Allow dropping data outside of item area in wxDataViewCtrl.

Implement this change for the generic and the native GTK versions and document
it.

Closes #16152.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@76416 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

docs/changes.txt

@@ -36,6 +36,7 @@ All (GUI):
 - Add wxFD_NO_FOLLOW style for wxFileDialog (Luca Bacci).
 - Add support for embedding bitmaps in generated SVG in wxSVGFileDC (iwbnwif).
 - Add support for sorting wxDataViewCtrl by multiple columns (Trigve).
+- Allow dropping data on wxDataViewCtrl background (Laurent Poujoulat).
 - Add wxHtmlWindow::SetDefaultHTMLCursor() (Jeff A. Marr).
 - Add default ctor and Create() to wxContextHelpButton (Hanmac).
 - Send events when toggling wxPropertyGrid nodes from keyboard (Armel Asselin).

interface/wx/dataview.h

@@ -3483,7 +3483,13 @@ public:
 
 
 
-    
+    /**
+        Returns the item affected by the event.
+
+        Notice that for @c wxEVT_DATAVIEW_ITEM_DROP_POSSIBLE and @c
+        wxEVT_DATAVIEW_ITEM_DROP event handlers, the item may be invalid,
+        indicating that the drop is about to happen outside of the item area.
+     */
     wxDataViewItem GetItem() const;
     void SetItem( const wxDataViewItem &item );
     void SetEditCanceled(bool editCancelled);

samples/dataview/dataview.cpp

@@ -862,8 +862,8 @@ void MyFrame::OnDropPossible( wxDataViewEvent &event )
 {
     wxDataViewItem item( event.GetItem() );
 
-    // only allow drags for item, not containers
-    if (m_music_model->IsContainer( item ) )
+    // only allow drags for item or background, not containers
+    if ( item.IsOk() && m_music_model->IsContainer( item ) )
         event.Veto();
 
     if (event.GetDataFormat() != wxDF_UNICODETEXT)
@@ -875,7 +875,7 @@ void MyFrame::OnDrop( wxDataViewEvent &event )
     wxDataViewItem item( event.GetItem() );
 
     // only allow drops for item, not containers
-    if (m_music_model->IsContainer( item ) )
+    if ( item.IsOk() && m_music_model->IsContainer( item ) )
     {
         event.Veto();
         return;
@@ -890,7 +890,10 @@ void MyFrame::OnDrop( wxDataViewEvent &event )
     wxTextDataObject obj;
     obj.SetData( wxDF_UNICODETEXT, event.GetDataSize(), event.GetDataBuffer() );
 
-    wxLogMessage( "Text dropped: %s", obj.GetText() );
+    if ( item.IsOk() )
+        wxLogMessage( "Text dropped on item %s: %s", m_music_model->GetTitle( item ), obj.GetText() );
+    else
+        wxLogMessage( "Text dropped on background: %s", obj.GetText() );
 }
 
 #endif // wxUSE_DRAG_AND_DROP

src/generic/datavgen.cpp

@@ -1608,13 +1608,10 @@ wxDragResult wxDataViewMainWindow::OnDragOver( wxDataFormat format, wxCoord x,
     m_owner->CalcUnscrolledPosition( xx, yy, &xx, &yy );
     unsigned int row = GetLineAt( yy );
 
-    if ((row >= GetRowCount()) || (xx > GetEndOfLastCol()))
-    {
-        RemoveDropHint();
-        return wxDragNone;
-    }
+    wxDataViewItem item;
 
-    wxDataViewItem item = GetItemByRow( row );
+    if ( row < GetRowCount() && xx <= GetEndOfLastCol() )
+        item = GetItemByRow( row );
 
     wxDataViewModel *model = GetModel();
 
@@ -1624,25 +1621,25 @@ wxDragResult wxDataViewMainWindow::OnDragOver( wxDataFormat format, wxCoord x,
     event.SetModel( model );
     event.SetDataFormat( format );
     event.SetDropEffect( def );
-    if (!m_owner->HandleWindowEvent( event ))
+    if ( !m_owner->HandleWindowEvent( event ) || !event.IsAllowed() )
     {
         RemoveDropHint();
         return wxDragNone;
     }
 
