private void OnLeftInkCanvasViewStrokesCollected(Xamarin.Forms.Inking.Interfaces.IInkPresenter sender, XInkStrokesCollectedEventArgs args)
{
LeftInkCanvasView.InvalidateCanvas(false, true);
}
private void LeftInkCanvasViewPresenter_StrokesErased(XInkPresenter sender, XInkStrokesErasedEventArgs args)
{
LeftInkCanvasView.InvalidateCanvas(false, true);
}