通过添加一些值绑定到Canvas.TopProperty

Question

我有这段代码：

<Rectangle x:Name="cage" Height="247" Canvas.Left="278" Canvas.Top="220" Width="450">
        <Rectangle.Fill>
            <ImageBrush Stretch="None" ImageSource="resources/cage.gif"/>
        </Rectangle.Fill>
    </Rectangle>

和

<Label x:Name="to1" Content="1" Canvas.Left="550" Canvas.Top="{Binding Source=cage, Path=Canvas.Top, Mode=OneWay}"  BorderBrush="#FF272727" BorderThickness="1" Height="38" Width="38" HorizontalContentAlignment="Center" VerticalContentAlignment="Center" FontSize="20" PreviewMouseDown="to1_PreviewMouseDown"/>

绑定正在运行，但我希望保持此元素相对于彼此的位置。换句话说，如果我移动笼子，topproperty的标签变成了“移动值+ 285”。怎么做？

Answer 1

考虑使用转换器作为位建议。

一个简单的例子应如下所示：

<强> XAML

<UserControl.Resources>
    <converterNamespace:LabelOffsetConverter x:Key="labelOffsetConverter"/>
</UserControl.Resources>

<Label x:Name="to1" Content="1" Canvas.Left="550" 
       Canvas.Top="{Binding Source=cage, Path=Canvas.Top, Mode=OneWay,
                    Converter={StaticResource labelOffsetConverter}"
       BorderBrush="#FF272727" 
       BorderThickness="1" 
       Height="38" Width="38" 
       HorizontalContentAlignment="Center" 
       VerticalContentAlignment="Center" 
       FontSize="20" PreviewMouseDown="to1_PreviewMouseDown"/>

转换代码

public class LabelOffsetConverter : IValueConverter
{
    public object Convert(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
    {
        if (!(value is double))
            return DependencyProperty.UnsetValue;

        double doubleValue = (double)value;
        return doubleValue + 285;
    }

    public object ConvertBack(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
    {
        // No need to implement, since the binding is in one way mode.
        throw new NotImplementedException();
    }
}

Answer 2

通过这种方式解决： 的 C＃

public class Label1offset : IValueConverter
    {
        public object Convert(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
        {
            if (!(value is double))
                return DependencyProperty.UnsetValue;


        double doubleValue = (double)value;
        return doubleValue + 65.0;
    }

    public object ConvertBack(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
    {
        // No need to implement, since the binding is in one way mode.
        throw new NotImplementedException();
    }
}
Binding binding1 = new Binding();
            binding1.Converter = new Label1offset();
            binding1.Source = cage;
            binding1.Path = new PropertyPath(Canvas.TopProperty);
            binding1.Mode = BindingMode.OneWay;
            to1.SetBinding(Canvas.TopProperty, binding1);