Question

我在MVVM中的滑块值数据绑定方面存在问题。当值发生变化时，我的预期值无法实现。我怎样才能解决我的问题呢？我有一个列表框，一个滑块和一个文本块。 listbox绑定到ListImage，滑块值和textblock文本绑定到CurrentImage。带命令的一个按钮导航lisbox项目。 CurrentImage是viewmodel中的一个属性。当我更改滑块的setter时，setter的新值被置于滑块setter的当前值并且listbox的排列被破坏。例如，当我的滑块的setter的值设置为50并且我再次将滑块的值更改为10时。我的滑块值从10导航到50而不是更多。它必须导航整个列表框，但它不能。有我的代码：

XAML：

<TextBlock Text="{Binding CurrentImage.Index}"/>
<Slider Height="23" HorizontalAlignment="Left" Margin="12,305,0,0" Name="slider1" VerticalAlignment="Top" Width="479" Maximum="{Binding ListImage.Count, Mode=OneTime}"
              Value="{Binding CurrentImage.Index, Mode=TwoWay}"
              SmallChange="1" />
<Button Content="{Binding DisplayPlay}" Command="{Binding PlayCommand}" Height="23" HorizontalAlignment="Left" Margin="507,305,0,0" Name="button1" VerticalAlignment="Top" Width="75" />
<ListBox Height="129" HorizontalAlignment="Left"  Margin="12,334,0,0" ItemsSource="{Binding ListImage}" SelectedItem="{Binding CurrentImage,Mode=TwoWay}" 
                 VerticalAlignment="Top" Width="472">

视图模型：

public class MainViewModel : ViewModelBase
{
    public ICommand PlayCommand { get; set; }
    private DispatcherTimer _Timer;
    public ImageDTO Image { get; set;}
    DataAccess AC = new DataAccess();
    public byte[] Bytes { get; set; }
    public MainViewModel()
    {
        ListImage = AC.OpenImages();
        CurrentImage = ListImage[0];
        Bytes = CurrentImage.Bytes;
        this.PlayCommand = new DelegateCommand(Play, CanPlay);
        DisplayPlay = "Play";
        _Timer = new DispatcherTimer();
        _Timer.Interval = new TimeSpan(0, 0, 0, 0, 2000 / 30);
        _Timer.Tick += new EventHandler(timer_Tick);
    }

    private string _DisplayPlay;
    public string DisplayPlay
    {
        get { return _DisplayPlay; }
        set
        {
            if (_DisplayPlay != value)
            {
                _DisplayPlay = value;
                OnPropertyChanged("DisplayPlay");
            }
        }
    }

    private List<ImageDTO> _ListImage;
    public List<ImageDTO> ListImage
    {
        get { return _ListImage; }
        set
        {
            if (_ListImage != value)
                _ListImage = value;
                OnPropertyChanged("ListImage");
        }
    }

    private ImageDTO _CurrentImage;
    public ImageDTO CurrentImage
    {
        get { return _CurrentImage; }
        set
        {
            if (_CurrentImage != value)
            {
                _CurrentImage = value;
                OnPropertyChanged("CurrentImage");
            }
        }
    }

    public bool CanPlay(object parameter)
    {
        return true;
    }
    public void Play(object parameter)
    {
        if (DisplayPlay == "Play")
        {
            DisplayPlay = "Pause";
            _Timer.Start();
        }
        else
        {
            _Timer.Stop();
            DisplayPlay = "Play";
        }
    }

    private void timer_Tick(object sender, EventArgs e)
    {
        int position = ListImage.FindIndex(x => x.Index == CurrentImage.Index);
        position++;
        if (position == ListImage.Count)
        {
            position = 0;
        }
        else
        {
            CurrentImage = ListImage[position];
        }
    }

Answer 1

也许这就是你想要的：

<StackPanel>
    <ListBox x:Name="ImageListBox" IsSynchronizedWithCurrentItem="True">
        <ListBoxItem>Image1</ListBoxItem>
        <ListBoxItem>Image2</ListBoxItem>
        <ListBoxItem>Image3</ListBoxItem>
        <ListBoxItem>Image4</ListBoxItem>
    </ListBox>
    <Slider Value="{Binding ElementName=ImageListBox, Path=SelectedIndex}" 
            Maximum="{Binding ElementName=ImageListBox, Path=Items.Count}"/>
</StackPanel>

您可能希望处理比此示例

更好的最大值

MVVM中的绑定滑块值

1 个答案: