feat(snapping): lanes only snap to themselves

lib/features/snapping/BpmnResizeSnapping.js

@@ -0,0 +1,55 @@
+import inherits from 'inherits';
+
+import ResizeSnapping from 'diagram-js/lib/features/snapping/ResizeSnapping';
+
+import { is } from '../../util/ModelUtil';
+
+import {
+  bottomLeft,
+  bottomRight,
+  topLeft,
+  topRight
+} from 'diagram-js/lib/features/snapping/SnapUtil';
+
+
+export default function BpmnResizeSnapping(injector) {
+  injector.invoke(ResizeSnapping, this);
+}
+
+inherits(BpmnResizeSnapping, ResizeSnapping);
+
+BpmnResizeSnapping.$inject = [ 'injector' ];
+
+BpmnResizeSnapping.prototype.addSnapTargetPoints = function(snapPoints, shape, target, direction) {
+  if (is(shape, 'bpmn:Lane')) {
+    return addLaneSnapPoints(shape, direction, snapPoints);
+  }
+
+  return ResizeSnapping.prototype.addSnapTargetPoints.call(this, snapPoints, shape, target, direction);
+};
+
+
+// helpers //////////
+
+/**
+ * Add snap points when resizing lane. Lanes only snap to themselves.
+ *
+ * @param {djs.model.shape} lane
+ * @param {string} direction
+ * @param {Object} snapPoints
+ *
+ * @returns {Object}
+ */
+function addLaneSnapPoints(lane, direction, snapPoints) {
+  if (direction === 'nw' || direction === 'n' || direction === 'w') {
+    snapPoints.add('corner', topLeft(lane));
+  } else if (direction === 'se' || direction === 's' || direction === 'e') {
+    snapPoints.add('corner', bottomRight(lane));
+  } else if (direction === 'ne') {
+    snapPoints.add('corner', topRight(lane));
+  } else if (direction === 'sw') {
+    snapPoints.add('corner', bottomLeft(lane));
+  }
+
+  return snapPoints;
+}

lib/features/snapping/index.js

@@ -1,5 +1,6 @@
 import BpmnConnectSnapping from './BpmnConnectSnapping';
 import BpmnCreateMoveSnapping from './BpmnCreateMoveSnapping';
+import BpmnResizeSnapping from './BpmnResizeSnapping';
 import SnappingModule from 'diagram-js/lib/features/snapping';
 
 export default {
@@ -9,5 +10,6 @@ export default {
     'createMoveSnapping'
   ],
   connectSnapping: [ 'type', BpmnConnectSnapping ],
-  createMoveSnapping: [ 'type', BpmnCreateMoveSnapping ]
+  createMoveSnapping: [ 'type', BpmnCreateMoveSnapping ],
+  resizeSnapping: [ 'type', BpmnResizeSnapping ]
 };