从ContentControl绑定前景

Question

I have a binding problem with WindowsPhone 8 and a ControlTemplate. Here is an example:

<UserControl.Resources>
<Style TargetType="Button">
    <Setter Property="Template">
        <Setter.Value>
            <ControlTemplate TargetType="Button">
                <ContentControl x:Name="ContentContainer" Foreground="Red" Content="{TemplateBinding Content}"/>
            </ControlTemplate>
        </Setter.Value>
    </Setter>
</Style>
</UserControl.Resources>

<Button>
    <Button.Content>
        <TextBlock Text="123"/>
    </Button.Content>
<Button>

I would like to use in my Button.Content the foreground "Red" I defined in the ContentContainer. But nothing works... The goal is to change the ContentContainer foreground in a VisualState in my Style. Can anyone help me?

Answer 1

You should do :

<Button Content="123"/>

Instead of putting a TextBlock.

However if you want to keep the TextBlock anyway, the you should do :

<Style TargetType="TextBlock">
            <Setter Property="Foreground">
                <Setter.Value>
                    red
                </Setter.Value>
            </Setter>
        </Style>

Answer 2

Managed to pull this off with a behavior. It's a pretty complicated solution, but it's the only one i found working :

First, some Util stuff :

public static class IEnumerableExt
{
    public static T FirstOrDefault<T>(this IEnumerable<T> source)
    {
        if (source.Count() > 0)
            return source.ElementAt(0);
        return default(T);
    }
}

and ...

public static class DependencyObjectExt
{
        public static DependencyObject GetChild(this DependencyObject @this, int childIndex)
        {
            return VisualTreeHelper.GetChild(@this, childIndex);
        }

        public static IEnumerable<DependencyObject> GetChildren(this DependencyObject @this)
        {
            for(int i = 0; i < VisualTreeHelper.GetChildrenCount(@this); i++)
            {
                yield return @this.GetChild(i);
            }
        }

        public static IEnumerable<T> FindChildrenOfType<T>(this DependencyObject @this) where T : DependencyObject
        {
            foreach(var child in @this.GetChildren())
            {
                if(child is T)
                {
                    yield return child as T;
                }
            }
        }

        public static IEnumerable<T> FindDescendantsOfType<T>(this DependencyObject @this) where T : DependencyObject
        {
            IEnumerable<T> result = Enumerable.Empty<T>();

            foreach(var child in @this.GetChildren())
            {
                if(child is T)
                {
                    result = result.Concat(child.ToEnumerable().Cast<T>());
                }
                result = result.Concat(child.FindDescendantsOfType<T>());
            }

            return result;
        }
}

Now, let's define a behavior that does the binding :

public class ContentControlForegroundBindingBehavior : Behavior<Control>
{
    public static DependencyProperty ParentProperty =
        DependencyProperty.Register("Parent", typeof(Control),
            typeof(ContentControlForegroundBindingBehavior), new PropertyMetadata(null));

    public Control Parent
    {
        get { return (Control)this.GetValue(ParentProperty); }
        set { this.SetValue(ParentProperty, value); }
    }


    protected override void OnAttached()
    {
        base.OnAttached();

        AssociatedObject.Loaded += (sender, e) =>
        {
            if (Parent == null) return;

            var control = AssociatedObject as Control;
            if (control == null) return;


            var contentControl = Parent.FindDescendantsOfType<ContentControl>().FirstOrDefault();
            if (contentControl == null) return;

            control.SetBinding(Control.ForegroundProperty, new Binding()
            {
                NotifyOnSourceUpdated = true,
                Mode = BindingMode.OneWay,
                UpdateSourceTrigger = UpdateSourceTrigger.PropertyChanged,
                BindsDirectlyToSource = true,
                Path = new PropertyPath(Control.ForegroundProperty),
                Source = contentControl
            });
        };
    }
}

What this behavior does is bind the control's foreground to the foreground of the ContentControl found in the template of the specified parent. This is how you use it (in xaml):

xmlns:i="clr-namespace:System.Windows.Interactivity;assembly=System.Windows.Interactivity" 
        xmlns:behaviors=" ---------- Your Behaviors Namespace ---------"

<Button x:Name="SomeName"
                Width="125"
                Height="30"
                Click="OnButtonClick"
                HorizontalAlignment="Left"
                VerticalAlignment="Top"
                Margin="50,54,0,0">
            <Button.Content>
                <controls:IconText Icon="SomeIcon.png"
                                   Text="SomeText">
                    <i:Interaction.Behaviors>
                        <behaviors:ContentControlForegroundBindingBehavior Parent="{Binding ElementName=SomeName}"/>
                    </i:Interaction.Behaviors>
                </controls:IconText>
            </Button.Content>
</Button>