Silverlight 如何绑定DataGridColumn.Visibility?
我有一个类似以下帖子的问题: 我需要Silverlight DataGrid中的一列根据ViewModel中的值进行可视/折叠。为了实现这一点,我尝试将Visibility属性绑定到ViewModel。但是,我很快发现Visibility属性不是DependencyProperty,因此它无法绑定 为了解决这个问题,我尝试将自己的DataGridTextColumn子类化。通过这个新类,我创建了DependencyProperty,它最终将更改推送到DataGridTextColumn.Visibility属性。如果我不进行数据绑定的话,这很有效。当我数据绑定到我的新属性时,它失败了,出现了一个AG_E_PARSER_BAD_property_VALUE异常Silverlight 如何绑定DataGridColumn.Visibility?,silverlight,datagrid,binding,visibility,Silverlight,Datagrid,Binding,Visibility,我有一个类似以下帖子的问题: 我需要Silverlight DataGrid中的一列根据ViewModel中的值进行可视/折叠。为了实现这一点,我尝试将Visibility属性绑定到ViewModel。但是,我很快发现Visibility属性不是DependencyProperty,因此它无法绑定 为了解决这个问题,我尝试将自己的DataGridTextColumn子类化。通过这个新类,我创建了DependencyProperty,它最终将更改推送到DataGridTextColumn.Vis
public class MyDataGridTextColumn : DataGridTextColumn
{
#region public Visibility MyVisibility
public static readonly DependencyProperty MyVisibilityProperty =
DependencyProperty.Register("MyVisibility", typeof(Visibility), typeof(MyDataGridTextColumn), new PropertyMetadata(Visibility.Visible, OnMyVisibilityPropertyChanged));
private static void OnMyVisibilityPropertyChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
{
var @this = d as MyDataGridTextColumn;
if (@this != null)
{
@this.OnMyVisibilityChanged((Visibility)e.OldValue, (Visibility)e.NewValue);
}
}
private void OnMyVisibilityChanged(Visibility oldValue, Visibility newValue)
{
Visibility = newValue;
}
public Visibility MyVisibility
{
get { return (Visibility)GetValue(MyVisibilityProperty); }
set { SetValue(MyVisibilityProperty, value); }
}
#endregion public Visibility MyVisibility
}
下面是XAML的一个小片段
<DataGrid ....>
<DataGrid.Columns>
<MyDataGridTextColumn Header="User Name"
Foreground="#FFFFFFFF"
Binding="{Binding User.UserName}"
MinWidth="150"
CanUserSort="True"
CanUserResize="False"
CanUserReorder="True"
MyVisibility="{Binding Converter={StaticResource BoolToVisibilityConverter}, Path=ShouldShowUser}"/>
<DataGridTextColumn .../>
</DataGrid.Columns>
</DataGrid>
一些重要事实。
- 转换器确实是在上面的本地资源中定义的
- 转换器是正确的,它被用于解决方案中的许多其他地方
- 如果我将MyVisibility属性的{Binding}语法替换为“Collapsed”,那么该列实际上会消失
- 如果我创建一个新的DependencyProperty(即字符串Foo),并绑定到它,我也会收到AG_e_PARSER_BAD_PROPERTY_VALUE异常
有人知道这为什么不起作用吗?datagrid列继承自DependencyObject,而不是FrameworkElement。在WPF中,这没什么大不了的。。。但在silverlight中,只能绑定到FrameworkElement对象。因此,当您尝试时,会收到AG_E_PARSER_BAD_PROPERTY_VALUE的描述性错误消息。从MyDataGridTextColumn类中,您可以获得周围的DataGrid。 然后将ViewModel从DataGrid的DataContext中取出,并向ViewModel的PropertyChanged事件添加一个处理程序。在处理程序中,您只需检查属性名及其值,并相应地更改列的可见性。 这不是最好的解决方案,但它应该会起作用;) 克里斯·曼奇尼 您不会创建绑定到数据网格列的“binding”属性。好吧,您可以编写“{Binding User.UserName}”,但它不会创建绑定,因为(正如zachary所说)datagrid列不会从FrameworkElement继承,也没有SetBinding方法。 所以表达式“{Binding User.UserName}”只是创建绑定对象并将其分配给列的Binding属性(该属性是绑定类型)。
然后datagrid column在生成单元格内容时(GenerateElement-protected方法)使用此绑定对象在生成的元素(例如,在生成的TextBlock的Text属性上)上设置绑定,这些元素是框架元素我不知道这会有多大帮助,但我自己在最新的项目中遇到了数据网格列缺少依赖属性的问题。我所做的是在网格列视图模型中创建一个事件,然后在客户机中组装网格时,使用闭包将网格列订阅到列视图模型。我的特别问题是宽度。它从轴网柱的视图模型类开始,类似于以下伪代码:
public delegate void ColumnResizedEvent(double width);
public class GridColumnViewModel : ViewModelBase
{
public event ColumnResizedEvent ColumnResized;
public void Resize(double newContainerWidth)
{
// some crazy custom sizing calculations -- don't ask...
