PHP imagecreate() PNG from any commonly used file-format?

Question

I currently have an image upload input that only accepts PNG, JPG/JPEG, GIF images. If the file is valid, it then proceeds to create a thumbnail from the image using

imagecreatefrompng()
imagecopy()
imagejpg()

This works fine, but ONLY for png images, obviously.

What is the most logical and efficient way to use "imagecreatefrompng()" except using the proper file format that was submitted? All I can think of is if/else using multiple "imagecreatefrom__()" but that doesn't seem right.

Also, how can my outputted format always be PNG no matter what was submitted instead of the current imagejpg() I have now.

Answer 1

You will have to use a switch and determine the image type like so:

    $extension = strtolower(strrchr($file, '.'));

    switch ($extension) {
        case '.jpg':
        case '.jpeg':
            $img = @imagecreatefromjpeg($file);
            break;
        case '.gif':
            $img = @imagecreatefromgif($file);
            break;
        case '.png':
            $img = @imagecreatefrompng($file);
            break;
        default:
            $img = false;
            break;
    }

-EDIT- Didn't see the second part of your question, you just need to save it using imagepng to save it to a PNG, no need to do anything else.