wpf - 如何使用 MVVM 在 ListView 中设置特定项目？

Question

我有一个这样的 Button 元素的 ListView:

 <ListView ItemsSource="{Binding DummyModelList}" SelectedItem="{Binding SelectedItem}">
     <ListViewItem >
          <Button Name="test" Grid.Row="0" Grid.Column="10" Grid.ColumnSpan="4" Grid.RowSpan="4" VerticalAlignment="Center" Background="Transparent" Command="{Binding DataContext.TestCommand, RelativeSource={RelativeSource FindAncestor, AncestorType=ListView}}">
               <Button.Template>
                    <ControlTemplate>
                         <Grid RenderTransformOrigin="0.5,0.5" x:Name="bg">
                              <Image Source="{Binding DataContext.SlidOnOffImg , RelativeSource={RelativeSource FindAncestor, AncestorType=ListView}}"/>
                         </Grid>
                   </ControlTemplate>
               </Button.Template>
          </Button>
     </ListViewItem >

在我的 View 模型中:

public class MyViewModel:BindableBase
 {

        private ObservableCollection<Slide> dummyModelList;
        public ObservableCollection<Slide> DummyModelList 
        {
            get { return dummyModelList; }
            set 
            { 
                dummyModelList = value;
                OnPropertyChanged(() => DummyModelList);
            }
        } 

        public string SlidOnOffImg { get; set; }


        private int selectedItem;
        public int SelectedItem //this property stores currently selected item from thumbnails list
        {
            get { return selectedItem; }

            set
            {
                selectedItem = value;
                OnPropertyChanged(() => SelectedItem);
            }

        public CompositeCommand TestCommand { get; set; }

        public MyViewModel(IRegionManager regionManager, IEventAggregator eventAggregator) //constructor
        {

            dummyModelList = new ObservableCollection<ISlide>() { new Slide(), new Slide(), new Slide()};

            TestCommand = new CompositeCommand();
            TestCommand.RegisterCommand(new DelegateCommand(ChangeImage));
        }

        private void ChangeImage()
        {

            if (dummyModelList.ElementAt(selectedItem).SlideExcluded)
                dummyModelList.ElementAt(selectedItem).SlideExcluded = false;
            else
                dummyModelList.ElementAt(selectedItem).SlideExcluded = true;

            SlidOnOffImg = dummyModelList.ElementAt(selectedItem).SlideONOFFImgPath;
            OnPropertyChanged(() => SlidOnOffImg);
        }
}

在我的模型中:

public class Slide : ISlide
{
    public bool SlideExcluded { get; set; }

    public string SlideONOFFImgPath 
    {
        get
        {
            if(SlideExcluded)
                return "/Assets/Visible_OFF.png";
            else
                return "/Assets/Visible_ON.png";
        }

    }

}

我的目标是让按钮的图像在按钮单击时在两个图像路径之间切换。它可以工作，但问题是列表中的所有按钮都会在单击某些按钮时更改图像路径。我只想要单击以更改图像路径的那个。

如何解决这个问题？

Answer 1

您需要在 XAML 中绑定(bind)到 SelectedIndex 而不是 SelectedItem。 SelectedIndex 保存对列表中项目索引的引用，SelectedItem 保存对列表中对象的引用。要么，要么更改您的 View 模型以使用实际对象而不是索引。