Output external image with cURL, but how do you change the width of the image?

问题

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?

回答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;
}

来源：https://stackoverflow.com/questions/5069286/output-external-image-with-curl-but-how-do-you-change-the-width-of-the-image