Added visual DnD indicator for left to right flow in QListView

Extended the behaviour already present in QAbstractItemView into
QListView. This means some code duplication which should maybe be refactored
at some point. (Seems to be the price to pay when some delegate does almost
the same thing as the base class).

No auto-test, as it's a drag-and-drop related task.

Reviewed-by: Thierry
Task-number: QTBUG-3730

1 files changed, 107 insertions, 2 deletions

diff --git a/src/gui/itemviews/qlistview.cpp b/src/gui/itemviews/qlistview.cpp
index f58f458..109d760 100644
--- a/src/gui/itemviews/qlistview.cpp
+++ b/src/gui/itemviews/qlistview.cpp
@@ -853,8 +853,13 @@ void QListView::resizeEvent(QResizeEvent *e)
 */
 void QListView::dragMoveEvent(QDragMoveEvent *e)
 {
-    if (!d_func()->commonListView->filterDragMoveEvent(e))
-        QAbstractItemView::dragMoveEvent(e);
+    Q_D(QListView);
+    if (!d->commonListView->filterDragMoveEvent(e)) {
+        if (viewMode() == QListView::ListMode && flow() == QListView::LeftToRight)
+            static_cast<QListModeViewBase *>(d->commonListView)->dragMoveEvent(e);
+        else
+            QAbstractItemView::dragMoveEvent(e);
+    }
 }
 
 
@@ -1804,6 +1809,16 @@ QItemSelection QListViewPrivate::selection(const QRect &rect) const
     return selection;
 }
 
+#ifndef QT_NO_DRAGANDDROP
+QAbstractItemView::DropIndicatorPosition QListViewPrivate::position(const QPoint &pos, const QRect &rect, const QModelIndex &idx) const
+{
+    if (viewMode == QListView::ListMode && flow == QListView::LeftToRight)
+        return static_cast<QListModeViewBase *>(commonListView)->position(pos, rect, idx);
+    else
+        return QAbstractItemViewPrivate::position(pos, rect, idx);
+}
+#endif
+
 /*
  * Common ListView Implementation
 */
@@ -1893,6 +1908,96 @@ void QListModeViewBase::paintDragDrop(QPainter *painter)
     // in IconMode, it makes no sense to show it
     dd->paintDropIndicator(painter);
 }
+
+QAbstractItemView::DropIndicatorPosition QListModeViewBase::position(const QPoint &pos, const QRect &rect, const QModelIndex &index) const
+{
+    QAbstractItemView::DropIndicatorPosition r = QAbstractItemView::OnViewport;
+    if (!dd->overwrite) {
+        const int margin = 2;
+        if (pos.x() - rect.left() < margin) {
+            r = QAbstractItemView::AboveItem;   // Visually, on the left
+        } else if (rect.right() - pos.x() < margin) {
+            r = QAbstractItemView::BelowItem;   // Visually, on the right
+        } else if (rect.contains(pos, true)) {
+            r = QAbstractItemView::OnItem;
+        }
+    } else {
+        QRect touchingRect = rect;
+        touchingRect.adjust(-1, -1, 1, 1);
+        if (touchingRect.contains(pos, false)) {
+            r = QAbstractItemView::OnItem;
+        }
+    }
+
+    if (r == QAbstractItemView::OnItem && (!(dd->model->flags(index) & Qt::ItemIsDropEnabled)))
+        r = pos.x() < rect.center().x() ? QAbstractItemView::AboveItem : QAbstractItemView::BelowItem;
+
+    return r;
+}
+
+void QListModeViewBase::dragMoveEvent(QDragMoveEvent *event)
+{
+    if (qq->dragDropMode() == QAbstractItemView::InternalMove
+        && (event->source() != qq || !(event->possibleActions() & Qt::MoveAction)))
+        return;
+
+    // ignore by default
+    event->ignore();
+
+    QModelIndex index = qq->indexAt(event->pos());
+    dd->hover = index;
+    if (!dd->droppingOnItself(event, index)
+        && dd->canDecode(event)) {
+
+        if (index.isValid() && dd->showDropIndicator) {
+            QRect rect = qq->visualRect(index);
+            dd->dropIndicatorPosition = position(event->pos(), rect, index);
+            switch (dd->dropIndicatorPosition) {
+            case QAbstractItemView::AboveItem:
+                if (dd->isIndexDropEnabled(index.parent())) {
+                    dd->dropIndicatorRect = QRect(rect.left(), rect.top(), 0, rect.height());
+                    event->accept();
+                } else {
+                    dd->dropIndicatorRect = QRect();
+                }
+                break;
+            case QAbstractItemView::BelowItem:
+                if (dd->isIndexDropEnabled(index.parent())) {
+                    dd->dropIndicatorRect = QRect(rect.right(), rect.top(), 0, rect.height());
+                    event->accept();
+                } else {
+                    dd->dropIndicatorRect = QRect();
+                }
+                break;
+            case QAbstractItemView::OnItem:
+                if (dd->isIndexDropEnabled(index)) {
+                    dd->dropIndicatorRect = rect;
+                    event->accept();
+                } else {
+                    dd->dropIndicatorRect = QRect();
+                }
+                break;
+            case QAbstractItemView::OnViewport:
+                dd->dropIndicatorRect = QRect();
+                if (dd->isIndexDropEnabled(qq->rootIndex())) {
+                    event->accept(); // allow dropping in empty areas
+                }
+                break;
+            }
+        } else {
+            dd->dropIndicatorRect = QRect();
+            dd->dropIndicatorPosition = QAbstractItemView::OnViewport;
+            if (dd->isIndexDropEnabled(qq->rootIndex())) {
+                event->accept(); // allow dropping in empty areas
+            }
+        }
+        dd->viewport->update();
+    } // can decode
+
+    if (dd->shouldAutoScroll(event->pos()))
+        qq->startAutoScroll();
+}
+
 #endif //QT_NO_DRAGANDDROP
 
 void QListModeViewBase::updateVerticalScrollBar(const QSize &step)