From b233ab957cd62aa253c863ff992027f024cd0c72 Mon Sep 17 00:00:00 2001
From: Nico Rehwaldt <nico.rehwaldt@camunda.com>
Date: Mon, 27 Apr 2015 16:50:09 +0200
Subject: [PATCH] feat(snapping): add bpmn-specific move snapping

This commit adds message flow + collaboration specific snapping by
subclassing the diagram-js provided default Snapping implementation.

* Add collaboration snapping
* Rename lib/util/{Name}.js -> lib/util/{Name}Util.js

Closes #255
---
 lib/Modeler.js                                |   1 -
 lib/draw/BpmnRenderer.js                      |   4 +-
 .../label-editing/LabelEditingProvider.js     |  29 ++--
 lib/features/modeling/BpmnLayouter.js         |   2 +-
 lib/features/modeling/BpmnUpdater.js          |  34 ++--
 lib/features/modeling/ElementFactory.js       |   2 +-
 lib/features/modeling/LabelSupport.js         |   2 +-
 lib/features/modeling/ModelingUtil.js         |  24 +--
 .../modeling/behavior/CreateBehavior.js       |   4 +-
 .../modeling/behavior/DropBehavior.js         |   2 +-
 .../modeling/behavior/RemoveBehavior.js       |   5 +-
 lib/features/modeling/rules/BpmnRules.js      |  10 +-
 lib/features/snapping/BpmnSnapping.js         | 150 ++++++++++++++++--
 lib/features/snapping/index.js                |   4 +-
 lib/import/BpmnImporter.js                    |   4 +-
 lib/util/Di.js                                |  16 --
 lib/util/DiUtil.js                            |  21 +++
 lib/util/{Label.js => LabelUtil.js}           |   0
 lib/util/ModelUtil.js                         |  31 ++++
 .../spec/features/modeling/AppendShapeSpec.js |   2 +-
 .../modeling/behavior/DropBehaviorSpec.js     |   2 +-
 21 files changed, 235 insertions(+), 114 deletions(-)
 delete mode 100644 lib/util/Di.js
 create mode 100644 lib/util/DiUtil.js
 rename lib/util/{Label.js => LabelUtil.js} (100%)
 create mode 100644 lib/util/ModelUtil.js

diff --git a/lib/Modeler.js b/lib/Modeler.js
index 507c52a5..8f78accb 100644
--- a/lib/Modeler.js
+++ b/lib/Modeler.js
@@ -64,7 +64,6 @@ Modeler.prototype._interactionModules = [
 Modeler.prototype._modelingModules = [
   // modeling components
   require('diagram-js/lib/features/keyboard'),
-  require('diagram-js/lib/features/snapping'),
   require('diagram-js/lib/features/move'),
   require('diagram-js/lib/features/bendpoints'),
   require('diagram-js/lib/features/resize'),
diff --git a/lib/draw/BpmnRenderer.js b/lib/draw/BpmnRenderer.js
index bbe20ff8..40077f89 100644
--- a/lib/draw/BpmnRenderer.js
+++ b/lib/draw/BpmnRenderer.js
@@ -11,7 +11,7 @@ var inherits = require('inherits'),
 
 var DefaultRenderer = require('diagram-js/lib/draw/Renderer'),
     TextUtil = require('diagram-js/lib/util/Text'),
-    DiUtil = require('../util/Di');
+    DiUtil = require('../util/DiUtil');
 
 var createLine = DefaultRenderer.createLine;
 
@@ -869,7 +869,7 @@ function BpmnRenderer(events, styles, pathMap) {
 
       var lane = renderer('bpmn:Lane')(p, element);
 
-      var expandedPool = DiUtil.isExpandedPool(getSemantic(element));
+      var expandedPool = DiUtil.isExpanded(element);
 
       if (expandedPool) {
         drawLine(p, [
diff --git a/lib/features/label-editing/LabelEditingProvider.js b/lib/features/label-editing/LabelEditingProvider.js
index 956bc06c..c046ff56 100644
--- a/lib/features/label-editing/LabelEditingProvider.js
+++ b/lib/features/label-editing/LabelEditingProvider.js
@@ -2,8 +2,10 @@
 
 var UpdateLabelHandler = require('./cmd/UpdateLabelHandler');
 
