update README and conditional logic for traces

Author: aulneau

README.md

@@ -158,6 +158,7 @@ All Fields except `<Info />` accept an `attr` property to bind them to a key in
 
 * `<TraceAccordion />`: `<Panel />` whose children are replicated into `<Folds />` connected to traces via `connectTraceToPlot()`.
 * `<LayoutPanel />`: `<Panel />` whose children are connected to the `layout` figure key
+* `<TraceRequiredPanel />`: `<LayoutPanel />` renders `<PanelEmpty />` if no trace data is set
 * `<AnnotationAccordion />`: `<Panel />` whose children are replicated into `<Folds />` connected to annotations via `connectAnnotationToLayout()`. For use in a `<LayoutPanel />`.
 * `<AxesFold />`: `<Fold />` whose children are bound to axis-specific keys. For use in a `<LayoutPanel />` in concert with `<AxesSelector />` (see below).
 * `<TraceMarkerSection />`: `<Section />` with trace-specific name handling. For use in containers bound to traces e.g. as children of `<TraceAccordion />`.

src/components/containers/TraceRequiredPanel.js

@@ -22,18 +22,14 @@ class TraceRequiredPanel extends Component {
       /**
        * Check if there is any trace data
        */
-      if (fullData.filter(trace => trace.visible).length === 0) {
-        if (hasTraces) {
-          this.setState({
-            hasTraces: false,
-          });
-        }
+      if (fullData.filter(trace => trace.visible).length === 0 && hasTraces) {
+        this.setState({
+          hasTraces: false,
+        });
       } else {
-        if (!hasTraces) {
-          this.setState({
-            hasTraces: true,
-          });
-        }
+        this.setState({
+          hasTraces: true,
+        });
       }
     }
   }