Cleanup StarDelegate example

Cleanup the StarDelegate example:
 - use QStyledItemDelegate instead QItemDelegate
 - use nullptr and other useful c++11 constructs
 - include the correct headers

Change-Id: If2f65fe7cbdcdd4571d10ffa98d36eeab7836bbb
Reviewed-by: Sze Howe Koh <szehowe.koh@gmail.com>
Reviewed-by: Paul Wicking <paul.wicking@qt.io>
Reviewed-by: Luca Beldi <v.ronin@yahoo.it>

examples/widgets/doc/src/stardelegate.qdoc

@@ -42,11 +42,11 @@
     editing takes place.
 
     Delegates are subclasses of QAbstractItemDelegate. Qt provides
-    QItemDelegate, which inherits QAbstractItemDelegate and handles
+    QStyledItemDelegate, which inherits QAbstractItemDelegate and handles
     the most common data types (notably \c int and QString). If we
     need to support custom data types, or want to customize the
     rendering or the editing for existing data types, we can subclass
-    QAbstractItemDelegate or QItemDelegate. See \l{Delegate Classes}
+    QAbstractItemDelegate or QStyledItemDelegate. See \l{Delegate Classes}
     for more information about delegates, and \l{Model/View
     Programming} if you need a high-level introduction to Qt's
     model/view architecture (including delegates).
@@ -62,9 +62,9 @@
        expressed as stars, such as "2 out of 5 stars" or "5 out of
        6 stars".
 
-    \li \c StarDelegate inherits QItemDelegate and provides support
+    \li \c StarDelegate inherits QStyledItemDelegate and provides support
        for \c StarRating (in addition to the data types already
-       handled by QItemDelegate).
+       handled by QStyledItemDelegate).
 
     \li \c StarEditor inherits QWidget and is used by \c StarDelegate
        to let the user edit a star rating using the mouse.
@@ -80,12 +80,12 @@
     \snippet itemviews/stardelegate/stardelegate.h 0
 
     All public functions are reimplemented virtual functions from
-    QItemDelegate to provide custom rendering and editing.
+    QStyledItemDelegate to provide custom rendering and editing.
 
     \section1 StarDelegate Class Implementation
 
     The \l{QAbstractItemDelegate::}{paint()} function is
-    reimplemented from QItemDelegate and is called whenever the view
+    reimplemented from QStyledItemDelegate and is called whenever the view
     needs to repaint an item:
 
     \snippet itemviews/stardelegate/stardelegate.cpp 0
@@ -93,7 +93,7 @@
     The function is invoked once for each item, represented by a
     QModelIndex object from the model. If the data stored in the item
     is a \c StarRating, we paint it ourselves; otherwise, we let
-    QItemDelegate paint it for us. This ensures that the \c
+    QStyledItemDelegate paint it for us. This ensures that the \c
     StarDelegate can handle the most common data types.
 
     If the item is a \c StarRating, we draw the background if the

examples/widgets/itemviews/stardelegate/main.cpp

@@ -101,10 +101,7 @@ int main(int argc, char *argv[])
     tableWidget.setEditTriggers(QAbstractItemView::DoubleClicked
                                 | QAbstractItemView::SelectedClicked);
     tableWidget.setSelectionBehavior(QAbstractItemView::SelectRows);
-
-    QStringList headerLabels;
-    headerLabels << "Title" << "Genre" << "Artist" << "Rating";
-    tableWidget.setHorizontalHeaderLabels(headerLabels);
+    tableWidget.setHorizontalHeaderLabels({"Title", "Genre", "Artist", "Rating"});
 
     populateTableWidget(&tableWidget);
 

examples/widgets/itemviews/stardelegate/stardelegate.cpp

@@ -65,7 +65,7 @@ void StarDelegate::paint(QPainter *painter, const QStyleOptionViewItem &option,
             painter->fillRect(option.rect, option.palette.highlight());
 
         starRating.paint(painter, option.rect, option.palette,
-                         StarRating::ReadOnly);
+                         StarRating::EditMode::ReadOnly);
     } else {
         QStyledItemDelegate::paint(painter, option, index);
     }
@@ -79,9 +79,8 @@ QSize StarDelegate::sizeHint(const QStyleOptionViewItem &option,
     if (index.data().canConvert<StarRating>()) {
         StarRating starRating = qvariant_cast<StarRating>(index.data());
         return starRating.sizeHint();
-    } else {
-        return QStyledItemDelegate::sizeHint(option, index);
     }
+    return QStyledItemDelegate::sizeHint(option, index);
 }
 //! [1]
 
@@ -96,9 +95,8 @@ QWidget *StarDelegate::createEditor(QWidget *parent,
         connect(editor, &StarEditor::editingFinished,
                 this, &StarDelegate::commitAndCloseEditor);
         return editor;
-    } else {
-        return QStyledItemDelegate::createEditor(parent, option, index);
     }
+    return QStyledItemDelegate::createEditor(parent, option, index);
 }
 //! [2]
 

examples/widgets/itemviews/stardelegate/stardelegate.h

@@ -57,9 +57,8 @@
 class StarDelegate : public QStyledItemDelegate
 {
     Q_OBJECT
-
 public:
-    StarDelegate(QWidget *parent = 0) : QStyledItemDelegate(parent) {}
+    using QStyledItemDelegate::QStyledItemDelegate;
 
     void paint(QPainter *painter, const QStyleOptionViewItem &option,
                const QModelIndex &index) const override;

examples/widgets/itemviews/stardelegate/stareditor.cpp

@@ -48,11 +48,11 @@
 **
 ****************************************************************************/
 
-#include <QtWidgets>
-
 #include "stareditor.h"
 #include "starrating.h"
 
+#include <QtWidgets>
+
 //! [0]
 StarEditor::StarEditor(QWidget *parent)
     : QWidget(parent)
@@ -71,34 +71,36 @@ QSize StarEditor::sizeHint() const
 void StarEditor::paintEvent(QPaintEvent *)
 {
     QPainter painter(this);
-    myStarRating.paint(&painter, rect(), this->palette(),
-                       StarRating::Editable);
+    myStarRating.paint(&painter, rect(), palette(),
+                       StarRating::EditMode::Editable);
 }
 //! [1]
 
 //! [2]
 void StarEditor::mouseMoveEvent(QMouseEvent *event)
 {
-    int star = starAtPosition(event->x());
+    const int star = starAtPosition(event->x());
 
     if (star != myStarRating.starCount() && star != -1) {
         myStarRating.setStarCount(star);
         update();
     }
+    QWidget::mouseMoveEvent(event);
 }
 //! [2]
 
 //! [3]
-void StarEditor::mouseReleaseEvent(QMouseEvent * /* event */)
+void StarEditor::mouseReleaseEvent(QMouseEvent *event)
 {
     emit editingFinished();
+    QWidget::mouseReleaseEvent(event);
 }
 //! [3]
 
 //! [4]
-int StarEditor::starAtPosition(int x)
+int StarEditor::starAtPosition(int x) const
 {
-    int star = (x / (myStarRating.sizeHint().width()
+    const int star = (x / (myStarRating.sizeHint().width()
                            / myStarRating.maxStarCount())) + 1;
     if (star <= 0 || star > myStarRating.maxStarCount())
         return -1;

examples/widgets/itemviews/stardelegate/stareditor.h

@@ -59,9 +59,8 @@
 class StarEditor : public QWidget
 {
     Q_OBJECT
-
 public:
-    StarEditor(QWidget *parent = 0);
+    StarEditor(QWidget *parent = nullptr);
 
     QSize sizeHint() const override;
     void setStarRating(const StarRating &starRating) {
@@ -78,7 +77,7 @@ protected:
     void mouseReleaseEvent(QMouseEvent *event) override;
 
 private:
-    int starAtPosition(int x);
+    int starAtPosition(int x) const;
 
     StarRating myStarRating;
 };

examples/widgets/itemviews/stardelegate/starrating.cpp

@@ -48,19 +48,18 @@
 **
 ****************************************************************************/
 
+#include "starrating.h"
+
 #include <QtWidgets>
 #include <cmath>
 
-#include "starrating.h"
-
-const int PaintingScaleFactor = 20;
+constexpr int PaintingScaleFactor = 20;
 
 //! [0]
 StarRating::StarRating(int starCount, int maxStarCount)
+    : myStarCount(starCount),
+      myMaxStarCount(maxStarCount)
 {
-    myStarCount = starCount;
-    myMaxStarCount = maxStarCount;
-
     starPolygon << QPointF(1.0, 0.5);
     for (int i = 1; i < 5; ++i)
         starPolygon << QPointF(0.5 + 0.5 * std::cos(0.8 * i * 3.14),
@@ -87,23 +86,19 @@ void StarRating::paint(QPainter *painter, const QRect &rect,
 
     painter->setRenderHint(QPainter::Antialiasing, true);
     painter->setPen(Qt::NoPen);
+    painter->setBrush(mode == EditMode::Editable ?
+                          palette.highlight() :
+                          palette.foreground());
 
-    if (mode == Editable) {
-        painter->setBrush(palette.highlight());
-    } else {
-        painter->setBrush(palette.foreground());
-    }
-
-    int yOffset = (rect.height() - PaintingScaleFactor) / 2;
+    const int yOffset = (rect.height() - PaintingScaleFactor) / 2;
     painter->translate(rect.x(), rect.y() + yOffset);
     painter->scale(PaintingScaleFactor, PaintingScaleFactor);
 
     for (int i = 0; i < myMaxStarCount; ++i) {
-        if (i < myStarCount) {
+        if (i < myStarCount)
             painter->drawPolygon(starPolygon, Qt::WindingFill);
-        } else if (mode == Editable) {
+        else if (mode == EditMode::Editable)
             painter->drawPolygon(diamondPolygon, Qt::WindingFill);
-        }
         painter->translate(1.0, 0.0);
     }
 

examples/widgets/itemviews/stardelegate/starrating.h

@@ -51,15 +51,15 @@
 #ifndef STARRATING_H
 #define STARRATING_H
 
-#include <QMetaType>
-#include <QPointF>
-#include <QVector>
+#include <QPainter>
+#include <QPolygonF>
+#include <QSize>
 
 //! [0]
 class StarRating
 {
 public:
-    enum EditMode { Editable, ReadOnly };
+    enum class EditMode { Editable, ReadOnly };
 
     explicit StarRating(int starCount = 1, int maxStarCount = 5);