WPF：系結值更改時如何編輯標簽？[復制]

我正在嘗試在 WPF 中創建用戶控制元件（使用 xceed）。我有一個組合框和一個 integerUpDown。

當其中一個更改其值時，標簽應更改其內容。第一個標簽只有一個簡單的系結到 integerUpDown，這是有效的。Visual StudioOnPropertyChanged()自動創建和 getter/setter，我嘗試使用它將結果系結到第二個標簽，但它不起作用。什么都沒發生。

這是我的 XAML：

<UserControl x:Class="WpfApp2.CardSelectionControl"
             xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
             xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" 
             xmlns:d="http://schemas.microsoft.com/expression/blend/2008" 
             xmlns:local="clr-namespace:WpfApp2" xmlns:xctk="http://schemas.xceed.com/wpf/xaml/toolkit"
             mc:Ignorable="d" 
             d:DesignHeight="450" d:DesignWidth="800">    

        <StackPanel Margin="5" Width="300" Height="400" Background="LightGray">
            
        <TextBox Margin="5" AcceptsReturn="True" FontSize="20" Padding="5" Height="70">placeholding</TextBox>

        <ComboBox SelectedIndex="{Binding SelectedIndex}" Background="Red" Margin="5">
                <ComboBoxItem Content="card1"></ComboBoxItem>
                <ComboBoxItem Content="card2"></ComboBoxItem>
        </ComboBox>

        <xctk:UIntegerUpDown Margin="5" x:Name="upDown" Value="{Binding Level}" ></xctk:UIntegerUpDown>

        <Label Height="50" Content="{Binding Level}"></Label>
        <Label Height="50" Content="{Binding Result}" ></Label>
            
        </StackPanel>
</UserControl>

后面的代碼：

using System.ComponentModel;
using System.Runtime.CompilerServices;
using System.Windows;

namespace WpfApp2
{
    public partial class CardSelectionControl : INotifyPropertyChanged
    {
        public event PropertyChangedEventHandler PropertyChanged;

        public int Level
        {
            get { OnPropertyChanged(); return (int)GetValue(LevelProperty); }
            set
            {
                OnPropertyChanged();
                SetValue(LevelProperty, value);
            }
        }

        public int SelectedIndex
        {
            get { OnPropertyChanged();  return (int)GetValue(SelectedIndexProperty); }
            set
            {
                OnPropertyChanged();
                SetValue(SelectedIndexProperty, value);
            }
        }

        public int Result
        {
            get { return (int)GetValue(ResultProperty); }
            set { SetValue(ResultProperty, value); }
        }

        protected void OnPropertyChanged([CallerMemberName] string propertyName = "")
        {
            if (SelectedIndex == 0) 
            { Result = Level * 2; }
            else if (SelectedIndex == 1) 
            { Result = Level * 3; }
        }

        public static readonly DependencyProperty ResultProperty =
            DependencyProperty.Register("Result", typeof(int), typeof(CardSelectionControl), new PropertyMetadata(20));

        public static readonly DependencyProperty LevelProperty =
            DependencyProperty.Register("Level", typeof(int), typeof(CardSelectionControl), new PropertyMetadata(10));

        public static readonly DependencyProperty SelectedIndexProperty =
            DependencyProperty.Register("SelectedIndex", typeof(int), typeof(CardSelectionControl), new PropertyMetadata(0));

        public CardSelectionControl()
        {
            DataContext = this;
            InitializeComponent();
        }
    }
}

uj5u.com熱心網友回復：

我假設您希望您的二傳手被呼叫，因此您為什么要OnPropertyChanged到處呼叫。它們不會被呼叫，因此您的代碼不會被執行。

相反，您可以向依賴項屬性添加回呼，以便知道值何時更改：

public static readonly DependencyProperty LevelProperty =
    DependencyProperty.Register("Level", 
                                typeof(int), 
                                typeof(CardSelectionControl), 
                                new PropertyMetadata(10, new PropertyChangedCallback(OnChanged)));
                                                         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

private static void OnChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
{
    var cardSelectionControl = (CardSelectionControl)d;
    cardSelectionControl.Recalculate();
}

我冒昧地更改OnPropertyChanged為Recalculate，也為組合框添加了一個PropertyChangedCallback，整個代碼變為：

public partial class CardSelectionControl : INotifyPropertyChanged
{
    public event PropertyChangedEventHandler PropertyChanged;

    public int Level
    {
        get { return (int)GetValue(LevelProperty); }
        set { SetValue(LevelProperty, value); }
    }

    public int SelectedIndex
    {
        get { return (int)GetValue(SelectedIndexProperty); }
        set { SetValue(SelectedIndexProperty, value); }
    }

    public int Result
    {
        get { return (int)GetValue(ResultProperty); }
        set { SetValue(ResultProperty, value); }
    }

    public void Recalculate()
    {
        if (SelectedIndex == 0)
            Result = Level * 2;
        else if (SelectedIndex == 1)
            Result = Level * 3;
    }

    public static readonly DependencyProperty ResultProperty =
        DependencyProperty.Register("Result", typeof(int), typeof(CardSelectionControl), new PropertyMetadata(20));

    public static readonly DependencyProperty LevelProperty =
        DependencyProperty.Register("Level", typeof(int), typeof(CardSelectionControl), new PropertyMetadata(10, new PropertyChangedCallback(OnChanged)));

    public static readonly DependencyProperty SelectedIndexProperty =
        DependencyProperty.Register("SelectedIndex", typeof(int), typeof(CardSelectionControl), new PropertyMetadata(0, new PropertyChangedCallback(OnChanged)));

    private static void OnChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
    {
        var cardSelectionControl = (CardSelectionControl)d;
        cardSelectionControl.Recalculate();
    }

    public CardSelectionControl()
    {
        DataContext = this;
        InitializeComponent();
    }
}

標籤：C＃ wpf xml 捆绑

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