Windows Phone 7 ListBox控件滚动分页加载数据
using System;using System.Net;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Documents;
using System.Windows.Ink;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Animation;
using System.Windows.Shapes;
using System.Windows.Controls.Primitives;
namespace SilverlightApplication1
{
public class ListBoxScrollPage
{
private static volatile ListBoxScrollPage instance;
private static object syncObj = new object();
public ListBoxScrollPage()
{
}
public static ListBoxScrollPage Instance
{
get
{
if (null == instance)
{
lock (syncObj)
{
if (null == instance)
{
instance = new ListBoxScrollPage();
}
}
}
return instance;
}
}
///
/// 使用视图树根据给定的子元素类型，从对象中查找子元素
///
///
///
///
private T FindChildOfType(DependencyObject element)
where T : class
{
if (null != element)
{
if (element is T)
return (element as T);
for (int i = 0; i < VisualTreeHelper.GetChildrenCount(element); i++)
{
DependencyObject child = VisualTreeHelper.GetChild(element, i);
T grandChild = FindChildOfType(child);
if (null != grandChild)
return grandChild;
}
}
return null;
}
///
/// 根据ScrollBar分页
///
///
///
public void PageByScroll(ListBox current, RoutedPropertyChangedEventHandler scrollBar_ValueChanged)
{
ScrollBar scrollBar = FindChildOfType(current);
if (null != scrollBar && scrollBar.Orientation != System.Windows.Controls.Orientation.Horizontal)
{
scrollBar.ValueChanged += scrollBar_ValueChanged;
}
}
//页面调用
//void MainPage_Loaded(object sender, RoutedEventArgs e)
//{
// ListBoxScrollPage.PageByScroll(ListBox, (obj, args) =>
// {
// ScrollBar scrollBar = sender as ScrollBar;
// object valueObj = scrollBar.GetValue(ScrollBar.ValueProperty);
// object maxObj = scrollBar.GetValue(ScrollBar.MinimumProperty);
// if (null != valueObj && maxObj != null)
// {
// double value = (double)valueObj;
// double max = (double)maxObj - 1.0;
// if (value >= max)
// {
#region 读取下一页的数据
#endregion
// }
// }
// });
//}
//
///
/// 根据ScrollViewer分页
///
///
///
//void lbxItem_LayoutUpdated(object sender, EventArgs e)
//{
// ScrollViewer scrollViewer = FindChildOfType(ListBox);//ScrollViewerscrollBar
// if (scrollViewer == null)
// {
// throw new InvalidOperationException("erro");
// }
// else
// { //判断当前滚动的高度是否大于或者等于scrollViewer实际可滚动高度，如果等于或者大于就证明到底了
// if (scrollViewer.VerticalOffset >= scrollViewer.ScrollableHeight)
// {
// #region 读取下一页的数据
// #endregion
// }
// }
//}
}
}
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