Silverlight实现DataGrid的Select All功能
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
Xaml
1
<
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：
1
public
partial
class
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
private
void
AddColumn(
object
sender, RoutedEventArgs e)
16
{
17
_dataContext.AddUser();
18
}
19
20
private
void
DeleteColumn(
object
sender, RoutedEventArgs e)
21
{
22
_dataContext.DeleteUser();
23
}
24
25
}
26
27
public
class
SelectAllViewModel : INotifyPropertyChanged
28
{
29
public
event
PropertyChangedEventHandler PropertyChanged;
30
public
ObservableCollection
<
UserViewModel
>
Users {
get
;
set
; }
31
32
public
bool
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
return
false
;
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
public
void
AddUser()
65
{
66
Users.Add(
new
UserViewModel(UserPropertyChanged));
67
}
68
69
public
void
DeleteUser()
70
{
71
if
(Users.Count
>
0
)
72
Users.RemoveAt(
0
);
73
}
74
75
private
void
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
private
void
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
public
class
UserViewModel : INotifyPropertyChanged
93
{
94
private
static
int
i
=
0
;
95
public
event
PropertyChangedEventHandler PropertyChanged;
96
97
public
UserViewModel(PropertyChangedEventHandler eventHandler)
98
{
99
this
.PropertyChanged
+=
eventHandler;
100
}
101
102
public
string
Name
103
{
104
get
{
return
"
Name
"
+
i
++
; }
105
}
106
107
private
bool
_isSelected;
108
public
bool
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。