private void OnGridViewDragOver(object sender, DragEventArgs e)
{
if (this.draggedItems.Count == 0)
{
return;
}
e.AcceptedOperation = DataPackageOperation.Move;
// lot of hacks in this method...
Point intersectingPoint = e.GetPosition(this.mainPage);
// first is to find a GridViewItem based on the current mouse position
FrameworkElement element = null;
int index = 0;
while (element == null && index < 2)
{
// use X from touch event, but find out Y because user can drag of an empty
// area (if he moves the first item of a column)
// get the one of the first GridViewItem in the list just to get its height + Y position
var container = this.gridviewTasks.ContainerFromIndex(index) as GridViewItem;
if (container == null)
{
return;
}
var point = container.TransformToVisual(this.mainPage).TransformPoint(new Point());
intersectingPoint.Y = point.Y + container.ActualHeight / 2;
element = VisualTreeHelper
.FindElementsInHostCoordinates(intersectingPoint, this.gridviewTasks)
.OfType <FrameworkElement>()
.FirstOrDefault(fe => fe.DataContext is ITask);
index++;
}
ITask task = null;
if (element != null && element.DataContext is ITask)
{
task = (ITask)element.DataContext;
}
if (task != null)
{
var smartCollection = ((FolderItemViewModel)this.gridviewTasks.DataContext).SmartCollection;
IFolder folder = task.Folder;
if (folder.TaskGroup != TaskGroup.Action)
{
Group <ITask> group = smartCollection.Items.FirstOrDefault(g => g.Contains(task));
if (group == this.currentTargetGroup)
{
return;
}
this.currentTargetGroup = group;
// find out the coordinates needed to display a visual indicator
var firstItem = this.currentTargetGroup[0];
var firstContainer = (GridViewItem)this.gridviewTasks.ContainerFromItem(firstItem);
if (firstContainer == null)
{
return;
}
var pA = firstContainer.TransformToVisual(this.dragDropHost).TransformPoint(new Point());
var lastItem = this.currentTargetGroup[this.currentTargetGroup.Count - 1];
var lastContainer = (GridViewItem)this.gridviewTasks.ContainerFromItem(lastItem);
if (lastContainer == null)
{
return;
}
var pB = lastContainer.TransformToVisual(this.dragDropHost).TransformPoint(new Point());
pB.X += lastContainer.ActualWidth;
pB.Y += lastContainer.ActualHeight;
var border = new Border
{
Background = this.highlightBrush,
Opacity = 0
};
border.AnimateOpacity(this.BackgroundIndicatorOpacity, TimeSpan.FromMilliseconds(DragDropHostAnimationTimeMs));
this.dragDropHost.Child = border;
border.Width = Math.Abs(pB.X - pA.X);
border.Height = this.dragDropHost.ActualHeight - 20;
border.VerticalAlignment = VerticalAlignment.Top;
border.HorizontalAlignment = HorizontalAlignment.Left;
border.Margin = new Thickness(Math.Abs(pA.X), Math.Abs(pA.Y), 0, 0);
}
}
}