将ComboBoxes绑定到枚举...在Silverlight中！

4 回答

• 0

  还有另一种方法可以将ComboBox绑定到枚举，而无需为所选项目定制转换器 . 你可以查看

  http://charlass.wordpress.com/2009/07/29/binding-enums-to-a-combobbox-in-silverlight/

  它不使用DescriptionAttributes ....但它对我来说很完美，所以我想这取决于它将被使用的场景

  回复于 2024-04-26T01:49:16+08:00
• 34

  唉，我说得太快了！至少在Silverlight 3中有a perfectly good solution . （它可能只有3，因为this thread表示在Silverlight 3中修复了与此相关的错误 . ）

  基本上，您需要为 ItemsSource 属性使用单个转换器，但它可以完全通用而不使用任何禁止的方法，只要您传递类型为 MyEnum 的属性的名称即可 . 数据绑定到 SelectedItem 完全没有痛苦;不需要转换器！好吧，至少只要您不想通过例如每个枚举值自定义字符串 . DescriptionAttribute ，嗯...可能还需要另一个转换器;希望我能把它变得通用 .

  Update: 我做了一个转换器，它的工作原理！遗憾的是，我现在必须绑定到 SelectedIndex ，但没关系 . 使用这些家伙：

  using System;
  using System.Collections.Generic;
  using System.ComponentModel;
  using System.Linq;
  using System.Windows.Data;
  
  namespace DomenicDenicola.Wpf
  {
      public class EnumToIntConverter : IValueConverter
      {
          public object Convert(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
          {
              // Note: as pointed out by Martin in the comments on this answer, this line
              // depends on the enum values being sequentially ordered from 0 onward,
              // since combobox indices are done that way. A more general solution would
              // probably look up where in the GetValues array our value variable
              // appears, then return that index.
              return (int)value;
          }
  
          public object ConvertBack(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
          {
              return Enum.Parse(targetType, value.ToString(), true);
          }
      }
      public class EnumToIEnumerableConverter : IValueConverter
      {
          private Dictionary<Type, List<object>> cache = new Dictionary<Type, List<object>>();
  
          public object Convert(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
          {
              var type = value.GetType();
              if (!this.cache.ContainsKey(type))
              {
                  var fields = type.GetFields().Where(field => field.IsLiteral);
                  var values = new List<object>();
                  foreach (var field in fields)
                  {
                      DescriptionAttribute[] a = (DescriptionAttribute[])field.GetCustomAttributes(typeof(DescriptionAttribute), false);
                      if (a != null && a.Length > 0)
                      {
                          values.Add(a[0].Description);
                      }
                      else
                      {
                          values.Add(field.GetValue(value));
                      }
                  }
                  this.cache[type] = values;
              }
  
              return this.cache[type];
          }
  
          public object ConvertBack(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
          {
              throw new NotImplementedException();
          }
      }
  }
  

  有了这种绑定XAML：

  <ComboBox x:Name="MonsterGroupRole"
            ItemsSource="{Binding MonsterGroupRole,
                                  Mode=OneTime,
                                  Converter={StaticResource EnumToIEnumerableConverter}}"
            SelectedIndex="{Binding MonsterGroupRole,
                                    Mode=TwoWay,
                                    Converter={StaticResource EnumToIntConverter}}" />
  

  这种资源声明XAML：

  <Application xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
               xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
               xmlns:ddwpf="clr-namespace:DomenicDenicola.Wpf">
      <Application.Resources>
          <ddwpf:EnumToIEnumerableConverter x:Key="EnumToIEnumerableConverter" />
          <ddwpf:EnumToIntConverter x:Key="EnumToIntConverter" />
      </Application.Resources>
  </Application>
  

  任何评论将不胜感激，因为我有点像XAML / Silverlight / WPF /等 . 新手 . 例如， EnumToIntConverter.ConvertBack 会慢，所以我应该考虑使用缓存吗？

  回复于 2024-04-26T01:49:16+08:00
• 4

  我发现枚举数据的简单封装更容易使用 .

  public ReadOnly property MonsterGroupRole as list(of string)
    get
      return [Enum].GetNames(GetType(GroupRoleEnum)).Tolist
    End get
  End Property
  
  private _monsterEnum as GroupRoleEnum
  Public Property MonsterGroupRoleValue as Integer
    get
      return _monsterEnum
    End get
    set(value as integer)
      _monsterEnum=value
    End set
  End Property
  

  ...

  <ComboBox x:Name="MonsterGroupRole"
        ItemsSource="{Binding MonsterGroupRole,
                              Mode=OneTime}"
        SelectedIndex="{Binding MonsterGroupRoleValue ,
                                Mode=TwoWay}" />
  

  这将完全取消转换器的需要...... :)

  回复于 2024-04-26T01:49:16+08:00
• 4

  以下是Windows 8.1 / Windows Phone通用应用程序的相同设置，主要更改如下： -

  • 框架中缺少DescriptionAttribute（或者至少我找不到它）

  • 反射如何工作的差异（使用TypeInfo.Declared字段）

  似乎XAML的顺序也很重要，我不得不将ItemsSource放在SelectedIndex之前，否则它不会调用ItemsSource绑定，例如

  <ComboBox
  ItemsSource="{Binding Path=MyProperty,Mode=OneWay, Converter={StaticResource EnumToIEnumerableConverter}}"
  SelectedIndex="{Binding Path=MyProperty, Mode=TwoWay, Converter={StaticResource EnumToIntConverter}}" 
  />
  

  代码如下

  namespace MyApp.Converters
  {
      using System;
      using System.Collections.Generic;
      using System.Linq;
      using System.Reflection;
      using Windows.UI.Xaml.Data;
      public class EnumToIntConverter : IValueConverter
      {
          public object Convert(object value, Type targetType, object parameter, string language)
          {
              // Note: as pointed out by Martin in the comments on this answer, this line
              // depends on the enum values being sequentially ordered from 0 onward,
              // since combobox indices are done that way. A more general solution would
              // probably look up where in the GetValues array our value variable
              // appears, then return that index.
              return (int) value;
          }
  
          public object ConvertBack(object value, Type targetType, object parameter, string language)
          {
              return value;
          }
      }
  
      public class EnumToIEnumerableConverter : IValueConverter
      {
          private readonly Dictionary<TypeInfo, List<object>> _cache = new Dictionary<TypeInfo, List<object>>();
  
          public object Convert(object value, Type targetType, object parameter, string language)
          {
              var type = value.GetType().GetTypeInfo();
              if (!_cache.ContainsKey(type))
              {
                  var fields = type.DeclaredFields.Where(field => field.IsLiteral);
                  var values = new List<object>();
                  foreach (var field in fields)
                  {
                      var a = (DescriptionAttribute[]) field.GetCustomAttributes(typeof(DescriptionAttribute), false);
                      if (a != null && a.Length > 0)
                      {
                          values.Add(a[0].Description);
                      }
                      else
                      {
                          values.Add(field.GetValue(value));
                      }
                  }
                  _cache[type] = values;
              }
              return _cache[type];
          }
  
          public object ConvertBack(object value, Type targetType, object parameter, string language)
          {
              throw new NotImplementedException();
          }
      }
      [AttributeUsage(AttributeTargets.Field)]
      public class DescriptionAttribute : Attribute
      {
          public string Description { get; private set; }
  
          public DescriptionAttribute(string description)
          {
              Description = description;
          }
      }
  }
  

  回复于 2024-04-26T01:49:16+08:00