c# - Xceed WPF propertyGrid 显示扩展集合的项目

Question

如何显示 ObservableCollection<> Xceed WPF PropertyGrid 中的自定义对象，其中每个列表项都可以展开以显示自定义对象属性。 (即:

----属性网格-----

核心类

• (+/-) ObservableCollection< CustomClass >

  • (+/-) CustomClass.Object1

    • 属性 1:值

    • 属性 2:值(value)

    • …

    • 属性N:值(value)

  • (+/-) CustomClass.Object2

    • 属性 1:值

    • 属性 2:值(value)

    • …

    • 属性N:值(value)

如果我使用 [ExpandableObject]在 ObservableCollection<> 上它只显示 Counts 属性。

编辑:(添加代码)

主窗口.xaml:

<Window x:Class="PropGridExample.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
        xmlns:xctk="http://schemas.xceed.com/wpf/xaml/toolkit"
        xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
        xmlns:local="clr-namespace:PropGridExample"
        mc:Ignorable="d"
        Title="MainWindow" Height="350" Width="525">
    <Grid>
        <xctk:PropertyGrid x:Name="PropertyGrid" SelectedObject="{Binding BindingItem}"></xctk:PropertyGrid>
    </Grid>
</Window>

主窗口.xaml.cs

public partial class MainWindow : Window
{
    public MainWindow()
    {
        MainWindowViewModel mwvm = new MainWindowViewModel();
        this.DataContext = mwvm;
        InitializeComponent();
    }
}

MainWindowViewModel.cs

public class MainWindowViewModel
{
    public Item BindingItem { get; set; }

    public MainWindowViewModel()
    {
        BindingItem = new Item();
    }

    public class Item
    {
        public int ID { get; set; }
        [ExpandableObject()]
        public ObservableCollection<CustomClass> Classes { get; set; }

        public Item()
        {
            ID = 1;
            Classes = new ObservableCollection<CustomClass>();
            Classes.Add(new CustomClass() { Name = "CustomFoo" });
        }
    }

    public class CustomClass
    {
        public string Name { get; set; }
        [ExpandableObject()]
        public ObservableCollection<type> Types { get; set; }

        public CustomClass()
        {
            Types = new ObservableCollection<type>();
            Types.Add(new type() { name = "foo", value = "bar" });
            Types.Add(new type() { name = "bar", value = "foo" });
        }
    }

    public class type
    {
        public string name { get; set; }
        public string value { get; set; }
    }
}

Answer 1

请注意，这个想法大部分来自 CodeProject project you linked to .这篇文章向您介绍了大部分内容，但正如您所注意到的，它并未展开 WPF PropertyGrid 集合中的每个项目。为此，每个“项目”都需要有一个 ExpandableObjectAttribute。

为了让 future 的 StackOverflow 读者能够理解，我将从头开始。

从头开始

所以，从这个例子开始:

public class MainWindowViewModel
{
  /// <summary> This the object we want to be able to edit in the data grid. </summary>
  public ComplexObject BindingComplexObject { get; set; }

  public MainWindowViewModel()
  {
    BindingComplexObject = new ComplexObject();
  }
}

public class ComplexObject
{
  public int ID { get; set; }

  public ObservableCollection<ComplexSubObject> Classes { get; set; }

  public ComplexObject()
  {
    ID = 1;
    Classes = new ObservableCollection<ComplexSubObject>();
    Classes.Add(new ComplexSubObject() { Name = "CustomFoo" });
    Classes.Add(new ComplexSubObject() { Name = "My Other Foo" });
  }
}

public class ComplexSubObject
{
  public string Name { get; set; }

  public ObservableCollection<SimpleValues> Types { get; set; }

  public ComplexSubObject()
  {
    Types = new ObservableCollection<SimpleValues>();
    Types.Add(new SimpleValues() { name = "foo", value = "bar" });
    Types.Add(new SimpleValues() { name = "bar", value = "foo" });
  }
}

public class SimpleValues
{
  public string name { get; set; }
  public string value { get; set; }
}

