静态属性未在UI中更新 [英] Static property not updating in UI

问题描述

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的建议，但到目前为止没有任何效果.我当前的代码如下:

I spent the last hour(s) trying to find an answer in google and stackoverflow. I followed different advices & suggestions, but nothing worked so far. My current code looks like this:

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);
                }
            }
        }
    }
}

吸气剂二传手都被称为. NotifyStaticPropertyChanged可以使用，并且我的UI不会更新.我添加了TextBlock来检查它是否更新.显然不是.

The getter & setter are both called. NotifyStaticPropertyChanged works and my UI does not update. I've added a TextBlock to check if it updates. Apparently it does not.

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

如果我在VM(当前DataContext)中定义一个属性，并将其绑定到TextBlock，它将使用当前值正确更新.

If I define a property in my VM (current DataContext), and bind it to a TextBlock, it updates correctly with the current value.

当前，将Slider的DependencyProperty Value绑定到此属性，以更新字体大小. (IsSnapToTickEnabled="True")

Currently the DependencyProperty Value of a Slider is bound to this property in order to update the font size. (IsSnapToTickEnabled="True")

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

如何使绑定与static属性一起正常工作? StaticPropertyChanged事件不为空.

How do I get the binding to work correctly with the static property ? The StaticPropertyChanged event is not null.

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

---

---

Edit 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);
}

推荐答案

请确保您的GetGlobalResource和SetGlobalResource方法能够按预期工作，并且事件签名正确.

Make sure that your GetGlobalResource and SetGlobalResource methods work as expected and that your event signature is correct.

您可以参考以下工作示例实现并将其与您的实现进行比较:

You could refer to the below working sample implementation and compare it to yours:

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:如果该事件是在基类中定义的，则无法使用.

It doesn't work if the event is defined in a base class though.

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必须在属性所在的同一类中定义，以便绑定进行更新:

The StaticPropertyChangedEvent must be defined in same class where property resides for the binding to get updated:

值未获得通知时视图静态属性更改

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