当绑定到引用保持不变的对象时，忽略PropertyChanged

Question

I'm pretty new to the WPF/Binding world, but now I'm using it for some time with some degrees of success.

Now I'm stuck with a problem very similar to the one described in this question , but regarding a class instead of an IEnumerable. I'm not sure if the behavior is intentional also for a class or if there is a way to solve it.

Let's say I have my simple custom class "Vector3" that contains 3 doubles Vector3.cs

    public class Vector3
    {
        public double X { get; set; }
        public double Y { get; set; }
        public double Z { get; set; }

        public Vector3(double x, double y, double z)
        {
            X = x;
            Y = y;
            Z = z;
        }

        public Vector3(Vector3 vec)
        {
            X = vec.X;
            Y = vec.Y;
            Z = vec.Z;
        }

        public override bool Equals(object obj)
        {
            if (!(obj is Vector3))
                return false;

            Vector3 other = obj as Vector3;

            return X == other.X && Y == other.Y && Z == other.Z;
        }

        public override int GetHashCode()
        {
            unchecked
            {
                return (X.GetHashCode() * 42) ^ Y.GetHashCode() + Z.GetHashCode();
            }
        }
    }

And I have a user-control that exposes a DependencyProperty of this type

ucVector3.xaml.cs

public partial class ucVector3 : UserControl
    {
        public static readonly DependencyProperty ValueProperty = DependencyProperty.Register("Value",
                     typeof(Vector3), typeof(ucVector3),
                     new FrameworkPropertyMetadata(null, new PropertyChangedCallback(_OnModelChanged)));

        private static void _OnModelChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
        {
            Console.WriteLine("Binding worked! I've received a new Vector3 " +
                              "with value X = " + (e.NewValue as Vector3).X); 
        }

        public Vector3 Value
        {
            get
            {
                return (Vector3)GetValue(ValueProperty);
            }
            set
            {
                SetValue(ValueProperty, value);
            }
        }
    ...

Then I try to use this user-control binding the Value property like in this example:

MainWindow.xaml

<Window x:Class="StackOverflow.Example.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
        xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
        xmlns:local="clr-namespace:StackOverflow.Example"
        mc:Ignorable="d"
        Title="MainWindow" Height="350" Width="525">
    <Grid Background="Azure">
        <Grid.RowDefinitions>
            <RowDefinition Height="5*"/>
            <RowDefinition Height="1*"/>
        </Grid.RowDefinitions>
        <Grid.ColumnDefinitions>
            <ColumnDefinition/>
            <ColumnDefinition/>
        </Grid.ColumnDefinitions>
        <Button Content="Update" Margin="5" Grid.Row="1" Grid.ColumnSpan="2" Click="Button_Click" />
        <local:ucVector3 Value="{Binding SameReference}" Margin="5" />
        <local:ucVector3 Value="{Binding NewReference}" Margin="5" Grid.Column="1" />
    </Grid>
</Window>

MainWindow.xaml.cs

    public partial class MainWindow : Window, INotifyPropertyChanged
    {
        #region INotifyPropertyChanged
        SynchronizationContext uiContext = SynchronizationContext.Current;
        public event PropertyChangedEventHandler PropertyChanged;

        protected virtual void OnPropertyChanged([CallerMemberName] string propertyName = null)
        {
            if (uiContext != SynchronizationContext.Current)
            {
                uiContext.Send(_ =>
                {
                    PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
                }, null);
            }
            else
            {
                PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
            }
        }
        #endregion

        private Vector3 newValue = new Vector3(0, 0, 0);

        public Vector3 SameReference { get; set; }
        public Vector3 NewReference { get; set; }

        public MainWindow()
        {
            this.DataContext = this;
            InitializeComponent();

        }

        private void Button_Click(object sender, RoutedEventArgs e)
        {
            newValue.X = newValue.X + 2;
            newValue.Y = newValue.Y + 3;
            newValue.Z = newValue.Z + 4;

            SameReference = newValue;
            NewReference = new Vector3(newValue);

            OnPropertyChanged("SameReference"); //successful notify, ignored values
            OnPropertyChanged("NewReference"); //successful notify, processed values
        }
    }

Pressing the button the first time both user-controls will be updated with (3,4,5), but from the second time, only the "NewReference" property will be updated in the right user-control.

I get that for IEnumerables WPF will propagate the OnPropertyChanged event only if the reference is different, and changes in the IEnumerable need to call the INotifyCollectionChanged event instead.

Why my "OnPropertyChanged("SameReference")" is not propagated? I changed the values, I want the event to propagate to update the interface, or I wouldn't call the event...

Is this behavior intentional? Why it checks the object reference and not maybe if it is Equals? Is there a way to "force" the event to go through? Or how should I organize my classes in this case?

Here you can download the example solution described in this question , created in VisualStudio2015.

Thanks to all for your time.

Answer 1

from i have seen in your project, you have to comment these lines in your ucVector3.xaml.cs, these lines avoid to update your usercontrol:

        if (value.X == lastNudValue.X && value.Y == lastNudValue.Y && value.Z == lastNudValue.Z)
           return;