为了让 WPF PropertyGrid 能够编辑 ObservableCollection 中的每个项目，我们需要为集合提供一个类型描述符，它将项目作为该集合的“属性”返回，以便可以编辑它们。因为我们不能静态地确定集合中的项目(因为每个集合都有不同数量的元素)，这意味着集合本身必须是 TypeDescriptor，这意味着实现 ICustomTypeDescriptor。

(注意只有 GetProperties 对我们的目的很重要，其余的只是委托(delegate)给 TypeDescriptor):

public class ExpandableObservableCollection<T> : ObservableCollection<T>,
                                                 ICustomTypeDescriptor
{
  PropertyDescriptorCollection ICustomTypeDescriptor.GetProperties()
  {
    // Create a collection object to hold property descriptors
    PropertyDescriptorCollection pds = new PropertyDescriptorCollection(null);

    for (int i = 0; i < Count; i++)
    {
      pds.Add(new ItemPropertyDescriptor<T>(this, i));
    }

    return pds;
  }

  #region Use default TypeDescriptor stuff

  AttributeCollection ICustomTypeDescriptor.GetAttributes()
  {
    return TypeDescriptor.GetAttributes(this, noCustomTypeDesc: true);
  }

  string ICustomTypeDescriptor.GetClassName()
  {
    return TypeDescriptor.GetClassName(this, noCustomTypeDesc: true);
  }

  string ICustomTypeDescriptor.GetComponentName()
  {
    return TypeDescriptor.GetComponentName(this, noCustomTypeDesc: true);
  }

  TypeConverter ICustomTypeDescriptor.GetConverter()
  {
    return TypeDescriptor.GetConverter(this, noCustomTypeDesc: true);
  }

  EventDescriptor ICustomTypeDescriptor.GetDefaultEvent()
  {
    return TypeDescriptor.GetDefaultEvent(this, noCustomTypeDesc: true);
  }

  PropertyDescriptor ICustomTypeDescriptor.GetDefaultProperty()
  {
    return TypeDescriptor.GetDefaultProperty(this, noCustomTypeDesc: true);
  }

  object ICustomTypeDescriptor.GetEditor(Type editorBaseType)
  {
    return TypeDescriptor.GetEditor(this, editorBaseType, noCustomTypeDesc: true);
  }

  EventDescriptorCollection ICustomTypeDescriptor.GetEvents()
  {
    return TypeDescriptor.GetEvents(this, noCustomTypeDesc: true);
  }

  EventDescriptorCollection ICustomTypeDescriptor.GetEvents(Attribute[] attributes)
  {
    return TypeDescriptor.GetEvents(this, attributes, noCustomTypeDesc: true);
  }

  PropertyDescriptorCollection ICustomTypeDescriptor.GetProperties(Attribute[] attributes)
  {
    return TypeDescriptor.GetProperties(this, attributes, noCustomTypeDesc: true);
  }

  object ICustomTypeDescriptor.GetPropertyOwner(PropertyDescriptor pd)
  {
    return this;
  }

  #endregion
}

此外，我们需要一个ItemPropertyDescriptor的实现，我在这里提供:

public class ItemPropertyDescriptor<T> : PropertyDescriptor
{
  private readonly ObservableCollection<T> _owner;
  private readonly int _index;

  public ItemPropertyDescriptor(ObservableCollection<T> owner, int index)
    : base("#" + index, null)
  {
    _owner = owner;
    _index = index;
  }

  public override AttributeCollection Attributes
  {
    get
    {
      var attributes = TypeDescriptor.GetAttributes(GetValue(null), false);
      if (!attributes.OfType<ExpandableObjectAttribute>().Any())
      {
        // copy all the attributes plus an extra one (the
        // ExpandableObjectAttribute)
        // this ensures that even if the type of the object itself doesn't have the
        // ExpandableObjectAttribute, it will still be expandable. 
        var newAttributes = new Attribute[attributes.Count + 1];
        attributes.CopyTo(newAttributes, newAttributes.Length - 1);
        newAttributes[newAttributes.Length - 1] = new ExpandableObjectAttribute();

