Question

我有一个＆＃34; A＆＃34;和Class＆＃34; VisibilityStateProvider＆＃34;每当A类的任何键发生变化时，我都会调用VisibilityStateProvider的NotifyVisibilityChanged，但GetVisibilityValue（key）方法永远不会被调用。并且可见性不会在UI上获得更新。

感谢您的帮助!!

     public class A:  IDictionary<string, object>, INotifyPropertyChanged

                {
                    public VisibilityStateProvider VisibilityProvider { get; set; }

                    public A()
                    {
                        VisibilityProvider = new VisibilityStateProvider(this);
                    }


                }
             public class VisibilityStateProvider : IPropertyStateProvider
                {
                    private A A;

                    public VisibilityStateProvider(A a)
                    {
                        A= a;
                    }
                 public bool this[string key]
                    {
                    get
                    {
                        return GetVisibilityValue(key);
                    }
                }
           private bool GetVisibilityValue(string key)
                  {
                     //returns true or false on basis of some condition.
                   }
         public void NotifyVisibilityChanged(string key)
            {
                var a= $"Item[{key}]";

                PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(a));
            }
            }
             public interface IPropertyStateProvider : INotifyPropertyChanged
                {
                    bool this[string key] { get;}
                }


            //xaml
            <TextBox Text="{Binding A[mf_number1], Mode=TwoWay}" Visibility="{Binding A.VisibilityProvider[mf_number1],Converter={StaticResource BoolToVisibilityConverter}}" ></TextBox >

Answer 1

我还没有检查完整的代码，所以在这里我将分享一个你需要知道的事情作为开始。在您的代码中，GetVisibilityValue（key）永远不会被调用，因为您没有以正确的方式调用它。请尝试以下代码作为测试：

 public A()
    {
        VisibilityProvider = new VisibilityStateProvider(this);
        var something = VisibilityProvider["test"];
    }

这里只有你像第二行一样打电话，才能调用下面的代码：

            get
                {
                    return GetVisibilityValue(key);
                }

UWP绑定不起作用

1 个答案: