QAbstractItemView: add virtual itemDelegateForIndex

and obsolete itemDelegate(index), which the new function replaces.

This allows itemviews to override the item delegate per index. The
existing APIs to set delegates for rows and columns doesn't work for
tree views, or other views where the delegate should depend on the
parent index as well.

Adjust all itemview code that accessed the QAIVPrivate's relevant
data structures directly to go through the virtual function.

[ChangeLog][QtWidgets][QAbstractItemView] The
itemDelegate(QModelIndex) member function has been made obsolete,
and has been replaced by a new virtual
itemDelegateForIndex(QModelIndex) member function that can be
overridden to give subclasses control over which item delegate
should be used for an index.

Change-Id: Ib03529c38797386d3a1d4cf3c5646e911d95daf5
Reviewed-by: Samuel Gaist <samuel.gaist@idiap.ch>
Reviewed-by: Lars Knoll <lars.knoll@qt.io>
Reviewed-by: Christian Ehrlicher <ch.ehrlicher@gmx.de>

7 files changed, 61 insertions, 41 deletions

diff --git a/src/widgets/itemviews/qabstractitemview.cpp b/src/widgets/itemviews/qabstractitemview.cpp
index 5d3fa4a088..d7e757d7d7 100644
--- a/src/widgets/itemviews/qabstractitemview.cpp
+++ b/src/widgets/itemviews/qabstractitemview.cpp
@@ -1006,10 +1006,21 @@ QAbstractItemDelegate *QAbstractItemView::itemDelegateForColumn(int column) cons
 }
 
 /*!
+    \fn QAbstractItemDelegate *QAbstractItemView::itemDelegate(const QModelIndex &index) const
+    \obsolete Use itemDelegateForIndex() instead.
     Returns the item delegate used by this view and model for
     the given \a index.
 */
-QAbstractItemDelegate *QAbstractItemView::itemDelegate(const QModelIndex &index) const
+
+/*!
+    \since 6.0
+
+    Returns the item delegate used by this view and model for
+    the given \a index.
+
+    \sa setItemDelegate(), setItemDelegateForRow(), setItemDelegateForColumn()
+*/
+QAbstractItemDelegate *QAbstractItemView::itemDelegateForIndex(const QModelIndex &index) const
 {
     Q_D(const QAbstractItemView);
     return d->delegateForIndex(index);
@@ -1723,7 +1734,7 @@ bool QAbstractItemView::viewportEvent(QEvent *event)
         option.rect = visualRect(index);
         option.state |= (index == currentIndex() ? QStyle::State_HasFocus : QStyle::State_None);
 