-var LabelUtil = require('./LabelUtil'),
-    DiUtil = require('../../util/Di');
+var LabelUtil = require('./LabelUtil');
+
+var is = require('../../util/ModelUtil').is,
+    isExpanded = require('../../util/DiUtil').isExpanded;
 
 
 var MIN_BOUNDS = {
@@ -46,11 +48,14 @@ function LabelEditingProvider(eventBus, canvas, directEditing, commandStack, inj
     eventBus.on('create.end', 500, function(e) {
 
       var element = e.shape,
-          businessObject = element.businessObject;
+          canExecute = e.context.canExecute;
 
-      if (businessObject.$instanceOf('bpmn:Task') ||
-          businessObject.$instanceOf('bpmn:TextAnnotation') ||
-          (businessObject.$instanceOf('bpmn:SubProcess') && !businessObject.di.isExpanded)) {
+      if (!canExecute) {
+        return;
+      }
+
+      if (is(element, 'bpmn:Task') || is(element, 'bpmn:TextAnnotation') ||
+          (is(element, 'bpmn:SubProcess') && !isExpanded(element))) {
 
         directEditing.activate(element);
       }
@@ -68,9 +73,6 @@ module.exports = LabelEditingProvider;
 
 LabelEditingProvider.prototype.activate = function(element) {
 
-  var semantic = element.businessObject,
-      di = semantic.di;
-
   var text = LabelUtil.getLabel(element);
 
   if (text === undefined) {
@@ -79,9 +81,8 @@ LabelEditingProvider.prototype.activate = function(element) {
 
   var bbox = this.getEditingBBox(element);
 
-  // adjust for expanded pools / lanes
-  if ((semantic.$instanceOf('bpmn:Participant') && DiUtil.isExpandedPool(semantic)) ||
-       semantic.$instanceOf('bpmn:Lane')) {
+  // adjust for expanded pools AND lanes
+  if ((is(element, 'bpmn:Participant') && isExpanded(element)) || is(element, 'bpmn:Lane')) {
 
     bbox.width = MIN_BOUNDS.width;
     bbox.height = MIN_BOUNDS.height;
@@ -90,8 +91,8 @@ LabelEditingProvider.prototype.activate = function(element) {
     bbox.y = bbox.mid.y - bbox.height / 2;
   }
 
-  // adjust for sub processes
-  if (semantic.$instanceOf('bpmn:SubProcess') && DiUtil.isExpanded(semantic, di)) {
+  // adjust for expanded sub processes
+  if (is(element, 'bpmn:SubProcess') && isExpanded(element)) {
 
     bbox.height = MIN_BOUNDS.height;
 
diff --git a/lib/features/modeling/BpmnLayouter.js b/lib/features/modeling/BpmnLayouter.js
index 7f50fae7..ecbf0507 100644
--- a/lib/features/modeling/BpmnLayouter.js
+++ b/lib/features/modeling/BpmnLayouter.js
@@ -8,7 +8,7 @@ var BaseLayouter = require('diagram-js/lib/layout/BaseLayouter'),
     LayoutUtil = require('diagram-js/lib/layout/LayoutUtil'),
     ManhattanLayout = require('diagram-js/lib/layout/ManhattanLayout');
 
-var is = require('./ModelingUtil').is;
+var is = require('../../util/ModelUtil').is;
 
 
 function BpmnLayouter() {}
diff --git a/lib/features/modeling/BpmnUpdater.js b/lib/features/modeling/BpmnUpdater.js
index b73bf175..29893111 100644
--- a/lib/features/modeling/BpmnUpdater.js
+++ b/lib/features/modeling/BpmnUpdater.js
@@ -1,12 +1,13 @@
 'use strict';
 
-var isArray = require('lodash/lang/isArray'),
-    assign = require('lodash/object/assign'),
-    forEach = require('lodash/collection/forEach');
+var assign = require('lodash/object/assign'),
+    inherits = require('inherits');
 
 var Collections = require('diagram-js/lib/util/Collections'),
     Model = require('diagram-js/lib/model');
 
