SDM-5545: when loading preview images, the spinner in only added once

openbis_standard_technologies/dist/core-plugins/eln-lims/1/as/webapps/eln-lims/html/js/views/DataSetForm/widgets/ImagePreviewIconLoader.js

@@ -34,7 +34,7 @@ function ImagePreviewIconLoader() {
     }
 
     this._shouldLoadPreview = function(node) {
-        return ! node.data.previewLoaded && node.data.fileSize <= profile.datasetViewerMaxFilesizeForImagePreview;
+        return ! node.data.previewLoading && ! node.data.previewLoaded && node.data.fileSize <= profile.datasetViewerMaxFilesizeForImagePreview;
     }
 
     this._addToQueue = function(node) {
@@ -89,6 +89,8 @@ function ImagePreviewIconLoader() {
      */
     this._loadImagePreview = function(params) {
 
+        params.node.data.previewLoading = true;
+
         var $span = $(params.node.span);
         var $imageContainer = $span.children("#image-container");
         
@@ -122,6 +124,7 @@ function ImagePreviewIconLoader() {
             $imageContainer.append($iconImg);
 
             params.node.data.previewLoaded = true;
+            params.node.data.previewLoading = false;
             params.done();
         });
     }