You can do it from code by placing the following code in Window Loaded
event handler, for example:
yourComboBox.ItemsSource = Enum.GetValues(typeof(EffectStyle)).Cast<EffectStyle>();
If you need to bind it in XAML you need to use ObjectDataProvider
to create object available as binding source:
<Window x:Class="YourNamespace.MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:System="clr-namespace:System;assembly=mscorlib"
xmlns:StyleAlias="clr-namespace:Motion.VideoEffects">
<Window.Resources>
<ObjectDataProvider x:Key="dataFromEnum" MethodName="GetValues"
ObjectType="{x:Type System:Enum}">
<ObjectDataProvider.MethodParameters>
<x:Type TypeName="StyleAlias:EffectStyle"/>
</ObjectDataProvider.MethodParameters>
</ObjectDataProvider>
</Window.Resources>
<Grid>
<ComboBox ItemsSource="{Binding Source={StaticResource dataFromEnum}}"
SelectedItem="{Binding Path=CurrentEffectStyle}" />
</Grid>
</Window>
Draw attention on the next code:
xmlns:System="clr-namespace:System;assembly=mscorlib"
xmlns:StyleAlias="clr-namespace:Motion.VideoEffects"
Guide how to map namespace and assembly you can read on MSDN.
I like for all objects that I'm binding to be defined in my ViewModel
, so I try to avoid using <ObjectDataProvider>
in the xaml when possible.
My solution uses no data defined in the View and no code-behind. Only a DataBinding, a reusable ValueConverter, a method to get a collection of descriptions for any Enum type, and a single property in the ViewModel to bind to.
When I want to bind an Enum
to a ComboBox
the text I want to display never matches the values of the Enum
, so I use the [Description()]
attribute to give it the text that I actually want to see in the ComboBox
. If I had an enum of days of the week, it would look something like this:
public enum DayOfWeek
{
// add an optional blank value for default/no selection
[Description("")]
NOT_SET = 0,
[Description("Sunday")]
SUNDAY,
[Description("Monday")]
MONDAY,
...
}
First I created helper class with a couple methods to deal with enums. One method gets a description for a specific value, the other method gets all values and their descriptions for a type.
public static class EnumHelper
{
public static string Description(this Enum value)
{
var attributes = value.GetType().GetField(value.ToString()).GetCustomAttributes(typeof(DescriptionAttribute), false);
if (attributes.Any())
return (attributes.First() as DescriptionAttribute).Description;
// If no description is found, the least we can do is replace underscores with spaces
// You can add your own custom default formatting logic here
TextInfo ti = CultureInfo.CurrentCulture.TextInfo;
return ti.ToTitleCase(ti.ToLower(value.ToString().Replace("_", " ")));
}
public static IEnumerable<ValueDescription> GetAllValuesAndDescriptions(Type t)
{
if (!t.IsEnum)
throw new ArgumentException($"{nameof(t)} must be an enum type");
return Enum.GetValues(t).Cast<Enum>().Select((e) => new ValueDescription() { Value = e, Description = e.Description() }).ToList();
}
}
Next, we create a ValueConverter
. Inheriting from MarkupExtension
makes it easier to use in XAML so we don't have to declare it as a resource.
[ValueConversion(typeof(Enum), typeof(IEnumerable<ValueDescription>))]
public class EnumToCollectionConverter : MarkupExtension, IValueConverter
{
public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
{
return EnumHelper.GetAllValuesAndDescriptions(value.GetType());
}
public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
{
return null;
}
public override object ProvideValue(IServiceProvider serviceProvider)
{
return this;
}
}
My ViewModel
only needs 1 property that my View
can bind to for both the SelectedValue
and ItemsSource
of the combobox:
private DayOfWeek dayOfWeek;
public DayOfWeek SelectedDay
{
get { return dayOfWeek; }
set
{
if (dayOfWeek != value)
{
dayOfWeek = value;
OnPropertyChanged(nameof(SelectedDay));
}
}
}
And finally to bind the ComboBox
view (using the ValueConverter
in the ItemsSource
binding)...
<ComboBox ItemsSource="{Binding Path=SelectedDay, Converter={x:EnumToCollectionConverter}, Mode=OneTime}"
SelectedValuePath="Value"
DisplayMemberPath="Description"
SelectedValue="{Binding Path=SelectedDay}" />
To implement this solution you only need to copy my EnumHelper
class and EnumToCollectionConverter
class. They will work with any enums. Also, I didn't include it here, but the ValueDescription
class is just a simple class with 2 public object properties, one called Value
, one called Description
. You can create that yourself or you can change the code to use a Tuple<object, object>
or KeyValuePair<object, object>
I used another solution using MarkupExtension.
I made class which provides items source:
public class EnumToItemsSource : MarkupExtension
{
private readonly Type _type;
public EnumToItemsSource(Type type)
{
_type = type;
}
public override object ProvideValue(IServiceProvider serviceProvider)
{
return Enum.GetValues(_type)
.Cast<object>()
.Select(e => new { Value = (int)e, DisplayName = e.ToString() });
}
}
That's almost all... Now use it in XAML:
<ComboBox DisplayMemberPath="DisplayName"
ItemsSource="{persons:EnumToItemsSource {x:Type enums:States}}"
SelectedValue="{Binding Path=WhereEverYouWant}"
SelectedValuePath="Value" />
Change 'enums:States' to your enum
Use ObjectDataProvider:
<ObjectDataProvider x:Key="enumValues"
MethodName="GetValues" ObjectType="{x:Type System:Enum}">
<ObjectDataProvider.MethodParameters>
<x:Type TypeName="local:ExampleEnum"/>
</ObjectDataProvider.MethodParameters>
</ObjectDataProvider>
and then bind to static resource:
ItemsSource="{Binding Source={StaticResource enumValues}}"
based on this article
Nick's answer has really helped me, but I realised it could be tweaked slightly, to avoid an extra class, ValueDescription. I remembered that there exists a KeyValuePair class already in the framework, so this can be used instead.
The code changes only slightly :
public static IEnumerable<KeyValuePair<string, string>> GetAllValuesAndDescriptions<TEnum>() where TEnum : struct, IConvertible, IComparable, IFormattable
{
if (!typeof(TEnum).IsEnum)
{
throw new ArgumentException("TEnum must be an Enumeration type");
}
return from e in Enum.GetValues(typeof(TEnum)).Cast<Enum>()
select new KeyValuePair<string, string>(e.ToString(), e.Description());
}
public IEnumerable<KeyValuePair<string, string>> PlayerClassList
{
get
{
return EnumHelper.GetAllValuesAndDescriptions<PlayerClass>();
}
}
and finally the XAML :
<ComboBox ItemSource="{Binding Path=PlayerClassList}"
DisplayMemberPath="Value"
SelectedValuePath="Key"
SelectedValue="{Binding Path=SelectedClass}" />
I hope this is helpful to others.
You'll need to create an array of the values in the enum, which can be created by calling System.Enum.GetValues(), passing it the Type
of the enum that you want the items of.
If you specify this for the ItemsSource
property, then it should be populated with all of the enum's values. You probably want to bind SelectedItem
to EffectStyle
(assuming it is a property of the same enum, and contains the current value).
There are many excellent answers to this question and I humbly submit mine. I find that mine is somewhat simpler and more elegant. It requires only a value converter.
Given an enum...
public enum ImageFormat
{
[Description("Windows Bitmap")]
BMP,
[Description("Graphics Interchange Format")]
GIF,
[Description("Joint Photographic Experts Group Format")]
JPG,
[Description("Portable Network Graphics Format")]
PNG,
[Description("Tagged Image Format")]
TIFF,
[Description("Windows Media Photo Format")]
WDP
}
and a value converter...
public class ImageFormatValueConverter : IValueConverter
{
public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
{
if (value is ImageFormat format)
{
return GetString(format);
}
return null;
}
public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
{
if (value is string s)
{
return Enum.Parse(typeof(ImageFormat), s.Substring(0, s.IndexOf(':')));
}
return null;
}
public string[] Strings => GetStrings();
public static string GetString(ImageFormat format)
{
return format.ToString() + ": " + GetDescription(format);
}
public static string GetDescription(ImageFormat format)
{
return format.GetType().GetMember(format.ToString())[0].GetCustomAttribute<DescriptionAttribute>().Description;
}
public static string[] GetStrings()
{
List<string> list = new List<string>();
foreach (ImageFormat format in Enum.GetValues(typeof(ImageFormat)))
{
list.Add(GetString(format));
}
return list.ToArray();
}
}
resources...
<local:ImageFormatValueConverter x:Key="ImageFormatValueConverter"/>
XAML declaration...
<ComboBox Grid.Row="9" ItemsSource="{Binding Source={StaticResource ImageFormatValueConverter}, Path=Strings}"
SelectedItem="{Binding Format, Converter={StaticResource ImageFormatValueConverter}}"/>
View model...
private ImageFormat _imageFormat = ImageFormat.JPG;
public ImageFormat Format
{
get => _imageFormat;
set
{
if (_imageFormat != value)
{
_imageFormat = value;
OnPropertyChanged();
}
}
}
Resulting combobox...
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