-    if (!event.IsAllowed())
+    if ( item.IsOk() )
+    {
+        if (m_dropHint && (row != m_dropHintLine))
+            RefreshRow( m_dropHintLine );
+        m_dropHint = true;
+        m_dropHintLine = row;
+        RefreshRow( row );
+    }
+    else
     {
         RemoveDropHint();
-        return wxDragNone;
     }
 
-
-    if (m_dropHint && (row != m_dropHintLine))
-        RefreshRow( m_dropHintLine );
-    m_dropHint = true;
-    m_dropHintLine = row;
-    RefreshRow( row );
-
     return def;
 }
 
@@ -1655,10 +1652,10 @@ bool wxDataViewMainWindow::OnDrop( wxDataFormat format, wxCoord x, wxCoord y )
     m_owner->CalcUnscrolledPosition( xx, yy, &xx, &yy );
     unsigned int row = GetLineAt( yy );
 
-    if ((row >= GetRowCount()) || (xx > GetEndOfLastCol()))
-        return false;
+    wxDataViewItem item;
 
-    wxDataViewItem item = GetItemByRow( row );
+    if ( row < GetRowCount() && xx <= GetEndOfLastCol())
+       item = GetItemByRow( row );
 
     wxDataViewModel *model = GetModel();
 
@@ -1667,10 +1664,7 @@ bool wxDataViewMainWindow::OnDrop( wxDataFormat format, wxCoord x, wxCoord y )
     event.SetItem( item );
     event.SetModel( model );
     event.SetDataFormat( format );
-    if (!m_owner->HandleWindowEvent( event ))
-        return false;
-
-    if (!event.IsAllowed())
+    if (!m_owner->HandleWindowEvent( event ) || !event.IsAllowed())
         return false;
 
     return true;
@@ -1684,10 +1678,10 @@ wxDragResult wxDataViewMainWindow::OnData( wxDataFormat format, wxCoord x, wxCoo
     m_owner->CalcUnscrolledPosition( xx, yy, &xx, &yy );
     unsigned int row = GetLineAt( yy );
 
-    if ((row >= GetRowCount()) || (xx > GetEndOfLastCol()))
-        return wxDragNone;
+    wxDataViewItem item;
 
-    wxDataViewItem item = GetItemByRow( row );
+    if ( row < GetRowCount() && xx <= GetEndOfLastCol() )
+        item = GetItemByRow( row );
 
     wxDataViewModel *model = GetModel();
 
@@ -1701,10 +1695,7 @@ wxDragResult wxDataViewMainWindow::OnData( wxDataFormat format, wxCoord x, wxCoo
     event.SetDataSize( obj->GetSize() );
     event.SetDataBuffer( obj->GetData() );
     event.SetDropEffect( def );
-    if (!m_owner->HandleWindowEvent( event ))
-        return wxDragNone;
-
-    if (!event.IsAllowed())
+    if ( !m_owner->HandleWindowEvent( event ) || !event.IsAllowed() )
         return wxDragNone;
 
     return def;

src/gtk/dataview.cpp

@@ -3562,8 +3562,6 @@ wxDataViewCtrlInternal::drag_data_received(GtkTreeDragDest *WXUNUSED(drag_dest),
                                            GtkSelectionData *selection_data)
 {
     wxDataViewItem item(GetOwner()->GTKPathToItem(path));
-    if ( !item )
-        return FALSE;
 
     wxDataViewEvent event( wxEVT_DATAVIEW_ITEM_DROP, m_owner->GetId() );
     event.SetEventObject( m_owner );
@@ -3587,8 +3585,6 @@ wxDataViewCtrlInternal::row_drop_possible(GtkTreeDragDest *WXUNUSED(drag_dest),
                                           GtkSelectionData *selection_data)
 {
     wxDataViewItem item(GetOwner()->GTKPathToItem(path));
-    if ( !item )
-        return FALSE;
 
     wxDataViewEvent event( wxEVT_DATAVIEW_ITEM_DROP_POSSIBLE, m_owner->GetId() );
     event.SetEventObject( m_owner );