[LYN-3356] Replaced GetSelectedEntities + size() with new API.

Code/Sandbox/Editor/EditorViewportWidget.cpp

@@ -1509,10 +1509,10 @@ bool EditorViewportWidget::AddCameraMenuItems(QMenu* menu)
     }
 
     action = customCameraMenu->addAction(tr("Look through entity"));
-    AzToolsFramework::EntityIdList selectedEntityList;
-    AzToolsFramework::ToolsApplicationRequests::Bus::BroadcastResult(selectedEntityList, &AzToolsFramework::ToolsApplicationRequests::GetSelectedEntities);
-    action->setCheckable(selectedEntityList.size() > 0 || m_viewSourceType == ViewSourceType::AZ_Entity);
-    action->setEnabled(selectedEntityList.size() > 0 || m_viewSourceType == ViewSourceType::AZ_Entity);
+    bool areAnyEntitiesSelected = false;
+    AzToolsFramework::ToolsApplicationRequestBus::BroadcastResult(areAnyEntitiesSelected, &AzToolsFramework::ToolsApplicationRequests::AreAnyEntitiesSelected);
+    action->setCheckable(areAnyEntitiesSelected || m_viewSourceType == ViewSourceType::AZ_Entity);
+    action->setEnabled(areAnyEntitiesSelected || m_viewSourceType == ViewSourceType::AZ_Entity);
     action->setChecked(m_viewSourceType == ViewSourceType::AZ_Entity);
     connect(action, &QAction::triggered, this, [this](bool isChecked)
         {

Code/Sandbox/Editor/TrackView/TrackViewDialog.cpp

@@ -807,18 +807,11 @@ void CTrackViewDialog::UpdateActions()
         m_actions[ID_TRACKVIEW_MUTE_ALL]->setEnabled(true);
         m_actions[ID_ADDSCENETRACK]->setEnabled(true);
 
-        AzToolsFramework::EntityIdList entityIds;
-        AzToolsFramework::ToolsApplicationRequests::Bus::BroadcastResult(
-            entityIds, &AzToolsFramework::ToolsApplicationRequests::GetSelectedEntities);
+        bool areAnyEntitiesSelected = false;
+        AzToolsFramework::ToolsApplicationRequestBus::BroadcastResult(
+            areAnyEntitiesSelected, &AzToolsFramework::ToolsApplicationRequests::AreAnyEntitiesSelected);
 
-        if (entityIds.empty())
-        {
-            m_actions[ID_ADDNODE]->setEnabled(false);
-        }
-        else
-        {
-            m_actions[ID_ADDNODE]->setEnabled(true);
-        }
+        m_actions[ID_ADDNODE]->setEnabled(areAnyEntitiesSelected);
     }
     else
     {
@@ -1569,12 +1562,12 @@ void CTrackViewDialog::OnAddSelectedNode()
             sequence->MarkAsModified();
         }
 
-        AzToolsFramework::EntityIdList entityIds;
-        AzToolsFramework::ToolsApplicationRequests::Bus::BroadcastResult(
-            entityIds, &AzToolsFramework::ToolsApplicationRequests::GetSelectedEntities);
+        int selectedEntitiesCount = 0;
+        AzToolsFramework::ToolsApplicationRequestBus::BroadcastResult(
+            selectedEntitiesCount, &AzToolsFramework::ToolsApplicationRequests::GetSelectedEntitiesCount);
 
         // check to make sure all nodes were added and notify user if they weren't
-        if (addedNodes.GetCount() != entityIds.size())
+        if (addedNodes.GetCount() != selectedEntitiesCount)
         {
             IMovieSystem* movieSystem = GetIEditor()->GetMovieSystem();
 

Code/Sandbox/Editor/TrackView/TrackViewNodes.cpp

@@ -1137,12 +1137,12 @@ void CTrackViewNodesCtrl::OnNMRclick(QPoint point)
                 CTrackViewAnimNodeBundle addedNodes = groupNode->AddSelectedEntities(m_pTrackViewDialog->GetDefaultTracksForEntityNode());
                 undoBatch.MarkEntityDirty(groupNode->GetSequence()->GetSequenceComponentEntityId());
 
-                AzToolsFramework::EntityIdList entityIds;
-                AzToolsFramework::ToolsApplicationRequests::Bus::BroadcastResult(
-                    entityIds, &AzToolsFramework::ToolsApplicationRequests::GetSelectedEntities);
+                int selectedEntitiesCount = 0;
+                AzToolsFramework::ToolsApplicationRequestBus::BroadcastResult(
+                    selectedEntitiesCount, &AzToolsFramework::ToolsApplicationRequests::GetSelectedEntitiesCount);
 
                 // check to make sure all nodes were added and notify user if they weren't
-                if (addedNodes.GetCount() != entityIds.size())
+                if (addedNodes.GetCount() != selectedEntitiesCount)
                 {
                     IMovieSystem* movieSystem = GetIEditor()->GetMovieSystem();