Brush up the graphgallery example

- Basic C++ polishing:
  - Use nullptr
  - Use initializer lists
  - Replace typedef by using
  - Port to qsizetype
  - Default functions
  - Fix up copy constructor and assignent

- Instantiate the main widget, BarGraph and ScatterGraph on the stack
  for proper clean up

Amends 00272ac80843d94217e4f1ea36392e22919afa22.

Pick-to: 6.5
Task-number: QTBUG-110698
Change-Id: Ibb9e3ecf5e20ebaaeac2483c768d7b5eb00c0558
Reviewed-by: Tomi Korpipää <tomi.korpipaa@qt.io>

15 files changed, 57 insertions, 67 deletions

diff --git a/examples/datavisualization/graphgallery/bargraph.h b/examples/datavisualization/graphgallery/bargraph.h
index dae991f9..79c78510 100644
--- a/examples/datavisualization/graphgallery/bargraph.h
+++ b/examples/datavisualization/graphgallery/bargraph.h
@@ -11,7 +11,7 @@ class BarGraph : public QObject
 {
     Q_OBJECT
 public:
-    explicit BarGraph();
+    BarGraph();
     ~BarGraph();
 
     bool initialize();
diff --git a/examples/datavisualization/graphgallery/graphmodifier.cpp b/examples/datavisualization/graphgallery/graphmodifier.cpp
index 56ec102a..2f79fa7a 100644
--- a/examples/datavisualization/graphgallery/graphmodifier.cpp
+++ b/examples/datavisualization/graphgallery/graphmodifier.cpp
@@ -36,8 +36,9 @@ GraphModifier::GraphModifier(Q3DBars *bargraph)
     m_graph->setMultiSeriesUniform(true);
     //! [2]
 
-    m_months << "January" << "February" << "March" << "April" << "May" << "June" << "July" << "August" << "September" << "October" << "November" << "December";
-    m_years << "2015" << "2016" << "2017" << "2018" << "2019" << "2020" << "2021" << "2022";
+    m_months = {"January", "February", "March", "April", "May", "June" , "July",
+                "August", "September", "October" , "November", "December"};
+    m_years = {"2015", "2016", "2017", "2018", "2019", "2020", "2021", "2022"};
 
     //! [3]
     m_temperatureAxis->setTitle("Average temperature");
@@ -161,11 +162,11 @@ void GraphModifier::resetTemperatureData()
     QBarDataRow *dataRow2= nullptr;
 
     dataSet->reserve(m_years.size());
-    for (int year = 0; year < m_years.size(); year++) {
+    for (qsizetype year = 0; year < m_years.size(); ++year) {
         // Create a data row
         dataRow = new QBarDataRow(m_months.size());
         dataRow2 = new QBarDataRow(m_months.size());
-        for (int month = 0; month < m_months.size(); month++) {
+        for (qsizetype month = 0; month < m_months.size(); ++month) {
             // Add data to the row
             (*dataRow)[month].setValue(tempOulu[year][month]);
             (*dataRow2)[month].setValue(tempHelsinki[year][month]);
diff --git a/examples/datavisualization/graphgallery/main.cpp b/examples/datavisualization/graphgallery/main.cpp
index 005ca1bf..88000d28 100644
--- a/examples/datavisualization/graphgallery/main.cpp
+++ b/examples/datavisualization/graphgallery/main.cpp
@@ -16,31 +16,31 @@ int main(int argc, char **argv)
     QApplication app(argc, argv);
 
     // Create bar graph
-    BarGraph *bars = new BarGraph();
-    if (!bars->initialize())
+    BarGraph bars;
+    if (!bars.initialize())
         return -1;
 
     // Create scatter graph
-    ScatterGraph *scatter = new ScatterGraph();
-    if (!scatter->initialize())
+    ScatterGraph scatter;
+    if (!scatter.initialize())
         return -1;
 
