/// <summary>
/// Processes a drag in the main grid.
/// </summary>
private void OnMainGridMouseMove(object sender, MouseEventArgs e)
{
// Exit if shift key and left mouse button aren't pressed
if (e.LeftButton != MouseButtonState.Pressed)
{
return;
}
if (Keyboard.Modifiers != ModifierKeys.Shift)
{
return;
}
/* We use the m_MouseDirection value in the
* OnMainGridCheckDropTarget() event handler. */
// Find the row the mouse button was pressed on
var row = FindVisualParent <DataGridRow>(e.OriginalSource as FrameworkElement);
m_OriginalIndex = row.GetIndex();
// If the row was already selected, begin drag
if ((row != null) && row.IsSelected)
{
// Get the grocery item represented by the selected row
var selectedItem = (GroceryItem)row.Item;
var finalDropEffect = DragDrop.DoDragDrop(row, selectedItem, DragDropEffects.Move);
if ((finalDropEffect == DragDropEffects.Move) && (m_TargetItem != null))
{
/* A drop was accepted. Determine the index of the item being
* dragged and the drop location. If they are different, then
* move the selectedItem to the new location. */
// Move the dragged item to its drop position
var oldIndex = m_ViewModel.GroceryList.IndexOf(selectedItem);
var newIndex = m_ViewModel.GroceryList.IndexOf(m_TargetItem);
if (oldIndex != newIndex)
{
m_ViewModel.GroceryList.Move(oldIndex, newIndex);
}
m_TargetItem = null;
}
}
}
/// <summary>
/// Process a row drop on the DataGrid.
/// </summary>
private void OnMainGridDrop(object sender, DragEventArgs e)
{
e.Effects = DragDropEffects.None;
e.Handled = true;
// Verify that this is a valid drop and then store the drop target
var row = FindVisualParent <DataGridRow>(e.OriginalSource as UIElement);
if (row != null)
{
m_TargetItem = row.Item as GroceryItem;
if (m_TargetItem != null)
{
e.Effects = DragDropEffects.Move;
}
}
// Erase last drop-line
if (m_OldRow != null)
{
m_OldRow.BorderThickness = new Thickness(0, 0, 0, 0);
}
}