PHP 使用纵横比调整图像大小

Question

我有这个 PHP 脚本，可以将图像大小调整为 50%（或任何预设百分比）

$filename = 'test.jpg';
$percent = 0.5;

// Content type
header('Content-Type: image/jpeg');

// Get new dimensions
list($width, $height) = getimagesize($filename);
$new_width = $width * $percent;
$new_height = $height * $percent;

// Resample
$image_p = imagecreatetruecolor($new_width, $new_height);
$image = imagecreatefromjpeg($filename);
imagecopyresampled($image_p, $image, 0, 0, 0, 0, $new_width, $new_height, $width, $height);

// Output
imagejpeg($image_p, null, 100);

现在，如果我想将 $new_width 指定为 1200 (px) 并告诉 $new_height 自动计算保持纵横比并将新图像的名称设置为“test-2.jpg”怎么办

$filename = 'test.jpg';

// Content type
header('Content-Type: image/jpeg');

// Get new dimensions
list($width, $height) = getimagesize($filename);
$new_width = 1200;
$new_height = // MUST BE AUTO;

// Resample
$image_p = imagecreatetruecolor($new_width, $new_height);
$image = imagecreatefromjpeg($filename);
imagecopyresampled($image_p, $image, 0, 0, 0, 0, $new_width, $new_height, $width, $height);

// Output
imagejpeg($image_p, null, 100);

Answer 1

你是这个意思吗？

// Get new dimensions
list($width, $height) = getimagesize($filename);
$new_width = 1200;
$new_height = ($height/$width)*$new_width;