        // overwrite the array
        attributes = new AttributeCollection(newAttributes);
      }

      return attributes;
    }
  }

  public override bool CanResetValue(object component)
  {
    return false;
  }

  public override object GetValue(object component)
  {
    return Value;
  }

  private T Value
    => _owner[_index];

  public override void ResetValue(object component)
  {
    throw new NotImplementedException();
  }

  public override void SetValue(object component, object value)
  {
    _owner[_index] = (T)value;
  }

  public override bool ShouldSerializeValue(object component)
  {
    return false;
  }

  public override Type ComponentType
    => _owner.GetType();

  public override bool IsReadOnly
    => false;

  public override Type PropertyType
    => Value?.GetType();
}

在大多数情况下，只需设置合理的默认值，您可以对其进行调整以满足您的需求。

需要注意的一件事是，您可以根据您的用例以不同方式实现 Attributes 属性。如果您不执行“如果不存在则将其添加到属性集合”，那么您需要将属性添加到要扩展的类/类型；如果您确实保留了该代码，那么无论类/类型是否具有属性，您都可以展开集合中的每个项目。

然后就变成了使用 ExpandableObservableCollection 代替 ObservableCollection 的问题。这种情况很糟糕，因为它意味着您的 ViewModel 中有类似 View 的东西，但是 ¯\_(ツ)_/¯。

此外，您需要将 ExpandableObjectAttribute 添加到属于 ExpandableObservableCollection 的每个属性。

代码转储

如果您在家跟随，则可以使用以下对话代码来运行该示例:

<Window x:Class="WpfDemo.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
        xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
        xmlns:local="clr-namespace:WpfDemo"
        xmlns:xctk="http://schemas.xceed.com/wpf/xaml/toolkit"
        mc:Ignorable="d"
        Title="MainWindow" Height="350" Width="525">
    <Grid>
      <xctk:PropertyGrid x:Name="It" />
    </Grid>
</Window>

-

using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
using System.Windows;

namespace WpfDemo
{
  /// <summary>
  /// Interaction logic for MainWindow.xaml
  /// </summary>
  public partial class MainWindow : Window
  {
    public MainWindow()
    {
      InitializeComponent();

      It.SelectedObject = new MainWindowViewModel().BindingComplexObject;
    }
  }
}

下面是完整的 ViewModel 实现:

using System;
using System.Collections.Generic;
using System.Collections.ObjectModel;
using System.ComponentModel;
using System.Linq;
using System.Threading.Tasks;
using Xceed.Wpf.Toolkit.PropertyGrid.Attributes;

namespace WpfDemo
{
  public class MainWindowViewModel
  {
    /// <summary> This the object we want to be able to edit in the data grid. </summary>
    public ComplexObject BindingComplexObject { get; set; }

    public MainWindowViewModel()
    {
      BindingComplexObject = new ComplexObject();
    }
  }

  [ExpandableObject]
  public class ComplexObject
  {
    public int ID { get; set; }

    [ExpandableObject]
    public ExpandableObservableCollection<ComplexSubObject> Classes { get; set; }

    public ComplexObject()
    {
      ID = 1;
      Classes = new ExpandableObservableCollection<ComplexSubObject>();
      Classes.Add(new ComplexSubObject() { Name = "CustomFoo" });
      Classes.Add(new ComplexSubObject() { Name = "My Other Foo" });
    }
  }

  [ExpandableObject]
  public class ComplexSubObject
  {
    public string Name { get; set; }

    [ExpandableObject]
    public ExpandableObservableCollection<SimpleValues> Types { get; set; }

    public ComplexSubObject()
    {
      Types = new ExpandableObservableCollection<SimpleValues>();
      Types.Add(new SimpleValues() { name = "foo", value = "bar" });
      Types.Add(new SimpleValues() { name = "bar", value = "foo" });
    }
  }

  public class SimpleValues
  {
    public string name { get; set; }
    public string value { get; set; }
  }

