性能進度條不可見

我在我的應用程序中使用性能進度條。我正在做的是在開始一些冗長的操作之前將進度條可視性設置爲可見，然後在操作完成時將其摺疊。但是在開始該操作之前它是不可見的。這裏是我的代碼性能進度條不可見

ucSearch.prograssBarCanvas.Visibility = System.Windows.Visibility.Visible; 
     var obj = wb1.InvokeScript("SearchText", ucSearch.txtSearch.Text.Trim()); 
     var result = JsonConvert.DeserializeObject<List<BookChapter>>(obj.ToString()); 
     if (result.Count == 0) 
     { 
      ucSearch.txtBlMessage.Visibility = System.Windows.Visibility.Visible; 
      ucSearch.lstBxResults.Visibility = System.Windows.Visibility.Collapsed; 
     } 
     else 
     { 
      ucSearch.txtBlMessage.Visibility = System.Windows.Visibility.Collapsed; 
      ucSearch.lstBxResults.Visibility = System.Windows.Visibility.Visible; 
     } 

     ucSearch.lstBxResults.DataContext = null; 
     ucSearch.lstBxResults.DataContext = result; 
     ucSearch.prograssBarCanvas.Visibility = System.Windows.Visibility.Collapsed;

我要問，爲什麼它是不可見的？

來源

2013-04-15 atul

標籤稱Windows Phone 7的任何機會構建Windows Phone 8的應用程序你獲得幫助？這些項目中不會顯示工具包「PerformanceProgressBar」。 –