ResizeColumn(newWidth);
}
public void ResizeColumn(double width)
{
var handler = ColumnResized;
if (handler != null)
handler(width);
}
}
然后是组装网格的代码:
public class CustomGrid
{
public CustomGrid(GridViewModel viewModel)
{
// some stuff that parses control metadata out of the view model.
// viewModel.Columns is a collection of GridColumnViewModels from above.
foreach(var column in viewModel.Columns)
{
var gridCol = new DataGridTextColumn( ... );
column.ColumnResized += delegate(double width) { gridCol.Width = new DataGridLength(width); };
}
}
}
在应用程序中调整datagrid的大小时,将拾取resize事件,并在网格绑定到的viewmodel上调用resize方法。这将依次调用每个轴网柱视图模型的resize方法。然后,网格列视图模型引发ColumnResized
事件,数据网格文本列订阅该事件,并更新其宽度
我意识到这并不能直接解决您的问题,但这是一种在没有依赖属性的情况下将视图模型“绑定”到数据网格列的方法。闭包是一个简单的构造,它很好地封装了我想要的行为,我身后的人也很容易理解它。我认为不难想象它如何被修改以适应能见度的变化。您甚至可以在页面/用户控件的加载事件中连接事件处理程序。以下是我使用一些技巧提出的解决方案 首先,您需要从DataGrid继承
public class DataGridEx : DataGrid
{
public IEnumerable<string> HiddenColumns
{
get { return (IEnumerable<string>)GetValue(HiddenColumnsProperty); }
set { SetValue(HiddenColumnsProperty, value); }
}
public static readonly DependencyProperty HiddenColumnsProperty =
DependencyProperty.Register ("HiddenColumns",
typeof (IEnumerable<string>),
typeof (DataGridEx),
new PropertyMetadata (HiddenColumnsChanged));
private static void HiddenColumnsChanged(object sender,
DependencyPropertyChangedEventArgs args)
{
var dg = sender as DataGrid;
if (dg==null || args.NewValue == args.OldValue)
return;
var hiddenColumns = (IEnumerable<string>)args.NewValue;
foreach (var column in dg.Columns)
{
if (hiddenColumns.Contains ((string)column.GetValue (NameProperty)))
column.Visibility = Visibility.Collapsed;
else
column.Visibility = Visibility.Visible;
}
}
}
公共类DataGridEx:DataGrid
{
公共IEnumerable隐藏列
{
get{return(IEnumerable)GetValue(HiddenColumnsProperty);}
set{SetValue(HiddenColumnsProperty,value);}
}
公共静态只读从属属性HiddenColumnsProperty=
DependencyProperty.Register(“HiddenColumns”,
类型(IEnumerable),
类型(DataGridEx),
新的不动产数据(HiddenColumnsChanged));
私有静态无效HiddenColumnsChanged(对象发送方,
DependencyPropertyChangedEventArgs(参数)
{
var dg=发送方作为数据网格;
if(dg==null | | args.NewValue==args.OldValue)
返回;
var hiddenColumns=(IEnumerable)args.NewValue;
foreach(dg.列中的var列)
{
if(hiddenColumns.Contains((string)column.GetValue(NameProperty)))
column.Visibility=Visibility.collection;
其他的
column.Visibility=可见性.Visibility;
}
}
}
DataGridEx类根据DataGridColumn及其子体的x:Name添加了一个新的DP来隐藏列
要在XAML中使用:
<my:DataGridEx x:Name="uiData"
DataContext="{Binding SomeDataContextFromTheVM}"
ItemsSource="{Binding Whatever}"
HiddenColumns="{Binding HiddenColumns}">
<sdk:DataGridTextColumn x:Name="uiDataCountOfItems">
Header="Count"
Binding={Binding CountOfItems}"
</sdk:DataGridTextColumn>
</my:DataGridEx>
Header=“计数”
Binding={Binding CountOfItems}”
您需要将它们添加到ViewModel或您使用的任何数据上下文中
