/// <summary>
/// Scroll to a selected index (with animation or not)
/// </summary>
internal void ScrollToSelectedIndex(PickerSelectorItem selectedItem, TimeSpan duration)
{
if (!templateApplied)
{
return;
}
var centerTopOffset = (this.ActualHeight / 2d) - (itemHeight) / 2d;
var deltaOffset = centerTopOffset - selectedItem.GetVerticalPosition();
if (Double.IsInfinity(deltaOffset) || Double.IsNaN(deltaOffset))
{
return;
}
if (duration == TimeSpan.Zero)
{
this.sliderVertical.Value += deltaOffset;
}
else
{
this.UpdatePositionsWithAnimationAsync(selectedItem, deltaOffset, duration);
}
}
/// <summary>
/// When manipulation is completed, go to the closest item
/// </summary>
private void OnManipulationCompleted(object sender, ManipulationCompletedRoutedEventArgs e)
{
PickerSelectorItem middleItem = GetMiddleItem();
// get rect
if (middleItem == null)
{
return;
}
// animate and scroll to
this.ScrollToSelectedIndex(middleItem, animationDuration);
}
/// <summary>
/// Translate items to a new offset
/// </summary>
private void UpdatePosition(Int32 startIndex, Int32 endIndex, Double offset)
{
for (Int32 i = startIndex; i < endIndex; i++)
{
PickerSelectorItem loopListItem = this.Children[i] as PickerSelectorItem;
if (loopListItem == null)
{
continue;
}
TranslateTransform translateTransform = loopListItem.GetTranslateTransform();
translateTransform.Y = offset;
}
}
/// <summary>
/// Updating with an animation (after a tap)
/// </summary>
private void UpdatePositionsWithAnimationAsync(PickerSelectorItem selectedItem, Double delta, TimeSpan duration)
{
animationSnap.From = selectedItem.GetTranslateTransform().Y;
animationSnap.To = selectedItem.GetTranslateTransform().Y + delta;
animationSnap.Duration = duration;
animationSnap.EasingFunction = new ExponentialEase {
EasingMode = EasingMode.EaseInOut
};
sliderVertical.ValueChanged -= OnVerticalOffsetChanged;
sliderVertical.Value = selectedItem.GetTranslateTransform().Y;
sliderVertical.ValueChanged += OnVerticalOffsetChanged;
this.storyboard.Completed += (sender, o) =>
{
if (SelectedItemChanged != null)
{
SelectedItemChanged(this, selectedItem);
}
};
this.storyboard.RunAsync();
}
/// <summary>
/// Updating with an animation (after a tap)
/// </summary>
private void UpdatePositionsWithAnimationAsync(PickerSelectorItem selectedItem, Double delta, TimeSpan duration)
{
if (Orientation == Orientation.Vertical)
{
animationSnap.From = selectedItem.GetTranslateTransform().Y;
animationSnap.To = selectedItem.GetTranslateTransform().Y + delta;
}
else
{
animationSnap.From = selectedItem.GetTranslateTransform().X;
animationSnap.To = selectedItem.GetTranslateTransform().X + delta;
}
animationSnap.Duration = duration;
animationSnap.EasingFunction = new ExponentialEase { EasingMode = EasingMode.EaseInOut };
internalSlider.ValueChanged -= OnOffsetChanged;
internalSlider.Value = Orientation == Orientation.Vertical
? selectedItem.GetTranslateTransform().Y
: selectedItem.GetTranslateTransform().X;
internalSlider.ValueChanged += OnOffsetChanged;
this.storyboard.Completed += (sender, o) =>
{
if (SelectedItemChanged != null)
{
SelectedItemChanged(this, selectedItem);
}
};
this.storyboard.RunAsync();
}
/// <summary>
/// Scroll to a selected index (with animation or not)
/// </summary>
internal void ScrollToSelectedIndex(PickerSelectorItem selectedItem, TimeSpan duration)
{
if (!templateApplied)
return;
var centerTopOffset = Orientation == Orientation.Vertical
? (this.ActualHeight / 2d) - (itemHeight) / 2d
: (this.ActualWidth / 2d) - (itemWidth) / 2d;
var deltaOffset = centerTopOffset -
(Orientation == Orientation.Vertical
? selectedItem.GetVerticalPosition()
: selectedItem.GetHorizontalPosition());
if (Double.IsInfinity(deltaOffset) || Double.IsNaN(deltaOffset))
return;
if (duration == TimeSpan.Zero)
this.internalSlider.Value += deltaOffset;
else
this.UpdatePositionsWithAnimationAsync(selectedItem, deltaOffset, duration);
}
/// <summary>
/// Arrange all items
/// </summary>
protected override Size ArrangeOverride(Size finalSize)
{
// Clip to ensure items dont override container
this.Clip = new RectangleGeometry {
Rect = new Rect(0, 0, finalSize.Width, finalSize.Height)
};
if (this.Children == null || this.Children.Count == 0)
{
var size = base.ArrangeOverride(finalSize);
var width = double.IsInfinity(size.Width) ? 400 : size.Width;
var height = double.IsInfinity(size.Height) ? 800 : size.Height;
return(new Size(width, height));
}
Double positionTop = 0d;
Double positionLeft = 0d;
PickerSelectorItem selectedItem = null;
// Must Create looping items count
foreach (PickerSelectorItem item in this.Children)
{
if (item == null)
{
continue;
}
Size desiredSize = item.DesiredSize;
if (double.IsNaN(desiredSize.Width) || double.IsNaN(desiredSize.Height))
{
continue;
}
item.RectPosition = new Rect(positionLeft, positionTop, desiredSize.Width, desiredSize.Height);
item.Arrange(item.RectPosition);
if (item.IsSelected)
{
selectedItem = item;
}
positionTop += desiredSize.Height;
}
templateApplied = true;
if (selectedItem != null)
{
this.UpdatePositions(sliderVertical.Value);
this.ScrollToSelectedIndex(selectedItem, TimeSpan.Zero);
//if (!isFirstLayoutPassed)
//{
// this.Dispatcher.RunAsync(CoreDispatcherPriority.Normal,
// () => this.ScrollToSelectedIndex(selectedItem, TimeSpan.Zero));
//}
//else
//{
//}
}
return(finalSize);
}