     // Create surface graph
-    SurfaceGraph *surface = new SurfaceGraph();
-    if (!surface->initialize())
+    SurfaceGraph surface;
+    if (!surface.initialize())
         return -1;
 
     // Create a tab widget for creating own tabs for Q3DBars, Q3DScatter, and Q3DSurface
-    QTabWidget *tabWidget = new QTabWidget();
-    tabWidget->setWindowTitle(QLatin1String("Graph Gallery"));
+    QTabWidget tabWidget;
+    tabWidget.setWindowTitle(QLatin1String("Graph Gallery"));
 
     // Add bars widget
-    tabWidget->addTab(bars->barsWidget(), QLatin1String("Bar Graph"));
+    tabWidget.addTab(bars.barsWidget(), QLatin1String("Bar Graph"));
     // Add scatter widget
-    tabWidget->addTab(scatter->scatterWidget(), QLatin1String("Scatter Graph"));
+    tabWidget.addTab(scatter.scatterWidget(), QLatin1String("Scatter Graph"));
     // Add surface widget
-    tabWidget->addTab(surface->surfaceWidget(), QLatin1String("Surface Graph"));
+    tabWidget.addTab(surface.surfaceWidget(), QLatin1String("Surface Graph"));
 
-    tabWidget->show();
+    tabWidget.show();
     return app.exec();
 }
diff --git a/examples/datavisualization/graphgallery/rainfalldata.cpp b/examples/datavisualization/graphgallery/rainfalldata.cpp
index ac366564..498e09ae 100644
--- a/examples/datavisualization/graphgallery/rainfalldata.cpp
+++ b/examples/datavisualization/graphgallery/rainfalldata.cpp
@@ -36,8 +36,9 @@ RainfallData::RainfallData()
     m_valueAxis->setAutoAdjustRange(true);
 
     // Set axis labels and titles
-    QStringList months;
-    months << "January" << "February" << "March" << "April" << "May" << "June" << "July" << "August" << "September" << "October" << "November" << "December";
+    QStringList months{"January", "February", "March", "April",
+                       "May", "June", "July", "August", "September", "October",
+                       "November","December"};
     m_rowAxis->setTitle("Year");
     m_colAxis->setTitle("Month");
     m_valueAxis->setTitle("rainfall (mm)");
@@ -82,9 +83,9 @@ void RainfallData::addDataSet()
         stream.setDevice(&dataFile);
         while (!stream.atEnd()) {
             QString line = stream.readLine();
-            if (line.startsWith("#")) // Ignore comments
+            if (line.startsWith('#')) // Ignore comments
                 continue;
-            QStringList strList = line.split(",", Qt::SkipEmptyParts);
+            QStringList strList = line.split(',', Qt::SkipEmptyParts);
             // Each line has three data items: Year, month, and rainfall value
             if (strList.size() < 3) {
                 qWarning() << "Invalid row read from data:" << line;
diff --git a/examples/datavisualization/graphgallery/scatterdatamodifier.cpp b/examples/datavisualization/graphgallery/scatterdatamodifier.cpp
index 5dff1548..9b61ab24 100644
--- a/examples/datavisualization/graphgallery/scatterdatamodifier.cpp
+++ b/examples/datavisualization/graphgallery/scatterdatamodifier.cpp
@@ -106,7 +106,7 @@ void ScatterDataModifier::changeStyle(int style)
     QComboBox *comboBox = qobject_cast<QComboBox *>(sender());
     if (comboBox) {
         m_style = QAbstract3DSeries::Mesh(comboBox->itemData(style).toInt());
-        if (m_graph->seriesList().size())
+        if (!m_graph->seriesList().isEmpty())
             m_graph->seriesList().at(0)->setMesh(m_style);
     }
 }
diff --git a/examples/datavisualization/graphgallery/scattergraph.cpp b/examples/datavisualization/graphgallery/scattergraph.cpp
index 17bb485b..b841a585 100644
--- a/examples/datavisualization/graphgallery/scattergraph.cpp
+++ b/examples/datavisualization/graphgallery/scattergraph.cpp
@@ -132,13 +132,13 @@ bool ScatterGraph::initialize()
     QObject::connect(modifier, &ScatterDataModifier::gridEnabledChanged,
                      gridCheckBox, &QCheckBox::setChecked);
     QObject::connect(itemStyleList, &QComboBox::currentIndexChanged, modifier,
-                     qOverload<int>(&ScatterDataModifier::changeStyle));
+                     &ScatterDataModifier::changeStyle);
 
