private static void DragSourceOnMouseMove(object sender, MouseEventArgs e)
{
var dragInfo = m_DragInfo;
if (dragInfo != null && !m_DragInProgress)
{
// the start from the source
var dragStart = dragInfo.DragStartPosition;
// do nothing if mouse left/right button is released or the pointer is captured
if (dragInfo.MouseButton == MouseButton.Left && e.LeftButton == MouseButtonState.Released)
{
m_DragInfo = null;
return;
}
if (DragDrop.GetCanDragWithMouseRightButton(dragInfo.VisualSource) && dragInfo.MouseButton == MouseButton.Right && e.RightButton == MouseButtonState.Released)
{
m_DragInfo = null;
return;
}
// current mouse position
var position = e.GetPosition((IInputElement)sender);
// prevent selection changing while drag operation
dragInfo.VisualSource?.ReleaseMouseCapture();
// only if the sender is the source control and the mouse point differs from an offset
if (dragInfo.VisualSource == sender &&
(Math.Abs(position.X - dragStart.X) > DragDrop.GetMinimumHorizontalDragDistance(dragInfo.VisualSource) ||
Math.Abs(position.Y - dragStart.Y) > DragDrop.GetMinimumVerticalDragDistance(dragInfo.VisualSource)))
{
dragInfo.RefreshSelectedItems(sender, e);
var dragHandler = TryGetDragHandler(dragInfo, sender as UIElement);
if (dragHandler.CanStartDrag(dragInfo))
{
dragHandler.StartDrag(dragInfo);
if (dragInfo.Effects != DragDropEffects.None)
{
var dataObject = dragInfo.DataObject;
if (dataObject == null)
{
if (dragInfo.Data == null)
{
// it's bad if the Data is null, cause the DataObject constructor will raise an ArgumentNullException
m_DragInfo = null; // maybe not necessary or should not set here to null
return;
}
dataObject = new DataObject(dragInfo.DataFormat.Name, dragInfo.Data);
}
try
{
m_DragInProgress = true;
CreateHintAdorners(sender, dragInfo);
var dragDropHandler = dragInfo.DragDropHandler ?? System.Windows.DragDrop.DoDragDrop;
var dragDropEffects = dragDropHandler(dragInfo.VisualSource, dataObject, dragInfo.Effects);
if (dragDropEffects == DragDropEffects.None)
{
dragHandler.DragCancelled();
}
dragHandler.DragDropOperationFinished(dragDropEffects, dragInfo);
DestroyHintAdorners();
}
catch (Exception ex)
{
if (!dragHandler.TryCatchOccurredException(ex))
{
throw;
}
}
finally
{
m_DragInProgress = false;
m_DragInfo = null;
}
}
}
}
}
}
private static void DragSourceOnMouseMove(object sender, MouseEventArgs e)
{
if (m_DragInfo != null && !m_DragInProgress)
{
// the start from the source
var dragStart = m_DragInfo.DragStartPosition;
// do nothing if mouse left/right button is released or the pointer is captured
if (m_DragInfo.MouseButton == MouseButton.Left && e.LeftButton == MouseButtonState.Released)
{
m_DragInfo = null;
return;
}
if (DragDrop.GetCanDragWithMouseRightButton(m_DragInfo.VisualSource) && m_DragInfo.MouseButton == MouseButton.Right && e.RightButton == MouseButtonState.Released)
{
m_DragInfo = null;
return;
}
// current mouse position
var position = e.GetPosition((IInputElement)sender);
// prevent selection changing while drag operation
m_DragInfo.VisualSource?.ReleaseMouseCapture();
// only if the sender is the source control and the mouse point differs from an offset
if (m_DragInfo.VisualSource == sender &&
(Math.Abs(position.X - dragStart.X) > SystemParameters.MinimumHorizontalDragDistance ||
Math.Abs(position.Y - dragStart.Y) > SystemParameters.MinimumVerticalDragDistance))
{
var dragHandler = TryGetDragHandler(m_DragInfo, sender as UIElement);
if (dragHandler.CanStartDrag(m_DragInfo))
{
dragHandler.StartDrag(m_DragInfo);
if (m_DragInfo.Effects != DragDropEffects.None && m_DragInfo.Data != null)
{
var data = m_DragInfo.DataObject;
if (data == null)
{
data = new DataObject(DataFormat.Name, m_DragInfo.Data);
}
else
{
data.SetData(DataFormat.Name, m_DragInfo.Data);
}
try {
m_DragInProgress = true;
var result = System.Windows.DragDrop.DoDragDrop(m_DragInfo.VisualSource, data, m_DragInfo.Effects);
if (result == DragDropEffects.None)
{
dragHandler.DragCancelled();
}
}
catch (Exception ex) {
if (!dragHandler.TryCatchOccurredException(ex))
{
throw;
}
}
finally {
m_DragInProgress = false;
}
m_DragInfo = null;
}
}
}
}
}
