Qt Designer: Refactor ConnectionModel::data() of the signal slot editor

The implementation was broken in the sense that it would
return column text strings for the font/color roles since enum
deprecatedMember was 0.

Restructure the code to use a switch and a helper for the column
text.

Cherry-picked from branch: dev

Change-Id: Ifb055519b796d4323c3aac7bf24ccac8facf1497

Change-Id: I43a9c7e9f48ecb2e51849ce53e939c80aae54d5a
Task-number: QTBUG-82924
Reviewed-by: cherrypickbot

2 files changed, 45 insertions, 34 deletions

diff --git a/src/designer/src/components/signalsloteditor/signalsloteditor_p.h b/src/designer/src/components/signalsloteditor/signalsloteditor_p.h
index 15d0563cf..1a44c101a 100644
--- a/src/designer/src/components/signalsloteditor/signalsloteditor_p.h
+++ b/src/designer/src/components/signalsloteditor/signalsloteditor_p.h
@@ -105,6 +105,9 @@ public:
     Connection *indexToConnection(const QModelIndex &index) const;
     void updateAll();
 
+    const SignalSlotConnection *connectionAt(const QModelIndex &index) const;
+    static QString columnText(const SignalSlotConnection *con, int column);
+
 private slots:
     void connectionAdded(Connection *con);
     void connectionRemoved(int idx);
diff --git a/src/designer/src/components/signalsloteditor/signalsloteditorwindow.cpp b/src/designer/src/components/signalsloteditor/signalsloteditorwindow.cpp
index 0868c9fe2..70668c362 100644
--- a/src/designer/src/components/signalsloteditor/signalsloteditorwindow.cpp
+++ b/src/designer/src/components/signalsloteditor/signalsloteditorwindow.cpp
@@ -236,62 +236,70 @@ int ConnectionModel::columnCount(const QModelIndex &parent) const
     return 4;
 }
 
+const SignalSlotConnection *ConnectionModel::connectionAt(const QModelIndex &index) const
+{
+    const int row = index.row();
+    return m_editor != nullptr && row >= 0 && row < m_editor->connectionCount()
+        ? static_cast<const SignalSlotConnection*>(m_editor->connection(row))
+        : nullptr;
+}
+
 QVariant ConnectionModel::data(const QModelIndex &index, int role) const
 {
     enum { deprecatedMember = 0 };
 
-    if ((role != Qt::DisplayRole && role != Qt::EditRole && role != Qt::FontRole && role != Qt::ForegroundRole) || !m_editor)
+    const SignalSlotConnection *con = connectionAt(index);
+    if (con == nullptr)
         return QVariant();
 
-    if (index.row() < 0 || index.row() >= m_editor->connectionCount()) {
-        return QVariant();
-    }
-
-    const SignalSlotConnection *con = static_cast<SignalSlotConnection*>(m_editor->connection(index.row()));
-    Q_ASSERT(con != nullptr);
-
     // Mark deprecated slots red/italic. Not currently in use (historically for Qt 3 slots in Qt 4),
     // but may be used again in the future.
-    if (deprecatedMember && role == Qt::ForegroundRole)
-        return QColor(Qt::red);
-    if (deprecatedMember && role ==  Qt::FontRole) {
-        QFont font = QApplication::font();
-        font.setItalic(true);
-        return font;
+    switch (role) {
+    case  Qt::ForegroundRole:
+        return deprecatedMember ? QColor(Qt::red) : QVariant();
+    case Qt::FontRole:
+        if (deprecatedMember) {
+            QFont font = QApplication::font();
+            font.setItalic(true);
+            return font;
+        }
+        return QVariant();
+    case Qt::DisplayRole:
+    case Qt::EditRole:
+        return ConnectionModel::columnText(con, index.column());
+    default:
+        break;
     }
 
-    static const QVariant senderDefault = tr("<sender>");
-    static const QVariant signalDefault = tr("<signal>");
-    static const QVariant receiverDefault = tr("<receiver>");
-    static const QVariant slotDefault = tr("<slot>");
+    return QVariant();
+}
+
+QString ConnectionModel::columnText(const SignalSlotConnection *con, int column)
+{
+    static const QString senderDefault = tr("<sender>");
+    static const QString signalDefault = tr("<signal>");
+    static const QString receiverDefault = tr("<receiver>");
+    static const QString slotDefault = tr("<slot>");
 
-    switch (index.column()) {
+    switch (column) {
         case 0: {
             const QString sender = con->sender();
-            if (sender.isEmpty())
-                return senderDefault;
-            return sender;
+            return sender.isEmpty() ? senderDefault : sender;
         }
         case 1: {
-            const QString signal = con->signal();
-            if (signal.isEmpty())
-                return signalDefault;
-            return signal;
+            const QString signalName = con->signal();
+            return signalName.isEmpty() ? signalDefault : signalName;
         }
         case 2: {
             const QString receiver = con->receiver();
-            if (receiver.isEmpty())
-                return receiverDefault;
-            return receiver;
+            return receiver.isEmpty() ? receiverDefault : receiver;
         }
         case 3: {
-            const QString slot = con->slot();
-            if (slot.isEmpty())
-                return slotDefault;
-            return slot;
+            const QString slotName = con->slot();
+            return slotName.isEmpty() ? slotDefault : slotName;
         }
     }
-    return QVariant();
+    return QString();
 }
 
 bool ConnectionModel::setData(const QModelIndex &index, const QVariant &data, int)