-        QAbstractItemDelegate *delegate = d->delegateForIndex(index);
+        QAbstractItemDelegate *delegate = itemDelegateForIndex(index);
         if (!delegate)
             return false;
         return delegate->helpEvent(he, this, option, index);
@@ -2734,7 +2745,7 @@ void QAbstractItemView::updateEditorGeometries()
             option.rect = visualRect(index);
             if (option.rect.isValid()) {
                 editor->show();
-                QAbstractItemDelegate *delegate = d->delegateForIndex(index);
+                QAbstractItemDelegate *delegate = itemDelegateForIndex(index);
                 if (delegate)
                     delegate->updateEditorGeometry(editor, option, index);
             } else {
@@ -2837,7 +2848,7 @@ void QAbstractItemView::closeEditor(QWidget *editor, QAbstractItemDelegate::EndE
         if (!isPersistent) {
             setState(NoState);
             QModelIndex index = d->indexForEditor(editor);
-            editor->removeEventFilter(d->delegateForIndex(index));
+            editor->removeEventFilter(itemDelegateForIndex(index));
             d->removeEditor(editor);
         }
         if (hadFocus) {
@@ -2907,7 +2918,7 @@ void QAbstractItemView::commitData(QWidget *editor)
     if (!index.isValid())
         return;
     d->currentlyCommittingEditor = editor;
-    QAbstractItemDelegate *delegate = d->delegateForIndex(index);
+    QAbstractItemDelegate *delegate = itemDelegateForIndex(index);
     editor->removeEventFilter(delegate);
     delegate->setModelData(editor, d->model, index);
     editor->installEventFilter(delegate);
@@ -3020,7 +3031,7 @@ QSize QAbstractItemView::sizeHintForIndex(const QModelIndex &index) const
     Q_D(const QAbstractItemView);
     if (!d->isIndexValid(index))
         return QSize();
-    const auto delegate = d->delegateForIndex(index);
+    const auto delegate = itemDelegateForIndex(index);
     QStyleOptionViewItem option;
     initViewItemOption(&option);
     return delegate ? delegate->sizeHint(option, index) : QSize();
@@ -3059,7 +3070,7 @@ int QAbstractItemView::sizeHintForRow(int row) const
         const QModelIndex index = d->model->index(row, c, d->root);
         if (QWidget *editor = d->editorForIndex(index).widget.data())
             height = qMax(height, editor->height());
-        if (const QAbstractItemDelegate *delegate = d->delegateForIndex(index))
+        if (const QAbstractItemDelegate *delegate = itemDelegateForIndex(index))
             height = qMax(height, delegate->sizeHint(option, index).height());
     }
     return height;
@@ -3090,7 +3101,7 @@ int QAbstractItemView::sizeHintForColumn(int column) const
         const QModelIndex index = d->model->index(r, column, d->root);
         if (QWidget *editor = d->editorForIndex(index).widget.data())
             width = qMax(width, editor->sizeHint().width());
-        if (const QAbstractItemDelegate *delegate = d->delegateForIndex(index))
+        if (const QAbstractItemDelegate *delegate = itemDelegateForIndex(index))
             width = qMax(width, delegate->sizeHint(option, index).width());
     }
     return width;
@@ -3283,7 +3294,7 @@ void QAbstractItemView::dataChanged(const QModelIndex &topLeft, const QModelInde
         const QEditorInfo &editorInfo = d->editorForIndex(topLeft);
         //we don't update the edit data if it is static
         if (!editorInfo.isStatic && editorInfo.widget) {
-            QAbstractItemDelegate *delegate = d->delegateForIndex(topLeft);
+            QAbstractItemDelegate *delegate = itemDelegateForIndex(topLeft);
             if (delegate) {
                 delegate->setEditorData(editorInfo.widget.data(), topLeft);
             }
@@ -4193,7 +4204,7 @@ QWidget *QAbstractItemViewPrivate::editor(const QModelIndex &index,
     Q_Q(QAbstractItemView);
     QWidget *w = editorForIndex(index).widget.data();
     if (!w) {
-        QAbstractItemDelegate *delegate = delegateForIndex(index);
+        QAbstractItemDelegate *delegate = q->itemDelegateForIndex(index);
         if (!delegate)
             return nullptr;
         w = delegate->createEditor(viewport, options, index);
@@ -4228,6 +4239,7 @@ QWidget *QAbstractItemViewPrivate::editor(const QModelIndex &index,
 
 void QAbstractItemViewPrivate::updateEditorData(const QModelIndex &tl, const QModelIndex &br)
 {
+    Q_Q(QAbstractItemView);
     // we are counting on having relatively few editors
     const bool checkIndexes = tl.isValid() && br.isValid();
     const QModelIndex parent = tl.parent();
@@ -4246,7 +4258,7 @@ void QAbstractItemViewPrivate::updateEditorData(const QModelIndex &tl, const QMo
                     || index.parent() != parent)))
             continue;
 
-        QAbstractItemDelegate *delegate = delegateForIndex(index);
+        QAbstractItemDelegate *delegate = q->itemDelegateForIndex(index);
         if (delegate) {
             delegate->setEditorData(editor, index);
         }
@@ -4369,7 +4381,7 @@ bool QAbstractItemViewPrivate::sendDelegateEvent(const QModelIndex &index, QEven
     q->initViewItemOption(&options);
     options.rect = q->visualRect(buddy);
     options.state |= (buddy == q->currentIndex() ? QStyle::State_HasFocus : QStyle::State_None);
-    QAbstractItemDelegate *delegate = delegateForIndex(index);
+    QAbstractItemDelegate *delegate = q->itemDelegateForIndex(index);
     return (event && delegate && delegate->editorEvent(event, model, options, buddy));
 }
 
