| public static TryGetVisualStateGroup ( DependencyObject dependencyObject, string groupName ) : VisualStateGroup | ||
| dependencyObject | DependencyObject | The dependency object. |
| groupName | string | The visual state group's name. |
| return | VisualStateGroup | |
/// <summary>
/// Should be called by the parent control before the base
/// OnApplyTemplate method is called.
/// </summary>
public void BeforeOnApplyTemplate()
{
if (UsesClosingVisualState)
{
// Unhook the event handler for the popup closed visual state group.
// This code is used to enable visual state transitions before
// actually setting the underlying Popup.IsOpen property to false.
VisualStateGroup groupPopupClosed = VisualStates.TryGetVisualStateGroup(Parent, VisualStates.GroupPopup);
if (null != groupPopupClosed)
{
groupPopupClosed.CurrentStateChanged -= OnPopupClosedStateChanged;
UsesClosingVisualState = false;
}
}
if (Popup != null)
{
Popup.Closed -= Popup_Closed;
}
}
/// <summary>
/// Builds the visual tree for the Picker control when a new template is
/// applied.
/// </summary>
public override void OnApplyTemplate()
{
base.OnApplyTemplate();
// Unhook the event handler for the popup closed visual state group.
// This code is used to enable visual state transitions before
// actually setting the underlying Popup.IsOpen property to false.
VisualStateGroup groupPopupClosed = VisualStates.TryGetVisualStateGroup(this, VisualStates.GroupPopup);
if (null != groupPopupClosed)
{
groupPopupClosed.CurrentStateChanged -= OnPopupClosedStateChanged;
_popupClosedVisualState = false;
}
base.OnApplyTemplate();
bool dropDownOpenInitialValue = IsDropDownOpen;
// todo: having the group does not mean having the closed state, which seems to be assumed.
groupPopupClosed = VisualStates.TryGetVisualStateGroup(this, VisualStates.GroupPopup);
if (null != groupPopupClosed)
{
groupPopupClosed.CurrentStateChanged += OnPopupClosedStateChanged;
_popupClosedVisualState = true;
}
// Set the template parts. Individual part setters remove and add
// any event handlers.
DropDownToggleButton = GetTemplateChild(ElementDropDownToggleName) as ToggleButton;
DropDownPopup = GetTemplateChild(ElementPopupName) as Popup;
Interaction.OnApplyTemplateBase();
// initialization has finished, we have all the necessary references
// possibly open DropDown.
if (dropDownOpenInitialValue)
{
IsDropDownOpen = true;
}
}
/// <summary>
/// TransitionProperty property changed handler.
/// </summary>
/// <param name="d">TransitioningContentControl that changed its Transition.</param>
/// <param name="e">Event arguments.</param>
private static void OnTransitionPropertyChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
{
var source = (TransitioningContentControl)d;
var oldTransition = e.NewValue as string;
var newTransition = e.NewValue as string;
if (source.IsTransitioning)
{
source.AbortTransition();
}
// find new transition
Storyboard newStoryboard = source.GetStoryboard(newTransition);
// unable to find the transition.
if (newStoryboard == null)
{
// could be during initialization of xaml that presentationgroups was not yet defined
if (VisualStates.TryGetVisualStateGroup(source, PresentationGroup) == null)
{
// will delay check
source.CurrentTransition = null;
}
else
{
// revert to old value
source.SetValue(TransitionProperty, oldTransition);
throw new ArgumentException(
string.Format(CultureInfo.CurrentCulture,
Properties.Resources.TransitioningContentControl_TransitionNotFound, newTransition));
}
}
else
{
source.CurrentTransition = newStoryboard;
}
}
