type for styling group focus highlights from node, see #708

js/accessibility/FocusHighlightFromNode.js

@@ -28,16 +28,21 @@ define( function( require ) {
       // {boolean} - if true, highlight will surround local bounds
       useLocalBounds: false,
 
-      // {boolean} - if true, dilation for bounds around node will increase, see setShapeFromNode()
-      useGroupDilation: false,
-
       // line width options, one for each highlight, will be calculated based on transform of this path unless provided
       outerLineWidth: null,
-      innerLineWidth: null
+      innerLineWidth: null,
+
+      // {null|number] - default value is function of node transform (minus translation), but can be set explicitly
+      // see FocusHighlightPath.getDilationCoefficient()
+      dilationCoefficient: null,
+
+      // {boolean} - if true, dilation for bounds around node will increase, see setShapeFromNode()
+      useGroupDilation: false
     }, options );
 
     this.useLocalBounds = options.useLocalBounds; // @private
     this.useGroupDilation = options.useGroupDilation; // @private
+    this.dilationCoefficient = options.dilationCoefficient; // @private
 
     FocusHighlightPath.call( this, null, options );
 
@@ -65,8 +70,9 @@ define( function( require ) {
     setShapeFromNode: function( node ) {
       this.nodeBounds = this.useLocalBounds ? node.localBounds : node.bounds;
 
-      // Figure out how much dilation to apply to the focus highlight around the node
-      var dilationCoefficient = this.useGroupDilation ? FocusHighlightPath.getGroupDilationCoefficient( node ) : FocusHighlightPath.getDilationCoefficient( node );
+      // Figure out how much dilation to apply to the focus highlight around the node, calculated unless specified
+      // with options
+      var dilationCoefficient = this.dilationCoefficient || ( this.useGroupDilation ? FocusHighlightPath.getGroupDilationCoefficient( node ) : FocusHighlightPath.getDilationCoefficient( node ) );
       var dilatedBounds = this.nodeBounds.dilated( dilationCoefficient );
 
       // Update the line width of the focus highlight based on the transform of the node

js/accessibility/GroupFocusHighlightFromNode.js

@@ -0,0 +1,42 @@
+// Copyright 2017, University of Colorado Boulder
+
+/**
+ * A FocusHighlightPath subtype that is based around a Node, with styling that makes it look like a group focus
+ * highlight.
+ * 
+ * @author Jesse Greenberg (PhET Interactive Simulations)
+ */
+define( function( require ) {
+  'use strict';
+
+  // modules
+  var FocusHighlightFromNode = require( 'SCENERY/accessibility/FocusHighlightFromNode' );
+  var FocusHighlightPath = require( 'SCENERY/accessibility/FocusHighlightPath' );
+  var inherit = require( 'PHET_CORE/inherit' );
+  var scenery = require( 'SCENERY/scenery' );
+
+  /**
+   *
+   * @param {Node|null} node
+   * @param {Object} [options]
+   * @constructor
+   */
+  function GroupFocusHighlightFromNode( node, options ) {
+
+    options = _.extend( {
+      outerStroke: FocusHighlightPath.OUTER_LIGHT_GROUP_FOCUS_COLOR,
+      innerStroke: FocusHighlightPath.INNER_LIGHT_GROUP_FOCUS_COLOR,
+
+      outerLineWidth: FocusHighlightPath.GROUP_OUTER_LINE_WIDTH,
+      innerLineWidth: FocusHighlightPath.GROUP_INNER_LINE_WIDTH,
+
+      useGroupDilation: true
+    }, options );
+
+    FocusHighlightFromNode.call( this, node, options );
+  }
+
+  scenery.register( 'GroupFocusHighlightFromNode', GroupFocusHighlightFromNode );
+
+  return inherit( FocusHighlightFromNode, GroupFocusHighlightFromNode );
+} );