TextView Compound Drawable Mvvm交叉绑定

Question

TextView 有一些 DrawableXXX 属性，如 DrawableStart、DrawableEnd、DrawableTop 等，以在 Drawable 旁边显示TextView 文字。是否可以使用 MvvmCross 绑定此属性？我试过在我的绑定中使用 local:MvxBind="Drawablename 'check'" 但它没有显示 MvxBind 错误：

Failed to create target binding for binding DrawableName for check

如果此绑定未在 MvvmCross 中实现，那么我将如何自己完成此操作？ N+28使用的方法是否仍然是添加自定义绑定的推荐方法？

Answer 1

目前没有任何 MvvmCross 定义用于添加复合可绘制对象的目标绑定。但是，您可以轻松添加自己的。如果您使用的是 MvvmCross 5+，则可以利用新类型的自定义绑定类。注意，下面的例子已经设置了drawable放在左边，但是你可以选择任意方向（或多个方向）放置.

public class CompoundDrawablesDrawableNameBinding : MvxAndroidTargetBinding<TextView, string>
{
    public const string BindingIdentifier = "CompoundDrawableName";

    public CompoundDrawablesDrawableNameBinding(TextView target) : base(target)
    {
    }

    public override MvxBindingMode DefaultMode => MvxBindingMode.OneWay;

    protected override void SetValueImpl(TextView target, string value)
    {
        var resources = AndroidGlobals.ApplicationContext.Resources;
        var id = resources.GetIdentifier(value, "drawable", AndroidGlobals.ApplicationContext.PackageName);
        if (id == 0)
        {
            MvxBindingTrace.Trace(MvxTraceLevel.Warning,
                "Value '{0}' was not a known compound drawable name", value);
            return;
        }

        target.SetCompoundDrawablesWithIntrinsicBounds(
            left: id,
            top: 0,
            right: 0,
            bottom: 0);
    }
}

然后在您的 Setup.cs

中注册

protected override void FillTargetFactories(IMvxTargetBindingFactoryRegistry registry)
{
    base.FillTargetFactories(registry);
    registry.RegisterCustomBindingFactory<TextView>(
        CompoundDrawablesDrawableNameBinding.BindingIdentifier,
        textView => new CompoundDrawablesDrawableNameBinding(textView));
}

然后在你的 XML 中你可以使用

local:MvxBind="CompoundDrawableName <<YOUR PROPERTY TO BIND TO>>"

TextView Compound Drawable Mvvm交叉绑定

TextView Compound Drawable MvvmCross Binding

xamarin.android

mvvmcross