[英]DataGridTextColumn Visibility Binding
I'm trying to bind column visibility to that of another element like this: 我正在尝试将列可见性绑定到这样的另一个元素:
<Window x:Class="WpfApplication1.MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
Title="MainWindow" Height="350" Width="525">
<Window.Resources>
<BooleanToVisibilityConverter x:Key="BooleanToVisibilityConverter" />
</Window.Resources>
<StackPanel>
<CheckBox x:Name="chkColumnVisible" Content="Show column" />
<DataGrid x:Name="MyDataGrid" AutoGenerateColumns="False">
<DataGrid.Columns>
<DataGridTextColumn Header="Column1" Visibility="{Binding ElementName=chkColumnVisible, Path=IsChecked, Converter={StaticResource BooleanToVisibilityConverter}}"/>
</DataGrid.Columns>
</DataGrid>
</StackPanel>
but I get this error in VS output: 但我在VS输出中收到此错误:
System.Windows.Data Error: 2 : Cannot find governing FrameworkElement or FrameworkContentElement for target element. BindingExpression:Path=IsChecked; DataItem=null; target element is 'DataGridTextColumn' (HashCode=48860040); target property is 'Visibility' (type 'Visibility')
Is there a pure XAML way to accomplish this? 有没有一种纯XAML方式可以做到这一点?
The columns of a DataGrid
are abstract objects not appearing in the visual or logical tree. DataGrid
的列是未出现在可视树或逻辑树中的抽象对象。 You cannot use ElementName
and RelativeSource
. 您不能使用
ElementName
和RelativeSource
。 Source
in combination with x:Reference
should work though: 与
x:Reference
结合使用的Source
应该可以工作:
Visibility="{Binding Source={x:Reference chkColumnVisible},
Path=IsChecked,
Converter={StaticResource BooleanToVisibilityConverter}}"
I wrote a markupextension for it: 我为此写了一个markupextension:
using System;
using System.ComponentModel;
using System.Linq;
using System.Reflection;
using System.Windows;
using System.Windows.Data;
using System.Windows.Markup;
using System.Xaml;
/// <summary>
/// Binds to the datacontext of the current root object or ElementName
/// </summary>
[MarkupExtensionReturnType(typeof(object))]
public class NinjaBinding : MarkupExtension
{
private static readonly DependencyObject DependencyObject = new DependencyObject();
private static readonly string[] DoNotCopy = { "Path", "Source", "ElementName", "RelativeSource", "ValidationRules" };
private static readonly PropertyInfo[] CopyProperties = typeof(Binding).GetProperties().Where(x => !DoNotCopy.Contains(x.Name)).ToArray();
public NinjaBinding()
{
}
public NinjaBinding(Binding binding)
{
Binding = binding;
}
public Binding Binding { get; set; }
private bool IsInDesignMode
{
get { return DesignerProperties.GetIsInDesignMode(DependencyObject); }
}
public override object ProvideValue(IServiceProvider serviceProvider)
{
if (Binding == null)
{
throw new ArgumentException("Binding == null");
}
if (IsInDesignMode)
{
return DefaultValue(serviceProvider);
}
Binding binding = null;
if (Binding.ElementName != null)
{
var reference = new Reference(Binding.ElementName);
var source = reference.ProvideValue(serviceProvider);
if (source == null)
{
throw new ArgumentException("Could not resolve element");
}
binding = CreateElementNameBinding(Binding, source);
}
else if (Binding.RelativeSource !=null)
{
throw new ArgumentException("RelativeSource not supported");
}
else
{
var rootObjectProvider = (IRootObjectProvider)serviceProvider.GetService(typeof(IRootObjectProvider));
if (rootObjectProvider == null)
{
throw new ArgumentException("rootObjectProvider == null");
}
binding = CreateDataContextBinding((FrameworkElement) rootObjectProvider.RootObject, Binding);
}
var provideValue = binding.ProvideValue(serviceProvider);
return provideValue;
}
private static Binding CreateElementNameBinding(Binding original, object source)
{
var binding = new Binding()
{
Path = original.Path,
Source = source,
};
SyncProperties(original, binding);
return binding;
}
private static Binding CreateDataContextBinding(FrameworkElement rootObject, Binding original)
{
string path = string.Format("{0}.{1}", FrameworkElement.DataContextProperty.Name, original.Path.Path);
var binding = new Binding(path)
{
Source = rootObject,
};
SyncProperties(original, binding);
return binding;
}
private static void SyncProperties(Binding source, Binding target)
{
foreach (var copyProperty in CopyProperties)
{
var value = copyProperty.GetValue(source);
copyProperty.SetValue(target, value);
}
foreach (var rule in source.ValidationRules)
{
target.ValidationRules.Add(rule);
}
}
private static object DefaultValue(IServiceProvider serviceProvider)
{
var provideValueTarget = (IProvideValueTarget)serviceProvider.GetService(typeof(IProvideValueTarget));
if (provideValueTarget == null)
{
throw new ArgumentException("provideValueTarget == null");
}
var dependencyProperty = (DependencyProperty)provideValueTarget.TargetProperty;
return dependencyProperty.DefaultMetadata.DefaultValue;
}
}
It enables binding to the DataContext of the current root object {Window, UserControl, ...} 它允许绑定到当前根对象{Window,UserControl,...}的DataContext。
Sample usage (Visible & Visibility are properties of the ViewModel): 用法示例(可见性和可见性是ViewModel的属性):
<DataGrid>
<DataGrid.Columns>
<DataGridTextColumn Header="DataContext" Visibility="{dataGridBox:NinjaBinding Binding={Binding Visibility}}" />
<DataGridTextColumn Header="Converter" Visibility="{dataGridBox:NinjaBinding Binding={Binding Visible, Converter={StaticResource BooleanToVisibilityConverter}}}" />
<DataGridTextColumn Header="ElementName" Visibility="{dataGridBox:NinjaBinding Binding={Binding IsChecked, ElementName=CheckBox, Converter={StaticResource BooleanToVisibilityConverter}}}" />
</DataGrid.Columns>
</DataGrid>
The solution from Johan Larsson works perfectly, only the FallbackValue from the Binding isn't forwarded, so I've changed it like this: 约翰·拉森(Johan Larsson)的解决方案效果很好,只有Binding中的FallbackValue不会转发,因此我将其更改为:
private object DefaultValue(IServiceProvider serviceProvider)
{
if (Binding.FallbackValue != null)
return Binding.FallbackValue;
var provideValueTarget = (IProvideValueTarget)serviceProvider.GetService(typeof(IProvideValueTarget));
if (provideValueTarget == null)
{
throw new ArgumentException("provideValueTarget == null");
}
var dependencyProperty = (DependencyProperty)provideValueTarget.TargetProperty;
return dependencyProperty.DefaultMetadata.DefaultValue;
}
So it could be used like this, here for example for Binding to a Header: 因此可以像这样使用它,例如在这里绑定到标题:
<DataGridTemplateColumn Header="{dataGridBox:NinjaBinding Binding={Binding MyHeaderName1, FallbackValue=HeadingNr1}}" />
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