A 'Binding' can only be set on a DependencyProperty of a DependencyObject

Question

Hi everyone, I'm trying to create a ToggleSwitch on WPF which based on ToggleButton by using UserControl.
Everything works fine but when I try to bind IsChecked property of a CheckBox to my ToggleSwitch, it throws me an error like the title .
Here is my code :
<UserControl x:Class="CustomControl.ToggleSwitchWPF"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:i="clr-namespace:System.Windows.Interactivity;assembly=System.Windows.Interactivity"
xmlns:ei="http://schemas.microsoft.com/expression/2010/interactions"
xmlns:System="clr-namespace:System;assembly=mscorlib"
Width="Auto"
Height="Auto">
<UserControl.Resources>
<System:Double x:Key="ControlHeight">23</System:Double>
<System:Double x:Key="ControlWidth">50</System:Double>
</UserControl.Resources>
<Grid Name="grdMainGrid"
VerticalAlignment="Stretch"
HorizontalAlignment="Stretch"
MinWidth="{StaticResource ControlWidth}"
MaxWidth="{Binding RelativeSource={RelativeSource Mode=Self}, Path=MinWidth}"
MinHeight="{StaticResource ControlHeight}"
MaxHeight="{Binding RelativeSource={RelativeSource Mode=Self}, Path=MinHeight}">
<!-- This is the main component of this UserControl -->
<ToggleButton Name="tbnMainToggleButton"
VerticalAlignment="Stretch"
HorizontalAlignment="Stretch"
Background="{x:Null}"
Click="btnMainToggleButton_Click"
Checked="btnMainToggleButton_Checked"
Unchecked="btnMainToggleButton_Unchecked">
<!-- Customize toggle button's template -->
<ToggleButton.Template>
<ControlTemplate TargetType="{x:Type ToggleButton}">
<Grid Width="{TemplateBinding Width}"
Height="{TemplateBinding Height}">
<Grid.ColumnDefinitions>
<ColumnDefinition Width="*"/>
<ColumnDefinition Width="*"/>
</Grid.ColumnDefinitions>
<i:Interaction.Behaviors>
<ei:FluidMoveBehavior AppliesTo="Children"
Duration="0:0:0.1">
<ei:FluidMoveBehavior.EaseX>
<SineEase EasingMode="EaseIn" />
</ei:FluidMoveBehavior.EaseX>
</ei:FluidMoveBehavior>
</i:Interaction.Behaviors>
<!-- This is the vertial border which contains the Vertial Bar -->
<Border Name="bdrVertialBarBorder"
VerticalAlignment="Stretch"
HorizontalAlignment="Stretch"
BorderBrush="Gray"
BorderThickness="1"
Grid.ColumnSpan="2">
<!-- This is the background inside the vertical border -->
<Border x:Name="bdrInsideVerticalBorder"
Grid.ColumnSpan="2"
Background="Green"
Margin="2"/>
</Border>
<!-- This is the object which runs from left to right or vice versa to indicate whether is toggle button is checked or not-->
<Border Name="Thumb"
Height="{Binding ElementName=bdrVertialBarBorder, Path=ActualHeight}"
CornerRadius="2"
Background="Black"
Margin="1, 0, 1, 0"
Grid.Column="0"/>
</Grid>
<ControlTemplate.Triggers>
<!-- This trigger is activated when the toggle button is checked -->
<Trigger Property="IsChecked"
Value="true">
<Setter Property="Grid.Column"
TargetName="Thumb"
Value="1"/>
<Setter TargetName="bdrInsideVerticalBorder"
Property="Background"
Value="Red"/>
</Trigger>
<!-- This trigger is activated when the toggle button is disabled -->
<Trigger Property="IsEnabled"
Value="false">
<Setter Property="Opacity"
Value="0.4"/>
</Trigger>
</ControlTemplate.Triggers>
</ControlTemplate>
</ToggleButton.Template>
</ToggleButton>
</Grid>
</UserControl>
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Data;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Imaging;
using System.Windows.Navigation;
using System.Windows.Shapes;
namespace CustomControl
/// <summary>
/// Interaction logic for ToggleSwitchWPF.xaml
/// </summary>
public partial class ToggleSwitchWPF : UserControl, INotifyPropertyChanged
#region Delegates
* Handler of Click Event
public delegate void ClickEventHandler(object sender);
* Handler of Checked event
public delegate void CheckedEventHandler(object sender);
* Handler of Unchecked event
public delegate void UncheckedEventHandler(object sender);
#endregion
#region Delegates' event
* Event of ClickEventHandler
public event ClickEventHandler Click;
* Event of CheckedEventHandler
public event CheckedEventHandler Checked;
* Event of UncheckedEventHandler
public event UncheckedEventHandler Unchecked;
#endregion
#region Properties
* Check whether is ToggleSwitch is checked or not
public bool? IsChecked
get
return tbnMainToggleButton.IsChecked;
set
// Change the check state of Main ToggleButton
tbnMainToggleButton.IsChecked = value;
// Fire the PropertyChanged event
NotifyPropertyChanged("IsChecked");
#endregion
#region Constructor
* Non-parameter constructor
public ToggleSwitchWPF()
InitializeComponent();
#endregion
#region Events
#region ToggleButton
* This event is fired the main ToggleButton is clicked
private void btnMainToggleButton_Click(object sender, RoutedEventArgs e)
// Invalid Click event
if (Click == null)
return;
// Fire the event
Click(sender);
* This event is fired when the main ToggleButton is checked
private void btnMainToggleButton_Checked(object sender, RoutedEventArgs e)
// Invalid Checked event
if (Checked == null)
return;
// Fire the event
Checked(sender);
* This event is fire when that main ToggleButton is Unchecked
private void btnMainToggleButton_Unchecked(object sender, RoutedEventArgs e)
// Invalid Unchecked event
if (Unchecked == null)
return;
// Fire the event
Unchecked(sender);
#endregion
#endregion
#region INotifyPropertyChanged Implementation
* Create an event to fire when a property is changed
public event PropertyChangedEventHandler PropertyChanged;
// This method is called by the Set accessor of each property.
// The CallerMemberName attribute that is applied to the optional propertyName
// parameter causes the property name of the caller to be substituted as an argument.
private void NotifyPropertyChanged(string propertyName)
// Invalid Event
if (PropertyChanged == null)
return;
// Fire the event
PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
#endregion
Can anyone help me to solve this problem please ?
Thank you

Answer 1

You have to implement IsChecked as dependency property. Like you can define as
public bool? IsChecked
    get { return (bool?)GetValue (IsCheckedProperty); }
    set { SetValue (IsCheckedProperty, value); }
public static readonly DependencyProperty IsCheckedProperty
    = DependencyProperty.Register (
        "IsChecked",
        typeof (bool?),
        typeof (ToggleSwitchWPF),
        new FrameworkPropertyMetadata (
            false,
            OnIsCheckedChanged
private static void OnIsCheckedChanged ( DependencyObject src, DependencyPropertyChangedEventArgs e )
    ver switch = src as ToggleSwitchWPF;
    switch.tbnMainToggleButton.IsChecked = e.NewValue as bool?;