Ejemplo n.º 1
0
        /// <summary>
        /// Slides the drag indicator (item snapshot) to the location of the dropped item,
        /// then performs the visibility swap and removes the dragging visual state.
        /// </summary>
        private void AnimateDrop(ReorderListBoxItem itemContainer)
        {
            GeneralTransform itemTransform = itemContainer.TransformToVisual(this.dragInterceptor);
            Rect itemRect = itemTransform.TransformBounds(new Rect(new Point(0, 0), itemContainer.RenderSize));
            double delta = Math.Abs(itemRect.Y - Canvas.GetTop(this.dragIndicator) -
                ((TranslateTransform)this.dragIndicator.RenderTransform).Y);
            if (delta > 0)
            {
                // Adjust the duration based on the distance, so the speed will be constant.
                TimeSpan duration = TimeSpan.FromSeconds(0.25 * delta / itemRect.Height);

                Storyboard dropStoryboard = new Storyboard();
                DoubleAnimation moveToDropAnimation = new DoubleAnimation();
                Storyboard.SetTarget(moveToDropAnimation, this.dragIndicator.RenderTransform);
                Storyboard.SetTargetProperty(moveToDropAnimation, new PropertyPath(TranslateTransform.YProperty));
                moveToDropAnimation.To = itemRect.Y - Canvas.GetTop(this.dragIndicator);
                moveToDropAnimation.Duration = duration;
                dropStoryboard.Children.Add(moveToDropAnimation);

                dropStoryboard.Completed += delegate
                {
                    this.dragItem = null;
                    itemContainer.Opacity = 1;
                    this.dragIndicator.Visibility = Visibility.Collapsed;
                    this.dragIndicator.Source = null;
                    ((TranslateTransform)this.dragIndicator.RenderTransform).Y = 0;
                    VisualStateManager.GoToState(itemContainer, ReorderListBoxItem.NotDraggingState, true);

                };
                dropStoryboard.Begin();
            }
            else
            {
                // There was no need for an animation, so do the visibility swap right now.
                this.dragItem = null;
                itemContainer.Opacity = 1;
                this.dragIndicator.Visibility = Visibility.Collapsed;
                this.dragIndicator.Source = null;
                VisualStateManager.GoToState(itemContainer, ReorderListBoxItem.NotDraggingState, true);
            }
        }