code: function() {
          return !(this.style && this.style.display == 'none' ||
                   !this.layer ||
                   this.layer && this.layer.styleMap &&
                   this.layer.styleMap.createSymbolizer(this, this.renderIntent).display == 'none' ||
                   this.layer && !this.layer.getVisibility());
      }
docs: Method: getVisibility
  Determine whether the feature is displayed or not. It may not displayed
  because:
  - its style display property is set to 'none',
  - it doesn't belong to any layer,
  - the styleMap creates a symbolizer with display property set to 'none'
  for it,
  - the layer which it belongs to is not visible.
  
  Returns:
  {Boolean} The feature is currently displayed.