最近在项目中遇到远程加载数据的问题,由于服务器采用分页方式返回数据,因此客户端也相应的制作了一个分页控件.代码相对简单,算做入门级的源码.
效果如图:
初步分析,分页功能只需要3个核心变量:PageIndex,PageSize,TotalCount,2个事件:PageChanging,PageChanged,1个方法InitData.
PageIndex:记录当前所在页
PageSize:记录每页显示的条目数
TotalCount:条目总数
由TotalCount和PageSize可以得到PageCount
PageChanging事件作为分页的预处理事件,修改事件参数PageChangingEventArgs的IsCancel属性可以取消分页,这个是参考其他分页控件的属性
PageChanged事件是分页后的处理事件,应用程序可以在此时获取PageIndex进行操作.
InitData方法在数据加载时调用(主要是TotalCount属性),用于初始化上面提到的核心变量.
WPF提供了很强大和实用的Binding功能,在开发控件时,应该尽量把属性设计成依赖属性.因此我把PageIndex,PageSize,TotalCount属性全部设计成依赖属性,并注册了部分回调方法.这样也可以很方便的实现控件和ViewModel的绑定.
核心代码如下:
/// /// DataPager.xaml 的交互逻辑 /// public partial class DataPager : UserControl, INotifyPropertyChanged { public DataPager() { InitializeComponent(); } /// /// 分页前处理的事件,如果设置e.IsCancel=True将取消分页 /// public event PageChangingRouteEventHandler PageChanging; /// /// 分页后处理的事件 /// public event PageChangedRouteEventHandler PageChanged; #region 依赖属性 /// /// 当前页 /// public int PageIndex { get { return (int)GetValue(PageIndexProperty); } set { SetValue(PageIndexProperty, value); } } // Using a DependencyProperty as the backing store for CurrentPage. This enables animation, styling, binding, etc... public static readonly DependencyProperty PageIndexProperty = DependencyProperty.Register("PageIndex", typeof(int), typeof(DataPager), new UIPropertyMetadata(1, (sender, e) => { var dp = sender as DataPager; dp.ChangeNavigationButtonState(); })); /// /// 每页显示数据大小 /// public int PageSize { get { return (int)GetValue(PageSizeProperty); } set { SetValue(PageSizeProperty, value); InitData(); } } // Using a DependencyProperty as the backing store for PageSize. This enables animation, styling, binding, etc... public static readonly DependencyProperty PageSizeProperty = DependencyProperty.Register("PageSize", typeof(int), typeof(DataPager), new UIPropertyMetadata(20, (sender, e) => { var dp = sender as DataPager; if (dp == null) return; dp.ChangeNavigationButtonState(); })); /// /// 记录数量 /// public int TotalCount { get { return (int)GetValue(TotalCountProperty); } set { SetValue(TotalCountProperty, value); } } // Using a DependencyProperty as the backing store for TotalCount. This enables animation, styling, binding, etc... public static readonly DependencyProperty TotalCountProperty = DependencyProperty.Register("TotalCount", typeof(int), typeof(DataPager), new UIPropertyMetadata(0, (sender, e) => { var dp = sender as DataPager; if (dp == null) return; dp.InitData(); dp.ChangeNavigationButtonState(); })); /// /// 总页数 /// public int PageCount { get { return (int)GetValue(PageCountProperty); } private set { SetValue(PageCountProperty, value); } } // Using a DependencyProperty as the backing store for PageCount. This enables animation, styling, binding, etc... public static readonly DependencyProperty PageCountProperty = DependencyProperty.Register("PageCount", typeof(int), typeof(DataPager), new UIPropertyMetadata(1)); /// /// 是否可以点击首页和上一页按钮 /// public bool CanGoFirstOrPrev { get { if (PageIndex <= 1) return false; return true; } } /// /// 是否可以点击最后页和下一页按钮 /// public bool CanGoLastOrNext { get { if (PageIndex >= PageCount) return false; return true; } } #endregion /// /// 点击首页按钮 /// /// /// private void btnFirst_Click(object sender, RoutedEventArgs e) { OnPageChanging(1); } /// /// 点击上一页按钮 /// /// /// private void btnPrev_Click(object sender, RoutedEventArgs e) { OnPageChanging(this.PageIndex - 1); } /// /// 点击下一页按钮 /// /// /// private void btnNext_Click(object sender, RoutedEventArgs e) { OnPageChanging(this.PageIndex + 1); } /// /// 点击末页按钮 /// /// /// private void btnLast_Click(object sender, RoutedEventArgs e) { OnPageChanging(this.PageCount); } /// /// 点击跳转按钮 /// /// /// private void btnGoTo_Click(object sender, RoutedEventArgs e) { int pageIndex = 1; try { pageIndex = Convert.ToInt32(txtPageIndex.Text); } catch { } finally { OnPageChanging(pageIndex); } } /// /// 页码更改 /// /// internal void OnPageChanging(int pageIndex) { if (pageIndex < 1) pageIndex = 1; if (pageIndex > this.PageCount) pageIndex = this.PageCount; var oldPageIndex = this.PageIndex; var newPageIndex = pageIndex; var eventArgs = new PageChangingEventArgs() { OldPageIndex = oldPageIndex, NewPageIndex = newPageIndex }; if (this.PageChanging != null) { this.PageChanging(this, eventArgs); } if (!eventArgs.IsCancel) { this.PageIndex = newPageIndex; if (this.PageChanged != null) { this.PageChanged.Invoke(this, new PageChangedEventArgs() { CurrentPageIndex = this.PageIndex }); } } } /// /// 通知导航按钮(首页,上一页,下一页,末页)状态的更改 /// void ChangeNavigationButtonState() { this.NotifyPropertyChanged("CanGoFirstOrPrev"); this.NotifyPropertyChanged("CanGoLastOrNext"); } /// /// 初始化数据 /// void InitData() { if (this.TotalCount == 0) { this.PageCount = 1; } else { this.PageCount = this.TotalCount % this.PageSize > 0 ? (this.TotalCount / this.PageSize) + 1 : this.TotalCount / this.PageSize; } if (this.PageIndex < 1) { this.PageIndex = 1; } if (this.PageIndex > this.PageCount) { this.PageIndex = this.PageCount; } if (this.PageSize < 1) { this.PageSize = 20; } } #region INotifyPropertyChanged成员 public event PropertyChangedEventHandler PropertyChanged; public void NotifyPropertyChanged(string propertyName) { if (this.PropertyChanged != null) { this.PropertyChanged.Invoke(this, new PropertyChangedEventArgs(propertyName)); } } #endregion }Xaml中使用如下:
<my:DataPager PageChanged="dataPager1_PageChanged" PageChanging="dataPager1_PageChanging" TotalCount="{Binding TotalCount}" PageSize="20" PageIndex="{Binding PageIndex}" x:Name="dataPager1" VerticalAlignment="Top" />
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