Introduce QItemDelegate::destroyEditor virtual invoked at editor close

This provides a stronger mechanism e.g when inheriting QItemDelegate.

It makes some things much easier e.g avoid delete of an editor
and maybe only delete depending on what the editor says itself.

This introduces a new virtual function.

Task-number: QTBUG-2299

Change-Id: I8410f8199775987dbacffd99e4c354fdadcdd21f
Reviewed-by: Stephen Kelly <stephen.kelly@kdab.com>

4 files changed, 28 insertions, 8 deletions

diff --git a/src/widgets/itemviews/qabstractitemdelegate.cpp b/src/widgets/itemviews/qabstractitemdelegate.cpp
index b34cfa377c..6184a5845a 100644
--- a/src/widgets/itemviews/qabstractitemdelegate.cpp
+++ b/src/widgets/itemviews/qabstractitemdelegate.cpp
@@ -232,7 +232,7 @@ QAbstractItemDelegate::~QAbstractItemDelegate()
     editor paints its own background (e.g., with
     \l{QWidget::}{setAutoFillBackground()}).
 
-    \sa setModelData() setEditorData()
+    \sa destroyEditor() setModelData() setEditorData()
 */
 QWidget *QAbstractItemDelegate::createEditor(QWidget *,
                                              const QStyleOptionViewItem &,
@@ -241,6 +241,19 @@ QWidget *QAbstractItemDelegate::createEditor(QWidget *,
     return 0;
 }
 
+
+/*!
+    A function called when the editor is no longer needed and should be
+    destroyed. The default behavior is a call to deleteLater on the editor.
+    It possible e.g. to avoid this delete by reimplementing this function.
+
+    \sa createEditor()
+*/
+void QAbstractItemDelegate::destroyEditor(QWidget *editor, const QModelIndex &) const
+{
+    editor->deleteLater();
+}
+
 /*!
     Sets the contents of the given \a editor to the data for the item
     at the given \a index. Note that the index contains information
diff --git a/src/widgets/itemviews/qabstractitemdelegate.h b/src/widgets/itemviews/qabstractitemdelegate.h
index 2cb1175a22..2c51dfcac8 100644
--- a/src/widgets/itemviews/qabstractitemdelegate.h
+++ b/src/widgets/itemviews/qabstractitemdelegate.h
@@ -88,6 +88,8 @@ public:
                                   const QStyleOptionViewItem &option,
                                   const QModelIndex &index) const;
 
+    virtual void destroyEditor(QWidget *editor, const QModelIndex &index) const;
+
     virtual void setEditorData(QWidget *editor, const QModelIndex &index) const;
 
     virtual void setModelData(QWidget *editor,
diff --git a/src/widgets/itemviews/qabstractitemview.cpp b/src/widgets/itemviews/qabstractitemview.cpp
index e6ba21e701..98a17a5178 100644
--- a/src/widgets/itemviews/qabstractitemview.cpp
+++ b/src/widgets/itemviews/qabstractitemview.cpp
@@ -1098,7 +1098,7 @@ void QAbstractItemView::reset()
     d->delayedReset.stop(); //make sure we stop the timer
     foreach (const QEditorInfo &info, d->indexEditorHash) {
         if (info.widget)
-            d->releaseEditor(info.widget.data());
+            d->releaseEditor(info.widget.data(), d->indexForEditor(info.widget.data()));
     }
     d->editorIndexHash.clear();
     d->indexEditorHash.clear();
@@ -2778,7 +2778,7 @@ void QAbstractItemView::closeEditor(QWidget *editor, QAbstractItemDelegate::EndE
         editor = ed;
 
         if (!isPersistent && editor)
-            d->releaseEditor(editor);
+            d->releaseEditor(editor, index);
     }
 
     // The EndEditHint part
@@ -3102,7 +3102,7 @@ void QAbstractItemView::closePersistentEditor(const QModelIndex &index)
             closeEditor(editor, QAbstractItemDelegate::RevertModelCache);
         d->persistent.remove(editor);
         d->removeEditor(editor);
-        d->releaseEditor(editor);
+        d->releaseEditor(editor, index);
     }
 }
 
@@ -3314,7 +3314,7 @@ void QAbstractItemView::rowsAboutToBeRemoved(const QModelIndex &parent, int star
             QEditorInfo info = d->indexEditorHash.take(index);
             i = d->editorIndexHash.erase(i);
             if (info.widget)
-                d->releaseEditor(editor);
+                d->releaseEditor(editor, index);
         } else {
             ++i;
         }
@@ -3393,7 +3393,7 @@ void QAbstractItemViewPrivate::_q_columnsAboutToBeRemoved(const QModelIndex &par
             QEditorInfo info = indexEditorHash.take(it.value());
             it = editorIndexHash.erase(it);
             if (info.widget)
-                releaseEditor(editor);
+                releaseEditor(editor, index);
         } else {
             ++it;
         }
diff --git a/src/widgets/itemviews/qabstractitemview_p.h b/src/widgets/itemviews/qabstractitemview_p.h
index ab2fc67ade..3826f3b4e9 100644
--- a/src/widgets/itemviews/qabstractitemview_p.h
+++ b/src/widgets/itemviews/qabstractitemview_p.h
@@ -200,13 +200,18 @@ public:
     // reimplemented in subclasses
     virtual void adjustViewOptionsForIndex(QStyleOptionViewItemV4*, const QModelIndex&) const {}
 
-    inline void releaseEditor(QWidget *editor) const {
+    inline void releaseEditor(QWidget *editor, const QModelIndex &index = QModelIndex()) const {
         if (editor) {
             QObject::disconnect(editor, SIGNAL(destroyed(QObject*)),
                                 q_func(), SLOT(editorDestroyed(QObject*)));
             editor->removeEventFilter(itemDelegate);
             editor->hide();
-            editor->deleteLater();
+            QAbstractItemDelegate *delegate = delegateForIndex(index);
+
+            if (delegate)
+                delegate->destroyEditor(editor, index);
+            else
+                editor->deleteLater();
         }
     }