feat(Segments Looping) : Fixed looping through Segments of SEG (#4793)

extensions/cornerstone/src/utils/index.ts

@@ -0,0 +1,7 @@
+import { handleSegmentChange } from './segmentUtils';
+
+const utils = {
+  handleSegmentChange,
+};
+
+export default utils;

extensions/cornerstone/src/utils/segmentUtils.ts

@@ -0,0 +1,47 @@
+import SegmentationServiceType from '../services/SegmentationService';
+
+export const handleSegmentChange = ({
+  direction,
+  segDisplaySet,
+  viewportId,
+  selectedSegmentObjectIndex,
+  segmentationService,
+}: {
+  direction: number;
+  segDisplaySet: AppTypes.DisplaySet;
+  viewportId: string;
+  selectedSegmentObjectIndex: number;
+  segmentationService: SegmentationServiceType;
+}) => {
+  const segmentationId = segDisplaySet.displaySetInstanceUID;
+  const segmentation = segmentationService.getSegmentation(segmentationId);
+
+  const { segments } = segmentation;
+
+  const numberOfSegments = Object.keys(segments).length;
+
+  // Get activeSegment each time because the user can select any segment from the list and thus the index should be updated
+  const activeSegment = segmentationService.getActiveSegment(viewportId);
+  if (activeSegment) {
+    // from the activeSegment get the actual object array index to be used
+    selectedSegmentObjectIndex = Object.values(segments).findIndex(
+      segment => segment.segmentIndex === activeSegment.segmentIndex
+    );
+  }
+  let newSelectedSegmentIndex = selectedSegmentObjectIndex + direction;
+
+  // Handle looping through list of segments
+  if (newSelectedSegmentIndex > numberOfSegments - 1) {
+    newSelectedSegmentIndex = 0;
+  } else if (newSelectedSegmentIndex < 0) {
+    newSelectedSegmentIndex = numberOfSegments - 1;
+  }
+
+  // Convert segmentationId from object array index to property value of type Segment
+  // Functions below use the segmentIndex object attribute so we have to do the conversion
+  const segmentIndex = Object.values(segments)[newSelectedSegmentIndex]?.segmentIndex;
+
+  segmentationService.setActiveSegment(segmentationId, segmentIndex);
+  segmentationService.jumpToSegmentCenter(segmentationId, segmentIndex, viewportId);
+  selectedSegmentObjectIndex = newSelectedSegmentIndex;
+};