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WPF C绑定代码-为什么这个简单的示例不起作用?

binding wpf .net c#

Greg · 技术社区 · 14 年前

<Window x:Class="testapp1.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        Title="MainWindow" Height="350" Width="525">
    <Grid>
        <Button  Height="23" HorizontalAlignment="Left" Margin="20,12,0,0" 
                 Name="testButton" VerticalAlignment="Top" Width="126" 
                 Click="testButton_Click" Content="Increase Counter" />
        <Label Content="{Binding Path=TestCounter}" Height="37" 
               HorizontalAlignment="Right" Margin="0,12,122,0" 
               Name="testLabel2" VerticalAlignment="Top" 
               BorderThickness="3" MinWidth="200"  />
    </Grid>
</Window>


namespace testapp1
{
    public partial class MainWindow : Window
    {
        public TestModel _model;

        public MainWindow()
        {
            InitializeComponent();

            InitializeComponent();
            _model = new TestModel();
            _model.TestCounter = 0;
            this.DataContext = _model;
        }

        private void testButton_Click(object sender, RoutedEventArgs e)
        {
            _model.TestCounter = _model.TestCounter + 1;
            Debug.WriteLine("TestCounter = " + _model.TestCounter);
        }
    }

    public class TestModel : DependencyObject
    {
        public int TestCounter { get; set; }
    }

}

3 回复 | 直到 12 年前

Gennady Vanin ÐÐµÐ½Ð½Ð°Ð´Ð¸Ð¹ ÐÐ°Ð½Ð¸Ð½ Mikael Svenson 12 年前

    public int TestCounter
    {
        get { return (int)GetValue(TestCounterProperty); }
        set { SetValue(TestCounterProperty, value); }
    }

    // Using a DependencyProperty as the backing store for TestCounter.  
    //This enables animation, styling, binding, etc...
    public static readonly DependencyProperty TestCounterProperty =
        DependencyProperty.Register
             ("TestCounter", 
              typeof(int), 
              typeof(TestModel), 
              new UIPropertyMetadata(0));

rudigrobler 14 年前

对于这个简单的示例,请考虑使用INotifyPropertyChanged而不是dependencProperties!

更新如果确实要使用DPs,请使用VS2010或 Dr WPF's snippets for VS2008 ?

Jason Goemaat 14 年前

可以在中实现INotifyPropertyChanged接口系统组件模型命名空间。我通常实现一个更改过的方法,该方法可以接受许多属性名并检查未设置的事件。我这样做是因为有时我有多个依赖于一个值的属性,我可以从所有属性设置器中调用一个方法。

public class TestModel : INotifyPropertyChanged
{
    int m_TestCounter;
    public int TestCounter {
        get {
            return m_TestCounter;
        }
        set {
            m_TestCounter = value;
            Changed("TestCounter");
        }
    }

    #region INotifyPropertyChanged Members

    public event PropertyChangedEventHandler PropertyChanged;

    #endregion

    void Changed(params string[] propertyNames)
    {
        if (PropertyChanged != null)
        {
            foreach (string propertyName in propertyNames)
            {
                PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
            }
        }
    }
}