Enable basic drag and drop support for the Places Panel

The dropping has not been implemented yet, however in the context of
this step the creating of the drag-pixmap is now forwarded to
the item-widgets. This allows creating some optimized dragging-pixmaps
e.g. for the details-view, where only the name and icon should
be provided as drag-pixmap.

9 files changed, 76 insertions, 5 deletions

diff --git a/src/kitemviews/kfileitemlistview.cpp b/src/kitemviews/kfileitemlistview.cpp
index b5cc343f4..e52865aa6 100644
--- a/src/kitemviews/kfileitemlistview.cpp
+++ b/src/kitemviews/kfileitemlistview.cpp
@@ -119,6 +119,9 @@ QPixmap KFileItemListView::createDragPixmap(const QSet<int>& indexes) const
 
     const int itemCount = indexes.count();
     Q_ASSERT(itemCount > 0);
+    if (itemCount == 1) {
+        return KItemListView::createDragPixmap(indexes);
+    }
 
     // If more than one item is dragged, align the items inside a
     // rectangular grid. The maximum grid size is limited to 5 x 5 items.
diff --git a/src/kitemviews/kitemlistcontroller.cpp b/src/kitemviews/kitemlistcontroller.cpp
index 6045f5020..b8d719d3b 100644
--- a/src/kitemviews/kitemlistcontroller.cpp
+++ b/src/kitemviews/kitemlistcontroller.cpp
@@ -1063,6 +1063,11 @@ void KItemListController::startDragging()
     const QPixmap pixmap = m_view->createDragPixmap(selectedItems);
     drag->setPixmap(pixmap);
 
+    // TODO: The vertical hotspot of -24 should be replaced by the
+    // height of the QCursor-pixmap.
+    const QPoint hotSpot(pixmap.width() / 2, -24);
+    drag->setHotSpot(hotSpot);
+
     drag->exec(Qt::MoveAction | Qt::CopyAction | Qt::LinkAction, Qt::CopyAction);
 }
 
diff --git a/src/kitemviews/kitemlistview.cpp b/src/kitemviews/kitemlistview.cpp
index 0f31cb5a1..ebcf48680 100644
--- a/src/kitemviews/kitemlistview.cpp
+++ b/src/kitemviews/kitemlistview.cpp
@@ -36,6 +36,7 @@
 
 #include <QCursor>
 #include <QGraphicsSceneMouseEvent>
+#include <QGraphicsView>
 #include <QPainter>
 #include <QPropertyAnimation>
 #include <QStyle>
@@ -566,8 +567,21 @@ KItemListHeader* KItemListView::header() const
 
 QPixmap KItemListView::createDragPixmap(const QSet<int>& indexes) const
 {
-    Q_UNUSED(indexes);
-    return QPixmap();
+    QPixmap pixmap;
+
+    if (indexes.count() == 1) {
+        KItemListWidget* item = m_visibleItems.value(indexes.toList().first());
+        QGraphicsView* graphicsView = scene()->views()[0];
+        if (item && graphicsView) {
+            pixmap = item->createDragPixmap(0, graphicsView);
+        }
+    } else {
+        // TODO: Not implemented yet. Probably extend the interface
+        // from KItemListWidget::createDragPixmap() to return a pixmap
+        // that can be used for multiple indexes.
+    }
+
+    return pixmap;
 }
 
 void KItemListView::editRole(int index, const QByteArray& role)
diff --git a/src/kitemviews/kitemlistview.h b/src/kitemviews/kitemlistview.h
index dd67b941b..de2d2a6bb 100644
--- a/src/kitemviews/kitemlistview.h
+++ b/src/kitemviews/kitemlistview.h
@@ -257,8 +257,7 @@ public:
 
     /**
      * @return Pixmap that is used for a drag operation based on the
-     *         items given by \a indexes. The default implementation returns
-     *         a null-pixmap.
+     *         items given by \a indexes.
      */
     virtual QPixmap createDragPixmap(const QSet<int>& indexes) const;
 
diff --git a/src/kitemviews/kitemlistwidget.cpp b/src/kitemviews/kitemlistwidget.cpp
index f304aa41d..45329afb3 100644
--- a/src/kitemviews/kitemlistwidget.cpp
+++ b/src/kitemviews/kitemlistwidget.cpp
@@ -360,6 +360,22 @@ QRectF KItemListWidget::expansionToggleRect() const
     return QRectF();
 }
 
