/// <summary>
/// Ends a <see cref="VideoTimelineSegment"/> drag operation and cleans up resources.
/// </summary>
private void EndSegmentDrag()
{
_segmentDragAdorner?.Detach();
_segmentDragAdorner = null;
_isDraggingSegment = false;
_segmentDragOrigin = null;
}
/// <summary>
/// Handles the <see cref="UIElement.PreviewDragLeave"/> routed event for the <see cref="tracksListBox"/>.
/// </summary>
/// <remarks>If a <see cref="VideoTimelineSegment"/> is being dragged, the drag operation is canceled.</remarks>
/// <inheritdoc cref="DragEventHandler"/>
private void OnTracksListBoxPreviewDragLeave(object sender, DragEventArgs e)
{
if (_isDraggingSegment)
{
_segmentDragAdorner?.Detach();
_segmentDragAdorner = null;
e.Handled = true;
}
}
/// <summary>
/// Handles the <see cref="UIElement.PreviewDragEnter"/> routed event for the <see cref="tracksListBox"/>.
/// </summary>
/// <remarks>Begins a dragging operation for a <see cref="VideoTimelineSegment"/>.</remarks>
/// <inheritdoc cref="DragEventHandler"/>
private void OnTracksListBoxPreviewDragEnter(object sender, DragEventArgs e)
{
if (_segmentDragAdorner == null)
{
Size?adornerRectangleSize = null;
if (e.Data.GetDataPresent(typeof(SegmentViewModelWeakReference)) && e.Data.GetDataPresent(typeof(Size)))
{
adornerRectangleSize = (Size)e.Data.GetData(typeof(Size));
_isDraggingSegment = true;
}
else if (e.Data.GetDataPresent(typeof(WeakReference <AddTrackSegmentCommandParameters>)))
{
if (!(e.Data.GetData(typeof(WeakReference <AddTrackSegmentCommandParameters>)) is WeakReference <AddTrackSegmentCommandParameters> addTrackSegmentActionDataRef) ||
!addTrackSegmentActionDataRef.TryGetTarget(out AddTrackSegmentCommandParameters addTrackSegmentActionData))
{
throw new InvalidOperationException($"Invalid reference to a {nameof(AddTrackSegmentCommandParameters)} object.");
}
Debug.Assert(tracksListBox.HasItems);
ListBoxItem listBoxItem = tracksListBox.ItemContainerGenerator.ContainerFromIndex(0) as ListBoxItem;
Debug.Assert(listBoxItem != null);
VideoTimelineTrack trackElement = listBoxItem.FindVisualChild <VideoTimelineTrack>();
Debug.Assert(trackElement != null);
double trackPixelsPerFrame = trackElement.PixelsPerFrame;
adornerRectangleSize = new Size(trackPixelsPerFrame * addTrackSegmentActionData.FrameDuration, trackElement.ActualHeight);
_segmentDragOrigin = trackElement.TranslatePoint(new Point((addTrackSegmentActionData.FrameDuration / 2) * trackPixelsPerFrame, 0d), tracksListBox);
_isDraggingSegment = true;
}
else
{
_isDraggingSegment = false;
}
if (_isDraggingSegment && adornerRectangleSize.HasValue)
{
_segmentDragAdorner = new TrackSegmentDragAdorner(adornedElement: tracksListBox,
segmentElementSize: adornerRectangleSize.Value);
_segmentDragAdorner.Attach();
}
}
}