Initial work on Nucleus parity merge

Packages/ohif-viewerbase/client/lib/getStackDataIfNotEmpty.js

@@ -0,0 +1,22 @@
+import { getElementIfNotEmpty } from './getElementIfNotEmpty.js';
+
+export function getStackDataIfNotEmpty(viewportIndex) {
+    const element = getElementIfNotEmpty(viewportIndex);
+    if (!element) {
+        return;
+    }
+
+    const stackToolData = cornerstoneTools.getToolState(element, 'stack');
+    if (!stackToolData ||
+        !stackToolData.data ||
+        !stackToolData.data.length) {
+        return;
+    }
+
+    const stack = stackToolData.data[0];
+    if (!stack) {
+        return;
+    }
+
+    return stack;
+}