protected override void OnRender(DrawingContext drawingContext)
{
base.OnRender(drawingContext);
if (AdornedElement == null || _pen == null || DoubleUtil.IsZero(_length))
{
return;
}
var screenPos = new Utils.Win32.POINT();
if (Utils.Win32.GetCursorPos(ref screenPos))
{
var pos = AdornedElement.PointFromScreen(new Point(screenPos.X, screenPos.Y));
drawingContext.DrawLine(_pen, new Point(pos.X, 0), new Point(pos.X, _length));
drawingContext.DrawLine(_pen, new Point(0, pos.Y), new Point(_length, pos.Y));
}
}
private void MoveChild(UIElement dragedChild)
{
var screenPos = new Utils.Win32.POINT();
if (!Utils.Win32.GetCursorPos(ref screenPos))
{
return;
}
var posToPanel = AssociatedObject.PointFromScreen(new Point(screenPos.X, screenPos.Y));
var dragedElement = dragedChild as FrameworkElement;
var childRect = new Rect(posToPanel.X - _cacheMouseDownToChildPos.X, DisabledYPosition ? _cacheChildToPanelPos.Y : (posToPanel.Y - _cacheMouseDownToChildPos.Y), dragedElement.ActualWidth, dragedElement.ActualHeight);
//find the child which has max overlapping area with dragedChild
Size? maxOverlapSize = null;
FrameworkElement maxOverlapChild = null;
foreach (FrameworkElement fe in AssociatedObject.Children)
{
if (fe == dragedElement)
{
continue;
}
var sp = fe.TranslatePoint(new Point(), AssociatedObject);
var overlapSize = GetOverlapSize(new Rect(sp, new Point(sp.X + fe.ActualWidth, sp.Y + fe.ActualHeight)), childRect);
if (overlapSize.IsEmpty)
{
continue;
}
if (maxOverlapSize == null || DoubleUtil.GreaterThan(overlapSize.Width * overlapSize.Height, maxOverlapSize.Value.Width * maxOverlapSize.Value.Height))
{
maxOverlapSize = overlapSize;
maxOverlapChild = fe;
}
}
//check the overlapping area whether match the exchanging child condition
if (!maxOverlapSize.HasValue || maxOverlapSize.Value.IsEmpty)
{
return;
}
if (DoubleUtil.GreaterThanOrClose(maxOverlapSize.Value.Width, maxOverlapChild.ActualWidth / 2) && DoubleUtil.GreaterThanOrClose(maxOverlapSize.Value.Height, maxOverlapChild.ActualHeight / 2))
{
var targetIndex = AssociatedObject.Children.IndexOf(maxOverlapChild);
if (IsFromItemsPanelTemplate)
{
var sourceIndex = AssociatedObject.Children.IndexOf(dragedChild);
if (ItemsContainer.ItemsSource != null)
{
if (MoveItemFromItemsSource != null)
{
MoveItemFromItemsSource(sourceIndex, targetIndex);
//if use ObservableCollection.Move(...) to exchange position, follow code is unnecessary.
//else use ObservableCollection.RemoveAt(...) and ObservableCollection.Insert(...) to exchange position, follow code is necessary.
_dragedChild = AssociatedObject.Children[targetIndex];
_dragedChild.Opacity = 0;
}
}
else
{
var sourceItem = ItemsContainer.Items[sourceIndex];
ItemsContainer.Items.RemoveAt(sourceIndex);
ItemsContainer.Items.Insert(targetIndex, sourceItem);
_dragedChild = AssociatedObject.Children[targetIndex];
_dragedChild.Opacity = 0;
}
}
else
{
AssociatedObject.Children.Remove(dragedChild);
AssociatedObject.Children.Insert(targetIndex, dragedChild);
}
}
}
