自定義控件中的故事板

Question

我在Silverlight中有一個用戶控件，我試圖將其轉換爲自定義控件。 usercontrol正在工作。 customcontrol正在工作，但它的故事板不工作。

控制是：

public class MyControl : Control 
{ 
    public MyControl() 
    { 
     DefaultStyleKey = typeof(MyControl); 
    } 

    public static readonly DependencyProperty IsStartingProperty = DependencyProperty.Register("IsStarting", typeof(bool), typeof(MyControl), new PropertyMetadata(new PropertyChangedCallback(OnIsStartingChanged))); 

    private static void OnIsStartingChanged(DependencyObject obj, DependencyPropertyChangedEventArgs e) 
    { 
     MyControl control = obj as MyControl; 
     if (control != null && control._layoutRoot != null && control._storyboard != null) 
     { 
      if ((bool)e.NewValue) 
      { 
       control._layoutRoot.Visibility = Visibility.Visible; 
       control._storyboard.Begin(); 
      } 
      else 
      { 
       control._layoutRoot.Visibility = Visibility.Collapsed; 
       control._storyboard.Stop(); 
      } 
     } 
    } 

    private Canvas _layoutRoot; 
    private Storyboard _storyboard; 

    public override void OnApplyTemplate() 
    { 
     _layoutRoot = GetTemplateChild("LayoutRoot") as Canvas; 
     _storyboard = GetTemplateChild("IndicatorStoryboard") as Storyboard; 
     base.OnApplyTemplate(); 
    } 

    public bool IsStarting 
    { 
     get { return (bool)GetValue(IsStartingProperty); } 
     set { SetValue(IsStartingProperty, value); } 
    } 
} 

在調試，control._storyboard.Begin（）沒有錯誤;但是我不能看到動畫...

是否有人有想法？如何與故事板一起工作？

預先感謝任何幫助

編輯：完整的源樣本可用：http://vpclip.virtua-peanuts.net/WindowsPhoneApplication1.zip

Answer 1

如果在按鈕點擊處理程序中將IsBusy設置爲true，您將看到動畫確實有效。問題是你在加載之前將它設置爲true，因此_layoutRoot和_storyboard爲空，並且動畫從不開始。

public class CustomBusyControl : Control 
{ 
    public CustomBusyControl() 
    { 
     DefaultStyleKey = typeof(CustomBusyControl); 
     Loaded += (s,e) => ToggleBusy(this); 
    } 

    public static readonly DependencyProperty IsBusyProperty = DependencyProperty.Register("IsBusy", typeof(bool), typeof(CustomBusyControl), new PropertyMetadata(new PropertyChangedCallback(OnIsBusyChanged))); 

    private static void OnIsBusyChanged(DependencyObject obj, DependencyPropertyChangedEventArgs e) 
    { 
     ToggleBusy(obj as CustomBusyControl); 
    } 

    private static void ToggleBusy(CustomBusyControl control) 
    { 
     if (control != null && control._layoutRoot != null && control._storyboard != null) 
     { 
      if ((bool)control.IsBusy) 
      { 
       control._layoutRoot.Visibility = Visibility.Visible; 
       control._storyboard.Begin(); 
      } 
      else 
      { 
       control._layoutRoot.Visibility = Visibility.Collapsed; 
       control._storyboard.Stop(); 
      } 
     } 
    } 

    private Canvas _layoutRoot; 
    private Storyboard _storyboard; 

    public override void OnApplyTemplate() 
    { 
     _layoutRoot = GetTemplateChild("LayoutRoot") as Canvas; 
     Debug.Assert(_layoutRoot != null, "LayoutRoot is null"); 
     _storyboard = GetTemplateChild("IndicatorStoryboard") as Storyboard; 
     base.OnApplyTemplate(); 
    } 

    public bool IsBusy 
    { 
     get { return (bool)GetValue(IsBusyProperty); } 
     set { SetValue(IsBusyProperty, value); } 
    } 
} 

Answer 2

這是把我的頭頂部，但如果移動「base.OnApplyTemplate（）會發生什麼; 「作爲OnApplyTemplate（）函數中的第一行？

public override void OnApplyTemplate() 
    { 
     base.OnApplyTemplate(); 
     _layoutRoot = GetTemplateChild("LayoutRoot") as Canvas; 
     _storyboard = GetTemplateChild("IndicatorStoryboard") as Storyboard; 
    } 

這有幫助嗎？