private void DragScrollBegin(Orientation orientation)
{
if (!this.ShouldDisplayScrollTip)
{
return;
}
DataGridContext dataGridContext = DataGridControl.GetDataGridContext(this);
if (dataGridContext == null)
{
return;
}
if (dataGridContext.DataGridControl == null)
{
return;
}
// Update items scrolling orientation and pixel scrolling
m_itemsScrollingOrientation = ScrollViewerHelper.GetItemScrollingOrientation(dataGridContext.DataGridControl);
if (m_itemsScrollingOrientation != orientation)
{
return;
}
this.Visibility = Visibility.Visible;
this.IsPixelScrolling = ScrollViewerHelper.IsPixelScrolling(dataGridContext.DataGridControl, dataGridContext.DataGridControl.ItemsHost, dataGridContext.DataGridControl.ScrollViewer);
this.RefreshScrollTipContent(m_scrollViewerTemplateHelper.GetScrollBar(orientation));
}
public static FrameworkElement GetLastVisibleContainer(
DataGridControl gridControl,
FrameworkElement container,
ScrollViewer scrollViewer)
{
FrameworkElement retval = null;
if (ScrollViewerHelper.IsPixelScrolling(gridControl, container, scrollViewer) == false)
{
//This means that the panel is performing Item Scrolling
//if the panel is Vertically scrolling the items (means the Horizontal Axis is Pixel scrolling)
if (ScrollViewerHelper.GetItemScrollingOrientation(gridControl, container, scrollViewer) == Orientation.Vertical)
{
retval = ScrollViewerHelper.ProcessLastVisibleContainer(gridControl,
scrollViewer.VerticalOffset,
scrollViewer.ViewportHeight,
scrollViewer.HorizontalOffset,
scrollViewer.ViewportWidth,
Orientation.Vertical);
}
//the panel is Horizontally scrolling the items (means the Vertically Axis is Pixel scrolling)
else
{
retval = ScrollViewerHelper.ProcessLastVisibleContainer(gridControl,
scrollViewer.HorizontalOffset,
scrollViewer.ViewportWidth,
scrollViewer.VerticalOffset,
scrollViewer.ViewportHeight,
Orientation.Horizontal);
}
}
else
{
Point pt = new Point();
if ((container is VirtualizingPanel) ||
(container is DataGridItemsHost) ||
(scrollViewer == null))
{
pt.X = 0;
pt.Y = 0;
}
else
{
pt.X = scrollViewer.HorizontalOffset;
pt.Y = scrollViewer.VerticalOffset;
}
Size size = new Size((scrollViewer != null) ? scrollViewer.ViewportWidth : container.ActualWidth,
(scrollViewer != null) ? scrollViewer.ViewportHeight : container.ActualHeight);
Rect visibleRect = new Rect(pt, size);
RectangleGeometry geo = new RectangleGeometry(visibleRect);
lock (ScrollViewerHelper.Current)
{
m_sVisibleChildList.Clear();
m_sGridControl = gridControl;
VisualTreeHelper.HitTest(container,
new HitTestFilterCallback(ScrollViewerHelper.MyFilterFunct),
new HitTestResultCallback(ScrollViewerHelper.UselessResultCallback),
new GeometryHitTestParameters(geo));
m_sGridControl = null;
FrameworkElement preservedChild = null;
Nullable <Vector> preservedOffset = null;
foreach (FrameworkElement child in m_sVisibleChildList)
{
Vector itemOffset = VisualTreeHelper.GetOffset(child);
Rect itemRect = new Rect(itemOffset.X, itemOffset.Y, child.ActualWidth, child.ActualHeight);
itemRect.Intersect(visibleRect);
switch (gridControl.ItemsPrimaryAxis)
{
case PrimaryAxis.Vertical:
if (DoubleUtil.AreClose(itemRect.Width, 0) == false)
{
if (DoubleUtil.AreClose(itemRect.Height, child.ActualHeight) == true)
{
if (ScrollViewerHelper.IsABetterLastRow(preservedChild, preservedOffset, itemOffset) == true)
{
preservedChild = child;
preservedOffset = itemOffset;
}
}
}
break;
case PrimaryAxis.Horizontal:
if (DoubleUtil.AreClose(itemRect.Width, child.ActualWidth) == true)
{
if (DoubleUtil.AreClose(itemRect.Height, 0) == false)
{
if (ScrollViewerHelper.IsABetterLastRow(preservedChild, preservedOffset, itemOffset) == true)
{
preservedChild = child;
preservedOffset = itemOffset;
}
}
}
break;
case PrimaryAxis.Both:
if ((DoubleUtil.AreClose(itemRect.Width, child.ActualWidth) == true) &&
(DoubleUtil.AreClose(itemRect.Height, child.ActualHeight) == true))
{
if (ScrollViewerHelper.IsABetterLastRow(preservedChild, preservedOffset, itemOffset) == true)
{
preservedChild = child;
preservedOffset = itemOffset;
}
}
break;
case PrimaryAxis.None:
if (itemRect.IsEmpty == false)
{
if ((DoubleUtil.AreClose(itemRect.Height, 0) == false) && (DoubleUtil.AreClose(itemRect.Width, 0) == false))
{
if (ScrollViewerHelper.IsABetterLastRow(preservedChild, preservedOffset, itemOffset) == true)
{
preservedChild = child;
preservedOffset = itemOffset;
}
}
}
break;
}
}
retval = preservedChild;
}//end lock (protection of shared static members with GetFirstVisibleItem() )
}
return(retval);
}