/// <summary>
/// Get control inside the specified layout template.
/// </summary>
/// <typeparam name="T"></typeparam>
/// <param name="mode">The layout mode in which the control is defined</param>
/// <param name="name">The 'x:Name' of the control</param>
/// <returns></returns>
/// <remarks>The caller must ensure the control is loaded. This is best done from <see cref="FrameworkElement.Loaded"/> event.</remarks>
public T GetSampleChild <T>(Design mode, string name)
where T : FrameworkElement
{
var presenter = (ContentPresenter)GetTemplateChild($"{mode}ContentPresenter");
return(VisualTreeHelperEx.GetFirstDescendant <T>(presenter, x => x.Name == name));
}
private void AddNavigationItems(MUXC.NavigationView nv)
{
var categories = Assembly.GetExecutingAssembly().DefinedTypes
.Where(x => x.Namespace?.StartsWith("Uno.Themes.Samples") == true)
.Select(x => new { TypeInfo = x, SamplePageAttribute = x.GetCustomAttribute <SamplePageAttribute>() })
.Where(x => x.SamplePageAttribute != null)
.Select(x => new Sample(x.SamplePageAttribute, x.TypeInfo.AsType()))
.OrderByDescending(x => x.SortOrder.HasValue)
.ThenBy(x => x.SortOrder)
.ThenBy(x => x.Title)
.GroupBy(x => x.Category);
foreach (var category in categories.OrderBy(x => x.Key))
{
var tier = 1;
var parentItem = default(MUXC.NavigationViewItem);
if (category.Key != SampleCategory.None)
{
parentItem = new MUXC.NavigationViewItem
{
Content = category.Key.GetDescription() ?? category.Key.ToString(),
SelectsOnInvoked = false,
Style = (Style)Resources[$"T{tier++}NavigationViewItemStyle"]
}.Apply(NavViewItemVisualStateFix);
AutomationProperties.SetAutomationId(parentItem, "Section_" + parentItem.Content);
nv.MenuItems.Add(parentItem);
}
foreach (var sample in category)
{
var item = new MUXC.NavigationViewItem
{
Content = sample.Title,
DataContext = sample,
Style = (Style)Resources[$"T{tier}NavigationViewItemStyle"]
}.Apply(NavViewItemVisualStateFix);
AutomationProperties.SetAutomationId(item, "Section_" + item.Content);
(parentItem?.MenuItems ?? nv.MenuItems).Add(item);
}
}
void NavViewItemVisualStateFix(MUXC.NavigationViewItem nvi)
{
// gallery#107: on uwp and uno, deselecting a NVI by selecting another NVI will leave the former in the "Selected" state
// to workaround this, we force reset the visual state when IsSelected becomes false
nvi.RegisterPropertyChangedCallback(MUXC.NavigationViewItemBase.IsSelectedProperty, (s, e) =>
{
if (!nvi.IsSelected)
{
// depending on the DisplayMode, a NVIP may or may not be used.
var nvip = VisualTreeHelperEx.GetFirstDescendant <MUXCP.NavigationViewItemPresenter>(nvi, x => x.Name == "NavigationViewItemPresenter");
VisualStateManager.GoToState((Control)nvip ?? nvi, "Normal", true);
}
});
}
}
private double GetRelativeOffset()
{
#if NETFX_CORE
// On UWP we can count on finding a ScrollContentPresenter.
var scp = VisualTreeHelperEx.GetFirstDescendant <ScrollContentPresenter>(_scrollViewer);
var content = scp?.Content as FrameworkElement;
var transform = _scrollingTabs.TransformToVisual(content);
return(transform.TransformPoint(new Point(0, 0)).Y - _scrollViewer.VerticalOffset);
#elif __IOS__
var transform = _scrollingTabs.TransformToVisual(_scrollViewer);
return(transform.TransformPoint(new Point(0, 0)).Y);
#else
var transform = _scrollingTabs.TransformToVisual(this);
return(transform.TransformPoint(new Point(0, 0)).Y - _top.ActualHeight);
#endif
}
private static void InstallIncrementalLoadingWorkaround(object sender, RoutedEventArgs _)
{
var lv = (ListView)sender;
var sv = VisualTreeHelperEx.GetFirstDescendant <ScrollViewer>(lv);
sv.ViewChanged += async(s, e) =>
{
if (lv.ItemsSource is not ISupportIncrementalLoading source)
{
return;
}
if (lv.Items.Count > 0 && !source.HasMoreItems)
{
return;
}
if (GetIsIncrementallyLoading(lv))
{
return;
}
// note: for simplicity, we assume the ItemsPanel is stacked vertically
// try to load more when there is less than half a page;
// sv.VerticalOffset only represents the top of rendered area,
// we need another sv.ViewportHeight (or 1.0 after division) to get to the bottom
if (((sv.ExtentHeight - sv.VerticalOffset) / sv.ViewportHeight) - 1.0 <= 0.5)
{
try
{
SetIsIncrementallyLoading(lv, true);
await source.LoadMoreItemsAsync(1);
}
catch (Exception ex)
{
typeof(ListViewExtensions).Log().Error("failed to load more items: ", ex);
}
finally
{
SetIsIncrementallyLoading(lv, false);
}
}
};
}