     QObject::connect(themeList, &QComboBox::currentIndexChanged, modifier,
-                     qOverload<int>(&ScatterDataModifier::changeTheme));
+                     &ScatterDataModifier::changeTheme);
 
     QObject::connect(shadowQuality, &QComboBox::currentIndexChanged, modifier,
-                     qOverload<int>(&ScatterDataModifier::changeShadowQuality));
+                     &ScatterDataModifier::changeShadowQuality);
 
     QObject::connect(modifier, &ScatterDataModifier::shadowQualityChanged, shadowQuality,
                      &QComboBox::setCurrentIndex);
diff --git a/examples/datavisualization/graphgallery/scattergraph.h b/examples/datavisualization/graphgallery/scattergraph.h
index 6e34082d..0d3b8fc3 100644
--- a/examples/datavisualization/graphgallery/scattergraph.h
+++ b/examples/datavisualization/graphgallery/scattergraph.h
@@ -11,7 +11,7 @@ class ScatterGraph : public QObject
 {
     Q_OBJECT
 public:
-    explicit ScatterGraph();
+    ScatterGraph();
     ~ScatterGraph();
 
     bool initialize();
diff --git a/examples/datavisualization/graphgallery/surfacegraph.h b/examples/datavisualization/graphgallery/surfacegraph.h
index 90494d17..92b448ad 100644
--- a/examples/datavisualization/graphgallery/surfacegraph.h
+++ b/examples/datavisualization/graphgallery/surfacegraph.h
@@ -11,7 +11,7 @@ class SurfaceGraph : public QObject
 {
     Q_OBJECT
 public:
-    explicit SurfaceGraph();
+    SurfaceGraph();
     ~SurfaceGraph();
 
     bool initialize();
diff --git a/examples/datavisualization/graphgallery/topographicseries.cpp b/examples/datavisualization/graphgallery/topographicseries.cpp
index d33fa6bd..ea0be77d 100644
--- a/examples/datavisualization/graphgallery/topographicseries.cpp
+++ b/examples/datavisualization/graphgallery/topographicseries.cpp
@@ -15,9 +15,7 @@ TopographicSeries::TopographicSeries()
     setBaseColor(Qt::white);
 }
 
-TopographicSeries::~TopographicSeries()
-{
-}
+TopographicSeries::~TopographicSeries() = default;
 
 void TopographicSeries::setTopographyFile(const QString file, float width, float height)
 {
diff --git a/examples/datavisualization/graphgallery/topographicseries.h b/examples/datavisualization/graphgallery/topographicseries.h
index 8c49c338..b54971a3 100644
--- a/examples/datavisualization/graphgallery/topographicseries.h
+++ b/examples/datavisualization/graphgallery/topographicseries.h
@@ -10,7 +10,7 @@ class TopographicSeries : public QSurface3DSeries
 {
     Q_OBJECT
 public:
-    explicit TopographicSeries();
+    TopographicSeries();
     ~TopographicSeries();
 
     void setTopographyFile(const QString file, float width, float height);
@@ -18,8 +18,6 @@ public:
     float sampleCountX() { return m_sampleCountX; }
     float sampleCountZ() { return m_sampleCountZ; }
 
