/** * Get the canvas * * @return Image_Canvas The canvas * @access private */ function &_getCanvas() { if ($this->_canvas !== null || $this->_canvas !== false) { return $this->_canvas; } elseif (is_a($this->_parent, 'Image_Graph_Common')) { $this->_canvas =& $this->_parent->_getCanvas(); return $this->_canvas; } else { $this->_error('Invalid canvas'); $result = null; return $result; } }