+var CommandInterceptor = require('diagram-js/lib/command/CommandInterceptor');
+
 
 /**
  * A handler responsible for updating the underlying BPMN 2.0 XML + DI
@@ -14,7 +15,8 @@ var Collections = require('diagram-js/lib/util/Collections'),
  */
 function BpmnUpdater(eventBus, bpmnFactory, connectionDocking) {
 
-  this._eventBus = eventBus;
+  CommandInterceptor.call(this, eventBus);
+
   this._bpmnFactory = bpmnFactory;
 
   var self = this;
@@ -122,6 +124,8 @@ function BpmnUpdater(eventBus, bpmnFactory, connectionDocking) {
   ], updateConnectionWaypoints);
 }
 
+inherits(BpmnUpdater, CommandInterceptor);
+
 module.exports = BpmnUpdater;
 
 BpmnUpdater.$inject = [ 'eventBus', 'bpmnFactory', 'connectionDocking'];
@@ -330,24 +334,4 @@ BpmnUpdater.prototype._getLabel = function(di) {
   }
 
   return di.label;
-};
-
-BpmnUpdater.prototype.pre = function(commands, callback) {
-  this.on(commands, 'preExecute', callback);
-};
-
-BpmnUpdater.prototype.executed = function(commands, callback) {
-  this.on(commands, 'executed', callback);
-};
-
-BpmnUpdater.prototype.reverted = function(commands, callback) {
-  this.on(commands, 'reverted', callback);
-};
-
-BpmnUpdater.prototype.on = function(commands, suffix, callback) {
-  commands = isArray(commands) ? commands : [ commands ];
-
-  forEach(commands, function(c) {
-    this._eventBus.on('commandStack.' + c + '.' + suffix, callback);
-  }, this);
-};
+};
\ No newline at end of file
diff --git a/lib/features/modeling/ElementFactory.js b/lib/features/modeling/ElementFactory.js
index 8387acc5..b074b5d3 100644
--- a/lib/features/modeling/ElementFactory.js
+++ b/lib/features/modeling/ElementFactory.js
@@ -4,7 +4,7 @@ var assign = require('lodash/object/assign'),
     inherits = require('inherits');
 
 var BaseElementFactory = require('diagram-js/lib/core/ElementFactory'),
-    LabelUtil = require('../../util/Label');
+    LabelUtil = require('../../util/LabelUtil');
 
 
 /**
diff --git a/lib/features/modeling/LabelSupport.js b/lib/features/modeling/LabelSupport.js
index d4a913c0..dd6bf489 100644
--- a/lib/features/modeling/LabelSupport.js
+++ b/lib/features/modeling/LabelSupport.js
@@ -3,7 +3,7 @@
 var assign = require('lodash/object/assign'),
     forEach = require('lodash/collection/forEach');
 
-var LabelUtil = require('../../util/Label');
+var LabelUtil = require('../../util/LabelUtil');
 
 var hasExternalLabel = LabelUtil.hasExternalLabel,
     getExternalLabelMid = LabelUtil.getExternalLabelMid;
diff --git a/lib/features/modeling/ModelingUtil.js b/lib/features/modeling/ModelingUtil.js
index 426a8d59..7aeac50e 100644
--- a/lib/features/modeling/ModelingUtil.js
+++ b/lib/features/modeling/ModelingUtil.js
@@ -31,26 +31,4 @@ function getSharedParent(a, b) {
   });
 }
 
-module.exports.getSharedParent = getSharedParent;
-
-/**
- * Is an element of the given BPMN type?
- *
- * @param  {djs.model.Base|ModdleElement} element
- * @param  {String} type
- * @return {Boolean}
- */
-function is(element, type) {
-  var bo = getBusinessObject(element);
-
-  return bo && bo.$instanceOf(type);
-}
-
-module.exports.is = is;
-
-
-function getBusinessObject(element) {
-  return (element && element.businessObject) || element;
-}
-
-module.exports.getBusinessObject = getBusinessObject;
\ No newline at end of file
+module.exports.getSharedParent = getSharedParent;
\ No newline at end of file
diff --git a/lib/features/modeling/behavior/CreateBehavior.js b/lib/features/modeling/behavior/CreateBehavior.js
index f574d29e..0db1e246 100644
--- a/lib/features/modeling/behavior/CreateBehavior.js
+++ b/lib/features/modeling/behavior/CreateBehavior.js
@@ -4,6 +4,7 @@ var inherits = require('inherits');
 
 var CommandInterceptor = require('diagram-js/lib/command/CommandInterceptor');
 
