private void HandleSquishingWhileDragging(double newTranslation)
{
double translationOfLastItem = -1 * CalculateElementOffset(GetElementCount() - 1);
double squishDistance = 0;
if (newTranslation > 0)
{
// We're squishing the first item
//
squishDistance = newTranslation;
_dragState.UnsquishTranslationAnimationTarget = 0;
_mediaStrip.RenderTransformOrigin = new Point(0, 0);
}
else if (newTranslation < translationOfLastItem)
{
// We're squishing the last item
//
squishDistance = translationOfLastItem - newTranslation;
_dragState.UnsquishTranslationAnimationTarget = translationOfLastItem;
_mediaStrip.RenderTransformOrigin = new Point(1, 0);
}
double squishScale = 1.0 - (squishDistance / _maxDraggingSquishDistance) * (1 - _minDraggingSquishScale);
// Apply the squish
//
_mediaStripCompositeTransform.ScaleX = squishScale;
// Update our state
//
_state = squishScale == 1.0 ? MediaViewerState.Dragging : MediaViewerState.DraggingAndSquishing;
}
/// <summary>
/// Initializes virtualization if all of the prerequisites are available, so it's safe to call once each is set.
/// </summary>
private void InitializeVirtualizationIfReady()
{
if ((_mediaStrip == null) ||
(_size == null))
{
// We don't have everything we need to initialize, wait for the next call
return;
}
//
// Initialize the virtualized item pool
//
_virtualizedItemPool = new List<VirtualizedItem>();
_mediaStrip.Children.Clear();
for (int index = 0; index < _virtualizedItemPoolSize; index++)
{
VirtualizedItem virtualizedItem = new VirtualizedItem(new Size(_size.Value.Width, _size.Value.Height));
virtualizedItem.DataTemplate = ItemTemplate;
virtualizedItem.ItemZoomed += OnItemZoomed;
virtualizedItem.ItemUnzoomed += OnItemUnzoomed;
_mediaStrip.Children.Add(virtualizedItem.RootFrameworkElement);
_virtualizedItemPool.Add(virtualizedItem);
}
if (_state == MediaViewerState.Uninitialized)
{
_state = MediaViewerState.Initialized;
}
ResetDisplayedElement();
ResetItemLayout();
}
private void CompleteDragInertiaAnimation()
{
if (_dragInertiaAnimation != null)
{
if (_state == MediaViewerState.InertiaAnimating)
{
_state = MediaViewerState.Initialized;
}
ScrollOffset = _dragInertiaAnimationTranslation.To.Value;
_dragInertiaAnimation.Stop();
_dragInertiaAnimation = null;
_dragInertiaAnimationTranslation = null;
UpdateDisplayedElement(_dragState.NewDisplayedElementIndex);
}
}
private void DragStartedEventHandler()
{
//Tracing.Trace("DragStartedEventHandler() MediaStripOffset = " + offsetHelper.MediaStripOffset);
int elementCount = GetElementCount();
_state = MediaViewerState.Dragging;
_dragState.LastDragUpdateTime = DateTime.Now;
_dragState.DragStartingMediaStripOffset = ScrollOffset;
_dragState.NetDragDistanceSincleLastDragStagnation = 0.0;
_dragState.IsDraggingFirstElement = _displayedElementIndex == 0;
_dragState.IsDraggingLastElement = _displayedElementIndex == elementCount - 1;
_dragState.GotDragDelta = false;
}
private void AnimateToElement(int elementIndex, TimeSpan animationDuration)
{
double animationEndingValue = -1 * CalculateElementOffset(elementIndex);
ConstructDragInertiaAnimation(animationEndingValue, animationDuration);
_state = MediaViewerState.InertiaAnimating;
_dragInertiaAnimation.Begin();
_dragState.NewDisplayedElementIndex = elementIndex;
}
protected override void OnManipulationDelta(ManipulationDeltaEventArgs e)
{
base.OnManipulationDelta(e);
if (e.PinchManipulation == null)
{
if (!IsZoomedInToItem() &&
(_state == MediaViewerState.Initialized) &&
(DragEnabled) &&
(GetElementCount() > 0))
{
_state = MediaViewerState.Dragging;
DragStartedEventHandler();
}
if ((_state == MediaViewerState.Dragging) ||
(_state == MediaViewerState.DraggingAndSquishing))
{
DragDeltaEventHandler(e.DeltaManipulation.Translation.X, e.DeltaManipulation.Translation.Y);
}
}
}
private void UnsquishAnimationComplete(object sender, EventArgs e)
{
if (_state == MediaViewerState.UnsquishAnimating)
{
_state = MediaViewerState.Initialized;
}
ScrollOffset = _unsquishAnimationTranslation.To.Value;
_unsquishAnimation.Stop();
_unsquishAnimation = null;
_unsquishAnimationTranslation = null;
}
private void StartUndoSquishAnimation()
{
// Build animation to undo squish
//
_unsquishAnimation = new Storyboard();
DoubleAnimation scaleAnimation = new DoubleAnimation();
_unsquishAnimationTranslation = new DoubleAnimation();
Storyboard.SetTarget(scaleAnimation, _mediaStripCompositeTransform);
Storyboard.SetTarget(_unsquishAnimationTranslation, _mediaStripCompositeTransform);
Storyboard.SetTargetProperty(scaleAnimation, new PropertyPath(CompositeTransform.ScaleXProperty));
Storyboard.SetTargetProperty(_unsquishAnimationTranslation, new PropertyPath(CompositeTransform.TranslateXProperty));
scaleAnimation.From = _mediaStripCompositeTransform.ScaleX;
_unsquishAnimationTranslation.From = _mediaStripCompositeTransform.TranslateX;
scaleAnimation.To = 1.0;
_unsquishAnimationTranslation.To = _dragState.UnsquishTranslationAnimationTarget;
scaleAnimation.Duration = new TimeSpan(0, 0, 0, 0, _unsquishAnimationMilliseconds);
_unsquishAnimationTranslation.Duration = scaleAnimation.Duration;
_unsquishAnimation.Children.Add(scaleAnimation);
_unsquishAnimation.Children.Add(_unsquishAnimationTranslation);
_unsquishAnimation.FillBehavior = FillBehavior.Stop;
_unsquishAnimation.Completed += UnsquishAnimationComplete;
_state = MediaViewerState.UnsquishAnimating;
_unsquishAnimation.Begin();
// Go ahead and set the values we're animating to their final values so when the storyboard ends, these will take effect
//
_mediaStripCompositeTransform.ScaleX = scaleAnimation.To.Value;
_mediaStripCompositeTransform.TranslateX = _unsquishAnimationTranslation.To.Value;
}
private void StartDragInertiaAnimation()
{
TimeSpan lastDragTimeDelta = DateTime.Now - _dragState.LastDragUpdateTime;
// Build animation to finish the drag
//
int elementIndexDelta = CalculateDragInertiaAnimationEndingValue();
TimeSpan animationDuration = CalculateDragInertiaAnimationDuration(lastDragTimeDelta);
AnimateToElement(_displayedElementIndex.Value + elementIndexDelta, animationDuration);
_state = MediaViewerState.InertiaAnimating;
}
