【发布时间】：2011-05-08 01:43:54
【问题描述】：
我有一个看起来像这样的多重绑定：
<UserControl.Visibility>
<MultiBinding Converter="{StaticResource isMouseOverToVisibiltyConverter}">
<Binding ElementName="otherElement" Path="IsMouseOver" />
<Binding RelativeSource="{RelativeSource Self}" Path="IsMouseOver" />
</MultiBinding>
</UserControl.Visibility>
而且，我希望能够在两个绑定的 IsMouseOver 变为 false 和 Visibility 设置为 Collapsed 之间添加延迟。
我发现了这个 DelayBinding 实现： http://www.paulstovell.com/wpf-delaybinding
但是，这不适用于 MultiBinding，我一直无法弄清楚如何制作一个适用于 MultiBinding 的产品。
我确实可以选择在代码隐藏中的事件中更改可见性，这会起作用，但如果有某种方法可以通过绑定系统来做到这一点，那就太好了。
有没有办法给 MultiBinding 增加延迟？
编辑：Ray，为了让您的课程能够编译和运行，我必须进行一些修复。但是，仍然有问题，因为更新没有被传播。似乎只更新一次目标属性。
[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;
}
EDIT2：尽管我无法让 Ray 的代码工作，但我已将其标记为答案，因为它会引导我找到一些可以工作的代码。有关我使用的代码，请参阅下面的答案。
【问题讨论】：
-
这个问题帮助我解决了我的问题，非常感谢！
-
看起来他们现在将延迟属性添加到多重绑定中。
标签： wpf multibinding