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; }
}
}
最佳答案
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();
}
}
关于c# - Xceed WPF propertyGrid 显示扩展集合的项目,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/36286530/