+QPixmap KItemListWidget::createDragPixmap(const QStyleOptionGraphicsItem* option,
+                                          QWidget* widget)
+{
+    QPixmap pixmap(size().toSize());
+    pixmap.fill(Qt::transparent);
+
+    QPainter painter(&pixmap);
+
+    const bool oldAlternateBackground = m_alternateBackground;
+    setAlternateBackground(false);
+    paint(&painter, option, widget);
+    setAlternateBackground(oldAlternateBackground);
+
+    return pixmap;
+}
+
 void KItemListWidget::dataChanged(const QHash<QByteArray, QVariant>& current,
                                   const QSet<QByteArray>& roles)
 {
diff --git a/src/kitemviews/kitemlistwidget.h b/src/kitemviews/kitemlistwidget.h
index fdb07d62e..55181faa8 100644
--- a/src/kitemviews/kitemlistwidget.h
+++ b/src/kitemviews/kitemlistwidget.h
@@ -175,6 +175,12 @@ public:
      */
     virtual QRectF expansionToggleRect() const;
 
+    /**
+     * @return Pixmap that is used when dragging an item. Per default the current state of the
+     *         widget is returned as pixmap.
+     */
+    virtual QPixmap createDragPixmap(const QStyleOptionGraphicsItem* option, QWidget* widget = 0);
+
 signals:
     void roleEditingCanceled(int index, const QByteArray& role, const QVariant& value);
     void roleEditingFinished(int index, const QByteArray& role, const QVariant& value);
diff --git a/src/kitemviews/kitemmodelbase.h b/src/kitemviews/kitemmodelbase.h
index 52fcaee36..129524b31 100644
--- a/src/kitemviews/kitemmodelbase.h
+++ b/src/kitemviews/kitemmodelbase.h
@@ -154,7 +154,8 @@ public:
     /**
      * @return MIME-data for the items given by \a indexes. The default implementation
      *         returns 0. The ownership of the returned instance is in the hand of the
-     *         caller of this method.
+     *         caller of this method. The method must be implemented if dragging of
+     *         items should be possible.
      */
     virtual QMimeData* createMimeData(const QSet<int>& indexes) const;
 
diff --git a/src/kitemviews/kstandarditemlistwidget.cpp b/src/kitemviews/kstandarditemlistwidget.cpp
index 3f470b8cf..0cd11d363 100644
--- a/src/kitemviews/kstandarditemlistwidget.cpp
+++ b/src/kitemviews/kstandarditemlistwidget.cpp
@@ -405,6 +405,32 @@ QRectF KStandardItemListWidget::selectionToggleRect() const
     return QRectF(pos, QSizeF(toggleSize, toggleSize));
 }
 
+QPixmap KStandardItemListWidget::createDragPixmap(const QStyleOptionGraphicsItem* option,
+                                                  QWidget* widget)
+{
+    QPixmap pixmap = KItemListWidget::createDragPixmap(option, widget);
+    if (m_layout != DetailsLayout || styleOption().extendedSelectionRegion) {
+        return pixmap;
+    }
+
+    // Only return the content of the text-column as pixmap
+    const int leftClip = m_pixmapPos.x();
+
+    const TextInfo* textInfo = m_textInfo.value("text");
+    const int rightClip = textInfo->pos.x() +
+                          textInfo->staticText.size().width() +
+                          2 * styleOption().padding;
+
+    QPixmap clippedPixmap(rightClip - leftClip + 1, pixmap.height());
+    clippedPixmap.fill(Qt::transparent);
+
+    QPainter painter(&clippedPixmap);
+    painter.drawPixmap(-leftClip, 0, pixmap);
+
+    return clippedPixmap;
+}
+
+
 KItemListWidgetInformant* KStandardItemListWidget::createInformant()
 {
     return new KStandardItemListWidgetInformant();
diff --git a/src/kitemviews/kstandarditemlistwidget.h b/src/kitemviews/kstandarditemlistwidget.h
index d942b89a9..90a6f5055 100644
--- a/src/kitemviews/kstandarditemlistwidget.h
+++ b/src/kitemviews/kstandarditemlistwidget.h
@@ -86,6 +86,7 @@ public:
     virtual QRectF textFocusRect() const;
     virtual QRectF expansionToggleRect() const;
     virtual QRectF selectionToggleRect() const;
+    virtual QPixmap createDragPixmap(const QStyleOptionGraphicsItem* option, QWidget* widget = 0);
 
     static KItemListWidgetInformant* createInformant();