Silverlight实现DataGrid的Select All功能 （转）

http://www.cnblogs.com/li-xiao/archive/2010/12/31/1923120.html

今天要实现一个DataGrid的Select All功能。查了一下，多是用EventHandler完成的，看起来觉得有点乱，所以自己写了一个。

 

 

代码很简单

 

<UserControl x:Class="SilverlightApp.SelectAllAndOrder.SelectAllPage"
 2     xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
 3     xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
 4     xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
 5     xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
 6     xmlns:Primitives="clr-namespace:System.Windows.Controls.Primitives;assembly=System.Windows.Controls.Data"
 7     mc:Ignorable="d"
 8     d:DesignHeight="500" d:DesignWidth="400" xmlns:sdk="http://schemas.microsoft.com/winfx/2006/xaml/presentation/sdk">
 9     
10 <UserControl.Resources>
11 <ResourceDictionary>            
12 <Style x:Key="SelectAllTemplate"  TargetType="Primitives:DataGridColumnHeader">
13 <Setter Property="ContentTemplate">
14 <Setter.Value>
15 <DataTemplate>
16 <CheckBox IsChecked="{Binding DataContext.IsSelectAll,Mode=TwoWay,ElementName=LayoutRoot}"/>
17 </DataTemplate>
18 </Setter.Value>
19 </Setter>
20 </Style>
21 <DataTemplate x:Key="CheckBoxColumn">
22 <CheckBox IsChecked="{Binding IsSelected, Mode=TwoWay}"/>
23 </DataTemplate>
24 </ResourceDictionary>        
25 </UserControl.Resources>
26     
27 <Grid x:Name="LayoutRoot" Margin="15" Background="White">
28 <Grid.RowDefinitions>
29 <RowDefinition Height="400"/>
30 <RowDefinition Height="Auto"/>
31 </Grid.RowDefinitions>
32         
33 <sdk:DataGrid ItemsSource="{Binding Users}" AutoGenerateColumns="False" IsReadOnly="True" RowHeight="25" CanUserReorderColumns="False">
34 <sdk:DataGrid.Columns>
35 <sdk:DataGridTemplateColumn Width="55" HeaderStyle="{StaticResource SelectAllTemplate}"
36                                                         CellTemplate="{StaticResource CheckBoxColumn}"></sdk:DataGridTemplateColumn>
37 <sdk:DataGridTextColumn Width="120" Header="姓名" Binding="{Binding Name}"/>                 
38 </sdk:DataGrid.Columns>
39 </sdk:DataGrid>
40         
41 <StackPanel Orientation="Horizontal" Grid.Row="1">
42 <Button Content="Add One Column" Click="AddColumn"/>
43 <Button Margin="10,0" Content="Delete One Column" Click="DeleteColumn"/>
44 </StackPanel>
45 </Grid>
46  </UserControl>
47  

 

 

本来打算在DataGridHeader的DataTemplate里直接绑定IsSelectAll了，但是Debug后发现没有DataContext。

后来又使用<sdk:DataGridTemplateColumn Header="{Binding XXX}" /> 这种方法，倒是有DataContext，但是是个Binding类型，不起作用。

最后找到了上面的方法。虽然经常用ElementName属性，但是从没这么用过。感觉很奇妙。

下面是后台代码：

 

publicpartialclass SelectAllPage : UserControl
  2 {
  3 private SelectAllViewModel _dataContext;
  4 
  5 public SelectAllPage()
  6     {
  7         InitializeComponent();
  8 
  9 this.Loaded += (s, e) =>
 10             {
 11 this.DataContext = _dataContext =new SelectAllViewModel();
 12             };
 13     }
 14 
 15 privatevoid AddColumn(object sender, RoutedEventArgs e)
 16     {
 17         _dataContext.AddUser();
 18     }
 19 
 20 privatevoid DeleteColumn(object sender, RoutedEventArgs e)
 21     {
 22         _dataContext.DeleteUser();
 23     }
 24                
 25 }
 26     
 27  publicclass SelectAllViewModel : INotifyPropertyChanged
 28 {
 29 publicevent PropertyChangedEventHandler PropertyChanged;
 30 public ObservableCollection<UserViewModel> Users { get; set; }
 31     
 32 publicbool IsSelectAll
 33     {
 34 get
 35         {
 36 int userCount = Users.Count;
 37 int selectedUserCount = Users.Count(u => u.IsSelected);
 38 if (userCount ==0) //  如果一列没有，则处于不被选中状态
 39  returnfalse;
 40 return userCount == selectedUserCount; //   当被选中的人数与总人数相等时处于选中状态
 41          }
 42 set
 43         {
 44 foreach (var mapping in Users)
 45             {
 46                 mapping.IsSelected = value;
 47             }
 48         }
 49     }
 50 
 51 public SelectAllViewModel()
 52     {
 53 //  在生成对象的时候注册PropertyChanged事件，这样当某个User被选中时就可以通知SelectAll进行状态更新
 54          Users =new ObservableCollection<UserViewModel>();
 55         Users.Add(new UserViewModel(UserPropertyChanged));
 56         Users.Add(new UserViewModel(UserPropertyChanged));
 57         Users.Add(new UserViewModel(UserPropertyChanged));
 58         Users.Add(new UserViewModel(UserPropertyChanged));
 59 
 60 //  注册CollectionChanged事件
 61          Users.CollectionChanged += UsersCollectionChanged;    
 62     }
 63 
 64 publicvoid AddUser()
 65     {
 66         Users.Add(new UserViewModel(UserPropertyChanged));
 67     }
 68 
 69 publicvoid DeleteUser()
 70     {
 71 if (Users.Count >0)
 72             Users.RemoveAt(0);
 73     }
 74 
 75 privatevoid UserPropertyChanged(object sender, PropertyChangedEventArgs e)
 76     {
 77 if (e.PropertyName =="IsSelected")
 78         {   //  如果是由于某一行前面的CheckBox被选中而触发改事件，则通知SelectAll更新时间
 79  if (this.PropertyChanged !=null)
 80                 PropertyChanged(this, new PropertyChangedEventArgs("IsSelectAll"));
 81         }
 82     }
 83 privatevoid UsersCollectionChanged(object sender, NotifyCollectionChangedEventArgs e)
 84     {
 85 //  如果表格里增加了列或减少了列，也应该通知SelectAll更新状态
 86 //  比如先全部选中，然后点击Add Column，这时新增加的列应该不被选中，因此SelectAll也应该不被选中
 87  if (this.PropertyChanged !=null)
 88             PropertyChanged(this, new PropertyChangedEventArgs("IsSelectAll"));
 89     }
 90 }
 91 
 92 publicclass UserViewModel : INotifyPropertyChanged
 93 {
 94 privatestaticint i =0;
 95 publicevent PropertyChangedEventHandler PropertyChanged;
 96 
 97 public UserViewModel(PropertyChangedEventHandler eventHandler)
 98     {
 99 this.PropertyChanged += eventHandler;
100     }
101 
102 publicstring Name
103     {
104 get { return"Name "+ i++; }
105     }
106 
107 privatebool _isSelected;
108 publicbool IsSelected
109     {
110 get { return _isSelected; }
111 set
112         {
113             _isSelected = value;
114 if (this.PropertyChanged !=null)   //  不是为了通知界面更新CheckBox状态，而是为了通知SelectAll更新状态
115                 PropertyChanged(this, new PropertyChangedEventArgs("IsSelected"));
116         }
117     }
118 }

 

 

这样就可以了。感觉Select All一般属于一种附属类的功能，如果大量使用EventHandler的话会感觉有点乱。