c# - SetCurrentValue myLabel.BackgroundProperty 不破坏绑定(bind)

Question

我有三个文本框和一个标签。使用 Multiconverter 将标签绑定(bind)到文本框中的文本。

XAML:

<Label Name="lbl" Content="Label" HorizontalAlignment="Left" Margin="336,128,0,0" VerticalAlignment="Top" Height="57" Width="93">
        <Label.Background>
            <MultiBinding Converter="{StaticResource converta}">
                <Binding ElementName="R" Path="Text" Mode="TwoWay" />
                <Binding ElementName="G" Path="Text" UpdateSourceTrigger="PropertyChanged" Mode="TwoWay" />
                <Binding ElementName="B" Path="Text" UpdateSourceTrigger="PropertyChanged" Mode="TwoWay" />
            </MultiBinding>

        </Label.Background>
    </Label> 
    <TextBox Name="R" HorizontalAlignment="Left" Height="23" Margin="250,214,0,0" TextWrapping="Wrap" Text="255" VerticalAlignment="Top" Width="120"/>
    <TextBox Name="B" HorizontalAlignment="Left" Height="23" Margin="271,242,0,0" TextWrapping="Wrap" Text="255" VerticalAlignment="Top" Width="120"/>
    <TextBox Name="G" HorizontalAlignment="Left" Height="23" Margin="155,275,0,0" TextWrapping="Wrap" Text="255" VerticalAlignment="Top" Width="120"/>

转换器

class converter : IMultiValueConverter
{

    public object Convert(object[] values, Type targetType, object parameter, CultureInfo culture)
    {

            return new System.Windows.Media.SolidColorBrush(Color.FromRgb(System.Convert.ToByte((values[0] as string)), System.Convert.ToByte((values[1] as string)), System.Convert.ToByte((values[2] as string))));

    }

    public object[] ConvertBack(object value, Type[] targetTypes, object parameter, CultureInfo culture)
    {
        byte R = (value as System.Windows.Media.Color?).Value.R;
        byte G = (value as System.Windows.Media.Color?).Value.G;
        byte B = (value as System.Windows.Media.Color?).Value.B;
        return new string[] {System.Convert.ToString(R),System.Convert.ToString(G),System.Convert.ToString(B)};

    }
    }

(显然，在现实世界中我会添加验证和类型检查)。

现在我想添加一个按钮来设置标签背景，像这样简单:

    lbl.Background= new SolidColorBrush(Color.FromRgb(
System.Convert.ToByte(121), 
System.Convert.ToByte(43), 
System.Convert.ToByte(15)));

显然，它打破了绑定(bind)。所以我尝试:

    SetCurrentValue(lbl.BackgroundProperty, 
new SolidColorBrush(
Color.FromRgb(System.Convert.ToByte(121), 
System.Convert.ToByte(43), 
System.Convert.ToByte(15))));

但是 VS 提示说

Member 'System.Windows.Controls.Control.BackgroundProperty' cannot be accessed with an instance reference; qualify it with a type name instead

如何在不破坏绑定(bind)的情况下在代码中设置标签背景的值？

注意:这是WPF，.Net 4.5

Answer 1

错误是 self 描述的，它告诉你 lbl.BackgroundProperty 不能那样设置。以下是执行此操作的正确方法。

        lbl.SetCurrentValue(BackgroundProperty,
                                   new SolidColorBrush(Color.FromRgb(System.Convert.ToByte(121),
                                                                     System.Convert.ToByte(43),
                                                                     System.Convert.ToByte(15))));