code: public function getViewBox(){
  
  		if(!empty($this->xmlDocument['viewBox'])){
  
  			$viewBox = $this->getValuesFromList($this->xmlDocument['viewBox']);
  			if(count($viewBox) !== 4){
  				return null;
  			}
  			return array(
  				'x' => $viewBox[0]*1,
  				'y' => $viewBox[1]*1,
  				'width' => $viewBox[2]*1,
  				'height' => $viewBox[3]*1,
  			);
  
  		}
  
  		if(!empty($this->xmlDocument['width']) && !empty($this->xmlDocument['height'])){
  
  			$width = trim($this->xmlDocument['width']);
  			$height = trim($this->xmlDocument['height']);
  			if(isset($this->unitInPixels[substr($width, -2)])){
  				$width = $width*$this->unitInPixels[substr($width, -2)];
  			}
  			if(isset($this->unitInPixels[substr($height, -2)])){
  				$height = $height*$this->unitInPixels[substr($height, -2)];
  			}
  			return array(
  				'x' => 0,
  				'y' => 0,
  				'width' => $width*1,
  				'height' => $height*1,
  			);
  
  		}
  
  		return null;
  
  	}
docs: returns an viewbox array containing x/y offsets and with/height
  
  @return array|null array with x,y,width,height values