Question

我目前在WPF 4.6.1中遇到双向绑定问题。它只是不起作用，我用这个例子。 https://www.c-sharpcorner.com/UploadFile/mahesh/binding-static-properties-in-wpf-4-5/

我的项目有两个窗口（在第一个窗口按下TextBlock时打开的数字小键盘和显示数据的窗体）。它还有一个静态类，用于保存在虚拟键盘上输入的信息。

这是打开键盘的TextBox

<TextBlock Margin="5 10 0 10" x:Name="submittedQty" Background="PaleVioletRed" HorizontalAlignment="Stretch" TextAlignment="Center" Text="{Binding Path=(local:TemporaryData.SubmittedQuantity), Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}" FontSize="22" FontWeight="Bold" MouseLeftButtonDown="submittedQty_MouseLeftButtonDown"/>

这是我的静态类，包含信息。

static class TemporaryData //Static Class
{
    private static string _SubmittedQuantity;
    private static string _ConfirmedQuantity;

    public static event EventHandler QuantityChanged;

    public static string SubmittedQuantity {
        get => _SubmittedQuantity;
        set
        {
            if (value != _SubmittedQuantity)
            {
                _SubmittedQuantity = value;
                if (QuantityChanged != null)
                    QuantityChanged(null, EventArgs.Empty);
            }

        }
    }

    public static string ConfirmedQuantity {
        get => _ConfirmedQuantity;
        set
        {
            if (value != _ConfirmedQuantity)
            {
                _ConfirmedQuantity = value;
                if (QuantityChanged != null)
                {
                    QuantityChanged(null, EventArgs.Empty);
                }

            }
        }
    }

在虚拟数字小键盘上按OK后，我执行以下方法：

    private void okBtn_Click(object sender, RoutedEventArgs e)
    {
        models.TemporaryData.ConfirmedQuantity = typedTextTxtBox.Text;
        this.Close();
    }

运行调试器我注意到当我在虚拟键盘上更新了我的值

if (QuantityChanged != null)

跳过

因为QuantityChanged为空。

当静态类的值发生变化时，有人能告诉我为什么它不会更新文本块吗？

由于

按照Clemens的建议后，我更新了我的代码如下：

更新 XML

<TextBlock Margin="5 10 0 10" x:Name="submittedQty" Background="PaleVioletRed" HorizontalAlignment="Stretch" TextAlignment="Center" Text="{Binding Path=(local:TemporaryData.SubmittedQuantity)}" FontSize="22" FontWeight="Bold" MouseLeftButtonDown="submittedQty_MouseLeftButtonDown"/>

静态类

static class TemporaryData
    {
        private static string _SubmittedQuantity;
        private static string _ConfirmedQuantity;

        //public static event EventHandler QuantityChanged;
        public static event EventHandler<PropertyChangedEventArgs> StaticPropertyChanged;

        public static string SubmittedQuantity {
            get => _SubmittedQuantity;
            set
            {
                if (value != _SubmittedQuantity)
                {
                    _SubmittedQuantity = value;
                    StaticPropertyChanged?.Invoke(null,
                        new PropertyChangedEventArgs(nameof(SubmittedQuantity)));
                }

            }
        }

        public static string ConfirmedQuantity {
            get => _ConfirmedQuantity;
            set
            {
                if (value != _ConfirmedQuantity)
                {
                    _ConfirmedQuantity = value;
                    StaticPropertyChanged?.Invoke(null,
                        new PropertyChangedEventArgs(nameof(ConfirmedQuantity)));
                }
            }
        }

Answer 1

QuantityChanged事件仅适用于Quantity属性。

为了通知SubmittedQuantity属性的更改值，应该有SubmittedQuantityChanged个事件：

public static event EventHandler SubmittedQuantityChanged;

public static string SubmittedQuantity
{
    get => _SubmittedQuantity;
    set
    {
        if (value != _SubmittedQuantity)
        {
            _SubmittedQuantity = value;
            SubmittedQuantityChanged?.Invoke(null, EventArgs.Empty);
        }
    }
}

IMO更好的选择是为所有静态属性使用公共属性更改事件：

public static event PropertyChangedEventHandler StaticPropertyChanged;

public static string SubmittedQuantity
{
    get => _SubmittedQuantity;
    set
    {
        if (value != _SubmittedQuantity)
        {
            _SubmittedQuantity = value;
            StaticPropertyChanged?.Invoke(null,
                new PropertyChangedEventArgs(nameof(SubmittedQuantity)));
        }
    }
}

有关详细信息，请参阅What's New in WPF Version 4.5 - Binding to static properties。

WPF双向绑定到静态属性

1 个答案: