Add possibility to control scrolling speed via setting ScrollDelay attached property.

GongSolutions.Wpf.DragDrop/DragDrop.cs

@@ -1,6 +1,8 @@
 using System;
 using System.Collections;
 using System.Linq;
+using System.Net;
+using System.Timers;
 using System.Windows;
 using System.Windows.Controls;
 using System.Windows.Controls.Primitives;
@@ -333,7 +335,21 @@ public static void SetDragMouseAnchorPoint(UIElement target, Point value)
  target.SetValue(DragMouseAnchorPointProperty, value);
  }
 
- public static IDragSource DefaultDragHandler
+
+ public static readonly DependencyProperty ScrollDelayProperty = DependencyProperty.RegisterAttached(
+ "ScrollDelay", typeof(double), typeof(DragDrop), new PropertyMetadata(default(double)));
+
+ public static void SetScrollDelay(DependencyObject element, double value)
+ {
+ element.SetValue(ScrollDelayProperty, value);
+ }
+
+ public static double GetScrollDelay(DependencyObject element)
+ {
+ return (double) element.GetValue(ScrollDelayProperty);
+ }
+
+ public static IDragSource DefaultDragHandler
  {
  get
  {
@@ -932,7 +948,24 @@ itemsControl is TabControl
  e.Effects = DragDropEffects.None;
  }
 
- Scroll(dropInfo.VisualTarget, e);
+
+ if (_canScroll)
+ {
+ _canScroll = false;
+ Scroll(dropInfo.VisualTarget, e);
+ var interval = GetScrollDelay(m_DragInfo.VisualSource);
+ if (interval > 0)
+ {
+ _canScrollDelayTimer.Interval = interval;
+ _canScrollDelayTimer.Start();
+ }
+ else
+ {
+ _canScroll = true;
+ }
+
+ }
+
  }
 
  private static void DropTarget_PreviewDrop(object sender, DragEventArgs e)
@@ -1013,5 +1046,13 @@ private static DropTargetAdorner DropTargetAdorner
  private static object m_ClickSupressItem;
  private static Point _adornerPos;
  private static Size _adornerSize;
+
+ private static bool _canScroll = true;
+ private static readonly Timer _canScrollDelayTimer = new Timer();
+
+ static DragDrop()
+ {
+ _canScrollDelayTimer.Elapsed += (sender, args) => _canScroll = true;
+ }
  }
 }