private IEnumerable<string> _hiddenColumns;
public IEnumerable<string> HiddenColumns
{
get { return _hiddenColumns; }
private set
{
if (value == _hiddenColumns)
return;
_hiddenColumns = value;
PropertyChanged (this, new PropertyChangedEventArgs("HiddenColumns"));
}
}
public void SomeWhereInYourCode ()
{
HiddenColumns = new List<string> {"uiDataCountOfItems"};
}
私有IEnumerable\u隐藏列;
公共IEnumerable隐藏列
{
获取{return\u hiddenColumns;}
专用设备
{
如果(值==\u h
using System;
using System.ComponentModel;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Data;
namespace XYZ.Controls
{
public class ExtendedDataGridTextColumn : DataGridTextColumn
{
private readonly Notifier _e;
private Binding _visibilityBinding;
public Binding VisibilityBinding
{
get { return _visibilityBinding; }
set
{
_visibilityBinding = value;
_e.SetBinding(Notifier.MyVisibilityProperty, _visibilityBinding);
}
}
public ExtendedDataGridTextColumn()
{
_e = new Notifier();
_e.PropertyChanged += ToggleVisibility;
}
private void ToggleVisibility(object sender, PropertyChangedEventArgs e)
{
if (e.PropertyName == "Visibility")
this.Visibility = _e.MyVisibility;
}
//Notifier class is just used to pass the property changed event back to the column container Dependency Object, leaving it as a private inner class for now
private class Notifier : FrameworkElement, INotifyPropertyChanged
{
public event PropertyChangedEventHandler PropertyChanged;
public Visibility MyVisibility
{
get { return (Visibility)GetValue(MyVisibilityProperty); }
private set { SetValue(MyVisibilityProperty, value); }
}
public static readonly DependencyProperty MyVisibilityProperty = DependencyProperty.Register("MyVisibility", typeof(Visibility), typeof(Notifier), new PropertyMetadata(MyVisibilityChanged));
private static void MyVisibilityChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
{
var n = d as Notifier;
if (n != null)
{
n.MyVisibility = (Visibility) e.NewValue;
n.PropertyChanged(n, new PropertyChangedEventArgs("Visibility"));
}
}
}
}
var n = d as Notifier;
if (n != null)
{
//Assign value in the callback will break the binding.
//n.MyVisibility = (Visibility)e.NewValue;
n.PropertyChanged(n, new PropertyChangedEventArgs("Visibility"));
}
public class ExtendedDataGridColumn : DataGridTemplateColumn
{
public static readonly DependencyProperty VisibilityProperty = DependencyProperty.Register("Visibility", typeof(Visibility), typeof(DataGridTemplateColumn), new PropertyMetadata(Visibility.Visible, VisibilityChanged));
public new Visibility Visibility
{
get { return (Visibility)GetValue(VisibilityProperty); }
set { SetValue(VisibilityProperty, value); }
}
private static void VisibilityChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
{
if ((DataGridTemplateColumn)d != null)
{
((DataGridTemplateColumn)d).Visibility = (Visibility)e.NewValue;
}
}
}