public virtual void ProcessMouseLeftButtonDown(MouseButtonEventArgs e)
{
if (e.Handled)
{
return;
}
#if DEBUG
this.CheckMouseEventArgs(e);
#endif
if (!this.DraggedElement.CaptureMouse())
{
Debug.Fail("The DragSourceManager was unable to capture the mouse on the dragged element.");
return;
}
//Get the current window (which can be a popup) on which the drag is happening
var parent = this.GetDraggedElementWindow();
this.InitialMousePositionToDragContainerAdorner = e.GetPosition(this.AdornerLayerInsideDragContainer);
this.InitialMousePositionToDraggedElement = e.GetPosition(this.DraggedElement);
this.MouseToScreenPositionFactor = DragSourceManager.CalculateMouseToScreenPositionFactor(parent);
this.ParentWindowIsPopup = (parent is Popup);
var draggedElementMousePosition = e.GetPosition(this.DraggedElement);
m_draggedElementMouseOffset = new Vector(draggedElementMousePosition.X, draggedElementMousePosition.Y);
}
private static Vector CalculateMouseToScreenPositionFactor(FrameworkElement element)
{
if (element == null)
{
return(new Vector(1d, 1d));
}
var source = PresentationSource.FromVisual(element);
if (source == null)
{
var parent = DragSourceManager.GetPopupParent(element);
while (parent != null)
{
source = PresentationSource.FromDependencyObject(parent);
if (source != null)
{
break;
}
parent = DragSourceManager.GetPopupParent(parent);
}
}
double x, y;
if (source != null)
{
var deviceUnits = source.CompositionTarget.TransformToDevice;
x = deviceUnits.M11;
y = deviceUnits.M22;
}
else
{
using (var hwnd = new HwndSource(new HwndSourceParameters()))
{
var deviceUnits = hwnd.CompositionTarget.TransformToDevice;
x = deviceUnits.M11;
y = deviceUnits.M22;
}
}
return(new Vector((x == 0d) ? 1d : 1d / x, (y == 0d) ? 1d : 1d / y));
}
private void SetupDragManager()
{
// We do not support DragDrop when there are no AdornerLayer because there wouldn't
// be any visual feedback for the operation.
if( AdornerLayer.GetAdornerLayer( this ) == null )
return;
DataGridContext dataGridContext = DataGridControl.GetDataGridContext( this );
DataGridControl dataGridControl = ( dataGridContext != null )
? dataGridContext.DataGridControl
: null;
// Can be null in design-time (edition of a style TargetType GroupByItem).
if( dataGridControl == null )
return;
Debug.Assert( m_dragSourceManager == null, "There might be problems when there is already a m_dragSourceManager." );
if( m_dragSourceManager != null )
{
m_dragSourceManager.PropertyChanged -= new PropertyChangedEventHandler( m_dragSourceManager_PropertyChanged );
m_dragSourceManager.DragOutsideQueryCursor -= new QueryCursorEventHandler( m_dragSourceManager_DragOutsideQueryCursor );
m_dragSourceManager.DroppedOutside -= new EventHandler( m_dragSourceManager_DroppedOutside );
}
// The DataGridControl's AdornerDecoratorForDragAndDrop must be used for dragging in order to include the
// RenderTransform the DataGridControl may performs. This AdornerDecorator is defined in the ControlTemplate
// as PART_DragDropAdornerDecorator
if( ( dataGridControl.DragDropAdornerDecorator != null )
&& ( dataGridControl.DragDropAdornerDecorator.AdornerLayer != null ) )
{
m_dragSourceManager = new DragSourceManager( this, dataGridControl.DragDropAdornerDecorator.AdornerLayer, dataGridControl );
}
else
{
System.Diagnostics.Debug.Assert( false, "The drag and drop functionnality won't be fully working properly: PART_DragDropAdornerDecorator was not found" );
m_dragSourceManager = new DragSourceManager( this, null, dataGridControl );
}
m_dragSourceManager.PropertyChanged += new PropertyChangedEventHandler( m_dragSourceManager_PropertyChanged );
m_dragSourceManager.DragOutsideQueryCursor += new QueryCursorEventHandler( m_dragSourceManager_DragOutsideQueryCursor );
m_dragSourceManager.DroppedOutside += new EventHandler( m_dragSourceManager_DroppedOutside );
}