How to do binding in WPF - C# - wpf

Question

I have following code:
<ControlTemplate x:Key="ViewItemTemplate"
TargetType="ListViewItem">
<StackPanel Orientation="Horizontal">
<CheckBox Margin="0,0,3,0" x:Name="CkBox">
<CkBox.IsChecked>
<Binding Path="IsSelected"
Mode="TwoWay">
<Binding.RelativeSource>
<RelativeSource Mode="TemplatedParent" />
</Binding.RelativeSource>
</Binding>
</CkBox.IsChecked>
<DataTrigger Binding="{Binding InvalidForeground}" Value="true">
<Setter TargetName="CkBoxVisual" Property="Foreground" Value="#999999"/>
</DataTrigger>
</CheckBox>
<ContentPresenter />
</StackPanel>
</ControlTemplate>
How can i bind InvalidForeground? I looked online for many example they tell to use DataTemplate. But when i add DataTemplate above StackPanel i get errors? Am i doing something wrong?
I am trying to bind InvalidForeground so i can add some code to it. I am getting an error: Cannot resolve symbol 'InvalidForeground' due to unknown DataContext.

Answer 1

It appears you are trying to declare a customized checkbox control to use within WPF application. As such, your "InvalidForeground" property would be exposed, but the template doesn't understand what its real type is expected.
I've posted another answer here which gave a full step-by-step for a custom button. The principles are the same, and I've tried to point out my understanding of of the declarations, the type, etc. Hopefully it can guide you on not just this, but other class templates too.

Answer 2

<ControlTemplate x:Key="ViewItemTemplate"
TargetType="ListViewItem">
<StackPanel Orientation="Horizontal">
<CheckBox Margin="0,0,3,0" x:Name="CkBox">
<CkBox.IsChecked>
<Binding Path="IsSelected"
Mode="TwoWay">
<Binding.RelativeSource>
<RelativeSource Mode="TemplatedParent" />
</Binding.RelativeSource>
</Binding>
</CkBox.IsChecked>
<DataTrigger Binding="{Binding InvalidForeground, RelativeSource={RelativeSource Mode=FindAncestor, AncestorType={x:Type Window}}}" Value="true">
<Setter TargetName="CkBoxVisual" Property="Foreground" Value="#999999"/>
</DataTrigger>
</CheckBox>
<ContentPresenter />
</StackPanel>
</ControlTemplate>
public partial class MainWindow : Window
{
public MainWindow()
{
InitializeComponent();
DataContext = this;
abc A = new abc();
A.InvalidForeground = true;
}
}
public class abc : INotifyPropertyChanged
{
private bool invalidForeGround;
public bool InvalidForeground
{
get
{ return invalidForeGround; }
set
{
invalidForeGround = value;
Notify("InvalidForeground");
}
}
private void Notify(string propName)
{
if (PropertyChanged != null)
PropertyChanged(this, new PropertyChangedEventArgs(propName));
}
public event PropertyChangedEventHandler PropertyChanged;
}
InvalidForeground must be the property in the DataContext of the Control whose template the above code is.I hope this will help