c# - 我需要在代码隐藏中调用 INotifyPropertyChanged() 吗？

Question

在我的程序中，我想禁用 contentPresenter当我的另一个contentPresenter获得焦点。每个演示者都由位于我的 MainWindowViewModel 中的一个属性表示.这也是 IsEnabled 的地方属性位于两个演示者。

两者都是 contentPresenters使用以下结构创建:UserControl -> ViewModel -> Data Model。

现在我正在尝试禁用必要的 contentPresenter通过更改 IsEnabled来自 contentPresenter 的代码隐藏的主窗口 ViewModel 中的属性得到关注。

contentPresenter用户控制代码隐藏:

public partial class EditBlockUC : UserControl
{
    public EditBlockViewModel ViewModel { get { return DataContext as EditBlockViewModel; } }

    public EditBlockUC()
    {
        InitializeComponent();
    }

    //Runs when the user control gets focus
    private void UserControl_GotFocus(object sender, RoutedEventArgs e)
    {
        //This UserControl has access to MainWindowViewModel through
        //it's own ViewModel, EditBlockViewModel         
        ViewModel.MainViewModel.LeftWidgetEnabled = false;
    }
}

线路:ViewModel.MainViewModel.LeftWidgetEnabled = false;成功更改主窗口 View 模型中的属性，但 View 不受影响。我可以通过找到调用 NotifyPropertyChange() 的方法来解决这个问题吗？ ？如果是这样，我该怎么做？

如果这是完全错误的解决方案，请告诉我，并帮助我解决问题。

谢谢

更新 1:

我的完整基类:

public class PropertyChangedBase : INotifyPropertyChanged
{
    public event PropertyChangedEventHandler PropertyChanged;
    protected virtual void OnPropertyChanged(string propertyName)
    {
        PropertyChangedEventHandler handler = PropertyChanged;
        if (handler != null) handler(this, new PropertyChangedEventArgs(propertyName));
    }

    public virtual void NotifyPropertyChange<TProperty>(Expression<Func<TProperty>> property)
    {
        var lambda = (LambdaExpression)property;

        MemberExpression memberExpression;
        if (lambda.Body is UnaryExpression)
        {
            var unaryExpression = (UnaryExpression)lambda.Body;
            memberExpression = (MemberExpression)unaryExpression.Operand;
        }
        else
            memberExpression = (MemberExpression)lambda.Body;

        OnPropertyChanged(memberExpression.Member.Name);
    }

    protected bool SetField<T>(ref T field, T value, string propertyName)
    {
        if (EqualityComparer<T>.Default.Equals(field, value)) return false;
        field = value;
        OnPropertyChanged(propertyName);
        return true;
    }
}

更新 2:

我的 LeftWidgetEnabled属性:

public bool LeftWidgetEnabled
{
    get { return _leftWidgetEnabled; }
    set { SetField(ref _leftWidgetEnabled, value, "LeftWidgetEnabled"); }
}

Answer 1

ViewModel.MainViewModel 类的 LeftWidgetEnabled 必须是这样的:

private bool leftWidgetEnabled;
public bool LeftWidgetEnabled
{
    get { return leftWidgetEnabled; }
    set { SetField(ref leftWidgetEnabled, value, "LeftWidgetEnabled"); }
}

此外，您的 MainViewModel 必须实现 INotifyPropertyChanged .

最好让 MainViewModel 从 ViewModelBase 继承并让 ViewModelBase 实现 INotifyPropertyChanged .

public class MainViewModel : ViewModelBase
{        
    private bool leftWidgetEnabled;
    public bool LeftWidgetEnabled
    {
        get { return leftWidgetEnabled; }
        set { SetField(ref leftWidgetEnabled, value, "LeftWidgetEnabled"); }
    }
}

public class ViewModelBase : INotifyPropertyChanged
{
    // boiler-plate
    public event PropertyChangedEventHandler PropertyChanged;
    protected virtual void OnPropertyChanged(string propertyName)
    {
        PropertyChangedEventHandler handler = PropertyChanged;
        if (handler != null) handler(this, new PropertyChangedEventArgs(propertyName));
    }
    protected bool SetField<T>(ref T field, T value, string propertyName)
    {
        if (EqualityComparer<T>.Default.Equals(field, value)) return false;
        field = value;
        OnPropertyChanged(propertyName);
        return true;
    }
}

更新 1

然后您的 ContentPresenter 应该像这样绑定(bind):

<ContentPresenter IsEnabled="{Binding Path=LeftWidgetEnabled}" />

虽然 UserControl 的 DataContext(ContentPresenter 开启)应该是 MainViewModel 的一个实例.

例如:

<UserControl 
    x:Class="MyApplication.UserControl1"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:d="http://schemas.microsoft.com/expression/blend/2008" 
    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" 
    xmlns:viewModels="**PATH TO YOUR VIEWMODELS-ASSEMBLY**"
    mc:Ignorable="d">

<UserControl.DataContext>
    <viewModels:MainViewModel />
</UserControl.DataContext>

    <ContentPresenter IsEnabled="{Binding Path=LeftWidgetEnabled}" />
</UserControl>