MVVMCross ValueConverter 布尔到 MvxColor/Color

Question

我试图为 MVVMCross 实现 ValueConverter，但显然它没有像我预期的那样工作。所以目前我刚得到另一个属性为我进行转换（MvxColor 到 TextColor）并将其绑定到我的布局。但是我宁愿使用值转换器，所以也许你知道我做错了什么：

我当前遇到的绑定错误：

    06-09 16:29:29.820 I/MvxBind (16312):  61,64 Problem seen during binding execution for binding TextColor for Changed - problem InvalidCastException: Specified cast is not valid.
06-09 16:29:29.820 I/MvxBind (16312):     at MvvmCross.Plugins.Color.Droid.BindingTargets.MvxTextViewTextColorBinding.SetValueImpl (System.Object target, System.Object value) [0x0000a] in <filename unknown>:0 
06-09 16:29:29.820 I/MvxBind (16312):   at MvvmCross.Binding.Bindings.Target.MvxConvertingTargetBinding.SetValue (System.Object value) [0x00088] in <filename unknown>:0 
06-09 16:29:29.820 I/MvxBind (16312):   at MvvmCross.Binding.Bindings.MvxFullBinding.UpdateTargetFromSource (System.Object value) [0x00024] in <filename unknown>:0 
MvxBind:Error: 61,64 Problem seen during binding execution for binding TextColor for Changed - problem InvalidCastException: Specified cast is not valid.
06-09 16:29:29.820 I/mono-stdout(16312): MvxBind:Error: 61,64 Problem seen during binding execution for binding TextColor for Changed - problem InvalidCastException: Specified cast is not valid.
06-09 16:29:29.820 I/mono-stdout(16312):      at MvvmCross.Plugins.Color.Droid.BindingTargets.MvxTextViewTextColorBinding.SetValueImpl (System.Object target, System.Object value) [0x0000a] in <filename unknown>:0 
      at MvvmCross.Plugins.Color.Droid.BindingTargets.MvxTextViewTextColorBinding.SetValueImpl (System.Object target, System.Object value) [0x0000a] in <filename unknown>:0 
  at MvvmCross.Binding.Bindings.Target.MvxConvertingTargetBinding.SetValue (System.Object value) [0x00088] in <filename unknown>:0 
06-09 16:29:29.830 I/mono-stdout(16312):   at MvvmCross.Binding.Bindings.Target.MvxConvertingTargetBinding.SetValue (System.Object value) [0x00088] in <filename unknown>:0 
  at MvvmCross.Binding.Bindings.MvxFullBinding.UpdateTargetFromSource (System.Object value) [0x00024] in <filename unknown>:0 
06-09 16:29:29.830 I/mono-stdout(16312):   at MvvmCross.Binding.Bindings.MvxFullBinding.UpdateTargetFromSource (System.Object value) [0x00024] in <filename unknown>:0 
[0:] MvxBind:Error: 61,64 Problem seen during binding execution for binding TextColor for Changed - problem InvalidCastException: Specified cast is not valid.
      at MvvmCross.Plugins.Color.Droid.BindingTargets.MvxTextViewTextColorBinding.SetValueImpl (System.Object target, System.Object value) [0x0000a] in <filename unknown>:0 
  at MvvmCross.Binding.Bindings.Target.MvxConvertingTargetBinding.SetValue (System.Object value) [0x00088] in <filename unknown>:0 
  at MvvmCross.Binding.Bindings.MvxFullBinding.UpdateTargetFromSource (System.Object value) [0x00024] in <filename unknown>:0

我的布局片段：

<EditText
      android:layout_width="fill_parent"
      android:layout_height="wrap_content"
      android:layout_weight="1"
      android:singleLine="true"
      android:inputType="numberDecimal|numberSigned"
      android:textColor="@color/schaefflerlightgreen"
      local:MvxBind="TextColor Changed,Converter=MvxBoolToColorValueConverter" />

我试用的两个转换器类：

    public class MvxBoolToMvxColorValueConverter: MvxColorValueConverter<bool>
{

    protected override MvxColor Convert(bool value, object parameter, CultureInfo culture)
    {
        if (value)
        {
            // FF0000
            return new MvxColor(255, 0, 0);
        }
        //227D41
        return new MvxColor(34, 125, 65);
    }
}

    public class MvxBoolToColorValueConverter : MvxValueConverter<bool, Color>
{

    protected override Color Convert(bool value, Type targetType, object parameter, CultureInfo culture)
    {
        if (value)
        {
            // FF0000
            return new Color(255, 0, 0);
        }
        //227D41
        return new Color(34, 125, 65);
    }

}

问题是绑定通常与 MvxColor-属性一起使用，只是转换似乎是个问题。所以可能我只是错过了一些东西。

非常感谢您的帮助。

伊迪丝：还有属性...

public bool Changed { get { return m_sValue != m_sSyncValue; } }

Answer 1

从绑定中的转换器名称中删除 Mvx-前缀和 ValueConverter-后缀：

改变

local:MvxBind="TextColor Changed,Converter=MvxBoolToColorValueConverter" />

到

local:MvxBind="TextColor Changed,Converter=BoolToColor" />

此行为在 documentation for ValueConverters 中描述：

This sweep locates all instanciable classes which implement IMvxValueConverter within your assemblies creates an instance of each one registers the instance with the name stripped of any Mvx prefix and any ValueConverter or Converter postfix. So, for example, the following class names will all be registered with the same ValueConverter name of "Foo":

Foo, FooValueConverter, FooConverter, MvxFooValueConverter, MvxFooConverter

MVVMCross ValueConverter 布尔到 MvxColor/Color

MVVMCross ValueConverter Bool To MvxColor/Color

c#

converter

xamarin.android

mvvmcross

xamarin