+var is = require('../../../util/ModelUtil').is;
 
 /**
  * BPMN specific create behavior
@@ -24,8 +25,7 @@ function CreateBehavior(eventBus, modeling) {
         shape = context.shape,
         position = context.position;
 
-    if (parent.businessObject.$instanceOf('bpmn:Process') &&
-        shape.businessObject.$instanceOf('bpmn:Participant')) {
+    if (is(parent, 'bpmn:Process') && is(shape, 'bpmn:Participant')) {
 
       // this is going to detach the process root
       // and set the returned collaboration element
diff --git a/lib/features/modeling/behavior/DropBehavior.js b/lib/features/modeling/behavior/DropBehavior.js
index bbbae2e6..1a80dfdf 100644
--- a/lib/features/modeling/behavior/DropBehavior.js
+++ b/lib/features/modeling/behavior/DropBehavior.js
@@ -5,7 +5,7 @@ var forEach = require('lodash/collection/forEach'),
 
 var CommandInterceptor = require('diagram-js/lib/command/CommandInterceptor');
 
-var is = require('../ModelingUtil').is,
+var is = require('../../../util/ModelUtil').is,
     getSharedParent = require('../ModelingUtil').getSharedParent;
 
 
diff --git a/lib/features/modeling/behavior/RemoveBehavior.js b/lib/features/modeling/behavior/RemoveBehavior.js
index 99491d8c..f8a8455f 100644
--- a/lib/features/modeling/behavior/RemoveBehavior.js
+++ b/lib/features/modeling/behavior/RemoveBehavior.js
@@ -4,6 +4,9 @@ var inherits = require('inherits');
 
 var CommandInterceptor = require('diagram-js/lib/command/CommandInterceptor');
 
+var is = require('../../../util/ModelUtil').is;
+
+
 /**
  * BPMN specific remove behavior
  */
@@ -24,7 +27,7 @@ function RemoveBehavior(eventBus, modeling) {
 
     // activate the behavior if the shape to be removed
     // is a participant
-    if (shape.businessObject.$instanceOf('bpmn:Participant')) {
+    if (is(shape, 'bpmn:Participant')) {
       context.collaborationRoot = parent;
     }
   }, true);
diff --git a/lib/features/modeling/rules/BpmnRules.js b/lib/features/modeling/rules/BpmnRules.js
index 836b6563..7f721cb7 100644
--- a/lib/features/modeling/rules/BpmnRules.js
+++ b/lib/features/modeling/rules/BpmnRules.js
@@ -6,8 +6,9 @@ var groupBy = require('lodash/collection/groupBy'),
     inherits = require('inherits');
 
 var getParents = require('../ModelingUtil').getParents,
-    is = require('../ModelingUtil').is,
-    getBusinessObject = require('../ModelingUtil').getBusinessObject;
+    is = require('../../../util/ModelUtil').is,
+    getBusinessObject = require('../../../util/ModelUtil').getBusinessObject,
+    isExpanded = require('../../../util/DiUtil').isExpanded;
 
 
 var RuleProvider = require('diagram-js/lib/features/rules/RuleProvider');
@@ -164,11 +165,6 @@ function getScopeParent(element) {
   return bo;
 }
 
-function isExpanded(element) {
-  var bo = getBusinessObject(element);
-  return bo.di.isExpanded;
-}
-
 function isSameScope(a, b) {
   var scopeParentA = getScopeParent(a),
       scopeParentB = getScopeParent(b);
diff --git a/lib/features/snapping/BpmnSnapping.js b/lib/features/snapping/BpmnSnapping.js
index 685937a2..a630ea5a 100644
--- a/lib/features/snapping/BpmnSnapping.js
+++ b/lib/features/snapping/BpmnSnapping.js
@@ -1,7 +1,23 @@
 'use strict';
 
