PHP - create thumbnail image from url

Question

I need a way (using built-in PHP libs) to pull down an image from URL and save it to local disk with resized/scaled WIDTH to 150px. I have been trying this:

Creating a thumbnail from an uploaded image

function makeThumbnails($updir, $img, $id)
{
    $thumbnail_width = 134;
    $thumbnail_height = 189;
    $thumb_beforeword = "thumb";
    $arr_image_details = getimagesize("$updir" . $id . '_' . "$img"); // pass id to thumb name
    $original_width = $arr_image_details[0];
    $original_height = $arr_image_details[1];
    if ($original_width > $original_height) {
        $new_width = $thumbnail_width;
        $new_height = intval($original_height * $new_width / $original_width);
    } else {
        $new_height = $thumbnail_height;
        $new_width = intval($original_width * $new_height / $original_height);
    }
    $dest_x = intval(($thumbnail_width - $new_width) / 2);
    $dest_y = intval(($thumbnail_height - $new_height) / 2);
    if ($arr_image_details[2] == 1) {
        $imgt = "ImageGIF";
        $imgcreatefrom = "ImageCreateFromGIF";
    }
    if ($arr_image_details[2] == 2) {
        $imgt = "ImageJPEG";
        $imgcreatefrom = "ImageCreateFromJPEG";
    }
    if ($arr_image_details[2] == 3) {
        $imgt = "ImagePNG";
        $imgcreatefrom = "ImageCreateFromPNG";
    }
    if ($imgt) {
        $old_image = $imgcreatefrom("$updir" . $id . '_' . "$img");
        $new_image = imagecreatetruecolor($thumbnail_width, $thumbnail_height);
        imagecopyresized($new_image, $old_image, $dest_x, $dest_y, 0, 0, $new_width, $new_height, $original_width, $original_height);
        $imgt($new_image, "$updir" . $id . '_' . "$thumb_beforeword" . "$img");
    }
}

That looks very promising but I can't figure out how to use it, and then whether it will do what I want. Concerns/needs:

1. What do these params mean: ($updir, $img, $id) -- Is $updir the location of the file? Or the location where I want it saved? Is $img a file handle or the name of the file? Or the new name of the file? What is $id for? The author didn't give any sample usage.
2. The function seems to require me to specify WIDTH and HEIGHT. I only want to specify WIDTH and let the height be proportional.
3. I need to pull images over 2 different types of URL: (1) The basic http://foo..., and (2) the data syntax: data:image/jpeg;base64,/9j/4AAQ....
4. Ideally I'd like to convert these images in all cases down to a compressed jpeg thumbnail (150px width, any height), even if the original image was not in jpg format.

What's the best way to accomplish this?

Answer 1

Just do this:

function Thumbnail($url, $filename, $width = 150, $height = true) {

 // download and create gd image
 $image = ImageCreateFromString(file_get_contents($url));

 // calculate resized ratio
 // Note: if $height is set to TRUE then we automatically calculate the height based on the ratio
 $height = $height === true ? (ImageSY($image) * $width / ImageSX($image)) : $height;

 // create image 
 $output = ImageCreateTrueColor($width, $height);
 ImageCopyResampled($output, $image, 0, 0, 0, 0, $width, $height, ImageSX($image), ImageSY($image));

 // save image
 ImageJPEG($output, $filename, 95); 

 // return resized image
 return $output; // if you need to use it
}

Use it like this:

Thumbnail("http://cdn.cutestpaw.com/wp-content/uploads/2013/01/l-Cute-Kitten.jpg", "kitten.jpg");

The trick here is to use PHP's internal automatic file detection for the incoming stream which is very good handled by ImageCreateFromString