按钮IsEnabled永远不会改变

Question

这是我的Button声明,用.xaml文件编写:

<dxlc:LayoutGroup Orientation="Horizontal"  Margin="5,15,0,5">
    <Grid MinWidth="100">
        <Grid.RowDefinitions>
            <RowDefinition Height="Auto"/>
            <RowDefinition Height="Auto"/>
        </Grid.RowDefinitions>
        <Button 
            IsEnabled="{Binding IsSearchCriteriaHasValue}" 
            Content="Search" 
            MaxHeight="25" 
            MaxWidth="70" 
            ClipToBounds="True"  
            VerticalAlignment="Center"
            HorizontalAlignment="Center" 
            HorizontalContentAlignment="Center"                  
            VerticalContentAlignment="Center" 
            Command="{Binding SearchCommand}"/>
    </Grid>
</dxlc:LayoutGroup>

这是返回true/false的函数,无论用户是否在搜索按钮旁边的搜索框中键入了任何搜索文本.该函数位于另一个.cs文件中:

public bool isButtonEnabled
{
    return (SearchBox.Selection.Count > 0);
}

问题是isEnabled的值永远不会改变,它保持为真,即按钮始终保持启用状态,或者如果我更改>符号,按钮始终处于禁用状态.有什么建议？

Answer 1

该IsSearchCriteriaHasValue需求引发一个事件,它改变了,你可以通过使用INotifyPropertyChanged界面:

public class Customer : INotifyPropertyChanged
{
    // INotifyPropertyChanged members
    public event PropertyChangedEventHandler PropertyChanged;

    public void OnPropertyChanged(PropertyChangedEventArgs e)
    {
        if (PropertyChanged != null)
        {
            PropertyChanged(this, e);
        }
    }

    // Your property
    private string _Name;

    public string Name
    {
        get
        {
            return _Name;
        }
        set
        {
           _Name = value;
           OnPropertyChanged(new PropertyChangedEventArgs("Name"));
        }
    }
}