Add a roles argument to the dataChanged signal.

This allows more granular reporting of what has changed.

This change is binary incompatible and source compatible.

Change-Id: I7c5beaee651a24780cc94e41383f7a80210bc603
Reviewed-by: Olivier Goffart <ogoffart@woboq.com>

src/corelib/kernel/qabstractitemmodel.cpp

@@ -1415,7 +1415,7 @@ QAbstractItemModel::~QAbstractItemModel()
 */
 
 /*!
-    \fn void QAbstractItemModel::dataChanged(const QModelIndex &topLeft, const QModelIndex &bottomRight)
+    \fn void QAbstractItemModel::dataChanged(const QModelIndex &topLeft, const QModelIndex &bottomRight, const QSet<int> &roles = QSet<int>())
 
     This signal is emitted whenever the data in an existing item changes.
 
@@ -1426,6 +1426,10 @@ QAbstractItemModel::~QAbstractItemModel()
     When reimplementing the setData() function, this signal must be emitted
     explicitly.
 
+    The optional roles argument can be used to specify which data roles have actually
+    been modified. An empty set in the roles argument means that all roles should be
+    considered modified.
+
     \sa headerDataChanged(), setData(), layoutChanged()
 */
 

src/corelib/kernel/qabstractitemmodel.h

@@ -45,6 +45,7 @@
 #include <QtCore/qvariant.h>
 #include <QtCore/qobject.h>
 #include <QtCore/qhash.h>
+#include <QtCore/qset.h>
 
 QT_BEGIN_HEADER
 
@@ -230,7 +231,7 @@ public:
 #endif
 
 Q_SIGNALS:
-    void dataChanged(const QModelIndex &topLeft, const QModelIndex &bottomRight);
+    void dataChanged(const QModelIndex &topLeft, const QModelIndex &bottomRight, const QSet<int> &roles = QSet<int>());
     void headerDataChanged(Qt::Orientation orientation, int first, int last);
     void layoutChanged();
     void layoutAboutToBeChanged();

tests/auto/corelib/kernel/qabstractitemmodel/tst_qabstractitemmodel.cpp

@@ -43,6 +43,7 @@
 #include <QtCore/QtCore>
 
 #include <QtWidgets/QSortFilterProxyModel>
+#include <QtWidgets/QStringListModel>
 
 //TESTED_CLASS=QAbstractListModel QAbstractTableModel
 //TESTED_FILES=
@@ -109,6 +110,8 @@ private slots:
 
     void testReset();
 
+    void testDataChanged();
+
 private:
     DynamicTreeModel *m_model;
 };
@@ -1780,6 +1783,64 @@ void tst_QAbstractItemModel::testReset()
 
 }
 
+class CustomRoleModel : public QStringListModel
+{
+    Q_OBJECT
+    Q_ENUMS(Roles)
+public:
+    enum Roles {
+        Custom1 = Qt::UserRole + 1,
+        Custom2,
+        UserRole
+    };
+
+    CustomRoleModel(QObject *parent = 0)
+      : QStringListModel(QStringList() << "a" << "b" << "c", parent)
+    {
+
+    }
+
+    void emitSignals()
+    {
+        const QModelIndex top = index(0, 0);
+        const QModelIndex bottom = index(2, 0);
+
+        emit dataChanged(top, bottom);
+        emit dataChanged(top, bottom, QSet<int>() << Qt::ToolTipRole);
+        emit dataChanged(top, bottom, QSet<int>() << Qt::ToolTipRole << Custom1);
+    }
+};
+
+Q_DECLARE_METATYPE(QSet<int>)
+
+void tst_QAbstractItemModel::testDataChanged()
+{
+    qRegisterMetaType<QSet<int> >();
+
+    CustomRoleModel model;
+
+    QSignalSpy withRoles(&model, SIGNAL(dataChanged(QModelIndex,QModelIndex,QSet<int>)));
+    QSignalSpy withoutRoles(&model, SIGNAL(dataChanged(QModelIndex,QModelIndex)));
+
+    model.emitSignals();
+
+    QCOMPARE(withRoles.size(), withoutRoles.size());
+    QCOMPARE(withRoles.size(), 3);
+
+    const QVariantList secondEmission = withRoles.at(1);
+    const QVariantList thirdEmission = withRoles.at(2);
+
+    const QSet<int> secondRoles = secondEmission.at(2).value<QSet<int> >();
+    const QSet<int> thirdRoles = thirdEmission.at(2).value<QSet<int> >();
+
+    QCOMPARE(secondRoles.size(), 1);
+    QVERIFY(secondRoles.contains(Qt::ToolTipRole));
+
+    QCOMPARE(thirdRoles.size(), 2);
+    QVERIFY(thirdRoles.contains(Qt::ToolTipRole));
+    QVERIFY(thirdRoles.contains(CustomRoleModel::Custom1));
+}
+
 
 QTEST_MAIN(tst_QAbstractItemModel)
 #include "tst_qabstractitemmodel.moc"