/// <summary>
/// Updates all controls that are listening for visual state changes with the correct
/// visual state.
/// </summary>
/// <remarks>
/// Typically used in conjunction with overriding <see cref="DetermineVisualState"/> to
/// signal that a different value may be returned even though the view state has not
/// changed.
/// </remarks>
public void InvalidateVisualState()
{
if (this._layoutAwareControls != null)
{
foreach (var layoutAwareControl in this._layoutAwareControls)
{
VisualStateManager.GoToState(layoutAwareControl, CurrentViewState.ToString(), false);
}
}
}
/// <summary>
/// Invoked as an event handler, typically on the <see cref="FrameworkElement.Loaded"/>
/// event of a <see cref="Control"/> within the page, to indicate that the sender should
/// start receiving visual state management changes that correspond to application view
/// state changes.
/// </summary>
/// <param name="sender">Instance of <see cref="Control"/> that supports visual state
/// management corresponding to view states.</param>
/// <param name="e">Event data that describes how the request was made.</param>
/// <remarks>The current view state will immediately be used to set the corresponding
/// visual state when layout updates are requested. A corresponding
/// <see cref="FrameworkElement.Unloaded"/> event handler connected to
/// <see cref="StopLayoutUpdates"/> is strongly encouraged. Instances of
/// <see cref="LayoutAwarePage"/> automatically invoke these handlers in their Loaded and
/// Unloaded events.</remarks>
/// <seealso cref="DetermineVisualState"/>
/// <seealso cref="InvalidateVisualState"/>
public void StartLayoutUpdates(object sender, RoutedEventArgs e)
{
var control = sender as Control;
if (control == null)
{
return;
}
if (this._layoutAwareControls == null)
{
// Start listening to view state changes when there are controls interested in updates
Window.Current.SizeChanged += this.WindowSizeChanged;
this._layoutAwareControls = new List <Control>();
}
this._layoutAwareControls.Add(control);
CurrentViewState = ViewStateHelper.GetViewState(ApplicationView.GetForCurrentView(), new Size(ActualWidth, ActualHeight));
// Set the initial visual state of the control
VisualStateManager.GoToState(control, CurrentViewState.ToString(), false);
}