以下面的代码为例:
public enum ExampleEnum { FooBar, BarFoo }
public class ExampleClass : INotifyPropertyChanged
{
private ExampleEnum example;
public ExampleEnum ExampleProperty
{ get { return example; } { /* set and notify */; } }
}
我想把属性ExampleProperty绑定到一个组合框，这样它就显示了选项“FooBar”和“BarFoo”，并在模式双向工作。最理想的情况下，我希望我的ComboBox定义看起来像这样:
<ComboBox ItemsSource="What goes here?" SelectedItem="{Binding Path=ExampleProperty}" />
目前我有处理程序的组合框。SelectionChanged和ExampleClass。在我手动绑定的窗口中安装了PropertyChanged事件。
有没有更好的或者某种权威的方法?你通常会使用转换器，你将如何填充组合框与正确的值?我现在甚至不想从i18n开始。
Edit
因此，一个问题得到了回答:我如何用正确的值填充组合框。
通过ObjectDataProvider从静态Enum中检索Enum值作为字符串列表。getvalue方法:
<Window.Resources>
<ObjectDataProvider MethodName="GetValues"
ObjectType="{x:Type sys:Enum}"
x:Key="ExampleEnumValues">
<ObjectDataProvider.MethodParameters>
<x:Type TypeName="ExampleEnum" />
</ObjectDataProvider.MethodParameters>
</ObjectDataProvider>
</Window.Resources>
这可以作为我的组合框的ItemsSource:
<ComboBox ItemsSource="{Binding Source={StaticResource ExampleEnumValues}}"/>
Code
public enum RULE
{
[Description( "Любые, без ограничений" )]
any,
[Description( "Любые если будет три в ряд" )]
anyThree,
[Description( "Соседние, без ограничений" )]
nearAny,
[Description( "Соседние если будет три в ряд" )]
nearThree
}
class ExtendRULE
{
public static object Values
{
get
{
List<object> list = new List<object>();
foreach( RULE rule in Enum.GetValues( typeof( RULE ) ) )
{
string desc = rule.GetType().GetMember( rule.ToString() )[0].GetCustomAttribute<DescriptionAttribute>().Description;
list.Add( new { value = rule, desc = desc } );
}
return list;
}
}
}
XAML
<StackPanel>
<ListBox ItemsSource= "{Binding Source={x:Static model:ExtendRULE.Values}}" DisplayMemberPath="desc" SelectedValuePath="value" SelectedValue="{Binding SelectedRule}"/>
<ComboBox ItemsSource="{Binding Source={x:Static model:ExtendRULE.Values}}" DisplayMemberPath="desc" SelectedValuePath="value" SelectedValue="{Binding SelectedRule}"/>
</StackPanel>
基于ageektrapped提供的已被接受但现已删除的答案，我创建了一个精简版，没有一些更高级的功能。这里包含的所有代码都允许您复制粘贴它，而不会被链接失效阻塞。
我使用System.ComponentModel.DescriptionAttribute，它实际上用于设计时描述。如果你不喜欢使用这个属性，你可以创建自己的属性，但我认为使用这个属性真的可以完成工作。如果不使用该属性，则名称将默认为代码中枚举值的名称。
public enum ExampleEnum {
[Description("Foo Bar")]
FooBar,
[Description("Bar Foo")]
BarFoo
}
下面是用作项目源的类:
public class EnumItemsSource : Collection<String>, IValueConverter {
Type type;
IDictionary<Object, Object> valueToNameMap;
IDictionary<Object, Object> nameToValueMap;
public Type Type {
get { return this.type; }
set {
if (!value.IsEnum)
throw new ArgumentException("Type is not an enum.", "value");
this.type = value;
Initialize();
}
}
public Object Convert(Object value, Type targetType, Object parameter, CultureInfo culture) {
return this.valueToNameMap[value];
}
public Object ConvertBack(Object value, Type targetType, Object parameter, CultureInfo culture) {
return this.nameToValueMap[value];
}
void Initialize() {
this.valueToNameMap = this.type
.GetFields(BindingFlags.Static | BindingFlags.Public)
.ToDictionary(fi => fi.GetValue(null), GetDescription);
this.nameToValueMap = this.valueToNameMap
.ToDictionary(kvp => kvp.Value, kvp => kvp.Key);
Clear();
foreach (String name in this.nameToValueMap.Keys)
Add(name);
}
static Object GetDescription(FieldInfo fieldInfo) {
var descriptionAttribute =
(DescriptionAttribute) Attribute.GetCustomAttribute(fieldInfo, typeof(DescriptionAttribute));
return descriptionAttribute != null ? descriptionAttribute.Description : fieldInfo.Name;
}
}
你可以像这样在XAML中使用它:
<Windows.Resources>
<local:EnumItemsSource
x:Key="ExampleEnumItemsSource"
Type="{x:Type local:ExampleEnum}"/>
</Windows.Resources>
<ComboBox
ItemsSource="{StaticResource ExampleEnumItemsSource}"
SelectedValue="{Binding ExampleProperty, Converter={StaticResource ExampleEnumItemsSource}}"/>
Code
public enum RULE
{
[Description( "Любые, без ограничений" )]
any,
[Description( "Любые если будет три в ряд" )]
anyThree,
[Description( "Соседние, без ограничений" )]
nearAny,
[Description( "Соседние если будет три в ряд" )]
nearThree
}
class ExtendRULE
{
public static object Values
{
get
{
List<object> list = new List<object>();
foreach( RULE rule in Enum.GetValues( typeof( RULE ) ) )
{
string desc = rule.GetType().GetMember( rule.ToString() )[0].GetCustomAttribute<DescriptionAttribute>().Description;
list.Add( new { value = rule, desc = desc } );
}
return list;
}
}
}
XAML
<StackPanel>
<ListBox ItemsSource= "{Binding Source={x:Static model:ExtendRULE.Values}}" DisplayMemberPath="desc" SelectedValuePath="value" SelectedValue="{Binding SelectedRule}"/>
<ComboBox ItemsSource="{Binding Source={x:Static model:ExtendRULE.Values}}" DisplayMemberPath="desc" SelectedValuePath="value" SelectedValue="{Binding SelectedRule}"/>
</StackPanel>
这是DevExpress基于Gregor S.投票最多的答案给出的具体答案(目前有128票)。
这意味着我们可以在整个应用程序中保持样式一致:
不幸的是，如果没有一些修改，最初的答案不能与DevExpress的ComboBoxEdit一起工作。
首先，ComboBoxEdit的XAML:
<dxe:ComboBoxEdit ItemsSource="{Binding Source={xamlExtensions:XamlExtensionEnumDropdown {x:myEnum:EnumFilter}}}"
SelectedItem="{Binding BrokerOrderBookingFilterSelected, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}"
DisplayMember="Description"
MinWidth="144" Margin="5"
HorizontalAlignment="Left"
IsTextEditable="False"
ValidateOnTextInput="False"
AutoComplete="False"
IncrementalFiltering="True"
FilterCondition="Like"
ImmediatePopup="True"/>
不用说，你需要将xamlExtensions指向包含XAML扩展类的命名空间(下面定义):
xmlns:xamlExtensions="clr-namespace:XamlExtensions"
我们必须将myEnum指向包含枚举的命名空间:
xmlns:myEnum="clr-namespace:MyNamespace"
然后，枚举:
namespace MyNamespace
{
public enum EnumFilter
{
[Description("Free as a bird")]
Free = 0,
[Description("I'm Somewhat Busy")]
SomewhatBusy = 1,
[Description("I'm Really Busy")]
ReallyBusy = 2
}
}
XAML中的问题是我们不能使用SelectedItemValue，因为这会抛出一个错误，因为setter是不可访问的(DevExpress，这是您的一部分疏忽)。所以我们必须修改我们的ViewModel来直接从对象中获取值:
private EnumFilter _filterSelected = EnumFilter.All;
public object FilterSelected
{
get
{
return (EnumFilter)_filterSelected;
}
set
{
var x = (XamlExtensionEnumDropdown.EnumerationMember)value;
if (x != null)
{
_filterSelected = (EnumFilter)x.Value;
}
OnPropertyChanged("FilterSelected");
}
}
为了完整起见，这里是原始答案(稍微重命名)的XAML扩展:
namespace XamlExtensions
{
/// <summary>
/// Intent: XAML markup extension to add support for enums into any dropdown box, see http://bit.ly/1g70oJy. We can name the items in the
/// dropdown box by using the [Description] attribute on the enum values.
/// </summary>
public class XamlExtensionEnumDropdown : MarkupExtension
{
private Type _enumType;
public XamlExtensionEnumDropdown(Type enumType)
{
if (enumType == null)
{
throw new ArgumentNullException("enumType");
}
EnumType = enumType;
}
public Type EnumType
{
get { return _enumType; }
private set
{
if (_enumType == value)
{
return;
}
var enumType = Nullable.GetUnderlyingType(value) ?? value;
if (enumType.IsEnum == false)
{
throw new ArgumentException("Type must be an Enum.");
}
_enumType = value;
}
}
public override object ProvideValue(IServiceProvider serviceProvider)
{
var enumValues = Enum.GetValues(EnumType);
return (
from object enumValue in enumValues
select new EnumerationMember
{
Value = enumValue,
Description = GetDescription(enumValue)
}).ToArray();
}
private string GetDescription(object enumValue)
{
var descriptionAttribute = EnumType
.GetField(enumValue.ToString())
.GetCustomAttributes(typeof (DescriptionAttribute), false)
.FirstOrDefault() as DescriptionAttribute;
return descriptionAttribute != null
? descriptionAttribute.Description
: enumValue.ToString();
}
#region Nested type: EnumerationMember
public class EnumerationMember
{
public string Description { get; set; }
public object Value { get; set; }
}
#endregion
}
}
免责声明:我与DevExpress没有任何关系。Telerik也是一个很棒的图书馆。
