protected void RaiseCurrentStateChanging(VisualStateGroup stateGroup, VisualState oldState, VisualState newState, Control control)
{
if (stateGroup == null)
{
throw new ArgumentNullException("stateGroup");
}
if (newState == null)
{
throw new ArgumentNullException("newState");
}
if (control == null)
{
throw new ArgumentNullException("control");
}
FrameworkElement root = VisualStateManager.GetTemplateRoot(control);
if (root == null)
{
return; // Ignore if a ControlTemplate hasn't been applied
}
stateGroup.RaiseCurrentStateChanging(root, oldState, newState, control);
}
private static bool GoToStateInternal(Control control, FrameworkElement element, VisualStateGroup group, VisualState state, bool useTransitions)
{
if (element == null)
{
throw new ArgumentNullException("element");
}
if (state == null)
{
throw new ArgumentNullException("state");
}
if (group == null)
{
throw new InvalidOperationException();
}
VisualState lastState = group.CurrentState;
if (lastState == state)
{
return(true);
}
// Get the transition Storyboard. Even if there are no transitions specified, there might
// be properties that we're rolling back to their default values.
VisualTransition transition = useTransitions ? VisualStateManager.GetTransition(element, group, lastState, state) : null;
// Generate dynamicTransition Storyboard
Storyboard dynamicTransition = GenerateDynamicTransitionAnimations(element, group, state, transition);
// If the transition is null, then we want to instantly snap. The dynamicTransition will
// consist of everything that is being moved back to the default state.
// If the transition.Duration and explicit storyboard duration is zero, then we want both the dynamic
// and state Storyboards to happen in the same tick, so we start them at the same time.
if (transition == null || (transition.GeneratedDuration == DurationZero &&
(transition.Storyboard == null || transition.Storyboard.Duration == DurationZero)))
{
// Start new state Storyboard and stop any previously running Storyboards
if (transition != null && transition.Storyboard != null)
{
group.StartNewThenStopOld(element, transition.Storyboard, state.Storyboard);
}
else
{
group.StartNewThenStopOld(element, state.Storyboard);
}
// Fire both CurrentStateChanging and CurrentStateChanged events
group.RaiseCurrentStateChanging(element, lastState, state, control);
group.RaiseCurrentStateChanged(element, lastState, state, control);
}
else
{
// In this case, we have an interstitial storyboard of duration > 0 and/or
// explicit storyboard of duration >0 , so we need
// to run them first, and then we'll run the state storyboard.
// we have to wait for both storyboards to complete before
// starting the steady state animations.
transition.DynamicStoryboardCompleted = false;
// Hook up generated Storyboard's Completed event handler
dynamicTransition.Completed += delegate(object sender, EventArgs e)
{
if (transition.Storyboard == null || transition.ExplicitStoryboardCompleted)
{
if (ShouldRunStateStoryboard(control, element, state, group))
{
group.StartNewThenStopOld(element, state.Storyboard);
}
group.RaiseCurrentStateChanged(element, lastState, state, control);
}
transition.DynamicStoryboardCompleted = true;
};
if (transition.Storyboard != null && transition.ExplicitStoryboardCompleted == true)
{
EventHandler transitionCompleted = null;
transitionCompleted = new EventHandler(delegate(object sender, EventArgs e)
{
if (transition.DynamicStoryboardCompleted)
{
if (ShouldRunStateStoryboard(control, element, state, group))
{
group.StartNewThenStopOld(element, state.Storyboard);
}
group.RaiseCurrentStateChanged(element, lastState, state, control);
}
transition.Storyboard.Completed -= transitionCompleted;
transition.ExplicitStoryboardCompleted = true;
});
// hook up explicit storyboard's Completed event handler
transition.ExplicitStoryboardCompleted = false;
transition.Storyboard.Completed += transitionCompleted;
}
// Start transition and dynamicTransition Storyboards
// Stop any previously running Storyboards
group.StartNewThenStopOld(element, transition.Storyboard, dynamicTransition);
group.RaiseCurrentStateChanging(element, lastState, state, control);
}
group.CurrentState = state;
return(true);
}
