XAML绑定到一个转换器 [英] XAML Binding to a converter

问题描述

我所试图做的是比较简单的。我只是想一个TranslateTransform的Y元素绑定在一个椭圆1/2椭圆的高度：

what I am trying to do is relatively simple. I am just trying to bind the Y element of a TranslateTransform on an ellipse to 1/2 the height of the ellipse:

    <Ellipse Name="EllipseOnlyLFA" Height="200" Fill="Yellow" HorizontalAlignment="Left" VerticalAlignment="Bottom" ClipToBounds="True">
        <Ellipse.Width>
            <Binding ElementName="EllipseOnlyLFA" Path="Height"/>
        </Ellipse.Width>
        <Ellipse.RenderTransform>
            <TranslateTransform>
                <TranslateTransform.Y>
                    <Binding Converter="MultiplyByFactor" ElementName="EllipseOnlyLFA" Path="Height"  ConverterParameter="0.5"/>
                </TranslateTransform.Y>
            </TranslateTransform>
        </Ellipse.RenderTransform>
    </Ellipse>

我也有以下转换器：

I also have the following converter:

public class MultiplyByFactor : IValueConverter
{
    public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
    {
        return ((double)value * (double)parameter);
    }

    public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
    {
        return true;
    }
}

我在XAML线得到一个错误，我实际使用的转换器。该错误是

I am getting an error on the XAML line where I actually use the converter. The error is

设置属性
'System.Windows.Data.Binding.Converter'
抛出一个异常。'行号'22'
和线位8。

'Set property 'System.Windows.Data.Binding.Converter' threw an exception.' Line number '22' and line position '8'.

任何人都可以阐明如何做一些轻这个？ 编辑：是的，我已经转换器作为资源添加

Can anyone shed some light on how to do this? Yes, I have the converter added as a resource.

推荐答案

有2件事错了与您的代码

There are 2 thing wrong with your code

1）你的转换器需要使用静态资源声明进行访问

1) your converter needs to be accessed using the StaticResource declaration

<Binding Converter="{StaticResource myMultiplyByFactor}" 
    ElementName="EllipseOnlyLFA" Path="Height"  ConverterParameter="0.5"/

2）你的转换参数是一个字符串默认情况下，所以你需要将其转换为一个双

2) Your converter parameter is a string by default, so you need to convert it to a double

public object Convert(object value, Type targetType, 
    object parameter, CultureInfo culture)
{
    var p = double.Parse((string)parameter);
    return ((double)value * p);

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