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RadioListBox: A ListBox with Radio Buttons (WPF Version)

By , 6 Sep 2009
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RadioListBoxWPF_Source

RadioListBoxWPF_Source

Introduction

This is the WPF version of my previous articles: CRadioListBox: A ListBox with Radio Buttons (MFC Version) and RadioListBox: A ListBox with Radio Buttons (WinForms Version). As explained in those articles, RadioListBox has the same functionalities as a regular ListBox, but with a different look and feel. Anyway, the RadioListBox control offers some advantages:

  • It is clearer that options are mutually exclusive with radio buttons.
  • It is a good alternative to a group of radio buttons because you have to maintain just one control, less memory use.
  • It inherits some useful features like scrolling, sorting, data binding, and multi-column.
  • It will be easier to change options dynamically, as shown in the demo application.
  • It will be easier to manage selection events, also shown in the demo application.

Using the Code

To implement RadioListBox into your project, you just need to do a few steps:

  • Include RadioListBox.xaml and RadioListBox.xaml.cs into your project.
  • Drop a RadioListBox object into your XAML form, or do it by hand. An alias for the System.Windows.Controls.Custom namespace will be useful.
  • Change the standard properties of the control, just like for a ListBox.
  • Use the IsTransparent property to mimic a group of RadioButtons.

That's all! Now you can use the radio button collection as a regular ListBox. You can add items with the Items.Add() method, the ItemsSource property, or directly into XAML. Finally, query for user selection with the SelectedIndex property. No more one-by-one evaluations.

RadioListBox Internals

The RadioListBox class is derived from WPF's ListBox class with a custom ControlTemplate to remove all undesired ListBox functionalities like selected item's background. To be consistent with the radio button model, multiple selection has been disabled. The resumed XAML implementation is the following:

<ListBox x:Class="System.Windows.Controls.Custom.RadioListBox"
       xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
       xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
       xmlns:s="clr-namespace:System;assembly=mscorlib" >
    <ListBox.Resources>
        <Style x:Key="{x:Type ListBoxItem}" TargetType="ListBoxItem">
            <Setter Property="SnapsToDevicePixels" Value="true"/>
            <Setter Property="OverridesDefaultStyle" Value="true"/>
            <Setter Property="Template">
                <Setter.Value>
                    <ControlTemplate TargetType="ListBoxItem">
                        <RadioButton x:Name="radio" Click="ItemRadioClick">
                            <RadioButton.Content>
                                <ContentPresenter ... />
                            </RadioButton.Content>
                        </RadioButton>
                    </ControlTemplate>
                </Setter.Value>
            </Setter>
        </Style>
    </ListBox.Resources>
    <ListBox.Template>
        <ControlTemplate>
            <Border BorderThickness="0" 
                  Padding="1,1,1,1" 
                  Background="Transparent" 
                  Name="theBorder" 
                  SnapsToDevicePixels="True">
                <ScrollViewer Padding="{TemplateBinding Control.Padding}" 
                              Focusable="False">
                  <ItemsPresenter 
                      SnapsToDevicePixels="{TemplateBinding UIElement.SnapsToDevicePixels}" />
                </ScrollViewer>
            </Border>
            <ControlTemplate.Triggers ... />
        </ControlTemplate>
    </ListBox.Template>
</ListBox>

As the radio buttons inside the ControlTemplate don't change the selection, this has to be done manually inside the ItemRadioClick event. Here, the ItemContainerGenerator property has an important role by converting between the ListBox's items contents and the ListBoxItem presentation object. Here is a summarized C# source code:

namespace System.Windows.Controls.Custom
{
    public partial class RadioListBox : ListBox
    {
        public RadioListBox() { ... }

        public new SelectionMode SelectionMode { ... }

        public bool IsTransparent { ... }

        private void ItemRadioClick(object sender, RoutedEventArgs e)
        {
            ListBoxItem sel = (e.Source as RadioButton).TemplatedParent as ListBoxItem;
            int newIndex = this.ItemContainerGenerator.IndexFromContainer(sel); ;
            this.SelectedIndex = newIndex;
        }

        protected override void OnSelectionChanged(SelectionChangedEventArgs e)
        {
            base.OnSelectionChanged(e);

            CheckRadioButtons(e.RemovedItems, false);
            CheckRadioButtons(e.AddedItems, true);
        }

        private void CheckRadioButtons(System.Collections.IList radioButtons, bool isChecked) 
        {
            foreach (object item in radioButtons)
            {
                ListBoxItem lbi = 
                  this.ItemContainerGenerator.ContainerFromItem(item) as ListBoxItem;

                if (lbi != null)
                {
                    RadioButton radio = lbi.Template.FindName("radio", lbi) as RadioButton;
                    if (radio != null)
                        radio.IsChecked = isChecked;
                }
            }
        }
    }
}

History

  • September 6th, 2009: First version.

License

This article, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

About the Author

Jaime Olivares
Architect Freelance (jaimeolivares.com)
Peru Peru


Computer Electronics professional, Software Architect and senior Windows C++ and C# developer with experience in many other programming languages, platforms and application areas including communications, simulation systems, GIS, 3D graphics and mobile platform.
Also have experience in development of electronic interfaces, specially for military applications.
Currently intensively working with Visual C# 2010 and TFS.
Can be reached at jaimeolivares.com

Comments and Discussions

 
GeneralMy vote of 5 PinmemberShailesh vora30-Sep-12 0:19 
GeneralBind a DataTable PinmemberMCTimotheus4-Feb-10 1:48 
GeneralRe: Bind a DataTable PinmemberJaime Olivares7-Feb-10 18:03 
GeneralRe: Bind a DataTable PinmemberMCTimotheus7-Feb-10 20:36 
Generala loop "for" Pinmemberpeug30-Jan-10 6:23 
GeneralRe: a loop "for" PinmemberJaime Olivares31-Jan-10 6:25 
JokeRe: a loop "for" Pinmemberpeug31-Jan-10 6:27 
GeneralListBox with checkbox Pinmemberpeug29-Jan-10 2:03 
GeneralRe: ListBox with checkbox PinmemberJaime Olivares31-Jan-10 6:30 
QuestionSpace between radio Pinmemberpeug29-Jan-10 0:09 
AnswerRe: Space between radio Pinmemberpeug31-Jan-10 6:28 
GeneralRe: Space between radio PinmemberJaime Olivares31-Jan-10 6:32 
GeneralBug Pinmembernaish_kewl30-Nov-09 14:41 
GeneralRe: Bug PinmemberJaime Olivares1-Dec-09 2:20 
GeneralRe: Bug Pinmembernaish_kewl3-Feb-10 11:51 
GeneralRe: Bug PinmemberJaime Olivares7-Feb-10 18:25 
GeneralRe: Bug Pinmembernaish_kewl8-Feb-10 12:07 
GeneralRe: Bug PinmemberJaime Olivares8-Feb-10 12:14 
GeneralRe: Bug PinmemberMember 83632665-Apr-12 10:25 
General"Checking" in XAML is better PinmemberGuillaume Leparmentier6-Sep-09 13:57 
GeneralRe: "Checking" in XAML is better PinmemberJaime Olivares6-Sep-09 15:31 
GeneralRe: "Checking" in XAML is better PinmemberGuillaume Leparmentier7-Sep-09 0:25 
GeneralRe: "Checking" in XAML is better PinmemberJaime Olivares7-Sep-09 3:01 
GeneralRe: "Checking" in XAML is better Pinmembernaish_kewl12-Oct-09 13:23 
GeneralRe: "Checking" in XAML is better Pinmemberanhldbk13-Aug-10 20:07 

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