@@ -4446,7 +4458,7 @@ QPixmap QAbstractItemViewPrivate::renderToPixmap(const QModelIndexList &indexes,
         option.rect = paintPairs.at(j).rect.translated(-r->topLeft());
         const QModelIndex &current = paintPairs.at(j).index;
         adjustViewOptionsForIndex(&option, current);
-        delegateForIndex(current)->paint(&painter, option, current);
+        q->itemDelegateForIndex(current)->paint(&painter, option, current);
     }
     return pixmap;
 }
diff --git a/src/widgets/itemviews/qabstractitemview.h b/src/widgets/itemviews/qabstractitemview.h
index 4b8effb63e..8addb76fbc 100644
--- a/src/widgets/itemviews/qabstractitemview.h
+++ b/src/widgets/itemviews/qabstractitemview.h
@@ -223,7 +223,12 @@ public:
     void setItemDelegateForColumn(int column, QAbstractItemDelegate *delegate);
     QAbstractItemDelegate *itemDelegateForColumn(int column) const;
 
-    QAbstractItemDelegate *itemDelegate(const QModelIndex &index) const;
+#if QT_DEPRECATED_SINCE(6, 0)
+    QT_DEPRECATED_VERSION_X_6_0("Use itemDelegateForIndex instead")
+    QAbstractItemDelegate *itemDelegate(const QModelIndex &index) const
+    { return itemDelegateForIndex(index); }
+#endif
+    virtual QAbstractItemDelegate *itemDelegateForIndex(const QModelIndex &index) const;
 
     virtual QVariant inputMethodQuery(Qt::InputMethodQuery query) const override;
 
diff --git a/src/widgets/itemviews/qabstractitemview_p.h b/src/widgets/itemviews/qabstractitemview_p.h
index fc9e6ee10a..3996257273 100644
--- a/src/widgets/itemviews/qabstractitemview_p.h
+++ b/src/widgets/itemviews/qabstractitemview_p.h
@@ -211,11 +211,12 @@ public:
 
     inline void releaseEditor(QWidget *editor, const QModelIndex &index = QModelIndex()) const {
         if (editor) {
+            Q_Q(const QAbstractItemView);
             QObject::disconnect(editor, SIGNAL(destroyed(QObject*)),
                                 q_func(), SLOT(editorDestroyed(QObject*)));
             editor->removeEventFilter(itemDelegate);
             editor->hide();
-            QAbstractItemDelegate *delegate = delegateForIndex(index);
+            QAbstractItemDelegate *delegate = q->itemDelegateForIndex(index);
 
             if (delegate)
                 delegate->destroyEditor(editor, index);
@@ -276,20 +277,6 @@ public:
         return state == QAbstractItemView::AnimatingState;
     }
 
-    inline QAbstractItemDelegate *delegateForIndex(const QModelIndex &index) const {
-        QMap<int, QPointer<QAbstractItemDelegate> >::ConstIterator it;
-
-        it = rowDelegates.find(index.row());
-        if (it != rowDelegates.end())
-            return it.value();
-
-        it = columnDelegates.find(index.column());
-        if (it != columnDelegates.end())
-            return it.value();
-
-        return itemDelegate;
-    }
-
     inline bool isIndexValid(const QModelIndex &index) const {
          return (index.row() >= 0) && (index.column() >= 0) && (index.model() == model);
     }
@@ -452,6 +439,20 @@ public:
     bool horizontalScrollModeSet;
 
