PHP Image Resizing Function

As speed is paramount to website efficiency, image re-sizing is a useful function for generating cached versions of images. The following allows you to define:-

• The source file (realpath)
• A destination filename (realpath)
• Maximum width (pixels)
• Maximum height (pixels)

It maintains the aspect ratio and automatically calibrates how to scale down high resolution images to the desired proportion.

	public function imageResize($source, $dest, $maxWidth, $maxHeight)
	{
	  $is = getimagesize($source);
	  $fw = (true || $is[0] >= $is[1]) ? $maxWidth : $maxHeight;
	  $fh = (true || $is[0] >= $is[1]) ? $maxHeight : $maxWidth;
	  $orientation = ($is[0] >= $is[1]) ? 0 : 1;

	  $iw = $is[0];
	  $ih = $is[1];
	  $t = 2;

	  if ($is[0] > $fw || $is[1] > $fh)
	  {
		if ($is[0] - $fw >= $is[1] - $fh)
		{
		  $iw = $fw;
		  $ih = ($fw / $is[0]) * $is[1];
		}
		else
		{
		  $ih = $fh;
		  $iw = ($ih / $is[1]) * $is[0];
		}

		$t = 1;
	  }

	  switch ($t)
	  {
		case 1:
		  $src = imagecreatefromjpeg($source);
		  $dst = imagecreatetruecolor( $iw, $ih );
		  imagecopyresampled($dst, $src, 0, 0, 0, 0, $iw, $ih, $is[0], $is[1]);
		  return imagejpeg($dst, $dest, 90);
		  break;
		case 2:
		  return copy($source, $dest);
		  break;
		default:
		  return false;
		  break;
	  }
	}