The properties of WPF elements can be bound to properties of other WPF Elements. Lets do some simple examples of binding one element to another.

For this tutorial, I assume you are in Visual Studio 2008.  I assume that you already know how to create a new Project and choose WPF Application.  All examples assume you have a new WPF Application.

I am the believer that one example isn’t enough, so I am going to give you three examples:

Example 1 – Binding and Element’s property to CheckBox.IsChecked

This example will demonstrate binding a Button‘s IsEnabled property to a CheckBox‘s IsChecked property.

Step 1 – Add the elements

1. Add two items from the Toolbox:
   • CheckBox
   • Button

   The Button is named button1 and the CheckBox is named checkBox1.

2. Change the text of the checkBox1 to “Enable button”.  This can be done either in the Properties or in the XAML.

Step 2 – Adding Binding to the Button

1. In the XAML, locate the button1 element.
2. Add the following to the button1 element:IsEnabled="{Binding ElementName=checkBox1, Path=IsChecked}"In your project, ElementName could be any item. In this example, we only have two elements so far: button1, and checkBox1.The XAML now looks like this (only two new lines exist):

   <Window x:Class="BindingATextBoxToASlider.Window1"
       xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
       xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
       Title="Window1" Height="300" Width="300">
       <Grid>
           <Button Content="Button" Height="23" Margin="12,34,416,0" Name="button1" VerticalAlignment="Top" Width="75" IsEnabled="{Binding ElementName=checkBox1, Path=IsChecked}"/>
           <CheckBox Content="CheckBox" Height="16" Margin="12,12,408,0" Name="checkBox1" VerticalAlignment="Top" />
       </Grid>
   </Window>
   

3. Compile and run your program.
4. Check and uncheck the box an watch the binding do its work as it enables and disables the button.

Ok, so that was pretty cool. We have a simple example of binding one Element to another.

You can shoot yourself in the foot or Don’t be stupid!

Yes, you can shoot yourself in the foot by doing something stupid.

You could bind an element to itself. Let’s try it just so you can see it happen.

Add the same binding you added to button1 to checkBox1.

Compile and see what happens.

Example 2 – Binding and Element’s property to Slider.Value

This example uses a Slider and a TextBox.

Step 1 – Add the elements

1. Add two items from the Toolbox:
   • TextBox
   • Slider

   The Slider is named slider1 and the TextBox is named textBox1.

Step 2 – Adding Binding to the TextBox

1. In the XAML, locate the textBox1 element.
2. Add the following to the textBox1 element:Text="{Binding ElementName=slider1, Path=Value}"ElementName can be any item. In this example, we only have two elements so far: slider1, and textBox1.The XAML now looks like this (only two new lines exist):

   <Window x:Class="BindingATextBoxToASlider.Window1"
       xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
       xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
       Title="Window1" Height="300" Width="300">
       <Grid>
          <TextBox Height="23" Margin="79,62,99,0" Name="textBox1" VerticalAlignment="Top" Text="{Binding ElementName=slider1, Path=Value}"/>
           <Slider Height="22" Margin="79,34,99,0" Name="slider1" VerticalAlignment="Top" />
       </Grid>
   </Window>
   

3. Compile and run your program.
4. Slide the slider and watch the binding do its work as its value is displayed in the textBox1 as it changes.

Calculations in XAML Bindings are Unsupported

Ok, so maybe you want to try to do calculations in the XAML Binding. It doesn’t work.

You can enter this and while it will compile, the Binding won’t work:

Text="{Binding ElementName=slider1, Path=(int)Value}"

You can enter this and while it will compile, the Binding won’t work:

Text="{Binding ElementName=slider1, Path=Value + 1}"

Example 3 – Binding and Element’s property to CheckBox.IsChecked

Ok, lets do a slight more complex example. We are going to have more than two elements. We are going to have a ListBox that contains a list of items (ListBoxItems). We are going to have a TextBox that displays the content of the selected item.

Step 1 – Add the elements

1. Add two items from the Toolbox:
   • TextBox
   • ListBox
2. Add multiple items to listBox1. This can be done either in the XAML or by clicking on the button for Items in the Properties of the listBox1.

