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Data Binding in WPF Controls

Posted by Mahesh Chand Articles | WPF August 11, 2008
This article shows how to add data binding support among controls in WPF.
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This article shows how to add data binding support among controls in WPF.  

The Binding Class

The mother of data binding in WPF is the Binding class. Let's take a quick look at how the Binding class glue two objects together to support real-time data transfer.

The Binding class provides the communication channel between two objects regardless of what these objects types. The object that consumes the data is called binding target and the object that provides the data is called binding source. A binding source can be a UIElement, a list object, a CLR object that is associated with ADO.NET data or Web Services, or an XmlNode that contains your XML data.

 

WPFControlsDBImg1.jpg

 

The data binding process in WPF has five objects - A binding target object, a binding target property, a binding source object, a binding source object property, and a binding object to build a link between these.  The target property must be a dependency property.

 

Data Binding with Controls

Now, using the above approach of the Binding class, we will create an application that will have a real-time data transfer between multiple controls on a WPF page.

We will create an application that looks like Figure 1. In Figure 1, we have a ListBox with a list of colors, a TextBox, and a Canvas. When we pick a color from the ListBox, the text of TextBox and color of Canvas changes dynamically to the color selected in the ListBox and this is possible to do all in XAML without writing a single line of code in the code behind file. 

 

WPFControlsDBImg2.jpg

Figure 1.

The XAML code of the page looks like following.

<StackPanel Orientation="Vertical">

    <TextBlock Margin="10,10,10,10" FontWeight="Bold">

        Pick a color from below list

    </TextBlock>

    <ListBox Name="mcListBox" Height="100" Width="100"

             Margin="10,10,0,0" HorizontalAlignment="Left" >

        <ListBoxItem>Orange</ListBoxItem>

        <ListBoxItem>Green</ListBoxItem>

        <ListBoxItem>Blue</ListBoxItem>

        <ListBoxItem>Gray</ListBoxItem>

        <ListBoxItem>LightGray</ListBoxItem>

        <ListBoxItem>Red</ListBoxItem>

    </ListBox>

   <TextBox Height="23" Name="textBox1" Width="120" Margin="10,10,0,0" HorizontalAlignment="Left"  >

        <TextBox.Text>

            <Binding ElementName="mcListBox" Path="SelectedItem.Content"/>

        </TextBox.Text>

    </TextBox>

    <Canvas Margin="10,10,0,0" Height="200" Width="200" HorizontalAlignment="Left" >

        <Canvas.Background>

            <Binding ElementName="mcListBox" Path="SelectedItem.Content"/>

        </Canvas.Background>

    </Canvas>

 

</StackPanel>  

If you look at the TextBox XAML code, you will see the Binding within the TextBox.Text property, which sets the binding from TextBox to another control and another control ID is ElementName and another control's property is Path. So in below code, we are setting the SelectedItem.Content property of ListBox to TextBox.Text property.

        <TextBox.Text>

            <Binding ElementName="mcListBox" Path="SelectedItem.Content"/>

        </TextBox.Text>

 

Now same applies to the Canvas.Background property, where we set it to the SelectedItem.Content of the ListBox. Now, every time you select an item in the ListBox, the TextBox.Text and Canvas.Background properties are set to that selected item in the ListBox.

<Canvas.Background>

    <Binding ElementName="mcListBox" Path="SelectedItem.Content"/>

</Canvas.Background>

 

Now if I pick Red from the ListBox, the output looks like Figure 2, where the color of the canvas is red and the text of TextBox is Red.

WPFControlsDBImg3.jpg

Figure 2

Summary

In this article, I discussed how to use the Binding class to provide real-time data transfer among WPF controls.

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