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using System;
using System.Collections.Specialized;
using System.ComponentModel;
using Windows.UI.Xaml;
using Windows.UI.Xaml.Controls;
using Windows.UI.Xaml.Media.Animation;
namespace Xamarin.Forms.Platform.WinRT
{
public class TabbedPageRenderer
: IVisualElementRenderer
{
Canvas _canvas;
bool _disposed;
TabsControl _tabs;
VisualElementTracker<Page, Canvas> _tracker;
public TabbedPage Page
{
get { return (TabbedPage)Element; }
}
protected VisualElementTracker<Page, Canvas> Tracker
{
get { return _tracker; }
set
{
if (_tracker == value)
return;
if (_tracker != null)
_tracker.Dispose();
_tracker = value;
}
}
public event EventHandler<VisualElementChangedEventArgs> ElementChanged;
public FrameworkElement ContainerElement
{
get { return _canvas; }
}
public VisualElement Element { get; private set; }
public void SetElement(VisualElement element)
{
if (element != null && !(element is TabbedPage))
throw new ArgumentException("Element must be a TabbedPage", "element");
var oldElement = Page;
Element = element;
if (oldElement != null)
{
oldElement.PropertyChanged -= OnElementPropertyChanged;
((INotifyCollectionChanged)oldElement.Children).CollectionChanged -= OnPagesChanged;
}
if (element != null)
{
if (_tracker == null)
{
_tabs = new TabsControl();
_canvas = new Canvas();
_canvas.ChildrenTransitions = new TransitionCollection
{
new EntranceThemeTransition()
};
Tracker = new BackgroundTracker<Canvas>(Panel.BackgroundProperty)
{
Element = (Page)element,
Control = _canvas,
Container = _canvas
};
_canvas.Loaded += OnLoaded;
_canvas.Unloaded += OnUnloaded;
}
_tabs.DataContext = element;
OnPagesChanged(Page.Children, new NotifyCollectionChangedEventArgs(NotifyCollectionChangedAction.Reset));
UpdateCurrentPage();
((INotifyCollectionChanged)Page.Children).CollectionChanged += OnPagesChanged;
element.PropertyChanged += OnElementPropertyChanged;
}
OnElementChanged(new VisualElementChangedEventArgs(oldElement, element));
}
public SizeRequest GetDesiredSize(double widthConstraint, double heightConstraint)
{
if (_canvas.Children.Count == 0)
return new SizeRequest();
var constraint = new Windows.Foundation.Size(widthConstraint, heightConstraint);
var child = (FrameworkElement)_canvas.Children[0];
var oldWidth = child.Width;
var oldHeight = child.Height;
child.Height = double.NaN;
child.Width = double.NaN;
child.Measure(constraint);
var result = new Size(Math.Ceiling(child.DesiredSize.Width), Math.Ceiling(child.DesiredSize.Height));
child.Width = oldWidth;
child.Height = oldHeight;
return new SizeRequest(result);
}
public void Dispose()
{
Dispose(true);
}
protected virtual void Dispose(bool disposing)
{
if (!disposing || _disposed)
return;
_disposed = true;
SetElement(null);
Tracker = null;
}
protected virtual void OnElementChanged(VisualElementChangedEventArgs e)
{
var changed = ElementChanged;
if (changed != null)
changed(this, e);
}
void OnPagesChanged(object sender, NotifyCollectionChangedEventArgs e)
{
e.Apply(Page.Children, _tabs.Items);
}
internal void OnTabSelected(Page tab)
{
CloseTabs();
Page.CurrentPage = tab;
}
void OnElementPropertyChanged(object sender, PropertyChangedEventArgs e)
{
if (e.PropertyName == "CurrentPage")
UpdateCurrentPage();
}
void UpdateCurrentPage()
{
var renderer = Page.CurrentPage.GetOrCreateRenderer();
_canvas.Children.Clear();
if (renderer != null)
_canvas.Children.Add(renderer.ContainerElement);
}
void OnLoaded(object sender, RoutedEventArgs args)
{
if (Page == null)
return;
ShowTabs();
Page.SendAppearing();
}
Windows.UI.Xaml.Controls.Page GetTopPage()
{
var frame = Window.Current.Content as Windows.UI.Xaml.Controls.Frame;
if (frame == null)
return null;
return frame.Content as Windows.UI.Xaml.Controls.Page;
}
AppBar GetOrCreateAppBar()
{
var npage = GetTopPage();
if (npage == null)
return null;
if (npage.TopAppBar == null)
npage.TopAppBar = new AppBar();
return npage.TopAppBar;
}
void ShowTabs()
{
var bar = GetOrCreateAppBar();
if (bar != null)
bar.Content = _tabs;
}
void CloseTabs()
{
var page = GetTopPage();
if (page == null)
return;
if (page.TopAppBar != null)
page.TopAppBar.IsOpen = false;
}
void RemoveTabs()
{
var page = GetTopPage();
if (page == null)
return;
// Explicitly unparent this.tabs so we can reuse
if (page.TopAppBar != null)
page.TopAppBar.Content = null;
page.TopAppBar = null;
}
void OnUnloaded(object sender, RoutedEventArgs args)
{
RemoveTabs();
if (Page != null)
Page.SendDisappearing();
}
}
}
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