WWF中Conditioned Activity Group的子Activity扩展CAG的WhenCondition属性代码解析

通过三个地方实现这个功能：这样放入CAG中的Activity在设计期间能在属性窗口中看到WhenCondition属性

1 CAG添加WhenCondition属性

2 实现设计时扩展接口 IExtenderProvider 的 ConditionPropertyProviderExtender

3 ConditionedActivityGroupDesigner 关联Activity和扩展实现

关于实现IExtenderProvider 的示例可参考文章

部分代码如下：

1

[Designer(typeof(ConditionedActivityGroupDesigner), typeof(IDesigner)), ToolboxItem(typeof(ActivityToolboxItem)), SRDescription("ConstrainedGroupActivityDescription"), ToolboxBitmap(typeof(ConditionedActivityGroup), "Resources.cag.png"), ActivityValidator(typeof(ConditionedActivityGroupValidator)), SRCategory("Standard")]
public sealed class ConditionedActivityGroup : CompositeActivity, IActivityEventListener<ActivityExecutionStatusChangedEventArgs>
{
 ......
  public static readonly DependencyProperty WhenConditionProperty;
}

2

[ProvideProperty("WhenCondition", typeof(Activity)), ProvideProperty("UnlessCondition", typeof(Activity))]
internalsealedclassConditionPropertyProviderExtender : IExtenderProvider
{
    public bool CanExtend(object extendee)
   {
        if ((extendee != this) && (extendeeisActivity))
        {
            return (((Activity) extendee).ParentisConditionedActivityGroup);
         }
         returnfalse;
    }
    
   public ActivityCondition   GetWhenCondition(Activity activity)   
   {       
        if (activity.ParentisConditionedActivityGroup)       
       {          
           return (activity.GetValue(ConditionedActivityGroup.WhenConditionProperty) asActivityCondition);        
        }       
       return null;   
    }                                                                                                          
    
   public  void  SetWhenCondition(Activity activity, ActivityCondition handler) 
   {
         if (activity.ParentisConditionedActivityGroup)      
         {            
              activity.SetValue(ConditionedActivityGroup.WhenConditionProperty, handler);      
         }   
   }

 3

//ConditionedActivityGroupDesigner的Initialize方法： 
protected override void Initialize(Activity activity)
{
      base.Initialize(activity);
      IExtenderListService service1 = (IExtenderListService) base.GetService(typeof(IExtenderListService));
      if (service1 != null)
      {
            bool flag1 = false;
            IExtenderProvider[] providerArray1 = service1.GetExtenderProviders();
            for (int num1 = 0; num1 < providerArray1.Length; num1++)
            {
                  IExtenderProvider provider1 = providerArray1[num1];
                  if (provider1.GetType() == typeof(ConditionPropertyProviderExtender))
                  {
                        flag1 = true;
                  }
            }
            if (!flag1)
            {
                  IExtenderProviderService service2 = (IExtenderProviderService) base.GetService(typeof(IExtenderProviderService));
                  if (service2 != null)
                  {
                        service2.AddExtenderProvider(new ConditionPropertyProviderExtender());
                  }
            }
      }
}