创建自定义按钮渲染器时覆盖转换错误 [英] Override conversion errors when creating custom button renderer

问题描述

我正在尝试覆盖 Xamarin Forms 中 Android 按钮渲染器的默认行为.我利用了(不是偷来的；)来自 https://docs.microsoft.com/en-us/xamarin/xamarin-forms/user-interface/visual/create 并创建了这个:

I am trying to override the default behavior of the Android button renderer in Xamarin Forms. I have leveraged (not stolen;) the source code from https://docs.microsoft.com/en-us/xamarin/xamarin-forms/user-interface/visual/create and have created this:

namespace Patron.Droid.Renderers
{
    public class MixedCaseButtonRenderer : Xamarin.Forms.Platform.Android.AppCompat.ButtonRenderer
    {
        public MixedCaseButtonRenderer(Context context) : base(context)
        {
        }

        protected override void OnElementChanged(ElementChangedEventArgs<Button> el)
        {
            base.OnElementChanged(el);

            if (el.OldElement != null)
            {
                // Cleanup
            }

            if (el.NewElement != null)
            {
                var button = (Button)this.Control;
                button.SetAllCaps(false);
            }
        }
    }
}

但是当我构建它时，我收到以下错误

But when I build it, I get the following errors

Severity    Code    Description Project File    Line    Suppression State
Error   CS0115  'MixedCaseButtonRenderer.OnElementChanged(ElementChangedEventArgs<Button>)': no suitable method found to override   Patron.Android  C:\Users\ThomH\workspace\patron\Patron\Patron\Patron.Android\Renderers\MixedCaseButtonRenderer.cs   22  Active
Error   CS0311  The type 'Android.Widget.Button' cannot be used as type parameter 'TElement' in the generic type or method 'ElementChangedEventArgs<TElement>'. There is no implicit reference conversion from 'Android.Widget.Button' to 'Xamarin.Forms.Element'.  Patron.Android  C:\Users\ThomH\workspace\patron\Patron\Patron\Patron.Android\Renderers\MixedCaseButtonRenderer.cs   22  Active
Error   CS1503  Argument 1: cannot convert from 'Xamarin.Forms.Platform.Android.ElementChangedEventArgs<Android.Widget.Button>' to 'Xamarin.Forms.Platform.Android.ElementChangedEventArgs<Xamarin.Forms.Button>'   Patron.Android  C:\Users\ThomH\workspace\patron\Patron\Patron\Patron.Android\Renderers\MixedCaseButtonRenderer.cs

推荐答案

Button 存在于 Android.Widget 和 Xamarin.Forms 中.您需要指定要使用的命名空间

Button exists in both Android.Widget and Xamarin.Forms. You need to specify which namespace you mean to use

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