protected override void SaveState(System.Collections.Generic.Dictionary <string, object> pageState)
{
if (pageState == null)
{
return;
}
base.SaveState(pageState);
pageState["scrollViewerOffsetProportion"] = ScrollViewerUtilities.GetScrollViewerOffsetProportion(_itemsGridViewScrollViewer);
}
private void ScrollBarVisibilityChanged(object sender, DependencyPropertyChangedEventArgs e)
{
var helper = (DependencyPropertyChangedHelper)sender;
if (((Visibility)e.NewValue) == Visibility.Visible)
{
ScrollViewerUtilities.ScrollToProportion(_itemsGridViewScrollViewer, _scrollViewerOffsetProportion);
helper.PropertyChanged -= ScrollBarVisibilityChanged;
}
;
if (_isPageLoading)
{
itemsGridView.LayoutUpdated += itemsGridView_LayoutUpdated;
_isPageLoading = false;
}
}
private void Page_SizeChanged(object sender, SizeChangedEventArgs e)
{
var scrollViewer = VisualTreeUtilities.GetVisualChild <ScrollViewer>(itemsGridView);
if (scrollViewer != null)
{
if (scrollViewer.ComputedHorizontalScrollBarVisibility == Visibility.Visible && scrollViewer.ComputedVerticalScrollBarVisibility == Visibility.Visible)
{
ScrollViewerUtilities.ScrollToProportion(scrollViewer, _scrollViewerOffsetProportion);
}
else
{
_horizontalScrollBarVisibilityEventToken = scrollViewer.RegisterPropertyChangedCallback(ScrollViewer.ComputedHorizontalScrollBarVisibilityProperty, ScrollBarVisibilityChanged);
_verticalScrollBarVisibilityEventToken = scrollViewer.RegisterPropertyChangedCallback(ScrollViewer.ComputedVerticalScrollBarVisibilityProperty, ScrollBarVisibilityChanged);
}
}
}
void Page_SizeChanged(object sender, SizeChangedEventArgs e)
{
var scrollViewer = VisualTreeUtilities.GetVisualChild <ScrollViewer>(itemsGridView);
if (scrollViewer != null)
{
if (scrollViewer.ComputedHorizontalScrollBarVisibility == Visibility.Visible && scrollViewer.ComputedVerticalScrollBarVisibility == Visibility.Visible)
{
ScrollViewerUtilities.ScrollToProportion(scrollViewer, _scrollViewerOffsetProportion);
}
else
{
DependencyPropertyChangedHelper horizontalHelper = new DependencyPropertyChangedHelper(scrollViewer, "ComputedHorizontalScrollBarVisibility");
horizontalHelper.PropertyChanged += ScrollBarVisibilityChanged;
DependencyPropertyChangedHelper verticalHelper = new DependencyPropertyChangedHelper(scrollViewer, "ComputedVerticalScrollBarVisibility");
verticalHelper.PropertyChanged += ScrollBarVisibilityChanged;
}
}
}
private void ScrollBarVisibilityChanged(DependencyObject sender, DependencyProperty dp)
{
if (((Visibility)sender.GetValue(dp)) == Visibility.Visible)
{
ScrollViewerUtilities.ScrollToProportion(_itemsGridViewScrollViewer, _scrollViewerOffsetProportion);
if (_horizontalScrollBarVisibilityEventToken != 0L)
{
sender.UnregisterPropertyChangedCallback(dp, _horizontalScrollBarVisibilityEventToken);
}
if (_verticalScrollBarVisibilityEventToken != 0L)
{
sender.UnregisterPropertyChangedCallback(dp, _verticalScrollBarVisibilityEventToken);
}
}
if (_isPageLoading)
{
itemsGridView.LayoutUpdated += ItemsGridView_LayoutUpdated;
_isPageLoading = false;
}
}
private void itemsGridView_LayoutUpdated(object sender, object e)
{
_scrollViewerOffsetProportion = ScrollViewerUtilities.GetScrollViewerOffsetProportion(_itemsGridViewScrollViewer);
}