UWP：根据条件更新 ItemTemplate 中的背景

Question

在 UWP 项目中，ListView 绑定到集合 player 对象。每个player 对象都有一个属性，例如HighScore。 ListView 的 ItemTemplate 显示每个玩家的 HighScore。我想更改ItemTemplate 中ItemTemplate 中Grid 的Background，当它的HighScore 匹配BiggestScore（页面DataContext 的属性）时。这代表了所有玩家的最大分数。 BiggestScore 在设置HighScore 后更新。

有什么想法可以实现这一点吗？

这里有一些示例代码，希望能说明各个部分。

XAML：

<Grid x:Name="root" Background="{ThemeResource ApplicationPageBackgroundThemeBrush}">
    <ListView x:Name="lvwPlayers" ItemsSource="{Binding Players}">
        <ListView.ItemTemplate>
            <DataTemplate>
                <Grid x:Name="grdHighScore" Background="Yellow">
                    <TextBlock Text="{Binding HighScore}"/>
                </Grid>
            </DataTemplate>
        </ListView.ItemTemplate>
    </ListView>
</Grid>

代码隐藏：

    public sealed partial class MainPage : Page
{
    public MainPage()
    {
        this.InitializeComponent();

        var allPlayers = new AllPlayers();

        allPlayers.Players.Add(new Player(100));
        allPlayers.Players.Add(new Player(112));
        allPlayers.Players.Add(new Player(1160));
        allPlayers.Players.Add(new Player(122));

        this.DataContext = allPlayers;
    }
}

玩家：

    public class Player : INotifyPropertyChanged
{
    protected void OnPropertyChanged([CallerMemberName] string caller = "")
    {
        PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(caller));
    }

    public event PropertyChangedEventHandler PropertyChanged;

    public Player( int high)
    {
        HighScore = high;
    }

    private int _highScore;
    public int HighScore
    {
        get { return _highScore; }
        set
        {
            _highScore = value;
            OnPropertyChanged();
        }
    }
}

所有玩家：

   public class AllPlayers : INotifyPropertyChanged
{
    public ObservableCollection<Player> Players { get; set; }

    public AllPlayers()
    {
        Players = new ObservableCollection<Player>();
    }

    protected void OnPropertyChanged([CallerMemberName] string caller = "")
    {
        PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(caller));
    }

    public event PropertyChangedEventHandler PropertyChanged;

    public void ChangeScore(int playerIndex, int highScore)
    {
        Players[playerIndex].HighScore = highScore;
    }

    private void UpdateBiggestScore()
    {
        BiggestScore = (from player in Players select player.HighScore).Max();
    }

    private int _biggestScore;
    public int BiggestScore
    {
        get { return _biggestScore; }
        set
        {
            _biggestScore = value;

            OnPropertyChanged();
        }
    }
}

Answer 1

在您的 DataContext 中创建属性，说明 HighScore 是否大于 BiggestScore，例如。布尔是最大的

绑定它：

Background={Binding IsBiggest, Converter=HighScoreToColorConverter}

YourConverter 可能类似于：

public class HighScoreToColorConverter : IValueConverter
{
    public object Convert(object value, Type targetType, object parameter, string language)
    {
        var isBiggest = (bool)value;
        var color = isBiggest ? new SolidColorBrush(Colors.Red) : new SolidColorBrush(Colors.Yellow);
        return color;
    }

public object ConvertBack(object value, Type targetType, object parameter, string language)
    {
        var color = value as SolidColorBrush;
        if (color != null)
        {
            return color == new SolidColorBrush(Colors.Red);
        }

        return false;
    }
}

Answer 2

您可以将背景颜色作为属性添加到您的播放器

private SolidColorBrush _backgroundColor = new SolidColorBrush(Colors.Yellow);
public SolidColorBrush BackgroundColor
{
    get { return _backgroundColor; }
    set
    {
        _backgroundColor= value;
        OnPropertyChanged();
    }
}

并将其绑定到网格的背景

<Grid x:Name="grdHighScore" Background="{Binding BackgroundColor}">
    <TextBlock Text="{Binding HighScore}"/>
</Grid>

更新最大分数时，获取分数最高的玩家对象并更新背景。同时将所有其他玩家的背景改回黄色。