+var inherits = require('inherits');
+
+var forEach = require('lodash/collection/forEach');
+
 var getBoundingBox = require('diagram-js/lib/util/Elements').getBBox;
 
+var Snapping = require('diagram-js/lib/features/snapping/Snapping'),
+    SnapUtil = require('diagram-js/lib/features/snapping/SnapUtil');
+
+var is = require('../../util/ModelUtil').is;
+
+var mid = SnapUtil.mid,
+    topLeft = SnapUtil.topLeft,
+    bottomRight = SnapUtil.bottomRight;
+
+var round = Math.round;
+
+
 /**
  * BPMN specific snapping functionality
  *
@@ -13,8 +29,12 @@ var getBoundingBox = require('diagram-js/lib/util/Elements').getBBox;
  */
 function BpmnSnapping(eventBus, canvas) {
 
+  // instantiate super
+  Snapping.call(this, eventBus, canvas);
+
+
   /**
-   * Drop articipant on process <> process elements snapping
+   * Drop participant on process <> process elements snapping
    */
 
   function initParticipantSnapping(context, shape, elements) {
@@ -55,27 +75,24 @@ function BpmnSnapping(eventBus, canvas) {
     };
 
     var snapTopLeft = snapBox,
-        snapBottomRight = {
-          x: snapBox.x + snapBox.width,
-          y: snapBox.y + snapBox.height
-        };
+        snapBottomRight = bottomRight(snapBox);
 
     if (currentTopLeft.x >= snapTopLeft.x) {
       event.x = snapTopLeft.x + 30 + shapeHalfWidth;
-      event.snapping = true;
+      event.snapped = true;
     } else
     if (currentBottomRight.x <= snapBottomRight.x) {
       event.x = snapBottomRight.x - 30 - shapeHalfWidth;
-      event.snapping = true;
+      event.snapped = true;
     }
 
     if (currentTopLeft.y >= snapTopLeft.y) {
       event.y = snapTopLeft.y + shapeHalfHeight;
-      event.snapping = true;
+      event.snapped = true;
     } else
     if (currentBottomRight.y <= snapBottomRight.y) {
       event.y = snapBottomRight.y - shapeHalfHeight;
-      event.snapping = true;
+      event.snapped = true;
     }
   }
 
@@ -86,8 +103,7 @@ function BpmnSnapping(eventBus, canvas) {
         rootElement = canvas.getRootElement();
 
     // snap participant around existing elements (if any)
-    if (shape.businessObject.$instanceOf('bpmn:Participant') &&
-        rootElement.businessObject.$instanceOf('bpmn:Process')) {
+    if (is(shape, 'bpmn:Participant') && is(rootElement, 'bpmn:Process')) {
 
       initParticipantSnapping(context, shape, rootElement.children);
     }
@@ -99,12 +115,120 @@ function BpmnSnapping(eventBus, canvas) {
         shape = context.shape,
         participantSnapBox = context.participantSnapBox;
 
-    if (!event.snapping && participantSnapBox) {
+    if (!event.snapped && participantSnapBox) {
       snapParticipant(participantSnapBox, shape, event);
     }
   });
 }
 
+inherits(BpmnSnapping, Snapping);
+
 BpmnSnapping.$inject = [ 'eventBus', 'canvas' ];
 
