/// <summary>
/// Layout all children
/// </summary>
protected override void LayoutChildren(double x, double y, double width, double height)
{
MeasureHeaders(width, height);
LayoutChild(_headerElement, new Rectangle(x, y, width, _headerSize.Request.Height));
LayoutChild(_stickyHeaderElement, new Rectangle(x, y, width, _stickyHeaderSize.Request.Height));
if (_relatedViews == null)
{
_relatedViews = new RelatedViews(this);
}
ScrollSource.TryGetNavigationBarProperties(_relatedViews.ContentPage, _relatedViews.NavigationPage, out double navigationBarHeight, out double navigationBarY, out bool isNavigationBarFloating, out bool isNavigationBarScrollable);
// Update headers translationY based on previous scroll
UpdateHeadersTranslationY(_scrollY, navigationBarHeight, navigationBarY, isNavigationBarFloating, isNavigationBarScrollable);
bool isHeaderLayoutInScrollViewer = VisualTreeHelper.GetParent <ScrollView>(this, typeof(NavigationPage)) != null;
if (isHeaderLayoutInScrollViewer)
{
double heightToAdd = 0;
if (_relatedViews.ContentPage != null && _relatedViews.NavigationPage != null && isNavigationBarFloating == false && isNavigationBarScrollable == true)
{
heightToAdd = navigationBarHeight;
}
LayoutChild(_contentElement, new Rectangle(x, y + _headerSize.Request.Height + _stickyHeaderSize.Request.Height + heightToAdd, width, height));
}
else
{
LayoutChild(_contentElement, new Rectangle(x, RootPage.Instance.SafeAreaInsest.Top, width, height));
}
}
/// <summary>
/// Add page content root element attached property list which contains all scroll hosts
/// </summary>
private static void OnIsEnabledChanged(BindableObject bindable, object oldValue, object newValue)
{
if ((bool)newValue == true)
{
View source = bindable as View;
RelatedViews relatedViews = new RelatedViews(source);
double oldScrollY = 0;
// Size changed
EventHandler sizeChangedEventHandler = null;
sizeChangedEventHandler = (object sender, EventArgs e) =>
{
UpdateScrollSourcePadding(relatedViews.HeaderLayout, relatedViews.ContentPage, relatedViews.NavigationPage, source);
};
source.SizeChanged += sizeChangedEventHandler;
if (bindable is ScrollView scrollView)
{
if (Device.RuntimePlatform == Device.UWP)
{
scrollView.Effects.Add(new ScrollEffect());
}
// Scrolled
EventHandler <ScrolledEventArgs> scrollEventHandler = null;
scrollEventHandler = (object sender, ScrolledEventArgs e) =>
{
HandleScrolling(relatedViews.HeaderLayout, relatedViews.ContentPage, relatedViews.NavigationPage, oldScrollY, e.ScrollY);
oldScrollY = e.ScrollY;
};
scrollView.Scrolled += scrollEventHandler;
}
else if (bindable is CollectionView collectionView)
{
// Scrolled
EventHandler <ItemsViewScrolledEventArgs> scrollEventHandler = null;
scrollEventHandler = (object sender, ItemsViewScrolledEventArgs e) =>
{
HandleScrolling(relatedViews.HeaderLayout, relatedViews.ContentPage, relatedViews.NavigationPage, oldScrollY, e.VerticalOffset);
oldScrollY = e.VerticalOffset;
};
collectionView.Scrolled += scrollEventHandler;
}
}
else
{
// TODO
}
}
private void OnTabViewPanChanged(object sender, PanChangedArgs args)
{
if (sender is CarouselView carouselView && carouselView.ItemsLayout is CarouselLayout carouselLayout)
{
if (_relatedViews == null)
{
_relatedViews = new RelatedViews(this);
}
foreach (View child in carouselLayout.Children)
{
ScrollView scrollView = VisualTreeHelper.FindVisualChildren <ScrollView>(child).FirstOrDefault();
if (scrollView != null && scrollView.ScrollY != _scrollY)
{
ScrollSource.UpdateScrollViewStart(this, _relatedViews.ContentPage, _relatedViews.NavigationPage, scrollView, _scrollY);
}
}
}
}
