Resize image in PHP

Question

I\'m wanting to write some PHP code which automatically resizes any image uploaded via a form to 147x147px, but I have no idea how to go about it (I\'m a relative PHP novice

Answer 1

Here is an extended version of the answer @Ian Atkin' gave. I found it worked extremely well. For larger images that is :). You can actually make smaller images larger if you're not careful. Changes: - Supports jpg,jpeg,png,gif,bmp files - Preserves transparency for .png and .gif - Double checks if the the size of the original isnt already smaller - Overrides the image given directly (Its what I needed)

So here it is. The default values of the function are the "golden rule"

function resize_image($file, $w = 1200, $h = 741, $crop = false)
   {
       try {
           $ext = pathinfo(storage_path() . $file, PATHINFO_EXTENSION);
           list($width, $height) = getimagesize($file);
           // if the image is smaller we dont resize
           if ($w > $width && $h > $height) {
               return true;
           }
           $r = $width / $height;
           if ($crop) {
               if ($width > $height) {
                   $width = ceil($width - ($width * abs($r - $w / $h)));
               } else {
                   $height = ceil($height - ($height * abs($r - $w / $h)));
               }
               $newwidth = $w;
               $newheight = $h;
           } else {
               if ($w / $h > $r) {
                   $newwidth = $h * $r;
                   $newheight = $h;
               } else {
                   $newheight = $w / $r;
                   $newwidth = $w;
               }
           }
           $dst = imagecreatetruecolor($newwidth, $newheight);

           switch ($ext) {
               case 'jpg':
               case 'jpeg':
                   $src = imagecreatefromjpeg($file);
                   break;
               case 'png':
                   $src = imagecreatefrompng($file);
                   imagecolortransparent($dst, imagecolorallocatealpha($dst, 0, 0, 0, 127));
                   imagealphablending($dst, false);
                   imagesavealpha($dst, true);
                   break;
               case 'gif':
                   $src = imagecreatefromgif($file);
                   imagecolortransparent($dst, imagecolorallocatealpha($dst, 0, 0, 0, 127));
                   imagealphablending($dst, false);
                   imagesavealpha($dst, true);
                   break;
               case 'bmp':
                   $src = imagecreatefrombmp($file);
                   break;
               default:
                   throw new Exception('Unsupported image extension found: ' . $ext);
                   break;
           }
           $result = imagecopyresampled($dst, $src, 0, 0, 0, 0, $newwidth, $newheight, $width, $height);
           switch ($ext) {
               case 'bmp':
                   imagewbmp($dst, $file);
                   break;
               case 'gif':
                   imagegif($dst, $file);
                   break;
               case 'jpg':
               case 'jpeg':
                   imagejpeg($dst, $file);
                   break;
               case 'png':
                   imagepng($dst, $file);
                   break;
           }
           return true;
       } catch (Exception $err) {
           // LOG THE ERROR HERE 
           return false;
       }
   }