/// <summary>
/// Updates Offset, Viewport, and Extent.
/// </summary>
internal void UpdateScrollingValues(ScrollBar scrollBar)
{
Offset = scrollBar.Value;
Viewport = scrollBar.ViewportSize;
Extent = scrollBar.Maximum - scrollBar.Minimum;
var parentGrid = FindControls.FindParent <ExtendedGridControl.ExtendedDataGrid>(scrollBar);
if (parentGrid != null)
{
UpdateItem(parentGrid, true);
}
}
private static void AttachToEvents(DependencyObject obj, DataTemplate dataTemplate, bool vertical)
{
DependencyObject source = obj;
var scrollViewer = FindElementOfType <ScrollViewer>(obj as FrameworkElement);
if (scrollViewer != null)
{
string scrollBarPartName = vertical ? "PART_VerticalScrollBar" : "PART_HorizontalScrollBar";
var scrollBar = FindName <ScrollBar>(scrollBarPartName, scrollViewer);
if (scrollBar != null)
{
var track = FindName <Track>("PART_Track", scrollBar);
if (track != null)
{
Thumb thumb = track.Thumb;
if (thumb != null)
{
// At this point, all of the control parts have been found.
// Attach to DragStarted to open the tooltip
thumb.DragStarted += delegate
{
var parentGrid = FindControls.FindParent <ExtendedGridControl.ExtendedDataGrid>(source);
if (parentGrid != null)
{
parentGrid.IsVerticalScrolling = true;
}
if (dataTemplate == null)
{
return;
}
ScrollingPreviewData data;
if (_previewToolTip == null)
{
// Create the ToolTip if this is the first time it's been used.
_previewToolTip = new ToolTip();
data = new ScrollingPreviewData();
_previewToolTip.Content = data;
}
else
{
data = _previewToolTip.Content as ScrollingPreviewData;
}
// Update the content in the ToolTip
if (data != null)
{
data.UpdateScrollingValues(scrollBar);
if (source is ScrollViewer)
{
parentGrid = FindControls.FindParent <ExtendedGridControl.ExtendedDataGrid>(source);
if (parentGrid != null)
{
data.UpdateItem(parentGrid, vertical);
}
}
else
{
data.UpdateItem(source as ItemsControl, vertical);
}
}
// Set the Placement and the PlacementTarget
_previewToolTip.PlacementTarget = thumb;
_previewToolTip.Placement = vertical
? PlacementMode.Left
: PlacementMode.Top;
_previewToolTip.VerticalOffset = 0.0;
_previewToolTip.HorizontalOffset = 0.0;
_previewToolTip.ContentTemplate = dataTemplate;
_previewToolTip.IsOpen = true;
};
// Attach to DragDelta to update the ToolTip's position
thumb.DragDelta += delegate
{
if (dataTemplate == null)
{
return;
}
if ((_previewToolTip != null) &&
// Check that we're within the range of the ScrollBar
(scrollBar.Value > scrollBar.Minimum) &&
(scrollBar.Value < scrollBar.Maximum))
{
// This is a little trick to cause the ToolTip to update its position next to the Thumb
if (vertical)
{
_previewToolTip.VerticalOffset =
Math.Abs(_previewToolTip.VerticalOffset - 0.0) < Epsilon ? 0.001 : 0.0;
}
else
{
_previewToolTip.HorizontalOffset =
Math.Abs(_previewToolTip.HorizontalOffset - 0.0) < Epsilon ? 0.001 : 0.0;
}
}
};
// Attach to DragCompleted to close the ToolTip
thumb.DragCompleted += delegate
{
var parentGrid = FindControls.FindParent <ExtendedGridControl.ExtendedDataGrid>(source);
if (parentGrid != null)
{
parentGrid.IsVerticalScrolling = false;
}
if (dataTemplate == null)
{
return;
}
if (_previewToolTip != null)
{
_previewToolTip.IsOpen = false;
}
};
// Attach to the Scroll event to update the ToolTip content
scrollBar.Scroll += delegate
{
if (dataTemplate == null)
{
return;
}
if (_previewToolTip != null)
{
// The ScrollBar's value isn't updated quite yet, so
// wait until Input priority
scrollBar.Dispatcher.BeginInvoke((NoParamCallback) delegate
{
var
data
=
(
ScrollingPreviewData
)
_previewToolTip
.
Content;
data
.
UpdateScrollingValues
(scrollBar);
data
.
UpdateItem
(source
as
ItemsControl,
vertical);
},
DispatcherPriority.Input);
}
};
return;
}
}
}
// At this point, something wasn't found. If the computed visibility is not visible,
// then add a handler to wait for it to become visible.
if ((vertical
? scrollViewer.ComputedVerticalScrollBarVisibility
: scrollViewer.ComputedHorizontalScrollBarVisibility) != Visibility.Visible)
{
DependencyPropertyDescriptor propertyDescriptor =
DependencyPropertyDescriptor.FromProperty(
vertical
? ScrollViewer.ComputedVerticalScrollBarVisibilityProperty
: ScrollViewer.ComputedHorizontalScrollBarVisibilityProperty, typeof(ScrollViewer));
if (propertyDescriptor != null)
{
EventHandler handler = delegate
{
if (dataTemplate == null)
{
return;
}
if ((vertical
? scrollViewer.ComputedVerticalScrollBarVisibility
: scrollViewer.ComputedHorizontalScrollBarVisibility) ==
Visibility.Visible)
{
EventHandler storedHandler =
GetWaitForVisibleScrollBar(source);
propertyDescriptor.RemoveValueChanged(scrollViewer,
storedHandler);
PostAttachToEvents(obj, dataTemplate, vertical);
}
};
SetWaitForVisibleScrollBar(source, handler);
propertyDescriptor.AddValueChanged(scrollViewer, handler);
}
}
}
}
