h: 500

Answer 1

您所需要的只是纵横比。这些方面的东西：

$fn = $_FILES['image']['tmp_name'];
$size = getimagesize($fn);
$ratio = $size[0]/$size[1]; // width/height
if( $ratio > 1) {
    $width = 500;
    $height = 500/$ratio;
}
else {
    $width = 500*$ratio;
    $height = 500;
}
$src = imagecreatefromstring(file_get_contents($fn));
$dst = imagecreatetruecolor($width,$height);
imagecopyresampled($dst,$src,0,0,0,0,$width,$height,$size[0],$size[1]);
imagedestroy($src);
imagepng($dst,$target_filename_here); // adjust format as needed
imagedestroy($dst);

您需要添加一些错误检查，但这应该可以帮助您入门。

Answer 2

使用 Colin Verot 编写的上传类。它有各种调整大小、编辑、水印等选项……太棒了！

该课程由互联网上的网站维护和使用，因此您可以信赖它！

看这里

即使这称为上传类，您也可以将相同的方法应用于服务器上已有的文件

如何使用

按照网站上的安装说明，非常简单，下载课程并将其放置在您的网站中。

然后，您的脚本将如下所示：

// Include the upload class
include('class.upload.php');

// Initiate the upload object based on the uploaded file field
$handle = new upload($_FILES['image_field']);

// Only proceed if the file has been uploaded
if($handle->uploaded) {
    // Set the new filename of the uploaded image
    $handle->file_new_name_body   = 'image_resized';
    // Make sure the image is resized
    $handle->image_resize         = true;
    // Set the width of the image
    $handle->image_x              = 100;
    // Ensure the height of the image is calculated based on ratio
    $handle->image_ratio_y        = true;
    // Process the image resize and save the uploaded file to the directory
    $handle->process('/home/user/files/');
    // Proceed if image processing completed sucessfully
    if($handle->processed) {
        // Your image has been resized and saved
        echo 'image resized';
        // Reset the properties of the upload object
        $handle->clean();
    }else{
        // Write the error to the screen
        echo 'error : ' . $handle->error;
    }
}