INotifyPropertyChanged用于静态变量

Question

我有一个非静态变量,INotifyPropertyChanged成功实现.然后我尝试将其设为全局,因此将其变为静态变量.但这一次,INotifyPropertyChanged不起作用.有解决方案吗

Answer 1

INotifyPropertyChanged适用于实例属性.一种解决方案是使用单例模式并保持INotifyPropertyChanged,另一种是使用您自己的事件来通知侦听器.

单身人士的例子

public sealed class MyClass: INotifyPropertyChanged
{
   private static readonly MyClass instance = new MyClass();
   private MyClass() {}

   public static MyClass Instance
   {
      get 
      {
         return instance; 
      }
   }

   // notifying property
   private string privMyProp;
   public string MyProp
   {
       get { return this.privMyProp; }

       set
       {
           if (value != this.privMyProp)
           {
               this.privMyProp = value;
               NotifyPropertyChanged("MyProp");
           }
       }
   }


   // INotifyPropertyChanged implementation
   public event PropertyChangedEventHandler PropertyChanged;

   private void NotifyPropertyChanged(String info)
   {
       var handler = PropertyChanged;
       if (handler != null)
       {
           handler(this, new PropertyChangedEventArgs(info));
       }
   }
}

编辑:在WPF 4.5中,他们为静态属性引入了属性更改机制:

您可以使用静态属性作为数据绑定的源.如果引发静态事件,数据绑定引擎会识别属性值何时更改.例如,如果SomeClass类定义了一个名为MyProperty的静态属性,则SomeClass可以定义在My​​Property的值更改时引发的静态事件.静态事件可以使用以下任一签名.

public static event EventHandler MyPropertyChanged;
public static event EventHandler<PropertyChangedEventArgs> StaticPropertyChanged;

Answer 2

非常好的例子,当我想将一些属性绑定到组件时,我将它用于应用程序中的一些常规设置

    public sealed class DataGridClass:INotifyPropertyChanged
{
      private static readonly DataGridClass instance = new DataGridClass();
      private DataGridClass() { }

      public static DataGridClass Instance
       {
          get 
          {
             return instance; 
          }
       }

    private int _DataGridFontSize {get;set;}

    public int DataGridFontSize
    {
        get { return _DataGridFontSize; }
        set { _DataGridFontSize = value;
            RaisePropertyChanged("DataGridFontSize");
        }
    }
    public event PropertyChangedEventHandler PropertyChanged;

    private void RaisePropertyChanged(string name)
    {
        if (PropertyChanged != null)
            PropertyChanged(this, new PropertyChangedEventArgs(name));
    }

设置启动属性:

DataGridClass.Instance.DataGridFontSize = 14(or read from xml)

将此绑定到组件属性

xmlns:static="clr-namespace:MyProject.Static"
<extgrid:ExtendedDataGrid x:Name="testGrid"  ClipboardCopyMode="IncludeHeader" AutoGenerateColumns="False">
<extgrid:ExtendedDataGrid.Resources>
    <Style TargetType="{x:Type DataGridCell}">
        <Setter Property="FontSize" 
        Value="{Binding Source={x:Static static:DataGridClass.Instance},
        Path=DataGridFontSize, Mode=OneWay,UpdateSourceTrigger=PropertyChanged}"/>
    </Style>
</extgrid:ExtendedDataGrid.Resources>

当您在应用程序中的某个位置更改此值,如"首选项" - > DataGrid FontSize - 它会自动更新此属性以使用UpdateSourceTrigger进行绑定

    private void comboBoxFontSize_DropDownClosed(object sender, EventArgs e)
    {
        DataGridClass.Instance.DataGridFontSize = Convert.ToInt32(comboBoxFontSize.Text);
    }


   <ComboBox Grid.Column="1" Grid.Row="0" Height="21" Width="75" Name="comboBoxFontSize" HorizontalAlignment="Left" 
                              VerticalAlignment="Center"  DropDownClosed="comboBoxFontSize_DropDownClosed" 
                              ItemsSource="{Binding Source={x:Static commands:ConstClass.ListOfFontSize},Mode=OneWay}" 
                              SelectedItem="{Binding Source={x:Static static:DataGridClass.Instance},Path=DataGridFontSize, 
                        Mode=OneWay,UpdateSourceTrigger=PropertyChanged}"/>