Windows Phone 7: how to determine whether the ListBox control is rolled to the end

If a large amount of data is bound to The ListBox control, loading is usually slow, there is an interactive solution to optimize this situation, that is, loading part of the data on the ListBox first, some data will be loaded when you scroll down The ListBox to the end. However, there are no related events or attributes in The ListBox control to determine when the ListBox is rolled to the end. The following describes a solution. The ListBox control encapsulates the scrollviewer control and scrollbar control. This is easy to handle. You can obtain the scrollviewer control encapsulated in the ListBox control, and then determine whether the ListBox control is rolled to the end through the attributes of the scrollviewer control. Next let's take a look. Code :

 <  Grid  X: Name  = "Contentpanel"  Grid. Row  = "1"  Margin  = "12, 0, 12, 0"  > 
  <  ListBox  Name  = "Listbox1"  Mousemove  = "Listbox#mousemove"     >  
  </  ListBox  >  
  </  Grid  > 

Using  System;
  Using  System. Collections. Generic;
  Using  System. windows;
  Using  System. Windows. controls;
  Using  System. Windows. input;
  Using  System. Windows. Media;
  Using  Microsoft. Phone. controls;

  Namespace Listboxupdate
{
  Public     Partial     Class  Mainpage: phoneapplicationpage
{
  Public  Mainpage ()
{
Initializecomponent ();

  For  (  Int  I  =     0 ; I  <     30  ; I  ++  )
{
Listbox1.items. Add (  "  Project  "  +  I );
}

}

  Private     Void  Listbox1_mousemove ( Object  Sender, mouseeventargs E)
{
  //  Obtain the subtype scrollviewer of ListBox  
  Scrollviewer  =  Findchildoftype  <  Scrollviewer  >  (Listbox1 );  //  Scrollviewer scrollbar  
   If  (Scrollviewer  =     Null  )
{
  Throw     New  Invalidoperationexception (  "  Erro  "  );
}
  Else 
{
  //  Determines whether the current rolling height is greater than or equal to the actual rolling height of scrollviewer.  
    If  (Scrollviewer. verticaloffset  > =  Scrollviewer. scrollableheight)
{
  //  Handling ListBox scrolling to the end  
    For  ( Int  I  =     0  ; I  <     10  ; I  ++  )
{
  Int  K  =  Listbox1.items. count;
Listbox1.items. Add ( "  Project  "     +  K );
K  ++  ;
}
}
}
}

  //  Obtain child types  
    Static  T findchildoftype  <  T >  (Dependencyobject root)  Where  T:  Class  
{
VaR queue  =     New  Queue  <  Dependencyobject  >  ();
Queue. enqueue (Root );

  While  (Queue. Count >     0  )
{
Dependencyobject current  =  Queue. dequeue ();
  For  (  Int  I  =  Visualtreehelper. getchildrencount (current)  -     1  ; 0     <=  I; I  --  )
{
VaR child  =  Visualtreehelper. getchild (current, I );
VaR typedchild  =  Child  As  T;
  If  (Typedchild  ! =    Null  )
{
  Return  Typedchild;
}
Queue. enqueue (child );
}
}
  Return     Null  ;
}
}
} 

Running Effect Do you have any better solutions ???     Below there is a person recommended to use an extended ListBox control lazylistbox, find the blog link: http://blogs.msdn.com/ B /ptorr/archive/2010/10/12/procrastination-ftw-lazylistbox-should-improve-your-scrolling-performance-and-responsiveness.aspx