/// <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();
}
}
}
/// <summary>
/// Handles the <see cref="VideoTimelineSegment.HorizontalResizeDragCompletedEvent"/> attached event
/// for a <see cref="VideoTimelineSegment"/> element.
/// </summary>
/// <inheritdoc cref="HorizontalResizeDragCompletedEventHandler"/>
private void OnTrackSegmentHorizontalResizeDragCompleted(object sender, HorizontalResizeDragCompletedEventArgs e)
{
if (_isResizingSegment)
{
VideoTimelineSegment segmentElement = e.OriginalSource as VideoTimelineSegment;
Debug.Assert(segmentElement != null);
VideoTimelineTrack trackElement = segmentElement.ParentTrackElement;
SegmentViewModelBase segmentViewModel = segmentElement.DataContext as SegmentViewModelBase;
Debug.Assert(segmentViewModel != null);
int frameDiff = (int)Math.Round(_segmentResizeAdorner.HorizontalOffset / trackElement.PixelsPerFrame);
if (frameDiff != 0)
{
if (e.HorizontalSide == HorizontalSide.Left)
{
int newStartFrame = segmentViewModel.StartFrame + frameDiff;
ViewModel.ChangeTrackSegmentStartFrame(segmentViewModel, newStartFrame);
}
else // e.HorizontalSide == HorizontalSide.Right
{
int newEndFrame = segmentViewModel.EndFrame + frameDiff;
ViewModel.ChangeTrackSegmentEndFrame(segmentViewModel, newEndFrame);
}
}
segmentElement.Clip = null;
_segmentResizeAdorner?.Detach();
_segmentResizeAdorner = null;
_isResizingSegment = false;
}
e.Handled = true;
}
/// <summary>
/// Tries to find the <see cref="VideoTimelineTrack"/> element and closest frame number
/// to the current drag location.
/// </summary>
/// <param name="dragEventArgs">(In) The <see cref="DragEventArgs"/> for the drag operation.</param>
/// <param name="draggedItemStartFrame">(In) The Start Frame of the <see cref="VideoTimelineSegment"/> being dragged.</param>
/// <param name="timelineTrackElement">(Out) If successful, the <see cref="VideoTimelineTrack"/> element.</param>
/// <param name="closestFrameNumber">(Out) If successful, the closest frame number.</param>
/// <returns>A <see cref="bool"/> value indicating success or failure.</returns>
private bool TryFindTrackElementAndClosestFrameNumber(DragEventArgs dragEventArgs, int draggedItemStartFrame, out VideoTimelineTrack timelineTrackElement, out int closestFrameNumber)
{
closestFrameNumber = -1;
timelineTrackElement = dragEventArgs.OriginalSource as VideoTimelineTrack;
if (timelineTrackElement == null)
{
if (!(tracksListBox.ContainerFromElement((DependencyObject)dragEventArgs.OriginalSource) is ListBoxItem listBoxItem) ||
(timelineTrackElement = listBoxItem.FindVisualChild <VideoTimelineTrack>()) == null)
{
return(false);
}
}
Point mousePositionInListBox = dragEventArgs.GetPosition(tracksListBox);
Vector dragPositionOffset = mousePositionInListBox - _segmentDragOrigin.Value;
double trackPixelsPerFrame = timelineTrackElement.PixelsPerFrame;
double segmentPixelLeftPosition = trackPixelsPerFrame * draggedItemStartFrame;
closestFrameNumber = (int)Math.Round((segmentPixelLeftPosition + dragPositionOffset.X) / trackPixelsPerFrame);
return(true);
}
/// <summary>
/// Handles the <see cref="VideoTimelineSegment.HorizontalResizeDraggingEvent"/> attached event
/// for a <see cref="VideoTimelineSegment"/> element.
/// </summary>
/// <inheritdoc cref="HorizontalResizeDraggingEventHandler"/>
private void OnTrackSegmentHorizontalResizeDragging(object sender, HorizontalResizeDragEventArgs e)
{
e.Handled = true;
VideoTimelineSegment segmentElement = e.OriginalSource as VideoTimelineSegment;
Debug.Assert(segmentElement != null);
VideoTimelineTrack trackElement = segmentElement.ParentTrackElement;
SegmentViewModelBase segmentViewModel = segmentElement.DataContext as SegmentViewModelBase;
Debug.Assert(segmentViewModel != null);
int frameDiff = (int)Math.Round(e.HorizontalChange / trackElement.PixelsPerFrame);
if (frameDiff == 0)
{
return;
}
int proposedStartFrame = segmentViewModel.StartFrame;
int proposedEndFrame = segmentViewModel.EndFrame;
double framePixelOffset = trackElement.PixelsPerFrame * frameDiff;
bool isContracting = false;
Rect segmentElementClipRect;
if (e.HorizontalSide == HorizontalSide.Left)
{
proposedStartFrame += frameDiff;
if (!ViewModel.CanChangeTrackSegmentStartFrame(segmentViewModel, proposedStartFrame))
{
return;
}
if (frameDiff > 0)
{
isContracting = true;
segmentElementClipRect = new Rect(framePixelOffset, 0d, segmentElement.ActualWidth - framePixelOffset, segmentElement.ActualHeight);
}
}
else // e.HorizontalSide == HorizontalSide.Right
{
proposedEndFrame += frameDiff;
if (!ViewModel.CanChangeTrackSegmentEndFrame(segmentViewModel, proposedEndFrame))
{
return;
}
if (frameDiff < 0)
{
isContracting = true;
segmentElementClipRect = new Rect(
new Size(segmentElement.ActualWidth + framePixelOffset, segmentElement.ActualHeight)
);
}
}
if (isContracting)
{
if (segmentElement.Clip is RectangleGeometry rectangleGeometry)
{
rectangleGeometry.Rect = segmentElementClipRect;
}
else
{
segmentElement.Clip = new RectangleGeometry(segmentElementClipRect);
}
}
else
{
segmentElement.Clip = null;
}
if (_segmentResizeAdorner == null)
{
UIElement segmentElementContainer = segmentElement.TemplatedParent as UIElement;
Debug.Assert(segmentElementContainer != null);
_segmentResizeAdorner = new TrackSegmentResizeAdorner(adornedElement: trackElement, segmentElement,
segmentElementLeftCoordinate: Canvas.GetLeft(segmentElementContainer),
attachPosition: e.HorizontalSide);
_segmentResizeAdorner.Attach();
_isResizingSegment = true;
}
_segmentResizeAdorner.HorizontalOffset = framePixelOffset;
_segmentResizeAdorner.ToolTipData.StartFrame = proposedStartFrame;
_segmentResizeAdorner.ToolTipData.EndFrame = proposedEndFrame;
}