WPF随笔（七）–分页控件

不管是桌面应用还是Web应用，表单、列表都是大部分应用常见的展现形式，而一个方便易用的分页控件能够很大程度上改善列表的交互体验。本篇就来说明如何用户控件实现一个简单的WPF分页控件。

页面结构

从展示层面来讲，一个分页控件一般会包括首页、尾页、上一页、下一页以及当前页码等内容，在精细一些可以加上跳转到特定页码、设置每页显示行数等功能。
本次的简单分页控件就暂时只包含首页、尾页、上页、下页的功能，页面结构如下。

    <Grid>
        <Grid.ColumnDefinitions>
            <ColumnDefinition Width="*" />
            <ColumnDefinition Width="*" />
        </Grid.ColumnDefinitions>
        <WrapPanel Grid.Column="0" VerticalAlignment="Center">
            <TextBlock>当前显示第</TextBlock>
            <TextBlock Name="txtIndex"/>
            <TextBlock>页，每页</TextBlock>
            <TextBlock Name="txtNumber">10</TextBlock>
            <TextBlock>条/共</TextBlock>
            <TextBlock Name="txtTotal">0</TextBlock>
            <TextBlock>条</TextBlock>
        </WrapPanel>
        <WrapPanel Grid.Column="1" VerticalAlignment="Center">
            <Button Name="btnFirst" Click="btnFirst_Click">首页</Button>
            <Button Name="btnPrev" Click="btnPrev_Click">上一页</Button >
            <Grid Name="grid">
                <StackPanel Orientation="Horizontal" x:Name="sp">
                    <TextBlock>1</TextBlock>
                    <TextBlock>2</TextBlock>
                    <TextBlock>3</TextBlock>
                </StackPanel>
            </Grid>
            <Button Name="btnNext" Click="btnNext_Click">下一页</Button >
            <Button Name="btnLast" Click="btnLast_Click">尾页</Button >
        </WrapPanel>
    </Grid>

代码实现

构建界面仅仅是第一步，界面与有效的代码结合起来才能实现必要的效果。代码的实现上主要包括两部分，第一部分是对数据源的操作，第二部分是首页、尾页等按钮的操作效果。

相关变量

        private DataTable _dt = new DataTable();//数据源
        private int _pageNum; //每页显示条数
        private int _pageIndex = 1;//当前页码
        public int PageIndex
        {
			get{return _pageIndex;}
			set{_pageIndex=value;}
		}
        private int _maxIndex = 1; //总页数
        private int _totalNum; //总条数
        private DataGrid _dg;//列表控件

数据操作

        #region 初始化数据

        public void ShowPages(DataGrid datagrid, DataTable datatable, int num)
        { 
   
            if (datatable != null) //&&datatable.Rows.Count>0
            { 
   
                _dt = datatable.Clone();
                _dg = datagrid;
                _pageNum = num;
                _pageIndex = 1;
                _totalNum = datatable.Rows.Count;
                if (datatable.Rows.Count % num == 0)
                { 
   
                    _maxIndex = datatable.Rows.Count / num;
                }
                else
                { 
   
                    _maxIndex = datatable.Rows.Count / num + 1;
                }
                foreach (DataRow dr in datatable.Rows)
                { 
   
                    _dt.ImportRow(dr);
                }
            }
            ReadDataTable();
        }

        #endregion

        #region 读取数据

        private void ReadDataTable()
        { 
   
            try
            { 
   
                DataTable tmpTable = _dt.Clone();
                int first = _pageNum * (_pageIndex - 1);
                first = first > 0 ? first : 0;
                if (_dt.Rows.Count >= _pageNum * _pageIndex )
                { 
   
                    for (int i = first; i < _pageNum * _pageIndex ; i++)
                    { 
   
                        tmpTable.ImportRow(_dt.Rows[i]);
                    }
                }
                else
                { 
   
                    for (int i = first; i < _dt.Rows.Count; i++)
                    { 
   
                        tmpTable.ImportRow(_dt.Rows[i]);
                    }
                }
                _dg.ItemsSource = tmpTable.DefaultView;
                tmpTable.Dispose();
            }
            catch (Exception ex)
            { 
   
