Question

考虑一下我必须根据两个属性设置样式：

<Label Style={Binding IsEnabled, Convert={x:Static IsEnabledToStyleConverter}} />

或

<Label Style={Binding IsRequired, Convert={x:Static IsEnabledToStyleConverter}} />

确定与IsEnabled或IsRequired绑定的用户是其他属性 - UseRequried。如何在UseRequired上选择这两个绑定盆地？

我试过方法：

另一个值转换器

我已创建自己的价值转换器：

public class ControlToLableStleConverter: IValueConverter
{
     public object Convert(object value..)
     {
          var myCtrl = (MyControl) value;
          if (myCtrl.UseRequired)
             //return style based on IsRequired property
          else
             //return style based on IsEnabled property
     }
}

但问题是样式在IsEnabled或IsRequired更改时没有变化。非常明显，所以这个解决方案已经解决了。

DataTrigger

我还创建了DataTriggers：

<Label>
<Label.Triggers>
    <DataTrigger Binding="{Binding UseRequired}" Value="True">
       <Setters>
           <Setter Property="Style" Value="{Binding IsRequired ....">
       </Setters>
    </DataTrigger>
    <DataTrigger Binding="{Binding UseRequired}" Value="False">
       <Setters>
           <Setter Property="Style" Value="{Binding IsEnabled ....">
       </Setters>
    </DataTrigger>
</Label.Triggers>
</Label>

但Label.Triggers只能包含EventTrigger元素。我还能做什么？

Answer 1

在这种情况下，您可以使用MultiBinding，但它可能非常详细：

<Label>
    <Label.Style>
        <MultiBinding Converter="{StaticResource yourConverter}">
            <Binding Path="IsEnabled" />
            <Binding Path="IsRequired" />
        </MultiBinding>
    </Label.Style>
</Label>

然后转换器：

public class StyleConverter : IMultiValueConverter {
    public object Convert(object[] values, Type targetType, object parameter, CultureInfo culture) {
        // take some caution here, because values can be null or DependencyProperty.UnsetValue in certain cases
        var enabled = (bool) values[0];
        var required = (bool) values[1];
        // choose style
    }

    public object[] ConvertBack(object value, Type[] targetTypes, object parameter, CultureInfo culture) {
        throw new NotImplementedException();
    }
}

Answer 2

在样式中设置触发器。

<Style TargetType="{x:Type MyControl}">
 <Style.Triggers>
  <DataTrigger Binding="{Binding UseRequired}" Value="True">
       <Setters>
           <!-- Set properties here, not the Style -->
       </Setters>
    </DataTrigger>
    <DataTrigger Binding="{Binding UseRequired}" Value="False">
       <Setters>
          <!-- Set properties here, not the Style -->           
       </Setters>
    </DataTrigger>
 </Style.Triggers>
</Style>

如果您无法更改属性，那么最佳选择是使用StyleSelector (MSDN)。

Answer 3

将此类逻辑放在后面的代码中并触发UseRequiered（或其他地方）的更改并触发所有属性更改，例如

public bool UseRequiered 
{ 
    get { return _UseRequried; }
    set { _UseRequried = value; DetermineStyle(); }// PropertyChanged in DetermineStyle()

}

public bool IsRequiered
{
    get { return _IsRequiered; }
    set { _IsRequiered = value; DetermineStyle();} // PropertyChanged in DetermineStyle()
}

public bool IsEnabled 
{ 
   get { return _IsEnabled; }
   set { _IsEnabled = value; DetermineStyle(); } // Prop change in DetermineStyle
}

private void DetermineStyle()
{
     _UseRequiered = { Whatever logic is deemed };
     _IsRequired  =  { Whatever logic is deemed };
     _IsEnabled   =  { Whatever logic is deemed };

     OnPropertyChanged("IsRequired");
     OnPropertyChanged("IsEnabled");
     OnPropertyChanged("UseRequiered"); 
}

构建复杂条件绑定的最佳方法

3 个答案: