ComboBox values disappears after selected when objects used for display
- by Gakk
I have a combobox where I want to display objects and have enum values returned. When first opened the combobox displays the items as supposed, but after a value is chosen it seems to disappear from the list. But if the combobox is active I can use the keyboard to navigate up and down between the other values, so they are in the list but only invisible.
I have created a little test application to show my problem. When started the application shows the combobox with all the choices (the two first are type of Object, the third is a String):
After the blue line is selected and when the combobox is opened again this line is missing:
When the line with the text "Green" is selected that line is still showing:
If I had chosen the red line the only thing that would still be in the list is the test "Green".
I am using .NET Framework 3.5.
Any hints or tips to why the elements disappears?
Here are all the code needed after starting a blank project in Visual Studio.
MainWindow.xaml.cs:
using System;
using System.Collections.Generic;
using System.Diagnostics;
namespace Test
{
public partial class MainWindow
{
public MainWindow()
{
InitializeComponent();
}
private ColorComboBoxValue _activeColor;
public ColorComboBoxValue ActiveColor
{
get { return _activeColor; }
set
{
_activeColor = value;
Debug.WriteLine("ActiveColor: " + _activeColor.Color);
}
}
}
public class ColorList : List<ColorComboBoxValue> { }
public class ColorComboBoxValue
{
public Color Color { get; set; }
public Object Object { get; set; }
}
public enum Color
{
Red,
Blue,
Green
}
}
MainWindow.xaml:
<Window x:Class="Test.MainWindow" x:Name="window"
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:local="clr-namespace:Test"
Title="ComboBoxTest" Height="100" Width="200">
<Window.Resources>
<local:ColorList x:Key="ColorList">
<local:ColorComboBoxValue Color="Red">
<local:ColorComboBoxValue.Object>
<Path Data="M0,0 L0,30 60,30 60,0 Z" Fill="Red"/>
</local:ColorComboBoxValue.Object>
</local:ColorComboBoxValue>
<local:ColorComboBoxValue Color="Blue">
<local:ColorComboBoxValue.Object>
<Path Data="M0,0 L0,30 60,30 60,0 Z" Fill="Blue"/>
</local:ColorComboBoxValue.Object>
</local:ColorComboBoxValue>
<local:ColorComboBoxValue Color="Green">
<local:ColorComboBoxValue.Object>
<System:String>Green</System:String>
</local:ColorComboBoxValue.Object>
</local:ColorComboBoxValue>
</local:ColorList>
</Window.Resources>
<ComboBox ItemsSource="{Binding Source={StaticResource ColorList}}"
SelectedItem="{Binding ActiveColor, ElementName=window}">
<ComboBox.ItemTemplate>
<DataTemplate>
<ContentPresenter Content="{Binding Path=Object}"/>
</DataTemplate>
</ComboBox.ItemTemplate>
</ComboBox>
</Window>
