private void OnRequestedThemeChanged()
{
if (GetTreeRoot() is FrameworkElement root)
{
// Update theme bindings in application resources
Resources?.UpdateThemeBindings();
// Update theme bindings in system resources
ResourceResolver.UpdateSystemThemeBindings();
PropagateThemeChanged(root);
}
void PropagateThemeChanged(object instance)
{
// Update ThemeResource references that have changed
if (instance is FrameworkElement fe)
{
fe.UpdateThemeBindings();
}
//Try Panel.Children before ViewGroup.GetChildren - this results in fewer allocations
if (instance is Controls.Panel p)
{
foreach (object o in p.Children)
{
PropagateThemeChanged(o);
}
}
else if (instance is ViewGroup g)
{
foreach (object o in g.GetChildren())
{
PropagateThemeChanged(o);
}
}
}
// On some platforms, the user-set root is not the topmost FrameworkElement
FrameworkElement GetTreeRoot()
{
var current = Windows.UI.Xaml.Window.Current.Content as FrameworkElement;
var parent = current?.GetVisualTreeParent();
while (parent is FrameworkElement feParent)
{
current = feParent;
parent = current?.GetVisualTreeParent();
}
return(current);
}
}