                MessageBox.Show(ex.Message);
            }
            finally
            { 
   
                DisplayPagingInfo();
            }
        }

        #endregion

        #region 显示数据

        private void DisplayPagingInfo()
        { 
   
            if (_pageIndex == 1)
            { 
   
                btnFirst.IsEnabled = false;
                btnPrev.IsEnabled = false;
            }
            else
            { 
   
                btnFirst.IsEnabled = true;
                btnPrev.IsEnabled = true;
            }
            if (_pageIndex == _maxIndex)
            { 
   
                btnNext.IsEnabled = false;
                btnLast.IsEnabled = false;
            }
            else
            { 
   
                btnLast.IsEnabled = true;
                btnNext.IsEnabled = true;
            }
            txtNumber.Text = _pageNum.ToString();
            txtTotal.Text = _totalNum.ToString();
            txtIndex.Text = _pageIndex .ToString();

            int num = 9;
            if (_maxIndex < num) num = _maxIndex - 1;//如果总页数不够10
            int currint = num / 2;
            int first = (_pageIndex > currint ? _pageIndex - currint : 1);//起始
            int last = (_pageIndex + currint > _maxIndex ? _maxIndex : _pageIndex + currint);//结束

            //为避免currentpage小于5时，以及避免最后几页显示不到10项,加上下面两行
            if (last <= num) last = num + 1;
            if (last - first < num) first = last - num;
            if (_pageIndex > _maxIndex) _pageIndex = _maxIndex;
            sp.Children.Clear();
            for (int i = first; i <= last; i++)
            { 
   
                TextBlock tb = new TextBlock();
                tb.Text = i.ToString();
                tb.TextAlignment = TextAlignment.Center;
                tb.MouseLeftButtonDown += tb_MouseLeftButtonDown;
                tb.MouseLeftButtonUp += tb_MouseLeftButtonUp;
                if (i == _pageIndex )
                { 
   
                    tb.IsEnabled = false;
                }
                sp.Children.Add(tb);
            }
        }

        private void tb_MouseLeftButtonUp(object sender, MouseButtonEventArgs e)
        { 
   
            TextBlock tb = sender as TextBlock;
            if (tb == null)
            { 
   
                return;
            }
            int index = int.Parse(tb.Text);
            _pageIndex = index;
            if (index > _maxIndex)
            { 
   
                _pageIndex = _maxIndex;
            }
            if (index < 1)
            { 
   
                _pageIndex = 1;
            }
            ReadDataTable();
        }

        private void tb_MouseLeftButtonDown(object sender, MouseButtonEventArgs e)
        { 
   
            e.Handled = true;
        }

        #endregion

操作按钮

        #region 首页
        private void btnFirst_Click(object sender, EventArgs e)
        { 
   
            _pageIndex= 1;
            ReadDataTable();
        }

        #endregion

        #region 上一页
        private void btnPrev_Click(object sender, EventArgs e)
        { 
   
            if (_pageIndex<= 1)
            { 
   
                return;
            }
            _pageIndex--;
            ReadDataTable();
        }

        #endregion

        #region 下一页
        private void btnNext_Click(object sender, EventArgs e)
        { 
   
            if (_pageIndex>= _maxIndex)
            { 
   
                return;
            }
            _pageIndex++;
            ReadDataTable();
        }

        #endregion

        #region 末页

        private void btnLast_Click(object sender, EventArgs e)
        { 
   
            _pageIndex= _maxIndex;
            ReadDataTable();
        }

        #endregion

使用示例

UI界面

<UserControl x:Class="WPFDemo.DataPageDemo" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" xmlns:d="http://schemas.microsoft.com/expression/blend/2008" xmlns:local="clr-namespace:WPFDemo" mc:Ignorable="d">
    <Grid>
        <Grid.RowDefinitions>
            <RowDefinition/>
            <RowDefinition Height="50" />
        </Grid.RowDefinitions>
        <DataGrid x:Name="dataGrid" SelectionMode="Extended" SelectionUnit="FullRow" Grid.Row="0">
            <DataGrid.Columns>
                <DataGridTextColumn Header="ID" Binding="{Binding ID}" Width="*" />
                <DataGridTextColumn Header="Name" Binding="{Binding Name}" Width="*" />
            </DataGrid.Columns>
        </DataGrid>
        <local:DataPager x:Name="dataPager" Grid.Row="1"/>
    </Grid>
</UserControl>

后台代码

private void BindData()
{ 
   
	int pageCount=10;
	DataTable dt=new DataTable();
	//此处为获取数据的代码
	dataPager.ShowPages(dataGrid, dt, pageCount);
}

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