-public Q_SLOTS:
-
 private:
     float m_sampleCountX = 0.f;
     float m_sampleCountZ = 0.f;
diff --git a/examples/datavisualization/graphgallery/variantbardatamapping.cpp b/examples/datavisualization/graphgallery/variantbardatamapping.cpp
index 2e375f10..acac28c8 100644
--- a/examples/datavisualization/graphgallery/variantbardatamapping.cpp
+++ b/examples/datavisualization/graphgallery/variantbardatamapping.cpp
@@ -3,21 +3,22 @@
 
 #include "variantbardatamapping.h"
 
-VariantBarDataMapping::VariantBarDataMapping()
-    : QObject(0)
-{
-}
+VariantBarDataMapping::VariantBarDataMapping() = default;
 
-VariantBarDataMapping::VariantBarDataMapping(const VariantBarDataMapping &other)
-    : QObject(0)
+VariantBarDataMapping::VariantBarDataMapping(const VariantBarDataMapping &other) :
+    QObject(nullptr),
+    m_rowIndex(other.m_rowIndex),
+    m_columnIndex(other.m_columnIndex),
+    m_valueIndex(other.m_valueIndex),
+    m_rowCategories(other.m_rowCategories),
+    m_columnCategories(other.m_columnCategories)
 {
-    operator=(other);
 }
 
 VariantBarDataMapping::VariantBarDataMapping(int rowIndex, int columnIndex, int valueIndex,
                                              const QStringList &rowCategories,
                                              const QStringList &columnCategories)
-    : QObject(0)
+    : QObject(nullptr)
 {
     m_rowIndex = rowIndex;
     m_columnIndex = columnIndex;
@@ -26,18 +27,17 @@ VariantBarDataMapping::VariantBarDataMapping(int rowIndex, int columnIndex, int
     m_columnCategories = columnCategories;
 }
 
-VariantBarDataMapping::~VariantBarDataMapping()
-{
-}
+VariantBarDataMapping::~VariantBarDataMapping() = default;
 
 VariantBarDataMapping &VariantBarDataMapping::operator=(const VariantBarDataMapping &other)
 {
-    m_rowIndex = other.m_rowIndex;
-    m_columnIndex = other.m_columnIndex;
-    m_valueIndex = other.m_valueIndex;
-    m_rowCategories = other.m_rowCategories;
-    m_columnCategories = other.m_columnCategories;
-
+    if (this != &other) {
+        m_rowIndex = other.m_rowIndex;
+        m_columnIndex = other.m_columnIndex;
+        m_valueIndex = other.m_valueIndex;
+        m_rowCategories = other.m_rowCategories;
+        m_columnCategories = other.m_columnCategories;
+    }
     return *this;
 }
 
diff --git a/examples/datavisualization/graphgallery/variantbardataproxy.cpp b/examples/datavisualization/graphgallery/variantbardataproxy.cpp
index e15a8148..3bc3ec13 100644
--- a/examples/datavisualization/graphgallery/variantbardataproxy.cpp
+++ b/examples/datavisualization/graphgallery/variantbardataproxy.cpp
@@ -3,10 +3,7 @@
 
 #include "variantbardataproxy.h"
 
-VariantBarDataProxy::VariantBarDataProxy() :
-    QBarDataProxy()
-{
-}
+VariantBarDataProxy::VariantBarDataProxy() = default;
 
 VariantBarDataProxy::VariantBarDataProxy(VariantDataSet *newSet,
                                          VariantBarDataMapping *mapping) :
@@ -24,7 +21,7 @@ VariantBarDataProxy::~VariantBarDataProxy()
 void VariantBarDataProxy::setDataSet(VariantDataSet *newSet)
 {
     if (!m_dataSet.isNull())
-        QObject::disconnect(m_dataSet.data(), 0, this, 0);
+        QObject::disconnect(m_dataSet.data(), nullptr, this, nullptr);
 
     m_dataSet = newSet;
 
