void Gesture_OnAction(BaseGestureRecognizer recgonizer, GestureRecognizerState state)
{
if (recgonizer.View != MediaItemsListView)
{
return;
}
var panGesture = recgonizer as PanGestureRecognizer;
Point translation = panGesture.GetTranslationInView(MainLayout);
Point velocity = panGesture.GetVelocityInView(MainLayout);
panGesture.SetTranslationInView(new Point(0, 0), MainLayout);
switch (panGesture.State)
{
case GestureRecognizerState.Began:
// MediaItemsListView.IsEnabled = false;
break;
case GestureRecognizerState.Changed:
var newY = _currentGridY + translation.Y;
newY = Math.Max(0, newY);
newY = Math.Min(400, newY);
Debug.WriteLine("newY {0} _currentGridY {1} _scrollPosition{2}", newY, _currentGridY, _scrollPosition);
bool willMoveList = false;
if (newY != _currentGridY)
{
willMoveList = _currentGridY > 0 || _scrollPosition <= 0 &&
newY > 0 && newY < Height - 100;
if (willMoveList)
{
_currentGridY = newY;
var bounds = MediaItemsListView.Bounds;
bounds.Y = _currentGridY;
MediaItemsListView.Layout(bounds);
}
MediaItemsListView.IsScrollEnabled = !willMoveList;
}
else
{
MediaItemsListView.IsScrollEnabled = true;
Debug.WriteLine("no move " + MediaItemsListView.IsScrollEnabled);
}
break;
case GestureRecognizerState.Cancelled:
case GestureRecognizerState.Ended:
case GestureRecognizerState.Failed:
MediaItemsListView.IsScrollEnabled = true;
if (_currentGridY != 0 && _currentGridY != 400)
{
_currentGridY = _currentGridY > 200 ? 400 : 0;
MediaItemsListView.LayoutTo(new Rectangle(0, _currentGridY, Width, Height));
}
break;
default:
break;
}
}
protected override void OnDisappearing()
{
base.OnDisappearing();
if (MediaItemsListView != null)
{
MediaItemsListView.RemoveAllGestureRecognizers();
}
}
protected override void LayoutChildren(double x, double y, double width, double height)
{
var complete = Math.Min(1, height / (ParentHeight));
MediaItemsListView.Opacity = complete;
TitleLabel.Opacity = complete;
MainLayout.RowDefinitions [0].Height = 40 * complete;
MainLayout.RowDefinitions [1].Height = MinimumHeightRequest + (160 * complete);
// Debug.WriteLine ("complete {0} height {1} ph{2}", complete, height, ParentHeight);
base.LayoutChildren(x, y, width, height);
MediaItemsListView.Layout(new Rectangle(0, MediaItemsListView.Bounds.Y, width, MediaItemsListView.Bounds.Height));
}
void MainLayout_OnLayoutChildren(double x, double y, double width, double height)
{
MediaItemsListView.Layout(new Rectangle(0, 0, Width, Height));
if (!_didLayoutContainer)
{
_contentBounds.Y = height - 100;
_contentBounds.X = width - 160;
_contentBounds.Width = 160;
_contentBounds.Height = 100;
_didLayoutContainer = true;
}
PageContainer.Layout(_contentBounds);
}
public GestureScrollListExample()
{
InitializeComponent();
MainLayout.OnLayoutChildren += MainLayout_OnLayoutChildren;
MediaItemsListView.ItemsSource = DataProvider.GetMediaItems();
_panGesture = new PanGestureRecognizer();
_panGesture.OnAction += Gesture_OnAction;
_panGesture.IsConsumingTouchesInParallel = true;
// _panGesture.CancelsTouchesInView = true;
// _panGesture.DelaysTouches = true;
// _panGesture.OnGestureShouldBeginDelegate += OnGestureShouldBegin;
MediaItemsListView.AddGestureRecognizer(_panGesture);
MediaItemsListView.OnScroll += MediaItemsListView_OnScroll;
}
void MainLayout_OnLayoutChildren(double x, double y, double width, double height)
{
MediaItemsListView.Layout(new Rectangle(0, _currentGridY, Width, Height));
Details.Layout(new Rectangle(0, 0, Width, 400));
}
