private static void OnDropTargetAdvisorChanged(DependencyObject depObj,
DependencyPropertyChangedEventArgs args)
{
UIElement targetElt = depObj as UIElement;
if (args.NewValue != null && args.OldValue == null)
{
targetElt.PreviewDragEnter += DropTarget_PreviewDragEnter;
targetElt.PreviewDragOver += DropTarget_PreviewDragOver;
targetElt.PreviewDragLeave += DropTarget_PreviewDragLeave;
targetElt.PreviewDrop += DropTarget_PreviewDrop;
targetElt.AllowDrop = true;
// Set the Drag source UI
IDropTargetAdvisor advisor = args.NewValue as IDropTargetAdvisor;
advisor.TargetUI = targetElt;
}
else if (args.NewValue == null && args.OldValue != null)
{
targetElt.PreviewDragEnter -= DropTarget_PreviewDragEnter;
targetElt.PreviewDragOver -= DropTarget_PreviewDragOver;
targetElt.PreviewDragLeave -= DropTarget_PreviewDragLeave;
targetElt.PreviewDrop -= DropTarget_PreviewDrop;
targetElt.AllowDrop = false;
}
}
/// <summary>
/// Handles the PreviewDragOver event of the DropTarget control.
/// </summary>
/// <param name="sender">The source of the event.</param>
/// <param name="e">The <see cref="System.Windows.DragEventArgs" /> instance containing the event data.</param>
private static void DropTargetPreviewDragOver(object sender, DragEventArgs e)
{
Debug.Assert(sender is UIElement, "Awaiting sender of type UIElement");
// Get the current drop target advisor
CurrentDropTargetAdvisor = GetDropTargetAdvisor((DependencyObject)sender);
UpdateEffects(e);
// Update position of the preview Adorner
adornerPosition = e.GetPosition((UIElement)sender);
PositionAdorner();
// Let the target do some stuff -----------------------
var dropPoint = e.GetPosition((UIElement)sender);
// Calculate displacement for (Left, Top)
var offset = e.GetPosition(overlayElt);
dropPoint.X = dropPoint.X - offset.X;
dropPoint.Y = dropPoint.Y - offset.Y;
CurrentDropTargetAdvisor.OnDropQuery(e.Data, dropPoint);
e.Handled = true;
}
private static bool UpdateEffects(object uobject, DragEventArgs e)
{
IDropTargetAdvisor advisor = GetDropTargetAdvisor(uobject as DependencyObject);
if (advisor.IsValidDataObject(e.Data) == false)
{
return(false);
}
if ((e.AllowedEffects & DragDropEffects.Move) == 0 &&
(e.AllowedEffects & DragDropEffects.Copy) == 0)
{
e.Effects = DragDropEffects.None;
return(true);
}
if ((e.AllowedEffects & DragDropEffects.Move) != 0 &&
(e.AllowedEffects & DragDropEffects.Copy) != 0)
{
if ((e.KeyStates & DragDropKeyStates.ControlKey) != 0)
{
}
e.Effects = ((e.KeyStates & DragDropKeyStates.ControlKey) != 0) ?
DragDropEffects.Copy : DragDropEffects.Move;
}
return(true);
}
static void CreatePreviewAdorner(object sender, DragEventArgs e)
{
// Set the Drag source UI
IDropTargetAdvisor adv = GetDropTargetAdvisor(sender as FrameworkElement);
adv.TargetUI = sender as UIElement;
// get the data
// get the UIFeedback
UIFeedback = adv.GetVisualFeedback(e.Data);
DoubleAnimation anim = new DoubleAnimation(0.75, new Duration(TimeSpan.FromMilliseconds(500)));
anim.From = 0.25;
anim.AutoReverse = true;
anim.RepeatBehavior = RepeatBehavior.Forever;
UIFeedback.BeginAnimation(UIElement.OpacityProperty, anim);
UIFeedback.IsHitTestVisible = false;
// add it to the adornment layer
AdornerLayer layer = AdornerLayer.GetAdornerLayer(sender as UIElement);
Overlay = new DropPreviewAdorner(UIFeedback, sender as UIElement, layer);
layer.Add(Overlay);
Overlay.Location = GetOverlaypoint(sender, e);
}
static bool UpdateEffects(object sender, DragEventArgs e)
{
IDropTargetAdvisor advisor = GetDropTargetAdvisor(sender as FrameworkElement);
if (!advisor.IsValidDataObject(e.Data))
{
return(false);
}
// TODO: cope with Link, Scroll
if ((e.AllowedEffects & DragDropEffects.Move) == 0 &&
(e.AllowedEffects & DragDropEffects.Copy) == 0)
{
e.Effects = DragDropEffects.None;
return(false);
}
if ((e.AllowedEffects & DragDropEffects.Move) != 0)
{
e.Effects = DragDropEffects.Move;
}
if ((e.AllowedEffects & DragDropEffects.Copy) != 0)
{
if ((e.AllowedEffects & DragDropEffects.Move) == 0 || (e.KeyStates & DragDropKeyStates.ControlKey) != 0)
{
e.Effects = DragDropEffects.Copy;
}
}
return(true);
}
/// <summary>
/// Handles the PreviewDragLeave event of the DropTarget control.
/// </summary>
/// <param name="sender">The source of the event.</param>
/// <param name="e">The <see cref="System.Windows.DragEventArgs" /> instance containing the event data.</param>
private static void DropTargetPreviewDragLeave(object sender, DragEventArgs e)
{
UpdateEffects(e);
RemovePreviewAdorner();
// Get the current drop target advisor
CurrentDropTargetAdvisor = GetDropTargetAdvisor((DependencyObject)sender);
CurrentDropTargetAdvisor.OnLeaveDropZone(e.Data);
e.Handled = true;
}
/// <summary>
/// Called when the input system reports an underlying drag event with drop area element as the drag target.
/// </summary>
/// <param name="sender">Drop area element.</param>
/// <param name="e">Contains arguments relevant to all drag-and-drop events.</param>
private static void DropTargetPreviewDragEnter(object sender, DragEventArgs e)
{
currentTargetAdvisor = GetDropTargetAdvisor(sender as DependencyObject);
if (UpdateEffects((UIElement)sender, e) == false)
{
return;
}
Point point = CalculateAdornerOffset(e);
CreatePreviewAdorner(point.X, point.Y);
e.Handled = true;
}
private static void DropTarget_PreviewDragEnter(object sender, DragEventArgs e)
{
// Get the current drop target advisor
CurrentDropTargetAdvisor = GetDropTargetAdvisor(sender as DependencyObject);
UpdateEffects(e);
// Setup the preview Adorner
_offsetPoint = new Point();
if (CurrentDropTargetAdvisor.ApplyMouseOffset && e.Data.GetData(DragOffsetFormat) != null)
{
_offsetPoint = (Point)e.Data.GetData(DragOffsetFormat);
}
CreatePreviewAdorner(sender as UIElement, e.Data);
e.Handled = true;
}
private static void DropTargetPreviewDrop(object sender, DragEventArgs e)
{
if (UpdateEffects(sender, e) == false)
{
return;
}
IDropTargetAdvisor advisor = GetDropTargetAdvisor(sender as DependencyObject);
Point dropPoint = e.GetPosition(sender as UIElement);
// Calculate displacement for (Left, Top)
Point offset = e.GetPosition(s_OverlayElement);
dropPoint.X = dropPoint.X - offset.X;
dropPoint.Y = dropPoint.Y - offset.Y;
advisor.OnDropCompleted(e.Data, dropPoint);
RemovePreviewAdorner();
s_OffsetPoint = new Point(0, 0);
}
private static void DropTarget_PreviewDragEnter(object sender, DragEventArgs e)
{
// Get the current drop target advisor
CurrentDropTargetAdvisor = GetDropTargetAdvisor(sender as DependencyObject);
if (UpdateEffects(sender, e) == false)
{
return;
}
// Setup the preview Adorner
UIElement feedbackUI = CurrentDropTargetAdvisor.GetVisualFeedback(e.Data);
_offsetPoint = CurrentDropTargetAdvisor.ApplyMouseOffset
? (Point)e.Data.GetData(DragOffsetFormat)
:
new Point();
CreatePreviewAdorner(sender as UIElement, feedbackUI);
e.Handled = true;
}
public static void SetDropTargetAdvisor(DependencyObject depObj, IDropTargetAdvisor advisor)
{
depObj.SetValue(DropTargetAdvisorProperty, advisor);
}
public static void SetDropTargetAdvisor(DependencyObject depObj,
IDropTargetAdvisor advisor)
{
depObj.SetValue(DropTargetAdvisorProperty, advisor);
}
private static void DropTarget_PreviewDragEnter(object sender, DragEventArgs e)
{
// Get the current drop target advisor
CurrentDropTargetAdvisor = GetDropTargetAdvisor(sender as DependencyObject);
CurrentDropTargetAdvisor.TargetUI = sender as UIElement;
UpdateEffects(e);
// Setup the preview Adorner
_offsetPoint = new Point();
if (CurrentDropTargetAdvisor.ApplyMouseOffset && e.Data.GetData(DragOffsetFormat) != null)
{
_offsetPoint = (Point) e.Data.GetData(DragOffsetFormat);
}
CreatePreviewAdorner(sender as UIElement, e.Data);
e.Handled = true;
}
public static void SetDropTargetAdvisor(FrameworkElement depo, IDropTargetAdvisor advisor)
{
depo.SetValue(DropTargetAdvisorProperty, advisor);
}
public static void SetDropTargetAdvisor(FrameworkElement depo, IDropTargetAdvisor advisor)
{
depo.SetValue(DropTargetAdvisorProperty, advisor);
}