  public class ExpandableObservableCollection<T> : ObservableCollection<T>,
                                                   ICustomTypeDescriptor
  {
    PropertyDescriptorCollection ICustomTypeDescriptor.GetProperties()
    {
      // Create a collection object to hold property descriptors
      PropertyDescriptorCollection pds = new PropertyDescriptorCollection(null);

      for (int i = 0; i < Count; i++)
      {
        pds.Add(new ItemPropertyDescriptor<T>(this, i));
      }

      return pds;
    }

    #region Use default TypeDescriptor stuff

    AttributeCollection ICustomTypeDescriptor.GetAttributes()
    {
      return TypeDescriptor.GetAttributes(this, noCustomTypeDesc: true);
    }

    string ICustomTypeDescriptor.GetClassName()
    {
      return TypeDescriptor.GetClassName(this, noCustomTypeDesc: true);
    }

    string ICustomTypeDescriptor.GetComponentName()
    {
      return TypeDescriptor.GetComponentName(this, noCustomTypeDesc: true);
    }

    TypeConverter ICustomTypeDescriptor.GetConverter()
    {
      return TypeDescriptor.GetConverter(this, noCustomTypeDesc: true);
    }

    EventDescriptor ICustomTypeDescriptor.GetDefaultEvent()
    {
      return TypeDescriptor.GetDefaultEvent(this, noCustomTypeDesc: true);
    }

    PropertyDescriptor ICustomTypeDescriptor.GetDefaultProperty()
    {
      return TypeDescriptor.GetDefaultProperty(this, noCustomTypeDesc: true);
    }

    object ICustomTypeDescriptor.GetEditor(Type editorBaseType)
    {
      return TypeDescriptor.GetEditor(this, editorBaseType, noCustomTypeDesc: true);
    }

    EventDescriptorCollection ICustomTypeDescriptor.GetEvents()
    {
      return TypeDescriptor.GetEvents(this, noCustomTypeDesc: true);
    }

    EventDescriptorCollection ICustomTypeDescriptor.GetEvents(Attribute[] attributes)
    {
      return TypeDescriptor.GetEvents(this, attributes, noCustomTypeDesc: true);
    }

    PropertyDescriptorCollection ICustomTypeDescriptor.GetProperties(Attribute[] attributes)
    {
      return TypeDescriptor.GetProperties(this, attributes, noCustomTypeDesc: true);
    }

    object ICustomTypeDescriptor.GetPropertyOwner(PropertyDescriptor pd)
    {
      return this;
    }

    #endregion
  }

  public class ItemPropertyDescriptor<T> : PropertyDescriptor
  {
    private readonly ObservableCollection<T> _owner;
    private readonly int _index;

    public ItemPropertyDescriptor(ObservableCollection<T> owner, int index)
      : base("#" + index, null)
    {
      _owner = owner;
      _index = index;
    }

    public override AttributeCollection Attributes
    {
      get
      {
        var attributes = TypeDescriptor.GetAttributes(GetValue(null), false);


        if (!attributes.OfType<ExpandableObjectAttribute>().Any())
        {
          // copy all the attributes plus an extra one (the
          // ExpandableObjectAttribute)
          // this ensures that even if the type of the object itself doesn't have the
          // ExpandableObjectAttribute, it will still be expandable. 
          var newAttributes = new Attribute[attributes.Count + 1];
          attributes.CopyTo(newAttributes, newAttributes.Length - 1);
          newAttributes[newAttributes.Length - 1] = new ExpandableObjectAttribute();

          // overwrite the original
          attributes = new AttributeCollection(newAttributes);
        }

        return attributes;
      }
    }

    public override bool CanResetValue(object component)
    {
      return false;
    }

    public override object GetValue(object component)
    {
      return Value;
    }

    private T Value
      => _owner[_index];

    public override void ResetValue(object component)
    {
      throw new NotImplementedException();
    }

    public override void SetValue(object component, object value)
    {
      _owner[_index] = (T)value;
    }

    public override bool ShouldSerializeValue(object component)
    {
      return false;
    }

    public override Type ComponentType
      => _owner.GetType();

    public override bool IsReadOnly
      => false;

    public override Type PropertyType
      => Value?.GetType();
  }
}