在Windows Phone上向自定义控件添加绑定

Question

I have created a custom image button for a project. This is based on the code provided at https://code.msdn.microsoft.com/windowsapps/Custom-Image-Button-in-4b300b62 .

I've adjusted the image button to suit my needs and it looks fine in the designer. However, I'm trying to bind the textblocks to a view model using a DependencyProperty.

The guts of the button looks like this

<StackPanel x:Name="Panel" Orientation="Horizontal" VerticalAlignment="Center">
    <Image Margin="10,0,-10,0" x:Name="Image" Width="48" Height="48" Source="/Assets/Images/mappin.png"/>
    <StackPanel Orientation="Vertical" VerticalAlignment="Center">
        <Grid x:Name="LayoutRoot" Background="Transparent">
            <Grid.RowDefinitions>
                <RowDefinition Height="*"/>
            </Grid.RowDefinitions>
            <TextBlock Width="400" x:Name="txtHeading" Text="Mooo" Grid.Row="0" TextAlignment="Center" Margin="20,0,-10,0" FontFamily="/TfL.CongestionCharge.WindowsPhone;component/Assets/Fonts/NJFont-Book.ttf#NJFont Book" />
            </Grid>
    </StackPanel>
</StackPanel>

Nothing amazing, but does what I need.

The code behind for the TextBlock dependency looks like this

public static readonly DependencyProperty TextDependencyProperty = DependencyProperty.Register(
   "Text",
   typeof(string),
   typeof(UserControl),
   new PropertyMetadata(null));

    public string Text
    {
        get
        {
            return GetValue(TextDependencyProperty) as string;
        }

        set
        {
            SetValue(TextDependencyProperty, txtHeading.GetType().GetProperty("System.String").GetValue(txtHeading, null));
        }
    }

(I was getting could not convert from a System.Windows.Bindable to System.String error originally, this code will compile but gives a null ref. exception in the setter)

Am I going about this the correct way and do I need to create a DependencyProperty if I try to bind to an ICommand or can I just use

private ICommand command;
public ICommand Command
    {
        get
        {
            return command;
        }

        set
        {
            command = value;
            command.Execute(value);
        }
    }

Answer 1

Change your setter to be "normal" one, instead:

SetValue(TextDependencyProperty, txtHeading.GetType().GetProperty("System.String").GetValue(txtHeading, null));

Use this:

SetValue(TextDependencyProperty, value);

Give your UserControl a name:

<UserControl ... x:Name="thisControl">

In your TextBlock use a binding to your control property:

Text="{Binding Text, ElementName=thisControl}"

Hope this helps.