Step 2 – Adding Binding to the TextBox

1. In the XAML, locate the textBox1 element.
2. Add the following to the textBox1 element:Text="{Binding ElementName=listBox1, Path=SelectedItem.Content}"Notice that we are using a property of a property for the Path. This is allowed. SelectedItem is a property of listBox1, and Content is a property of SelectedItem.The XAML now looks like this (only two new lines exist):

   <Window x:Class="BindingATextBoxToAListBoxSelectedItem.Window1"
       xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
       xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
       Title="Window1" Height="300" Width="300">
       <Grid>
           <TextBox Height="23" Margin="12,23,12,0" Name="textBox1" VerticalAlignment="Top" Text="{Binding ElementName=listBox1, Path=SelectedItem.Content}"/>
           <ListBox Margin="12,52,12,110" Name="listBox1">
               <ListBoxItem>c:</ListBoxItem>
               <ListBoxItem>d:</ListBoxItem>
               <ListBoxItem>e:</ListBoxItem>
               <ListBoxItem>f:</ListBoxItem>
               <ListBoxItem>g:</ListBoxItem>
               <ListBoxItem>h:</ListBoxItem>
           </ListBox>
       </Grid>
   </Window>
   

3. Compile and run your program.
4. Select different items in the list and watch the textBox1 change to display the content of the selected item.

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Introduction

This document assumes that you understand the concepts of object oriented programming and more specifically with C# programming, such as Classes or Objects, Methods, Properties, Events, etc. If not, it will be much harder to follow along.

This tutorial will cover the basics of data Binding in a WPF application. When you are done with this tutorial, you should be able to create a basic WPF-based graphical program that uses Binding. We will cover the different types of data Binding as well as what works and sometimes what doesn’t.

What is data Binding?

The idea of data Binding is to link a variable of any Type (int, string, object, etc…) to a graphical object’s Property that has the same type.

For example, lets say you have a Button object called myButton in your GUI like this: Click Me!. The words “Click Me!” is a string property in the Button object: myButton.Text.

Imagine you have a string variable called strProperty in some part of your code that on its own has no way to interact with your GUI code. Lets say you want to change the myButton.Text property to match that string variable. Binding allows the button’s text string to always match a string property in some other object not really related to your GUI so if you change strProperty to equal “Enable” your button text will look like Enable. If you then change the strProperty to “Disable” the button text will automatically change to be Disable without out your back end code having to make any interaction with the GUI on its own.

Without Binding, you would have to write code yourself that would interact with the GUI and update the myButton.Text property when ever you update the string in code. In order to do this without Binding, you would also have to intermingle your background code with your GUI code. This can make it difficult to update or modify your GUI because GUI code is strung throughout all parts of your application. You don’t just have to update your GUI, you have to update all your code that interacts with the GUI.

So Binding allows you to have a back end code that is independent of the GUI. This is especially useful when the GUI needs to be updated or improved or when multiple GUIs exists (skins) and you can switch between them.

There are programming styles associated with developing a GUI separate from the back-end. Two of which are Model-View-Control (MVC) or Model-View-ViewModel (MVVM). This tutorial is not going to cover these, however, it is probably wise for you become familiar with these.

However, there is no reason you are limited to Binding to back end code. You can bind to code that is in the WPF GUI and very powerful applications can be written with little to no back end code.

Requirements for data Binding in WPF

In order to using data Binding, you should have the following requirements:

1. Your project should be a WPF Application, or your project should include a WPF Window or WPF Control.
2. Objects your elements bind to should implement System.ComponentModel.INotifyPropertyChanged.

Types of data Binding and resources

There is are multiple types of Binding. Elements bind to some type of resource and there are multiple types of resources. Static and Dynamic resource binding which uses the StaticResource Markup Extension or the DynamicResource Markup Extension.

The Binding source can also be “any public property, including properties of other controls, common language runtime (CLR) objects, XAML elements, ADO.NET DataSets, XML Fragments, and so forth.” (Reference: http://msdn.microsoft.com/en-us/magazine/cc163299.aspx).

Go to next: 1.1 Binding one element property to another

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