TemplateBinding in a nested template in Silverlight 4

Question

I've implemented a control, CommandTextBox, which I want to be a text box with a button right next to it (so it almost appears within the text box).

The button should be an image which I can bind to an icon. It's fairly straightfoward stuff...

public class CommandTextBox : TextBox
{
    /// <summary>
    /// The image property.
    /// </summary>
    public static readonly DependencyProperty ImageProperty = DependencyProperty.Register(
        "Image", typeof(ImageSource), typeof(CommandTextBox), null);

    /// <summary>
    ///     Initializes a new instance of the <see cref = "CommandTextBox" /> class.
    /// </summary>
    public CommandTextBox()
    {
        this.DefaultStyleKey = typeof(CommandTextBox);
    }

    /// <summary>
    ///     Gets or sets the image.
    /// </summary>
    /// <value>
    ///     The image.
    /// </value>
    public ImageSource Image
    {
        get
        {
            return (ImageSource)this.GetValue(ImageProperty);
        }

        set
        {
            this.SetValue(ImageProperty, value);
        }
    }
}

I have a template as follows...

<Style TargetType="Controls:CommandTextBox">
        <Setter Property="Template">
            <Setter.Value>
                <ControlTemplate TargetType="Controls:CommandTextBox">
                    <Grid>
                        <Grid.ColumnDefinitions>
                            <ColumnDefinition Width="*" />
                            <ColumnDefinition Width="Auto" />
                        </Grid.ColumnDefinitions>

                        <TextBox Grid.Column="0" Text="{TemplateBinding Text}"/>

                        <Button Grid.Column="1" 
                                Content="Search" >
                            <Button.Template>
                                <ControlTemplate>
                                    <Image Source="{TemplateBinding Image}" />
                                </ControlTemplate>
                            </Button.Template>
                        </Button>

                    </Grid>
                </ControlTemplate>
            </Setter.Value>
        </Setter>
    </Style>

But I get an error due to the template binding in the image. I sortof understand why, it's because the Template has changed now so the binding context isn't the same but I don't know how to overcome it.

Do I need to create a seperate ImageButton control so I can just do a normal template binding or is there another way?

Thanks Ben

Answer 1

I have managed to get this to work by changing the style as follows:

    <Style TargetType="appControls:CommandTextBox">
        <Setter Property="Template">
            <Setter.Value>
                <ControlTemplate TargetType="appControls:CommandTextBox">
                    <Grid>
                        <Grid.ColumnDefinitions>
                            <ColumnDefinition Width="*" />
                            <ColumnDefinition Width="Auto" />
                        </Grid.ColumnDefinitions>
                        <TextBox Grid.Column="0" Text="{TemplateBinding Text}"/>
                        <Button Grid.Column="1" >
                            <Button.Content>                                
<Image DataContext="{TemplateBinding Image}" Source="{Binding}" />                               
                            </Button.Content>
                        </Button>
                    </Grid>
                </ControlTemplate>
            </Setter.Value>
        </Setter>
    </Style>

I'm not using a seperate template for the Button. My XAML with the control is:

<controls:CommandTextBox Text="Text" Image="/MyApp.Silverlight;component/Assets/Images/Amber_Triangle.png"></controls:CommandTextBox>

This appears to achieve the result you were after. The control renders on my test page as expected.