Unbreak internal DnD by using null MimeData

Regression from 67b0fcea (which
implements external DnD). QMimeData of internal DnD is never null,
it always contains internal MimeType (but empty byte array)

Change-Id: Ie12e9c3b7a3c7cebfd98064bb2fafec27c20a442
Reviewed-on: https://gerrit.libreoffice.org/68673
Tested-by: Jenkins
Reviewed-by: Katarina Behrens <Katarina.Behrens@cib.de>

vcl/inc/qt5/Qt5Tools.hxx

@@ -118,6 +118,8 @@ inline sal_uInt16 getFormatBits(QImage::Format eFormat)
     }
 }
 
+static const QString sInternalMimeType = "application/x-libreoffice-dnditem";
+
 typedef struct _cairo_surface cairo_surface_t;
 struct CairoDeleter
 {

vcl/inc/qt5/Qt5Widget.hxx

@@ -66,8 +66,6 @@ class Qt5Widget : public QWidget
     void inputMethodEvent(QInputMethodEvent*) override;
     QVariant inputMethodQuery(Qt::InputMethodQuery) const override;
 
-    const QString m_InternalMimeType = "application/x-libreoffice-dnditem";
-
 public slots:
     static void showTooltip(const OUString& rTip);
 

vcl/qt5/Qt5Frame.cxx

@@ -29,6 +29,7 @@
 #include <Qt5Menu.hxx>
 #include <Qt5DragAndDrop.hxx>
 
+#include <QtCore/QMimeData>
 #include <QtCore/QPoint>
 #include <QtCore/QSize>
 #include <QtGui/QIcon>
@@ -1109,7 +1110,7 @@ void Qt5Frame::draggingStarted(const int x, const int y, const QMimeData* pQMime
     aEvent.SourceActions = css::datatransfer::dnd::DNDConstants::ACTION_MOVE;
 
     css::uno::Reference<css::datatransfer::XTransferable> xTransferable;
-    if (pQMimeData)
+    if (!pQMimeData->hasFormat(sInternalMimeType))
         xTransferable = new Qt5DnDTransferable(pQMimeData);
     else
         xTransferable = Qt5DragSource::m_ActiveDragSource->GetTransferable();
@@ -1141,7 +1142,7 @@ void Qt5Frame::dropping(const int x, const int y, const QMimeData* pQMimeData)
     aEvent.SourceActions = css::datatransfer::dnd::DNDConstants::ACTION_MOVE;
 
     css::uno::Reference<css::datatransfer::XTransferable> xTransferable;
-    if (pQMimeData)
+    if (!pQMimeData->hasFormat(sInternalMimeType))
         xTransferable = new Qt5DnDTransferable(pQMimeData);
     else
         xTransferable = Qt5DragSource::m_ActiveDragSource->GetTransferable();

vcl/qt5/Qt5Widget.cxx

@@ -193,7 +193,7 @@ void Qt5Widget::startDrag()
 {
     // internal drag source
     QMimeData* mimeData = new QMimeData;
-    mimeData->setData(m_InternalMimeType, nullptr);
+    mimeData->setData(sInternalMimeType, nullptr);
 
     QDrag* drag = new QDrag(this);
     drag->setMimeData(mimeData);
@@ -202,7 +202,7 @@ void Qt5Widget::startDrag()
 
 void Qt5Widget::dragEnterEvent(QDragEnterEvent* event)
 {
-    if (event->mimeData()->hasFormat(m_InternalMimeType))
+    if (event->mimeData()->hasFormat(sInternalMimeType))
         event->accept();
     else
         event->acceptProposedAction();