与 IValueConverter 绑定不起作用

Question

我正在尝试从TextColor的标签绑定ViewCell ：

Label myLabel = new Label { Text = "SomeText" };

myLabel.SetBinding(Label.TextColorProperty,
    new Binding("TheTextColor", BindingMode.TwoWay, new LabelTextColorConverter()));

这是转换器：

public class LabelTextColorConverter : IValueConverter
{
    public bool OldValue { get; set; }

    public object Convert(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
    {
        OldValue = (bool) value;
        Debug.WriteLine("asdadasdsadsada");
        if ((bool)value)
            return Color.Red;
        else
            return Color.Silver;
    }

    public object ConvertBack(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
    {
        Debug.WriteLine("qwqweqewqeeqe");
        return OldValue;
    }
}

调试输出不会出现，颜色也不会改变。 我看不出有什么不对。

Answer 1

为什么你需要双向绑定？ 我认为没有必要。

myLabel.SetBinding(Label.TextColorProperty, new Binding("TheTextColor", BindingMode.OneWay, new LabelTextColorConverter()));

然后：

public class LabelTextColorConverter : IValueConverter
{
    public object Convert(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
    {
        bool val = (bool)value;

        if (val)
            return Color.Red;
        else
            return Color.Silver;
    }

    public object ConvertBack(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
    {
        throw new NotImplementedException();
    }
}

...它应该可以正常工作。 还要确保您为页面/控件正确设置了 BindingContext。