/// <summary>
/// Allows subclasses to override the GoToState logic.
/// </summary>
protected virtual bool GoToStateCore(Control control, FrameworkElement templateRoot, string stateName, VisualStateGroup group, VisualState state, bool useTransitions)
{
return(GoToStateInternal(control, templateRoot, group, state, useTransitions));
}
/// <summary>
/// Get the most appropriate transition between two states.
/// </summary>
/// <param name="element">Element being transitioned.</param>
/// <param name="group">Group being transitioned.</param>
/// <param name="from">VisualState being transitioned from.</param>
/// <param name="to">VisualState being transitioned to.</param>
/// <returns>
/// The most appropriate transition between the desired states.
/// </returns>
internal static VisualTransition GetTransition(FrameworkElement element, VisualStateGroup group, VisualState from, VisualState to)
{
if (element == null)
{
throw new ArgumentNullException("element");
}
if (group == null)
{
throw new ArgumentNullException("group");
}
if (to == null)
{
throw new ArgumentNullException("to");
}
VisualTransition best = null;
VisualTransition defaultTransition = null;
int bestScore = -1;
IList <VisualTransition> transitions = (IList <VisualTransition>)group.Transitions;
if (transitions != null)
{
foreach (VisualTransition transition in transitions)
{
if (defaultTransition == null && transition.IsDefault)
{
defaultTransition = transition;
continue;
}
int score = -1;
VisualState transitionFromState = group.GetState(transition.From);
VisualState transitionToState = group.GetState(transition.To);
if (from == transitionFromState)
{
score += 1;
}
else if (transitionFromState != null)
{
continue;
}
if (to == transitionToState)
{
score += 2;
}
else if (transitionToState != null)
{
continue;
}
if (score > bestScore)
{
bestScore = score;
best = transition;
}
}
}
return(best ?? defaultTransition);
}
private static Storyboard GenerateDynamicTransitionAnimations(FrameworkElement root, VisualStateGroup group, VisualState newState, VisualTransition transition)
{
Storyboard dynamic = new Storyboard();
if (transition != null && transition.GeneratedDuration != null)
{
dynamic.Duration = transition.GeneratedDuration;
}
else
{
dynamic.Duration = new Duration(TimeSpan.Zero);
}
Dictionary <TimelineDataToken, Timeline> currentAnimations = FlattenTimelines(group.CurrentStoryboards);
Dictionary <TimelineDataToken, Timeline> transitionAnimations = FlattenTimelines(transition != null ? transition.Storyboard : null);
Dictionary <TimelineDataToken, Timeline> newStateAnimations = FlattenTimelines(newState.Storyboard);
// Remove any animations that the transition already animates.
// There is no need to create an interstitial animation if one already exists.
foreach (KeyValuePair <TimelineDataToken, Timeline> pair in transitionAnimations)
{
currentAnimations.Remove(pair.Key);
newStateAnimations.Remove(pair.Key);
}
// Generate the "to" animations
foreach (KeyValuePair <TimelineDataToken, Timeline> pair in newStateAnimations)
{
// The new "To" Animation -- the root is passed as a reference point for name
// lookup.
Timeline toAnimation = GenerateToAnimation(root, pair.Value, true);
// If the animation is of a type that we can't generate transition animations
// for, GenerateToAnimation will return null, and we should just keep going.
if (toAnimation != null)
{
toAnimation.Duration = dynamic.Duration;
dynamic.Children.Add(toAnimation);
}
// Remove this from the list of current state animations we have to consider next
currentAnimations.Remove(pair.Key);
}
// Generate the "from" animations
foreach (KeyValuePair <TimelineDataToken, Timeline> pair in currentAnimations)
{
Timeline fromAnimation = GenerateFromAnimation(root, pair.Value);
if (fromAnimation != null)
{
fromAnimation.Duration = dynamic.Duration;
dynamic.Children.Add(fromAnimation);
}
}
return(dynamic);
}
/// <summary>
/// If the stateGroupsRoot or control is removed from the tree, then the new
/// storyboards will not be able to resolve target names. Thus,
/// if the stateGroupsRoot or control is not in the tree, don't start the new
/// storyboards.
/// </summary>
private static bool ShouldRunStateStoryboard(FrameworkElement control, FrameworkElement stateGroupsRoot, VisualState state, VisualStateGroup group)
{
bool controlInTree = true;
bool stateGroupsRootInTree = true;
// We cannot simply check control.IsLoaded because the control may not be in the visual tree
// even though IsLoaded is true. Instead we will check that it can find a PresentationSource
// which would tell us it's in the visual tree.
if (control != null)
{
// If it's visible then it's in the visual tree, so we don't even have to look for a
// PresentationSource
if (!control.IsVisible)
{
controlInTree = (PresentationSource.FromVisual(control) != null);
}
}
if (stateGroupsRoot != null)
{
if (!stateGroupsRoot.IsVisible)
{
stateGroupsRootInTree = (PresentationSource.FromVisual(stateGroupsRoot) != null);
}
}
return(controlInTree && stateGroupsRootInTree && (state == group.CurrentState));
}
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);
}
internal static bool TryGetState(IList <VisualStateGroup> groups, string stateName, out VisualStateGroup group, out VisualState state)
{
for (int groupIndex = 0; groupIndex < groups.Count; ++groupIndex)
{
VisualStateGroup g = groups[groupIndex];
VisualState s = g.GetState(stateName);
if (s != null)
{
group = g;
state = s;
return(true);
}
}
group = null;
state = null;
return(false);
}