private void DragSource_PreviewMouseLeftButtonDown(object sender, MouseButtonEventArgs e)
{
try
{
Visual visual = e.OriginalSource as Visual;
_topWindow = (Window)DragDropHelper.FindAncestor(typeof(Window), visual);
_initialMousePosition = e.GetPosition(_topWindow);
string adornerLayerName = GetAdornerLayer(sender as DependencyObject);
_adornerLayer = (Canvas)_topWindow.FindName(adornerLayerName);
string dropTargetName = GetDropTarget(sender as DependencyObject);
_dropTarget = (UIElement)_topWindow.FindName(dropTargetName);
_draggedData = (sender as FrameworkElement).DataContext;
}
catch (Exception exc)
{
Console.WriteLine("Exception in DragDropHelper: " + exc.InnerException.ToString());
}
}
// Drag = mouse down + move by a certain amount
private void DragSource_PreviewMouseMove(object sender, MouseEventArgs e)
{
if (!_mouseCaptured && _draggedData != null)
{
// Only drag when user moved the mouse by a reasonable amount.
if (DragDropHelper.IsMovementBigEnough(_initialMousePosition, e.GetPosition(_topWindow)))
{
_adorner = (DragDropAdornerBase)GetDragDropControl(sender as DependencyObject);
_adorner.DataContext = _draggedData;
_adorner.Opacity = 0.7;
_adornerLayer.Visibility = Visibility.Visible;
_adornerLayer.Children.Add(_adorner);
_mouseCaptured = Mouse.Capture(_adorner);
Canvas.SetLeft(_adorner, _initialMousePosition.X - 20);
Canvas.SetTop(_adorner, _initialMousePosition.Y - 15);
_adornerLayer.PreviewMouseMove += new MouseEventHandler(_adorner_MouseMove);
_adornerLayer.PreviewMouseUp += new MouseButtonEventHandler(_adorner_MouseUp);
}
}
}
