我正在尝试使用MvxValueConverter根据布尔值设置LinearLayout的背景颜色。转换器如下：
public class BackgroundColorValueConverter : MvxValueConverter<bool, MvxColor>
{
private static readonly MvxColor TrueBGColor = new MvxColor(0xDB, 0xFF, 0xCE);
private static readonly MvxColor FalseBGColor = new MvxColor(0xD6, 0xF6, 0xFF);
protected override MvxColor Convert(bool value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
{
return value ? TrueBGColor : FalseBGColor;
}
}
在我的AXML布局中，我有以下代码：
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:local="http://schemas.android.com/apk/res-auto"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
local:MvxBind="BackgroundColor MyBooleanValue, Converter=BackgroundColor">
<TextView
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:gravity="center"
android:textSize="18dp"
local:MvxBind="Text MyText" />
</LinearLayout>
我遇到了以下错误：
Failed to create target binding for binding BackgroundColor for MyBooleanValue
完整的错误跟踪如下：
MvxBind:Error: 8.58 Problem seen during binding execution for binding BackgroundColor for MyBooleanValue - problem InvalidCastException: Cannot cast from source type to destination type.
03-05 14:18:46.434 I/mono-stdout(16474): MvxBind:Error: 8.58 Problem seen during binding execution for binding BackgroundColor for MyBooleanValue - problem InvalidCastException: Cannot cast from source type to destination type.
03-05 14:18:46.434 I/mono-stdout(16474): at Cirrious.MvvmCross.Plugins.Color.Droid.BindingTargets.MvxViewBackgroundColorBinding.SetValueImpl (System.Object target, System.Object value) [0x00000] in <filename unknown>:0
at Cirrious.MvvmCross.Plugins.Color.Droid.BindingTargets.MvxViewBackgroundColorBinding.SetValueImpl (System.Object target, System.Object value) [0x00000] in <filename unknown>:0
at Cirrious.MvvmCross.Binding.Bindings.Target.MvxConvertingTargetBinding.SetValue (System.Object value) [0x00000] in <filename unknown>:0
03-05 14:18:46.434 I/mono-stdout(16474): at Cirrious.MvvmCross.Binding.Bindings.Target.MvxConvertingTargetBinding.SetValue (System.Object value) [0x00000] in <filename unknown>:0
at Cirrious.MvvmCross.Binding.Bindings.MvxFullBinding.UpdateTargetFromSource (System.Object value) [0x00000] in <filename unknown>:0
所以，我真的不确定接下来该怎么做。我尝试的东西可能可行吗？我是否使用了正确的MvvmCross转换器？任何指针都将不胜感激。
更新：
将转换器更改为：
public class BackgroundColorValueConverter : MvxColorValueConverter
{
private static readonly MvxColor TrueBGColor = new MvxColor(0xDB, 0xFF, 0xCE);
private static readonly MvxColor FalseBGColor = new MvxColor(0xD6, 0xF6, 0xFF);
protected override MvxColor Convert(object value, object parameter, System.Globalization.CultureInfo culture)
{
return (bool)value ? TrueBGColor : FalseBGColor;
}
}
...解决了我的问题。我在我的LinearLayout上也添加了TextColor MyBooleanValue，Converter = TextColor，它的功能类似于BackgroundColorValueConverter，我收到了同样关于无法创建目标绑定的错误信息。
当我改变了我的AXML如下：
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:local="http://schemas.android.com/apk/res-auto"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
local:MvxBind="BackgroundColor MyBooleanValue, Converter=BackgroundColor">
<TextView
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:gravity="center"
android:textSize="18dp"
local:MvxBind="Text MyText; TextColor MyBooleanValue, Converter=TextColor" />
</LinearLayout>
...所有的内容都按照预期运行。对于未来可能偶然遇到这个问题的人：不要尝试在LinearLayout上绑定TextColor，因为它不起作用！
LinearLayout上的TextColor的一些事情（以及对于像我这样的笨蛋它不起作用）。 - Walter W Kennedy IV