private static void DragMultiSelectEnabled_ListView_PreviewMouseLeftButtonUp(object sender, MouseButtonEventArgs e)
{
var listView = sender as ListView;
Point currentPointOnListView = e.GetPosition(listView);
ListViewDragSelectAdorner dragSelectAdorner = GetListViewDragSelectAdorner(listView);
// select the item when adorner is not displayed.
if (!IsCtrlShiftDown() && dragSelectAdorner == null)
{
HitTestResult hitTestResult = VisualTreeHelper.HitTest(listView, currentPointOnListView);
var hitItem = hitTestResult == null ? null : GetAncestorListViewItem(hitTestResult.VisualHit);
if (hitItem != null)
{
listView.UnselectAll();
hitItem.Focus();
hitItem.IsSelected = true;
}
}
SetDragMultiSelectStartPoint(listView, null);
if (dragSelectAdorner != null)
{
RemoveListViewDragSelectAdorner(listView);
listView.ReleaseMouseCapture();
// prevent deselecting by default listview behavior
if (!IsCtrlShiftDown())
{
e.Handled = true;
}
}
}
private static void RemoveListViewDragSelectAdorner(ListView listView)
{
var target = GetListViewItemsPanel(listView);
AdornerLayer adornerLayer = AdornerLayer.GetAdornerLayer(target);
ListViewDragSelectAdorner dragSelectAdorner = GetListViewDragSelectAdorner(listView);
adornerLayer.Remove(dragSelectAdorner);
SetListViewDragSelectAdorner(listView, null);
}
private static void AddListViewDragSelectAdorner(ListView listView, Point startPoint)
{
var target = GetListViewItemsPanel(listView);
AdornerLayer adornerLayer = AdornerLayer.GetAdornerLayer(target);
ListViewDragSelectAdorner dragSelectAdorner = new ListViewDragSelectAdorner(target)
{
StartPoint = startPoint, EndPoint = startPoint
};
adornerLayer.Add(dragSelectAdorner);
SetListViewDragSelectAdorner(listView, dragSelectAdorner);
}
private static void DragMultiSelectEnabled_ListView_Scrolled(object sender, ScrollChangedEventArgs e)
{
var listView = sender as ListView;
ListViewDragSelectAdorner dragSelectAdorner = GetListViewDragSelectAdorner(listView);
if (dragSelectAdorner != null)
{
dragSelectAdorner.StartPoint = new Point(
dragSelectAdorner.StartPoint.X - e.HorizontalChange,
dragSelectAdorner.StartPoint.Y - e.VerticalChange);
}
}
private static void DragMultiSelectEnabled_ListView_PreviewMouseMove(object sender, MouseEventArgs e)
{
var listView = sender as ListView;
var itemsPanel = GetListViewItemsPanel(listView);
ListViewDragSelectAdorner dragSelectAdorner = GetListViewDragSelectAdorner(listView);
Point currentPointOnItemsPanel = e.GetPosition(itemsPanel);
Point?dragStartPointNull = GetDragMultiSelectStartPoint(listView);
if (e.MouseDevice.LeftButton == MouseButtonState.Pressed)
{
// start drag adorner
if (dragSelectAdorner == null && dragStartPointNull.HasValue)
{
Point dragStartPoint = dragStartPointNull.Value;
if (Math.Abs(dragStartPoint.X - currentPointOnItemsPanel.X) > SystemParameters.MinimumHorizontalDragDistance ||
Math.Abs(dragStartPoint.Y - currentPointOnItemsPanel.Y) > SystemParameters.MinimumVerticalDragDistance)
{
AddListViewDragSelectAdorner(listView, dragStartPoint);
listView.CaptureMouse();
if (!IsCtrlShiftDown())
{
listView.UnselectAll();
}
}
else
{
// nothing to do
}
}
dragSelectAdorner = GetListViewDragSelectAdorner(listView);
if (dragSelectAdorner != null)
{
// Expand the adorner
dragSelectAdorner.EndPoint = currentPointOnItemsPanel;
// select the items being under the adorner
var items = itemsPanel.Children;
foreach (ListViewItem item in items)
{
item.IsSelected = IsItemUnderAdorner(itemsPanel, item, dragSelectAdorner);
}
}
}
}
private static bool IsItemUnderAdorner(UIElement parent, FrameworkElement item, ListViewDragSelectAdorner adorner)
{
Point iTopLeft = item.TranslatePoint(new Point(0, 0), parent);
Point iRightButtom = item.TranslatePoint(new Point(item.ActualWidth, item.ActualHeight), parent);
double aLeft = Math.Min(adorner.StartPoint.X, adorner.EndPoint.X);
double aRight = Math.Max(adorner.StartPoint.X, adorner.EndPoint.X);
double aTop = Math.Min(adorner.StartPoint.Y, adorner.EndPoint.Y);
double aButtom = Math.Max(adorner.StartPoint.Y, adorner.EndPoint.Y);
return(IsRangeOverlap(iTopLeft.X, iRightButtom.X, aLeft, aRight) &&
IsRangeOverlap(iTopLeft.Y, iRightButtom.Y, aTop, aButtom));
}
private static void SetListViewDragSelectAdorner(DependencyObject obj, ListViewDragSelectAdorner value)
{
obj.SetValue(ListViewDragSelectAdornerProperty, value);
}
