c# - WPF .NET 弹出窗口 - 悬停时打开，如果鼠标悬停则保持打开

Question

我有一个 Textblock，当鼠标悬停在它上面时，我想在上面打开一个 Popup。我已使用 MultiBinding 将 IsOpen 属性绑定(bind)到 Popup 的 IsMouseOver 和 TextBlock 的 IsMouseOver，它工作正常，除了当鼠标从文本移动到弹出窗口时，弹出窗口闪烁。

闪烁的原因是幕后事件的执行顺序:

鼠标从textblock移动到popup--IsMouseOver of textblock 设置为false --> 转换器被调用，两个参数都为 false --> 只有 popup 的 IsMouseOver 被设置为 true --> 转换器执行，两个参数都为 false，弹出窗口消失 --> 转换器调用并再次执行，因为另一个之前为弹出窗口的 IsMouseOver 引发了事件，这次 Popup 的 IsMouseOver True --> 弹出窗口再次出现。我已经尝试添加 StaysOpen=False，但它永远不会关闭/行为与预期不同。

问题:如何避免闪烁？

代码:

<Grid>
    <ListBox ItemsSource="{Binding RandomNames}">
        <ListBox.ItemTemplate>
            <DataTemplate>
                <Grid>
                    <Grid.ColumnDefinitions>
                        <ColumnDefinition></ColumnDefinition>
                        <ColumnDefinition></ColumnDefinition>
                    </Grid.ColumnDefinitions>
                    <TextBlock Text="Name: "
                               Grid.Column="0"/>
                    <TextBlock Grid.Column="1"
                               x:Name="NameBlock"
                               Text="{Binding}">
                        <TextBlock.Style>
                            <Style TargetType="TextBlock">
                                <Style.Triggers>
                                    <Trigger Property="IsMouseOver" Value="True">
                                        <Setter Property="Foreground" Value="Red" />
                                    </Trigger>
                                </Style.Triggers>
                            </Style>
                        </TextBlock.Style>
                    </TextBlock>
                    <Popup x:Name="PopupX"
                           Grid.Column="1"
                           PlacementTarget="{Binding ElementName=NameBlock}"
                           Placement="Bottom">
                        <!--<Popup.IsOpen>
                            <MultiBinding Converter="{StaticResource PopupIsOpenConverter}">
                                <Binding ElementName="PopupX" Path="IsMouseOver" Mode="OneWay" />
                                <Binding ElementName="NameBlock" Path="IsMouseOver" Mode="OneWay" />
                            </MultiBinding>
                        </Popup.IsOpen>-->
                        <Popup.Style>
                            <Style TargetType="Popup">
                                <Setter Property="IsOpen" Value="True" />
                                <Style.Triggers>
                                    <MultiDataTrigger>
                                        <MultiDataTrigger.Conditions>
                                            <Condition Binding="{Binding IsMouseOver, ElementName=NameBlock}" Value="False" />
                                            <Condition Binding="{Binding IsMouseOver, RelativeSource={RelativeSource Self}}" Value="False" />
                                        </MultiDataTrigger.Conditions>
                                        <Setter Property="IsOpen" Value="False" />
                                    </MultiDataTrigger>
                                </Style.Triggers>
                            </Style>
                        </Popup.Style>
                        <TextBlock Text="{Binding}"
                                   Foreground="Coral" />
                    </Popup>
                </Grid>
            </DataTemplate>
        </ListBox.ItemTemplate>
    </ListBox>
</Grid>

转换器代码

[ValueConversion(typeof(bool), typeof(bool))]
public class PopupIsOpenConverter : IMultiValueConverter
{
    public object Convert(object[] values, Type targetType, object parameter, CultureInfo culture)
    {
        return values.Any(value => value is bool && (bool) value);
    }
    public object[] ConvertBack(object value, Type[] targetTypes, object parameter, CultureInfo culture)
    {
        throw new ActionNotSupportedException();
    }
}

Answer 1

感谢this post ，我能够使用延迟多重绑定(bind)解决问题。请注意，多绑定(bind)转换器是通用的，可以接受任何常规多绑定(bind)转换器加上延迟。

我的 XAML:

<Popup.IsOpen>
    <local:DelayedMultiBindingExtension Converter="{StaticResource PopupIsOpenConverter}" Delay="0:0:0.01">
        <Binding ElementName="PopupX" Path="IsMouseOver" Mode="OneWay" />
        <Binding ElementName="RecipientsTextBlock" Path="IsMouseOver" Mode="OneWay" />
    </local:DelayedMultiBindingExtension>
</Popup.IsOpen>

我的多重绑定(bind)转换器:

[ContentProperty("Bindings")]
internal sealed class DelayedMultiBindingExtension : MarkupExtension, IMultiValueConverter, INotifyPropertyChanged
{
    public event PropertyChangedEventHandler PropertyChanged;

    public Collection<BindingBase> Bindings { get; }

    public IMultiValueConverter Converter { get; set; }

    public object ConverterParameter { get; set; }

    public CultureInfo ConverterCulture { get; set; }

    public BindingMode Mode { get; set; }

    public UpdateSourceTrigger UpdateSourceTrigger { get; set; }

    private object _undelayedValue;
    private object _delayedValue;
    private DispatcherTimer _timer;

    public object CurrentValue
    {
        get { return _delayedValue; }
        set
        {
            _delayedValue = _undelayedValue = value;
            _timer.Stop();
        }
    }

    public int ChangeCount { get; private set; } // Public so Binding can bind to it

    public TimeSpan Delay
    {
        get { return _timer.Interval; }
        set { _timer.Interval = value; }
    }

    public DelayedMultiBindingExtension()
    {
        this.Bindings = new Collection<BindingBase>();
        _timer = new DispatcherTimer();
        _timer.Tick += Timer_Tick;
        _timer.Interval = TimeSpan.FromMilliseconds(10);
    }

    public override object ProvideValue(IServiceProvider serviceProvider)
    {
        var valueProvider = serviceProvider.GetService(typeof(IProvideValueTarget)) as IProvideValueTarget;
        if (valueProvider == null) return null;

        var bindingTarget = valueProvider.TargetObject as DependencyObject;
        var bindingProperty = valueProvider.TargetProperty as DependencyProperty;

        var multi = new MultiBinding { Converter = this, Mode = Mode, UpdateSourceTrigger = UpdateSourceTrigger };
        foreach (var binding in Bindings) multi.Bindings.Add(binding);
        multi.Bindings.Add(new Binding("ChangeCount") { Source = this, Mode = BindingMode.OneWay });

        var bindingExpression = BindingOperations.SetBinding(bindingTarget, bindingProperty, multi);

        return bindingTarget.GetValue(bindingProperty);
    }

    public object Convert(object[] values, Type targetType, object parameter, CultureInfo culture)
    {
        var newValue = Converter.Convert(values.Take(values.Length - 1).ToArray(),
                                         targetType,
                                         ConverterParameter,
                                         ConverterCulture ?? culture);

        if (Equals(newValue, _undelayedValue)) return _delayedValue;
        _undelayedValue = newValue;
        _timer.Stop();
        _timer.Start();

        return _delayedValue;
    }

    public object[] ConvertBack(object value, Type[] targetTypes, object parameter, CultureInfo culture)
    {
        return Converter.ConvertBack(value, targetTypes, ConverterParameter, ConverterCulture ?? culture)
                        .Concat(new object[] { ChangeCount }).ToArray();
    }

    private void Timer_Tick(object sender, EventArgs e)
    {
        _timer.Stop();
        _delayedValue = _undelayedValue;
        ChangeCount++;
        PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(nameof(ChangeCount)));
    }
}