Windows UAP: get page current visual state - winrt-xaml

Question

I know I can use VisualStateManager.GoToState to set visual state programatically.
However, how can get current visual state if visual state is triggered from XAML?

Answer 1

Firstly, you have to understand there are several current visual states for one control. But there is one current visual state for one visual state group (and several visual state group for one control).
For a particular Visual State Group, you can use the event CurrentStateChanged (or CurrentStateChanging) in order to catch the visual state changing :
<VisualStateManager.VisualStateGroups>
<VisualStateGroup x:Name="Custom"
CurrentStateChanged="CustomGroup_CurrentStateChanged">
and in C# :
private void CustomGroup_CurrentStateChanged(object sender, VisualStateChangedEventArgs e)
{
Debug.WriteLine(e.NewState.Name);
}
If you can't modify the XAML code of a VisualStateGroup, you can query the VisualStateGroups collection of a control with the method VisualStateManagner.GetVisualStateGroups :
foreach(var group in VisualStateManager.GetVisualStateGroups(aControl))
{
var currentStateName = group.CurrentState.Name;
}
If you need to check the state changes for a particular Visual State Group, you need his name (for example "CommonStates") and can do something like :
var aControl = this;
var visualStateGroupName = "CommonStates";
var myVsg = VisualStateManager.GetVisualStateGroups(aControl).FirstOrDefault(vsg => vsg.Name == visualStateGroupName);
var currentState = myVsg.CurrentState;
myVsg.CurrentStateChanged += (s, e) =>
{
currentState = e.NewState;
};

Answer 2

Handling the state manually, not a crazy idea. Here's how:
public sealed partial class MainPage : Page
{
public MainPage()
{
InitializeComponent();
MyVisualStateGroup.CurrentStateChanged += (s, e) =>
HandleState(AdaptiveVisualStateGroup.CurrentState);
}
private void HandleState(VisualState currentState)
{
// TODO
}
}
Make sense?
One more important thing to remember. It is possible for more than one visual state to be active. When you ask in your question what the page visual state is, that is a loaded question. A single visual state group can have only one active visual state. But a page can have more than one visual state group. This means a page can have more then one active visual states. I know that in many cases there is a single visual state group. But I wanted to let you know that the question itself is tricky because of multi-visual state groups.
Best of luck!