Drag and drop in QListWidget would not preserve the selection

Now, when dropping items, these will remain selected, and in the same visual
order as when dragged.

Auto-test included for the items moving part. For the rest, it's a
drag-and-drop thing.

Reviewed-by: Olivier

3 files changed, 80 insertions, 13 deletions

diff --git a/src/gui/itemviews/qlistwidget.cpp b/src/gui/itemviews/qlistwidget.cpp
index a978d0f..5dd1d76 100644
--- a/src/gui/itemviews/qlistwidget.cpp
+++ b/src/gui/itemviews/qlistwidget.cpp
@@ -169,6 +169,20 @@ QListWidgetItem *QListModel::take(int row)
     return item;
 }
 
+void QListModel::move(int srcRow, int dstRow)
+{
+    if (srcRow == dstRow
+        || srcRow < 0 || srcRow >= items.count()
+        || dstRow < 0 || dstRow >= items.count())
+        return;
+
+    beginMoveRows(QModelIndex(), srcRow, srcRow, QModelIndex(), dstRow);
+    if (srcRow < dstRow)
+        --dstRow;
+    items.move(srcRow, dstRow);
+    endMoveRows();
+}
+
 int QListModel::rowCount(const QModelIndex &parent) const
 {
     return parent.isValid() ? 0 : items.count();
@@ -1804,22 +1818,15 @@ void QListWidget::dropEvent(QDropEvent *event) {
 
             if (persIndexes.contains(topIndex))
                 return;
+            qSort(persIndexes); // The dropped items will remain in the same visual order.
 
             QPersistentModelIndex dropRow = model()->index(row, col, topIndex);
 
-            QList<QListWidgetItem *> taken;
-            for (int i = 0; i < persIndexes.count(); ++i)
-                taken.append(takeItem(persIndexes.at(i).row()));
-
-            // insert them back in at their new positions
+            int r = row == -1 ? count() : (dropRow.row() >= 0 ? dropRow.row() : row);
             for (int i = 0; i < persIndexes.count(); ++i) {
-                // Either at a specific point or appended
-                if (row == -1) {
-                    insertItem(count(), taken.takeFirst());
-                } else {
-                    int r = dropRow.row() >= 0 ? dropRow.row() : row;
-                    insertItem(qMin(r, count()), taken.takeFirst());
-                }
+                const QPersistentModelIndex &pIndex = persIndexes.at(i);
+                d->listModel()->move(pIndex.row(), r);
+                r = pIndex.row() + 1;   // Dropped items are inserted contiguously and in the right order.
             }
 
             event->accept();
diff --git a/src/gui/itemviews/qlistwidget_p.h b/src/gui/itemviews/qlistwidget_p.h
index 69cfa26..b5f28e3 100644
--- a/src/gui/itemviews/qlistwidget_p.h
+++ b/src/gui/itemviews/qlistwidget_p.h
@@ -77,7 +77,7 @@ public:
         { return *i2 < *i1; }
 };
 
-class QListModel : public QAbstractListModel
+class Q_AUTOTEST_EXPORT QListModel : public QAbstractListModel
 {
     Q_OBJECT
 public:
@@ -90,6 +90,7 @@ public:
     void insert(int row, const QStringList &items);
     void remove(QListWidgetItem *item);
     QListWidgetItem *take(int row);
+    void move(int srcRow, int dstRow);
 
     int rowCount(const QModelIndex &parent = QModelIndex()) const;
 
diff --git a/tests/auto/qlistwidget/tst_qlistwidget.cpp b/tests/auto/qlistwidget/tst_qlistwidget.cpp
index e825c8f..5c6ed54 100644
--- a/tests/auto/qlistwidget/tst_qlistwidget.cpp
+++ b/tests/auto/qlistwidget/tst_qlistwidget.cpp
@@ -46,6 +46,7 @@
 #include <qlist.h>
 
 #include <qlistwidget.h>
+#include <private/qlistwidget_p.h>
 
 //TESTED_CLASS=
 //TESTED_FILES=
@@ -95,6 +96,8 @@ private slots:
     void insertItem();
     void insertItems_data();
     void insertItems();
+    void moveItemsPriv_data();
+    void moveItemsPriv();
 
     void itemAssignment();
     void item_data();
@@ -849,6 +852,62 @@ void tst_QListWidget::removeItems()
 
 }
 
+void tst_QListWidget::moveItemsPriv_data()
+{
+    QTest::addColumn<int>("rowCount");
+    QTest::addColumn<int>("srcRow");
+    QTest::addColumn<int>("dstRow");
+    QTest::addColumn<bool>("shouldHaveSignaled");
+
+    QTest::newRow("Empty") << 0 << 0 << 0 << false;
+    QTest::newRow("Overflow src") << 5 << 5 << 2 << false;
+    QTest::newRow("Underflow src") << 5 << -1 << 2 << false;
+    QTest::newRow("Overflow dst") << 5 << 2 << 5 << false;
+    QTest::newRow("Underflow dst") << 5 << 2 << -1 << false;
+    QTest::newRow("Same place") << 5 << 2 << 2 << false;
+    QTest::newRow("Up") << 5 << 4 << 2 << true;
+    QTest::newRow("Down") << 5 << 2 << 4 << true;
+}
+
+void tst_QListWidget::moveItemsPriv()
+{
+    QFETCH(int, rowCount);
+    QFETCH(int, srcRow);
+    QFETCH(int, dstRow);
+    QFETCH(bool, shouldHaveSignaled);
+
+    for (int r = 0; r < rowCount; ++r)
+        new QListWidgetItem(QString::number(r), testWidget);
+
+    QListModel *model = dynamic_cast<QListModel *>(testWidget->model());
+    QVERIFY(model);
+    QSignalSpy beginMoveSpy(model, SIGNAL(rowsAboutToBeMoved(QModelIndex,int,int,QModelIndex,int)));
+    QSignalSpy movedSpy(model, SIGNAL(rowsMoved(QModelIndex,int,int,QModelIndex,int)));
+    model->move(srcRow, dstRow);
+
+    if (shouldHaveSignaled) {
+        if (srcRow < dstRow)
+            QCOMPARE(testWidget->item(dstRow - 1)->text(), QString::number(srcRow));
+        else
+            QCOMPARE(testWidget->item(dstRow)->text(), QString::number(srcRow));
+
+        QCOMPARE(beginMoveSpy.count(), 1);
+        const QList<QVariant> &beginMoveArgs = beginMoveSpy.takeFirst();
+        QCOMPARE(beginMoveArgs.at(1).toInt(), srcRow);
+        QCOMPARE(beginMoveArgs.at(2).toInt(), srcRow);
+        QCOMPARE(beginMoveArgs.at(4).toInt(), dstRow);
+
+        QCOMPARE(movedSpy.count(), 1);
+        const QList<QVariant> &movedArgs = movedSpy.takeFirst();
+        QCOMPARE(movedArgs.at(1).toInt(), srcRow);
+        QCOMPARE(movedArgs.at(2).toInt(), srcRow);
+        QCOMPARE(movedArgs.at(4).toInt(), dstRow);
+    } else {
+        QCOMPARE(beginMoveSpy.count(), 0);
+        QCOMPARE(movedSpy.count(), 0);
+    }
+}
+
 void tst_QListWidget::itemStreaming_data()
 {
     QTest::addColumn<QString>("text");