-module.exports = BpmnSnapping;
\ No newline at end of file
+module.exports = BpmnSnapping;
+
+
+BpmnSnapping.prototype.initSnap = function(event) {
+
+  var context = event.context,
+      shape = context.shape,
+      shapeMid,
+      shapeBounds,
+      shapeTopLeft,
+      shapeBottomRight,
+      snapContext;
+
+
+  snapContext = Snapping.prototype.initSnap.call(this, event);
+
+  if (is(shape, 'bpmn:Participant')) {
+    // assign higher priority for outer snaps on participants
+    snapContext.setSnapLocations([ 'top-left', 'bottom-right', 'mid' ]);
+  }
+
+
+  if (shape) {
+
+    shapeMid = mid(shape, event);
+
+    shapeBounds = {
+      width: shape.width,
+      height: shape.height,
+      x: isNaN(shape.x) ? round(shapeMid.x - shape.width / 2) : shape.x,
+      y: isNaN(shape.y) ? round(shapeMid.y - shape.height / 2) : shape.y,
+    };
+
+    shapeTopLeft = topLeft(shapeBounds);
+    shapeBottomRight = bottomRight(shapeBounds);
+
+    snapContext.setSnapOrigin('top-left', {
+      x: shapeTopLeft.x - event.x,
+      y: shapeTopLeft.y - event.y
+    });
+
+    snapContext.setSnapOrigin('bottom-right', {
+      x: shapeBottomRight.x - event.x,
+      y: shapeBottomRight.y - event.y
+    });
+
+
+    forEach(shape.outgoing, function(c) {
+      var docking = c.waypoints[0];
+
+      docking = docking.original || docking;
+
+      snapContext.setSnapOrigin(c.id + '-docking', {
+        x: docking.x - event.x,
+        y: docking.y - event.y
+      });
+    });
+
+    forEach(shape.incoming, function(c) {
+      var docking = c.waypoints[c.waypoints.length - 1];
+
+      docking = docking.original || docking;
+
+      snapContext.setSnapOrigin(c.id + '-docking', {
+        x: docking.x - event.x,
+        y: docking.y - event.y
+      });
+    });
+  }
+};
+
+
+BpmnSnapping.prototype.addTargetSnaps = function(snapPoints, shape, target) {
+
+  var siblings = this.getSiblings(shape, target);
+
+
+  forEach(siblings, function(s) {
+    snapPoints.add('mid', mid(s));
+
+    if (is(s, 'bpmn:Participant')) {
+      snapPoints.add('top-left', topLeft(s));
+      snapPoints.add('bottom-right', bottomRight(s));
+    }
+  });
+
+  forEach(shape.incoming, function(c) {
+
+    if (siblings.indexOf(c.source) === -1) {
+      snapPoints.add('mid', mid(c.source));
+
+      var docking = c.waypoints[0];
+      snapPoints.add(c.id + '-docking', docking.original || docking);
+    }
+  });
+
+
+  forEach(shape.outgoing, function(c) {
+
+    if (siblings.indexOf(c.target) === -1) {
+      snapPoints.add('mid', mid(c.target));
+
+      var docking = c.waypoints[c.waypoints.length - 1];
+      snapPoints.add(c.id + '-docking', docking.original || docking);
+    }
+  });
+};
\ No newline at end of file
diff --git a/lib/features/snapping/index.js b/lib/features/snapping/index.js
index 0cef69b0..cbe1b135 100644
--- a/lib/features/snapping/index.js
+++ b/lib/features/snapping/index.js
@@ -1,4 +1,4 @@
 module.exports = {
-  __init__: [ 'bpmnSnapping' ],
-  bpmnSnapping: [ 'type', require('./BpmnSnapping') ]
+  __init__: [ 'snapping' ],
+  snapping: [ 'type', require('./BpmnSnapping') ]
 };
\ No newline at end of file
diff --git a/lib/import/BpmnImporter.js b/lib/import/BpmnImporter.js
index 3fba3152..be3c5c10 100644
--- a/lib/import/BpmnImporter.js
+++ b/lib/import/BpmnImporter.js
@@ -3,11 +3,11 @@
 var assign = require('lodash/object/assign'),
     map = require('lodash/collection/map');
 
