使用cURL输出外部图像，但是如何更改图像的宽度？

Question

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

$url = $_GET['url']; 

$ch = curl_init(); 

curl_setopt($ch, CURLOPT_URL, $url); 
curl_setopt($ch, CURLOPT_CONNECTTIMEOUT, 0); 
curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1); 
curl_setopt($ch, CURLOPT_BINARYTRANSFER, 1); 

$file = curl_exec($ch); 

curl_close($ch);

echo $file;

Can anyone please tell me how I can change the width of $file to 300px?

Answer 1

If the image is heading for a browser inside an <img> tag, then you can get the browser to rescale it by changing the width attribute.

Otherwise you need to grab the file and rescale it in your PHP code before outputting it.

You can use imagecopyresampled() to do that, calculating the height. Then outputting the result.

Example, following on from obtaining the image in to $file from the code above.

$img = @imagecreatefromstring($file);

if ($img === false) {
    echo $file;
    exit;
}

$width = imagesx($img);
$height = imagesy($img);

$newWidth = 300;

$ratio = $newWidth / $width;
$newHeight = $ratio * $height;


$resized = @imagecreatetruecolor($newWidth, $newHeight);

if ($resized === false) {
    echo $file;
    exit;
}

$quality = 90;

if (@imagecopyresampled($resized, $img, 0, 0, 0, 0, $newWidth, $newHeight, $width, $height)) {
    @imagejpeg($resized, NULL, $quality);
} else {
    echo $file;
}