How do I resize and convert an uploaded image to a PNG using GD?

Question

I want to allow users to upload avatar-type images in a variety of formats (GIF, JPEG, and PNG at least), but to save them all as PNG database BLOBs

Answer 1

Something like this, perhaps:

 $max_width ) { 
      $percentage = ($height / ($width / $max_width)) > $max_height ?
           $height / $max_height :
           $width / $max_width;
   }
   elseif ( $height > $max_height) {
      $percentage = ($width / ($height / $max_height)) > $max_width ? 
           $width / $max_width :
           $height / $max_height;
   }
   $new_width = $width / $percentage;
   $new_height = $height / $percentage;

   //scaled image
   $out = imagecreatetruecolor($new_width, $new_height);
   imagecopyresampled($out, $img, 0, 0, 0, 0, $new_width, $new_height, $width, $height);

   //output image
   imagepng($out);
?>

I haven't tested the code so there might be some syntax errors, however it should give you a fair presentation on how it could be done. Also, I assumed a PNG file. You might want to have some kind of switch statement to determine the file type.