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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