c# - XAML 转换器如何做更多事情？

Question

在 angular 中可以对文本进行一些过滤，例如:

<div ng-bind="vm.value | filter1| filter2| filter3"

并且当序列被维护时。这是如何在 XAML 中完成的？特别是 xamarin。

Answer 1

这是通过使用 Xamarin Forms 中的转换器完成的:

<?xml version="1.0" encoding="utf-8" ?>
<ContentPage xmlns="http://xamarin.com/schemas/2014/forms"
         xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
         x:Class="XamlSamples.SharedResourcesPage"
         Title="Shared Resources Page">
 <ContentPage.Resources>
   <ResourceDictionary>
     <local:DoubleToIntConverter x:Key="intConverter" />
   </ResourceDictionary>
 </ContentPage.Resources>
  <StackLayout>
   <Label Text="{Binding Color.R,
          Converter={StaticResource intConverter},
          ConverterParameter=255,
          StringFormat='R={0:X2}'}" />
  </StackLayout>
</ContentPage>

转换器:

class DoubleToIntConverter : IValueConverter
{
    public object Convert(object value, Type targetType,
                          object parameter, CultureInfo culture)
    {
        double multiplier;

        if (!Double.TryParse(parameter as string, out multiplier))
            multiplier = 1;

        return (int)Math.Round(multiplier * (double)value);
    }

    public object ConvertBack(object value, Type targetType,
                              object parameter, CultureInfo culture)
    {
        double divider;

        if (!Double.TryParse(parameter as string, out divider))
            divider = 1;

        return ((double)(int)value) / divider;
    }
}

更多信息在这里:https://developer.xamarin.com/guides/xamarin-forms/user-interface/xaml-basics/data_binding_basics/