@@ -76,7 +73,7 @@ void VariantBarDataProxy::handleItemsAdded(int index, int count)
 void VariantBarDataProxy::handleDataCleared()
 {
     // Data cleared, reset array
-    resetArray(0);
+    resetArray(nullptr);
 }
 
 void VariantBarDataProxy::handleMappingChanged()
@@ -91,7 +88,7 @@ void VariantBarDataProxy::resolveDataSet()
     // If we have no data or mapping, or the categories are not defined, simply clear the array
     if (m_dataSet.isNull() || m_mapping.isNull() || !m_mapping->rowCategories().size()
             || !m_mapping->columnCategories().size()) {
-        resetArray(0);
+        resetArray(nullptr);
         return;
     }
     const VariantDataItemList &itemList = m_dataSet->itemList();
@@ -103,7 +100,7 @@ void VariantBarDataProxy::resolveDataSet()
     const QStringList &columnList = m_mapping->columnCategories();
 
     // Sort values into rows and columns
-    typedef QHash<QString, float> ColumnValueMap;
+    using ColumnValueMap = QHash<QString, float>;
     QHash <QString, ColumnValueMap> itemValueMap;
     for (const VariantDataItem *item : itemList) {
         itemValueMap[item->at(rowIndex).toString()][item->at(columnIndex).toString()]
@@ -114,7 +111,7 @@ void VariantBarDataProxy::resolveDataSet()
     QBarDataArray *newProxyArray = new QBarDataArray;
     for (const QString &rowKey : rowList) {
         QBarDataRow *newProxyRow = new QBarDataRow(columnList.size());
-        for (int i = 0; i < columnList.size(); i++)
+        for (qsizetype i = 0; i < columnList.size(); ++i)
             (*newProxyRow)[i].setValue(itemValueMap[rowKey][columnList.at(i)]);
         newProxyArray->append(newProxyRow);
     }
diff --git a/examples/datavisualization/graphgallery/variantbardataproxy.h b/examples/datavisualization/graphgallery/variantbardataproxy.h
index d2ed185a..3b5bcfef 100644
--- a/examples/datavisualization/graphgallery/variantbardataproxy.h
+++ b/examples/datavisualization/graphgallery/variantbardataproxy.h
@@ -7,8 +7,6 @@
 #include "variantdataset.h"
 #include "variantbardatamapping.h"
 #include <QtDataVisualization/qbardataproxy.h>
-#include <QtCore/qstringlist.h>
-#include <QtCore/qmap.h>
 #include <QtCore/qpointer.h>
 
 //! [0]
diff --git a/examples/datavisualization/graphgallery/variantdataset.cpp b/examples/datavisualization/graphgallery/variantdataset.cpp
index 400ff2a4..c0bfa9d3 100644
--- a/examples/datavisualization/graphgallery/variantdataset.cpp
+++ b/examples/datavisualization/graphgallery/variantdataset.cpp
@@ -3,10 +3,7 @@
 
 #include "variantdataset.h"
 
-VariantDataSet::VariantDataSet()
-    : QObject(0)
-{
-}
+VariantDataSet::VariantDataSet() = default;
 
 VariantDataSet::~VariantDataSet()
 {
diff --git a/examples/datavisualization/graphgallery/variantdataset.h b/examples/datavisualization/graphgallery/variantdataset.h
index ce52db10..219e58cf 100644
--- a/examples/datavisualization/graphgallery/variantdataset.h
+++ b/examples/datavisualization/graphgallery/variantdataset.h
@@ -7,8 +7,8 @@
 #include <QtCore/qvariantlist.h>
 
 //! [0]
-typedef QVariantList VariantDataItem;
-typedef QList<VariantDataItem *> VariantDataItemList;
+using VariantDataItem = QVariantList;
+using VariantDataItemList = QList<VariantDataItem *>;
 //! [0]
 
 class VariantDataSet : public QObject