静态属性未在 UI 中更新

Question

我花了最后一个小时试图在 google 和 stackoverflow 中找到答案。我遵循了不同的建议和建议，但到目前为止没有任何效果。我当前的代码如下所示：

public class GlobalManager : ViewModelBase
{
    static object _LockObject_GFS = new object();
    static double _GlobalFontSize;
    public static double GlobalFontSize
    {
        get
        {
            lock (_LockObject_GFS)
            {
                _GlobalFontSize = GetGlobalResource<double>(LambdaHelper.MemberToString(() => GlobalFontSize));
                return _GlobalFontSize;
            }
        }
        set
        {
            lock (_LockObject_GFS)
            {
                if (_GlobalFontSize != value)
                {
                    _GlobalFontSize = value;
                    SetGlobalResource(value, LambdaHelper.MemberToString(() => GlobalFontSize));
                    NotifyStaticPropertyChanged(() => GlobalFontSize);
                }
            }
        }
    }
}

getter 和 setter 都被调用。 NotifyStaticPropertyChanged 有效，我的 UI 没有更新。我添加了一个TextBlock 来检查它是否更新。显然没有。

<TextBlock Text="{Binding Path=(global:GlobalManager.GlobalFontSize), Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}"/>

如果我在我的 VM（当前 DataContext）中定义一个属性，并将其绑定到 TextBlock，它会正确更新为当前值。

目前Slider 的DependencyProperty Value 绑定到此属性以更新字体大小。 (IsSnapToTickEnabled="True")

public double GlobalFontSize
{
    get { return GlobalManager.GlobalFontSize; }
    set { GlobalManager.GlobalFontSize = value; NotifyPropertyChanged(() => GlobalFontSize); }
}

如何让绑定与静态属性一起正常工作？ StaticPropertyChanged 事件不为空。

StaticPropertyChanged?.Invoke(null, new PropertyChangedEventArgs(propertyName));

---

编辑 1：

public static void NotifyStaticPropertyChanged(string propertyName)
{
    StaticPropertyChanged?.Invoke(null, new PropertyChangedEventArgs(propertyName));
}

public static void NotifyStaticPropertyChanged<T>(Expression<Func<T> > property)
{
    var expr = property.Body as MemberExpression;
    if (expr == null)
        throw new ArgumentException("Lambda does not contain member expression. () => MyClassOrObject.Property");
    NotifyStaticPropertyChanged(expr.Member.Name);
}

Answer 1

确保您的 GetGlobalResource 和 SetGlobalResource 方法按预期工作并且您的事件签名正确。

您可以参考下面的工作示例实现并将其与您的进行比较：

public class GlobalManager
{
    static object _LockObject_GFS = new object();
    static double _GlobalFontSize;
    public static double GlobalFontSize
    {
        get
        {
            lock (_LockObject_GFS)
            {
                return _GlobalFontSize;
            }
        }
        set
        {
            lock (_LockObject_GFS)
            {
                if (_GlobalFontSize != value)
                {
                    _GlobalFontSize = value;
                    NotifyStaticPropertyChanged(()=> GlobalFontSize);
                }
            }
        }
    }

    public static event EventHandler<PropertyChangedEventArgs> StaticPropertyChanged;

    public static void NotifyStaticPropertyChanged(string propertyName)
    {
        StaticPropertyChanged?.Invoke(null, new PropertyChangedEventArgs(propertyName));
    }

    public static void NotifyStaticPropertyChanged<T>(Expression<Func<T>> property)
    {
        var expr = property.Body as MemberExpression;
        if (expr == null)
            throw new ArgumentException("Lambda does not contain member expression. () => MyClassOrObject.Property");
        NotifyStaticPropertyChanged(expr.Member.Name);
    }
}

编辑：如果事件是在基类中定义的，则它不起作用。

public abstract class MyBaseViewModel
{
    public static event EventHandler<PropertyChangedEventArgs> StaticPropertyChanged;

    public static void NotifyStaticPropertyChanged(string propertyName)
    {
        StaticPropertyChanged?.Invoke(null, new PropertyChangedEventArgs(propertyName));
    }

    public static void NotifyStaticPropertyChanged<T>(Expression<Func<T>> property)
    {
        var expr = property.Body as MemberExpression;
        if (expr == null)
            throw new ArgumentException("Lambda does not contain member expression. () => MyClassOrObject.Property");
        NotifyStaticPropertyChanged(expr.Member.Name);
    }
}

public class GlobalManager : MyBaseViewModel
{
    static object _LockObject_GFS = new object();
    static double _GlobalFontSize = 10.0;
    public static double GlobalFontSize
    {
        get
        {
            lock (_LockObject_GFS)
            {
                return _GlobalFontSize;
            }
        }
        set
        {
            lock (_LockObject_GFS)
            {
                if (_GlobalFontSize != value)
                {
                    _GlobalFontSize = value;
                    NotifyStaticPropertyChanged("GlobalFontSize");
                }
            }
        }
    }
}

StaticPropertyChangedEvent 必须定义在属性所在的同一类中，才能更新绑定：

View is not getting notified when value of static Property Changes