快速构建Windows 8风格应用25-数据绑定

如何将UI元素与数据进行绑定

<TextBox x:Name="MyTextBox" Text="Text" Foreground="{Binding Brush1, Mode=OneWay}"/>

MyColors textcolor = new MyColors();

textcolor.Brush1 = new SolidColorBrush(Colors.Red);

MyTextBox.DataContext = textcolor;

数据绑定的方向

数据更改通知

// Create a class that implements INotifyPropertyChanged.

public class MyColors : INotifyPropertyChanged

{

    private SolidColorBrush _Brush1;

 

    // Declare the PropertyChanged event.

    public event PropertyChangedEventHandler PropertyChanged;

 

    // Create the property that will be the source of the binding.

    public SolidColorBrush Brush1

    {

        get { return _Brush1; }

        set

        {

            _Brush1 = value;

            // Call NotifyPropertyChanged when the source property

            // is updated.

            NotifyPropertyChanged("Brush1");

        }

    }

 

    // NotifyPropertyChanged will raise the PropertyChanged event,

    // passing the source property that is being updated.

    public void NotifyPropertyChanged(string propertyName)

    {

        if (PropertyChanged != null)

        {

            PropertyChanged(this,

                new PropertyChangedEventArgs(propertyName));

        }

    }

}

数据转换

// Custom class implements the IValueConverter interface.

public class DateToStringConverter : IValueConverter

{

 

    #region IValueConverter Members

 

    // Define the Convert method to change a DateTime object to

    // a month string.

    public object Convert(object value, Type targetType,

        object parameter, string language)

    {

        // value is the data from the source object.

        DateTime thisdate = (DateTime)value;

        int monthnum = thisdate.Month;

        string month;

        switch (monthnum)

        {

            case 1:

                month = "January";

                break;

            case 2:

                month = "February";

                break;

            default:

                month = "Month not found";

                break;

        }

        // Return the value to pass to the target.

        return month;

 

    }

 

    // ConvertBack is not implemented for a OneWay binding.

    public object ConvertBack(object value, Type targetType,

        object parameter, string language)

    {

        throw new NotImplementedException();

    }

 

    #endregion

}

<UserControl.Resources>

  <local:DateToStringConverter x:Key="Converter1"/>

</UserControl.Resources>

 

...

 

<TextBlock Grid.Column="0"

  Text="{Binding Month, Converter={StaticResource Converter1}}"/>

支持的绑定方案

方案	C#
绑定到对象	可以为任何对象
从绑定对象中获取属性更改更新	数据对象必须实现 INotifyPropertyChanged 接口
绑定到集合	使用 List(Of T)
从绑定集合中获取集合更改更新	使用 ObservableCollection(Of T)
实现支持绑定的集合	扩展   List(Of T)   或实现   IList 、 IList （属于   Object ）、 IEnumerable  或   IEnumerable （属于  Object ）。绑定到通用  IList(Of T)  和  IEnumerable(Of T)  的操作不受支持
实现支持集合更改更新的集合	扩展 ObservableCollection(Of T)   或实现（非通用） IList   和   INotifyCollectionChanged
实现支持增量加载的集合	扩展   ObservableCollection(Of T)   或实现（非通用） IList   和   INotifyCollectionChanged 。此外，还实现 ISupportIncrementalLoading