我有一个类似于这样的多绑定：
<UserControl.Visibility>
<MultiBinding Converter="{StaticResource isMouseOverToVisibiltyConverter}">
<Binding ElementName="otherElement" Path="IsMouseOver" />
<Binding RelativeSource="{RelativeSource Self}" Path="IsMouseOver" />
</MultiBinding>
</UserControl.Visibility>
我希望能在绑定的IsMouseOver属性值变为false和Visibility被设置为Collapsed之间增加一些延迟时间。
我找到了这个DelayBinding的实现方式：http://www.paulstovell.com/wpf-delaybinding。但是，这并不适用于MultiBinding，而且我一直无法弄清楚如何使其适用于MultiBinding。
我可以在代码后台中使用事件来更改Visibility，这样也能够实现目标。但如果有一种方法能够通过绑定系统来实现这一点，那就更好了。
是否有一些方法能够在MultiBinding上添加延迟？
编辑：Ray，为了让你的类编译和运行，我不得不进行一些修复。然而，还是有些问题，因为更新没有被传播。它似乎只更新了一次目标属性。
[ContentProperty("Bindings")]
public class DelayedMultiBindingExtension : MarkupExtension, IMultiValueConverter, INotifyPropertyChanged
{
public Collection<BindingBase> Bindings { get; private set; }
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; }
public object CurrentValue { get { return _delayedValue; } set { _delayedValue = _undelayedValue = value; _timer.Stop(); } }
private object _undelayedValue;
private object _delayedValue;
private DispatcherTimer _timer;
public int ChangeCount { get; private set; } // Public so Binding can bind to it
public DelayedMultiBindingExtension()
{
this.Bindings = new Collection<BindingBase>();
_timer = new DispatcherTimer();
_timer.Tick += _timer_Tick;
_timer.Interval = TimeSpan.FromMilliseconds(500);
}
public override object ProvideValue(IServiceProvider serviceProvider)
{
var valueProvider = serviceProvider.GetService(typeof(IProvideValueTarget)) as IProvideValueTarget;
if (valueProvider != 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);
}
return null;
}
public object Convert(object[] values, Type targetType, object parameter, CultureInfo culture)
{
object newValue =
Converter.Convert(
values.Take(values.Length - 1).ToArray(),
targetType,
ConverterParameter,
ConverterCulture ?? culture);
if (!object.Equals(newValue, _undelayedValue))
{
_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++;
if (PropertyChanged != null)
PropertyChanged(this, new PropertyChangedEventArgs("ChangeCount"));
}
public event PropertyChangedEventHandler PropertyChanged;
}
编辑2：虽然我无法让Ray的代码正常工作，但我将其标记为答案，因为它引导我找到了一些可行的代码。请查看下面的答案，以获取我使用的代码。