 private:
+    inline QAbstractItemDelegate *delegateForIndex(const QModelIndex &index) const {
+        QMap<int, QPointer<QAbstractItemDelegate> >::ConstIterator it;
+
+        it = rowDelegates.find(index.row());
+        if (it != rowDelegates.end())
+            return it.value();
+
+        it = columnDelegates.find(index.column());
+        if (it != columnDelegates.end())
+            return it.value();
+
+        return itemDelegate;
+    }
+
     mutable QBasicTimer delayedLayout;
     mutable QBasicTimer fetchMoreTimer;
 };
diff --git a/src/widgets/itemviews/qlistview.cpp b/src/widgets/itemviews/qlistview.cpp
index 141937da75..721b9aa0d3 100644
--- a/src/widgets/itemviews/qlistview.cpp
+++ b/src/widgets/itemviews/qlistview.cpp
@@ -1083,7 +1083,7 @@ void QListView::paintEvent(QPaintEvent *e)
             previousRow = row;
         }
 
-        d->delegateForIndex(*it)->paint(&painter, option, *it);
+        itemDelegateForIndex(*it)->paint(&painter, option, *it);
     }
 
 #if QT_CONFIG(draganddrop)
@@ -1883,14 +1883,15 @@ QModelIndex QListViewPrivate::closestIndex(const QRect &target,
 
 QSize QListViewPrivate::itemSize(const QStyleOptionViewItem &option, const QModelIndex &index) const
 {
+    Q_Q(const QListView);
     if (!uniformItemSizes) {
-        const QAbstractItemDelegate *delegate = delegateForIndex(index);
+        const QAbstractItemDelegate *delegate = q->itemDelegateForIndex(index);
         return delegate ? delegate->sizeHint(option, index) : QSize();
     }
     if (!cachedItemSize.isValid()) { // the last item is probaly the largest, so we use its size
         int row = model->rowCount(root) - 1;
         QModelIndex sample = model->index(row, column, root);
-        const QAbstractItemDelegate *delegate = delegateForIndex(sample);
+        const QAbstractItemDelegate *delegate = q->itemDelegateForIndex(sample);
         cachedItemSize = delegate ? delegate->sizeHint(option, sample) : QSize();
     }
     return cachedItemSize;
diff --git a/src/widgets/itemviews/qlistview_p.h b/src/widgets/itemviews/qlistview_p.h
index 0701bc8c71..085c4866b1 100644
--- a/src/widgets/itemviews/qlistview_p.h
+++ b/src/widgets/itemviews/qlistview_p.h
@@ -493,7 +493,7 @@ inline QSize QCommonListViewBase::itemSize(const QStyleOptionViewItem &opt, cons
     { return dd->itemSize(opt, idx); }
 
 inline QAbstractItemDelegate *QCommonListViewBase::delegate(const QModelIndex &idx) const
-    { return dd->delegateForIndex(idx); }
+    { return qq->itemDelegateForIndex(idx); }
 
 inline bool QCommonListViewBase::isHidden(int row) const { return dd->isHidden(row); }
 inline int QCommonListViewBase::hiddenCount() const { return dd->hiddenRows.count(); }
diff --git a/src/widgets/itemviews/qtableview.cpp b/src/widgets/itemviews/qtableview.cpp
index cf927ef30d..f82473e60c 100644
--- a/src/widgets/itemviews/qtableview.cpp
+++ b/src/widgets/itemviews/qtableview.cpp
@@ -1050,7 +1050,7 @@ void QTableViewPrivate::drawCell(QPainter *painter, const QStyleOptionViewItem &
 
     q->style()->drawPrimitive(QStyle::PE_PanelItemViewRow, &opt, painter, q);
 
-    q->itemDelegate(index)->paint(painter, opt, index);
+    q->itemDelegateForIndex(index)->paint(painter, opt, index);
 }
 
 /*!
@@ -1067,7 +1067,7 @@ int QTableViewPrivate::widthHintForIndex(const QModelIndex &index, int hint, con
         int max = editor->maximumSize().width();
         hint = qBound(min, hint, max);
     }
-    hint = qMax(hint, q->itemDelegate(index)->sizeHint(option, index).width());
+    hint = qMax(hint, q->itemDelegateForIndex(index)->sizeHint(option, index).width());
     return hint;
 }
 
