WPF中如何获取被点击的ObservableCollection元素的索引？

1. 修复ViewModel的属性递归错误 #

你的Numbers属性get访问器存在递归调用问题，会导致栈溢出，需改为返回私有字段：

private ObservableCollection<int> numbers = new ObservableCollection<int>() { 10, 10, 10, 10, 10, 10 };
public ObservableCollection<int> Numbers
{
    get => numbers; // 返回私有字段numbers，而非属性本身
    set
    {
        if (value != numbers)
        {
            numbers = value;
            PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(nameof(Numbers)));
        }
    }
}

2. 修正XAML按钮绑定语法 #

自定义按钮的Nums依赖属性需要明确指定，修正后的XAML：

<UniformGrid x:Name="Nums" Grid.Row="1" Rows="1">
    <local:Nums Nums="{Binding Numbers[0]}" Stroke="Red" Click="Button_Clicked" />
    <local:Nums Nums="{Binding Numbers[1]}" Stroke="Red" Click="Button_Clicked" />
    <local:Nums Nums="{Binding Numbers[2]}" Stroke="Red" Click="Button_Clicked" />
    <local:Nums Nums="{Binding Numbers[3]}" Stroke="Red" Click="Button_Clicked" />
    <local:Nums Nums="{Binding Numbers[4]}" Stroke="Red" Click="Button_Clicked" />
    <local:Nums Nums="{Binding Numbers[5]}" Stroke="Red" Click="Button_Clicked" />
</UniformGrid>

3. 实现点击事件的数值修改逻辑 #

通过UniformGrid的Children集合获取点击按钮的索引，然后修改对应位置的数值：

private void Button_Clicked(object sender, RoutedEventArgs e)
{
    var clickedBtn = sender as Nums;
    if (clickedBtn == null) return;

    // 获取按钮在集合中的索引
    int index = Nums.Children.IndexOf(clickedBtn);

    // 仅处理非末尾按钮（末尾按钮无右侧元素）
    if (index < numberChangerViewModel.Numbers.Count - 1)
    {
        numberChangerViewModel.Numbers[index] -= 1;
        numberChangerViewModel.Numbers[index + 1] += 1;
    }
}

4. 确保UI实时更新 #

ObservableCollection仅在元素增删时触发更新，修改值不会自动通知UI，需将int替换为实现INotifyPropertyChanged的自定义类：

public class NumberItem : INotifyPropertyChanged
{
    private int _value;
    public int Value
    {
        get => _value;
        set
        {
            if (_value != value)
            {
                _value = value;
                PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(nameof(Value)));
            }
        }
    }

    public event PropertyChangedEventHandler PropertyChanged;
}

更新ViewModel的集合类型：

private ObservableCollection<NumberItem> numbers = new ObservableCollection<NumberItem>()
{
    new NumberItem { Value = 10 },
    new NumberItem { Value = 10 },
    new NumberItem { Value = 10 },
    new NumberItem { Value = 10 },
    new NumberItem { Value = 10 },
    new NumberItem { Value = 10 }
};
public ObservableCollection<NumberItem> Numbers
{
    get => numbers;
    set
    {
        if (value != numbers)
        {
            numbers = value;
            PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(nameof(Numbers)));
        }
    }
}

最后修改XAML绑定路径：

<local:Nums Nums="{Binding Numbers[0].Value}" Stroke="Red" Click="Button_Clicked" />
<!-- 其余按钮同理，将Numbers[index]改为Numbers[index].Value -->

内容的提问来源于stack exchange，提问作者Jeredriq Demas