WP8.1 AppBar大小更改

Question

How do I monitor AppBar's size changes? Specifically, I want to know when it gets opened(to show secondary commands and labels underneath icons). There is a SizeChanged event, but it fires only before AppBar is shown on the screen.

Answer 1

CommandBar has Opened and Closed events. They are fired when SecondayCommands are shown/hidden.

Note that those events will be fired only if you have SecondayCommands in your AppBar.

As I've checked - Opening/Closing your AppBar doesn't change its ActualHeight. If you want to see its size changing you can play with ClosedDisplayMode - for example put this code in your AppBarButton.Click :

private void AppBarToggleButton_Click(object sender, RoutedEventArgs e)
{
    Debug.WriteLine(BottomAppBar.ActualHeight.ToString());
    if (BottomAppBar.ClosedDisplayMode == AppBarClosedDisplayMode.Compact)
       BottomAppBar.ClosedDisplayMode = AppBarClosedDisplayMode.Minimal;
    else BottomAppBar.ClosedDisplayMode = AppBarClosedDisplayMode.Compact;
}

The code above changes ActualHeight and thus SizeChanged event is being fired.