Silverlight data affecting look .. VisualStateManger .. color according to data value

In Silverlight how do I get the color of a button to change according to the value of it开发者_开发知识库s contents .. e.g. '0' = red , '1' = green ..

I have taken a look at the VisualStateManger but cannot see how to do it .. I can see it is easy for mouseovers etc .. but not for values of data.

What you need is a value converter, that is an implementation of IValueConverter. In this blog article you find the code for a StringToObjectConverter which you can use for your task. I'll reproduce the code here:-

using System;
using System.Windows;
using System.Windows.Data;
using System.Linq;
using System.Windows.Markup;

namespace SilverlightApplication1
{
    [ContentProperty("Items")]
    public class StringToObjectConverter : IValueConverter
    {
        public ResourceDictionary Items { get; set; }
        public string DefaultKey { get; set; }

        public StringToObjectConverter()
        {
            DefaultKey = "__default__";
        }

        public virtual object Convert(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
        {
            if (value != null && Items.Contains(value.ToString()))
                return Items[value.ToString()];
            else
                return Items[DefaultKey];
        }

        public virtual object ConvertBack(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
        {
            return Items.FirstOrDefault(kvp => value.Equals(kvp.Value)).Key;
        }
    }
}

Now you can add an instance of this converter to the resources in you your user control:-

 <UserControl.Resources>
     <local:StringToObjectConverter x:Key="StatusToBrush">
         <ResourceDictionary>
             <SolidColorBrush Color="Red" x:Key="0" />
             <SolidColorBrush Color="Green" x:Key="1" />
             <SolidColorBrush Color="Silver" x:Key="__default__" /> 
         </ResourceDictionary>
     </local:StringToObjectConverter>
 </UserControl>

Now you can bind the Background to your value:-

 <Button Background="{Binding Value, Converter={StaticResource StatusToBrush}}">
    <TextBlock Text="{Binding Value}" />
 </Button>