@@ -1089,7 +1089,7 @@ int QTableViewPrivate::heightHintForIndex(const QModelIndex &index, int hint, QS
     if (wrapItemText) {// for wrapping boundaries
         option.rect.setY(q->rowViewportPosition(index.row()));
         int height = q->rowHeight(index.row());
-        // if the option.height == 0 then q->itemDelegate(index)->sizeHint(option, index) will be wrong.
+        // if the option.height == 0 then q->itemDelegateForIndex(index)->sizeHint(option, index) will be wrong.
         // The option.height == 0 is used to conclude that the text is not wrapped, and hence it will
         // (exactly like widthHintForIndex) return a QSize with a long width (that we don't use) -
         // and the height of the text if it was/is on one line.
@@ -1104,7 +1104,7 @@ int QTableViewPrivate::heightHintForIndex(const QModelIndex &index, int hint, QS
         if (showGrid)
             option.rect.setWidth(option.rect.width() - 1);
     }
-    hint = qMax(hint, q->itemDelegate(index)->sizeHint(option, index).height());
+    hint = qMax(hint, q->itemDelegateForIndex(index)->sizeHint(option, index).height());
     return hint;
 }
 
diff --git a/src/widgets/itemviews/qtreeview.cpp b/src/widgets/itemviews/qtreeview.cpp
index 56df15f237..dedc27501f 100644
--- a/src/widgets/itemviews/qtreeview.cpp
+++ b/src/widgets/itemviews/qtreeview.cpp
@@ -1621,6 +1621,7 @@ void QTreeViewPrivate::calcLogicalIndices(
 */
 int QTreeViewPrivate::widthHintForIndex(const QModelIndex &index, int hint, const QStyleOptionViewItem &option, int i) const
 {
+    Q_Q(const QTreeView);
     QWidget *editor = editorForIndex(index).widget.data();
     if (editor && persistent.contains(editor)) {
         hint = qMax(hint, editor->sizeHint().width());
@@ -1628,7 +1629,7 @@ int QTreeViewPrivate::widthHintForIndex(const QModelIndex &index, int hint, cons
         int max = editor->maximumSize().width();
         hint = qBound(min, hint, max);
     }
-    int xhint = delegateForIndex(index)->sizeHint(option, index).width();
+    int xhint = q->itemDelegateForIndex(index)->sizeHint(option, index).width();
     hint = qMax(hint, xhint + (isTreePosition(index.column()) ? indentationForItem(i) : 0));
     return hint;
 }
@@ -1802,7 +1803,7 @@ void QTreeView::drawRow(QPainter *painter, const QStyleOptionViewItem &option,
             opt.state = oldState;
         }
 
-        d->delegateForIndex(modelIndex)->paint(painter, opt, modelIndex);
+        itemDelegateForIndex(modelIndex)->paint(painter, opt, modelIndex);
     }
 
     if (currentRowHasFocus) {
@@ -3015,7 +3016,7 @@ int QTreeView::indexRowSizeHint(const QModelIndex &index) const
                 int max = editor->maximumSize().height();
                 height = qBound(min, height, max);
             }
-            int hint = d->delegateForIndex(idx)->sizeHint(option, idx).height();
+            int hint = itemDelegateForIndex(idx)->sizeHint(option, idx).height();
             height = qMax(height, hint);
         }
     }
@@ -3274,7 +3275,7 @@ QPixmap QTreeViewPrivate::renderTreeToPixmapForAnimation(const QRect &rect) cons
         option.rect = q->visualRect(index);
         if (option.rect.isValid()) {
 
-            if (QAbstractItemDelegate *delegate = delegateForIndex(index))
+            if (QAbstractItemDelegate *delegate = q->itemDelegateForIndex(index))
                 delegate->updateEditorGeometry(editor, option, index);
 
             const QPoint pos = editor->pos();