-var LabelUtil = require('../util/Label');
+var LabelUtil = require('../util/LabelUtil');
 
 var hasExternalLabel = LabelUtil.hasExternalLabel,
     getExternalLabelBounds = LabelUtil.getExternalLabelBounds,
-    isExpanded = require('../util/Di').isExpanded,
+    isExpanded = require('../util/DiUtil').isExpanded,
     elementToString = require('./Util').elementToString;
 
 
diff --git a/lib/util/Di.js b/lib/util/Di.js
deleted file mode 100644
index cfc6d3d4..00000000
--- a/lib/util/Di.js
+++ /dev/null
@@ -1,16 +0,0 @@
-'use strict';
-
-module.exports.isExpandedPool = function(semantic) {
-  return !!semantic.processRef;
-};
-
-module.exports.isExpanded = function(semantic) {
-
-  // Is type expanded by default?
-  var isDefaultExpanded = !(semantic.$instanceOf('bpmn:SubProcess') || semantic.$instanceOf('bpmn:CallActivity'));
-
-  // For non default expanded types -> evaluate the expanded flag
-  var isExpanded = isDefaultExpanded || semantic.di.isExpanded;
-
-  return isExpanded;
-};
diff --git a/lib/util/DiUtil.js b/lib/util/DiUtil.js
new file mode 100644
index 00000000..09453978
--- /dev/null
+++ b/lib/util/DiUtil.js
@@ -0,0 +1,21 @@
+'use strict';
+
+var is = require('./ModelUtil').is,
+    getBusinessObject = require('./ModelUtil').getBusinessObject;
+
+module.exports.isExpanded = function(element) {
+
+  if (is(element, 'bpmn:CallActivity')) {
+    return false;
+  }
+
+  if (is(element, 'bpmn:SubProcess')) {
+    return getBusinessObject(element).di.isExpanded;
+  }
+
+  if (is(element, 'bpmn:Participant')) {
+    return !!getBusinessObject(element).processRef;
+  }
+
+  return true;
+};
diff --git a/lib/util/Label.js b/lib/util/LabelUtil.js
similarity index 100%
rename from lib/util/Label.js
rename to lib/util/LabelUtil.js
diff --git a/lib/util/ModelUtil.js b/lib/util/ModelUtil.js
new file mode 100644
index 00000000..7dc0056d
--- /dev/null
+++ b/lib/util/ModelUtil.js
@@ -0,0 +1,31 @@
+'use strict';
+
+/**
+ * Is an element of the given BPMN type?
+ *
+ * @param  {djs.model.Base|ModdleElement} element
+ * @param  {String} type
+ *
+ * @return {Boolean}
+ */
+function is(element, type) {
+  var bo = getBusinessObject(element);
+
+  return bo && bo.$instanceOf(type);
+}
+
+module.exports.is = is;
+
+
+/**
+ * Return the business object for a given element.
+ *
+ * @param  {djs.model.Base|ModdleElement} element
+ *
+ * @return {ModdleElement}
+ */
+function getBusinessObject(element) {
+  return (element && element.businessObject) || element;
+}
+
+module.exports.getBusinessObject = getBusinessObject;
diff --git a/test/spec/features/modeling/AppendShapeSpec.js b/test/spec/features/modeling/AppendShapeSpec.js
index 138fac96..cb0cd2e8 100644
--- a/test/spec/features/modeling/AppendShapeSpec.js
+++ b/test/spec/features/modeling/AppendShapeSpec.js
@@ -10,7 +10,7 @@ var modelingModule = require('../../../../lib/features/modeling'),
     coreModule = require('../../../../lib/core');
 
 
-var LabelUtil = require('../../../../lib/util/Label');
+var LabelUtil = require('../../../../lib/util/LabelUtil');
 
 
 describe('features/modeling - append shape', function() {
diff --git a/test/spec/features/modeling/behavior/DropBehaviorSpec.js b/test/spec/features/modeling/behavior/DropBehaviorSpec.js
index 5336d902..cd5753f8 100644
--- a/test/spec/features/modeling/behavior/DropBehaviorSpec.js
+++ b/test/spec/features/modeling/behavior/DropBehaviorSpec.js
@@ -4,7 +4,7 @@ var TestHelper = require('../../../../TestHelper');
 
 /* global bootstrapModeler, inject */
 
-var is = require('../../../../../lib/features/modeling/ModelingUtil').is,
+var is = require('../../../../../lib/util/ModelUtil').is,
     find = require('lodash/collection/find');
 
 var modelingModule = require('../../../../../lib/features/modeling'),