public async void OnSelectionChanged(InkCanvasSelectionChangingEventArgs args)
{
if (IsSelectionDifferent(args.GetSelectedStrokes()))
{
// We make the previously selected strokes unselected
var strokesToUpdate = new Dictionary <string, string>();
DrawingModel?.SelectedStrokes?.Where(x => x.Value == UserId).ForEach(x => strokesToUpdate[x.Key] = null);
// We make the currently selected strokes selected
var selectedStrokes = new List <StrokeModel>();
foreach (var s in args.GetSelectedStrokes())
{
var stroke = s as StrokeModel;
if (stroke == null || IsSelectedByOtherUser(stroke))
{
continue;
}
selectedStrokes.Add(stroke as StrokeModel);
}
SelectedStrokesIds = new HashSet <string>(selectedStrokes.Select(x => x.Id));
SelectedStrokesIds.ForEach(x => strokesToUpdate[x] = UserId);
SelectionChanged?.Invoke(SelectedStrokes);
args.SetSelectedStrokes(new StrokeCollection(SelectedStrokes));
if (!IsOffline)
{
await DatabaseService.Ref(DatabasePaths.Drawings)
.Child(Id)
.Child(DatabasePaths.SelectedStrokes)
.Update(strokesToUpdate);
}
}
}
/// <summary>
/// Prevent user from selecting eraser strokes
/// </summary>
/// <param name="sender"></param>
/// <param name="e"></param>
void selectionChanging(object sender, InkCanvasSelectionChangingEventArgs e)
{
StrokeCollection selectedStrokes = e.GetSelectedStrokes();
StrokeCollection actuallySelectedStrokes = new StrokeCollection();
foreach (Stroke stroke in selectedStrokes)
{
if (stroke.DrawingAttributes.Color != Color.FromRgb(255, 255, 255))
{
actuallySelectedStrokes.Add(stroke);
}
}
e.SetSelectedStrokes(actuallySelectedStrokes);
}
/// <summary>
/// OnSelectionChanging raised when selection is changing on the InkAnalysisCanvas
/// we use this to select entire nodes instead of just a stroke
/// </summary>
protected override void OnSelectionChanging(InkCanvasSelectionChangingEventArgs e)
{
StrokeCollection currentSelectedStrokes = e.GetSelectedStrokes();
if (currentSelectedStrokes.Count > 0)
{
ContextNodeCollection nodes =
_inkAnalyzer.FindInkLeafNodes(e.GetSelectedStrokes());
if (nodes.Count > 0)
{
StrokeCollection expandedSelection = new StrokeCollection();
//add all related strokes if they aren't part of selectedStrokes already
foreach (ContextNode node in nodes)
{
expandedSelection.Add(node.Strokes);
}
//modify the collection
e.SetSelectedStrokes(expandedSelection);
}
}
base.OnSelectionChanging(e);
}