To run the sample, open it in Visual Studio 2008. Then simply compile and run the application.
Several points on using the sample:
Code description
Here are some code excerpts. In function ListView1_PreviewMouseLeftButtonDown called in the beginning of drag operation we create a set of selected items (Dictionary with null values) and pass it to the DragDrop.DoDragDrop(...) function as data item:
Dictionary shapes = new Dictionary();
if (ListView1.SelectedItems.Count == 0)
return;
foreach(Shape shape in ListView1.SelectedItems)
{
shapes[shape] = null;
}
Shape currentShape = ListView1.Items[index] as Shape;
if (!shapes.ContainsKey(currentShape))
return;
DragDrop.DoDragDrop(this.ListView1, shapes, allowedEffects);
Function ListView1_Drop (the one implementing the drop operation) is slightly more complicated. First we record the list item into which the selected items are dropped:
int index = this.GetCurrentIndex(e.GetPosition);
...
Shape dropTargetShape = myShapes[index];
Then we build a list of selected items to be dropped:
List dropList = new List();
foreach(Shape shape in myShapes)
{
if (!selectedShapes.ContainsKey(shape))
continue;
dropList.Add(shape);
}
We need this step in order to ensure that the dropped items are in the same order as they were originally. (In ListView.SelectedItems collection the items are stored in the order in which they are selected, not in the order in which they are in the ListView).
Then we remove all the selected items from the collection myShapes (which is the collection of ListView items):
foreach(Shape shape in dropList)
{
myShapes.Remove(shape);
}
Then we get the (possibly) new index of the drop target item within the modified collection:
int selectIndex = myShapes.IndexOf(dropTargetShape);
Finally we insert the items into the collection before the drop target item:
for(int i = 0; i < dropList.Count; i++)
{
Shape shape = dropList[i];
myShapes.Insert(i + selectIndex, shape);
...
}