Polish the model/view tutorial examples

- Reorder the class declarations, moving private sections last
- Make constructors explicit
- Add space to the comments
- Introduce auto
- Replace slot MainWindow::showWindowTitle() by a direct
  connection to slot QWidget::setWindowTitle().

Change-Id: Ic229162434dfef5f2767d0b4e186759ca0f821f3
Reviewed-by: Richard Moe Gustavsen <richard.gustavsen@qt.io>
(cherry picked from commit 8751ca3daeaa2a500a37b070cdcce5a5bb7a165f)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>

examples/widgets/tutorials/modelview/1_readonly/mymodel.h

@@ -12,7 +12,8 @@ class MyModel : public QAbstractTableModel
 {
     Q_OBJECT
 public:
-    MyModel(QObject *parent = nullptr);
+    explicit MyModel(QObject *parent = nullptr);
+
     int rowCount(const QModelIndex &parent = QModelIndex()) const override;
     int columnCount(const QModelIndex &parent = QModelIndex()) const override;
     QVariant data(const QModelIndex &index, int role = Qt::DisplayRole) const override;

examples/widgets/tutorials/modelview/2_formatting/mymodel.h

@@ -10,7 +10,8 @@ class MyModel : public QAbstractTableModel
 {
     Q_OBJECT
 public:
-    MyModel(QObject *parent = nullptr);
+    explicit MyModel(QObject *parent = nullptr);
+
     int rowCount(const QModelIndex &parent = QModelIndex()) const override;
     int columnCount(const QModelIndex &parent = QModelIndex()) const override;
     QVariant data(const QModelIndex &index, int role = Qt::DisplayRole) const override;

examples/widgets/tutorials/modelview/3_changingmodel/mymodel.h

@@ -11,14 +11,17 @@ class MyModel : public QAbstractTableModel
 {
     Q_OBJECT
 public:
-    MyModel(QObject *parent = nullptr);
+    explicit MyModel(QObject *parent = nullptr);
+
     int rowCount(const QModelIndex &parent = QModelIndex()) const override;
     int columnCount(const QModelIndex &parent = QModelIndex()) const override;
     QVariant data(const QModelIndex &index, int role = Qt::DisplayRole) const override;
-private:
-    QTimer *timer;
+
 private slots:
     void timerHit();
+
+private:
+    QTimer *timer;
 };
 
 #endif // MYMODEL_H

examples/widgets/tutorials/modelview/4_headers/mymodel.h

@@ -10,7 +10,8 @@ class MyModel : public QAbstractTableModel
 {
     Q_OBJECT
 public:
-    MyModel(QObject *parent = nullptr);
+    explicit MyModel(QObject *parent = nullptr);
+
     int rowCount(const QModelIndex &parent = QModelIndex()) const override;
     int columnCount(const QModelIndex &parent = QModelIndex()) const override;
     QVariant data(const QModelIndex &index, int role = Qt::DisplayRole) const override;

examples/widgets/tutorials/modelview/5_edit/mainwindow.cpp

@@ -11,15 +11,10 @@ MainWindow::MainWindow(QWidget *parent)
     , tableView(new QTableView(this))
 {
     setCentralWidget(tableView);
-    MyModel *myModel = new MyModel(this);
+    auto *myModel = new MyModel(this);
     tableView->setModel(myModel);
 
     // transfer changes to the model to the window title
     connect(myModel, &MyModel::editCompleted,
-            this, &MainWindow::showWindowTitle);
-}
-
-void MainWindow::showWindowTitle(const QString &title)
-{
-    setWindowTitle(title);
+            this, &QWidget::setWindowTitle);
 }

examples/widgets/tutorials/modelview/5_edit/mainwindow.h

@@ -14,12 +14,11 @@ QT_END_NAMESPACE
 class MainWindow : public QMainWindow
 {
     Q_OBJECT
+public:
+    explicit MainWindow(QWidget *parent = nullptr);
+
 private:
     QTableView *tableView;
-public:
-    MainWindow(QWidget *parent = nullptr);
-public slots:
-    void showWindowTitle(const QString &title);
 };
 
 #endif // MAINWINDOW_H

examples/widgets/tutorials/modelview/6_treeview/mainwindow.h

@@ -16,14 +16,16 @@ QT_END_NAMESPACE
 class MainWindow : public QMainWindow
 {
     Q_OBJECT
+public:
+    explicit MainWindow(QWidget *parent = nullptr);
+
 private:
-    QTreeView *treeView;
-    QStandardItemModel *standardModel;
     QList<QStandardItem *> prepareRow(const QString &first,
                                       const QString &second,
                                       const QString &third) const;
-public:
-    MainWindow(QWidget *parent = nullptr);
+
+    QTreeView *treeView;
+    QStandardItemModel *standardModel;
 };
 
 #endif // MAINWINDOW_H

examples/widgets/tutorials/modelview/7_selections/mainwindow.cpp

@@ -14,18 +14,18 @@ MainWindow::MainWindow(QWidget *parent)
     , standardModel(new QStandardItemModel(this))
 {
     setCentralWidget(treeView);
-    QStandardItem *rootNode = standardModel->invisibleRootItem();
+    auto *rootNode = standardModel->invisibleRootItem();
 
 
     // defining a couple of items
-    QStandardItem *americaItem = new QStandardItem("America");
-    QStandardItem *mexicoItem =  new QStandardItem("Canada");
-    QStandardItem *usaItem =     new QStandardItem("USA");
-    QStandardItem *bostonItem =  new QStandardItem("Boston");
-    QStandardItem *europeItem =  new QStandardItem("Europe");
-    QStandardItem *italyItem =   new QStandardItem("Italy");
-    QStandardItem *romeItem =    new QStandardItem("Rome");
-    QStandardItem *veronaItem =  new QStandardItem("Verona");
+    auto *americaItem = new QStandardItem("America");
+    auto *mexicoItem =  new QStandardItem("Canada");
+    auto *usaItem =     new QStandardItem("USA");
+    auto *bostonItem =  new QStandardItem("Boston");
+    auto *europeItem =  new QStandardItem("Europe");
+    auto *italyItem =   new QStandardItem("Italy");
+    auto *romeItem =    new QStandardItem("Rome");
+    auto *veronaItem =  new QStandardItem("Verona");
 
     // building up the hierarchy
     rootNode->    appendRow(americaItem);
@@ -59,7 +59,7 @@ void MainWindow::selectionChangedSlot(const QItemSelection & /*newSelection*/, c
     // find out the hierarchy level of the selected item
     int hierarchyLevel = 1;
     QModelIndex seekRoot = index;
-    while (seekRoot.parent() != QModelIndex()) {
+    while (seekRoot.parent().isValid()) {
         seekRoot = seekRoot.parent();
         hierarchyLevel++;
     }

examples/widgets/tutorials/modelview/7_selections/mainwindow.h

@@ -16,13 +16,15 @@ QT_END_NAMESPACE
 class MainWindow : public QMainWindow
 {
     Q_OBJECT
+public:
+    explicit MainWindow(QWidget *parent = nullptr);
+
+private slots:
+    void selectionChangedSlot(const QItemSelection &newSelection, const QItemSelection &oldSelection);
+
 private:
     QTreeView *treeView;
     QStandardItemModel *standardModel;
-private slots:
-    void selectionChangedSlot(const QItemSelection &newSelection, const QItemSelection &oldSelection);
-public:
-    MainWindow(QWidget *parent = nullptr);
 };
 
 #endif // MAINWINDOW_H