Fix debug crash because intermediate function result goes out of scope (#9)

* Fix crash because intermediate function result goes out of scope, same as:
ManiVaultStudio/Scatterplot@29c0bc0

* This plugin only handles points

* Move variables to if

* default destructor

* Remove unused variable

Author: alxvth

DVRTransferFunction/src/TransferFunctionPlugin.cpp

@@ -87,18 +87,12 @@ TransferFunctionPlugin::TransferFunctionPlugin(const PluginFactory* factory) :
         if (datasetsMimeData->getDatasets().count() > 1)
             return dropRegions;
 
-        const auto& dataset         = datasetsMimeData->getDatasets().first();
-        const auto datasetGuiName   = dataset->text();
-        const auto datasetId        = dataset->getId();
-        const auto dataType         = dataset->getDataType();
-        const auto dataTypes        = DataTypes({ PointType , ColorType, ClusterType });
-
-        // Check if the data type can be dropped
-        if (!dataTypes.contains(dataType))
-            dropRegions << new DropWidget::DropRegion(this, "Incompatible data", "This type of data is not supported", "exclamation-circle", false);
+        const auto dataset         = datasetsMimeData->getDatasets().first();
 
         // Points dataset is about to be dropped
-        if (dataType == PointType) {
+        if (dataset->getDataType() == PointType) {
+            const auto datasetGuiName = dataset->text();
+            const auto datasetId = dataset->getId();
 
             // Get points dataset from the core
             auto candidateDataset = mv::data().getDataset<Points>(datasetId);
@@ -125,6 +119,10 @@ TransferFunctionPlugin::TransferFunctionPlugin(const PluginFactory* factory) :
                 }
             }
         }
+        else
+        {
+            dropRegions << new DropWidget::DropRegion(this, "Incompatible data", "This type of data is not supported", "exclamation-circle", false);
+        }
 
         return dropRegions;
     });
@@ -155,10 +153,6 @@ TransferFunctionPlugin::TransferFunctionPlugin(const PluginFactory* factory) :
     getLearningCenterAction().addVideos(QStringList({ "Practitioner", "Developer" }));
 }
 
-TransferFunctionPlugin::~TransferFunctionPlugin()
-{
-}
-
 void TransferFunctionPlugin::init()
 {
     auto layout = new QVBoxLayout();

DVRTransferFunction/src/TransferFunctionPlugin.h

@@ -31,7 +31,7 @@ class TransferFunctionPlugin : public ViewPlugin
 
 public:
     TransferFunctionPlugin(const PluginFactory* factory);
-    ~TransferFunctionPlugin() override;
+    ~TransferFunctionPlugin() override = default;
 
     void init() override;
 
@@ -95,8 +95,6 @@ class TransferFunctionPlugin : public ViewPlugin
     QPointer<MaterialSettings>			_materialSettings;          /** Material settings action */
     QPointer<HorizontalToolbarAction>   _primaryToolbarAction;      /** Horizontal toolbar for primary content */
 
-    static const std::int32_t LAZY_UPDATE_INTERVAL = 2;
-
 };
 
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