Initial work on Nucleus parity merge

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

@@ -0,0 +1,27 @@
+import { $ } from 'meteor/jquery';
+
+export function getElementIfNotEmpty(viewportIndex) {
+    // Meteor template helpers run more often than expected
+    // They often seem to run just before the whole template is rendered
+    // This meant that the onRendered event hadn't fired yet, so the
+    // element wasn't enabled / set empty yet. The check here
+    // for canvases under the 'enabled' element div is to prevent
+    // 'undefined' errors from the helper functions
+
+    var imageViewerViewports = $('.imageViewerViewport'),
+        element = imageViewerViewports.get(viewportIndex),
+        canvases = imageViewerViewports.eq(viewportIndex).find('canvas');
+
+    if (!element || $(element).hasClass('empty') || canvases.length === 0) {
+        return;
+    }
+
+    // Check to make sure the element is enabled.
+    try {
+        var enabledElement = cornerstone.getEnabledElement(element);
+    } catch(error) {
+        return;
+    }
+
+    return element;
+}