<?php

resize_image('myImg.png', 150, 150);

function resize_image($src_name, $w, $h)
{

    $src = imagecreatefrompng($src_name);

    // Getting som imageinfo
    list($width, $height, $image_type) = getimagesize($src_name);

    // keeping the ratio
    if($height > $width)    {
        $ratio = $h / $height;

        $new_width = $width * $ratio;
        $new_height = $height * $ratio;
    }
    else {
        $ratio = $w / $width;

        $new_width = $width * $ratio;
        $new_height = $height * $ratio;
    }

    // Creates a temp-image
    $temp = imagecreatetruecolor($new_width, $new_height);
    // Stängar av alphablendnig för att kunna spara alphakanalen
    imagealphablending($temp, false);

    // Fixar filnamn
    $newName = explode('.', $src_name);
    $newName = 'images/'.$newName[0];
    $newName .= '.png'; // Saves png

    // resizing
    imagecopyresampled($temp, $src, 0, 0, 0, 0, $new_width, $new_height, $width, $height);
    // Activates the alpha-channel
    imagesavealpha($temp, true);
    // Saves the image
    imagepng($temp, $newName);

    // destroy the objects
    imagedestroy($src);
    imagedestroy($temp);
}

?>