在自定义渲染器Xamarin Android中使用RatingBar

using Android.Widget;
using Xamarin.Forms;
using Xamarin.Forms.Platform.Android;

[assembly: ExportRenderer(typeof(RatingBar), typeof(CustomRatingBarRenderer))]
namespace YourNamespace
{
    public class CustomRatingBarRenderer : ViewRenderer<RatingBar, Android.Widget.RatingBar>, IRatingBarOnRatingBarChangeListener
    {
        protected override void OnElementChanged(ElementChangedEventArgs<RatingBar> e)
        {
            base.OnElementChanged(e);

            if (Control == null)
            {
                var ratingBar = new Android.Widget.RatingBar(Context);
                ratingBar.OnRatingBarChangeListener = this;
                SetNativeControl(ratingBar);
            }

            if (e.NewElement != null)
            {
                Control.Rating = e.NewElement.Rating;
                Control.StepSize = e.NewElement.StepSize;
            }
        }

        public void OnRatingChanged(RatingBar ratingBar, float rating, bool fromUser)
        {
            if (Element != null && fromUser)
            {
                Element.Rating = rating;
            }
        }
    }
}

using Xamarin.Forms;

namespace YourNamespace
{
    public class MainPage : ContentPage
    {
        public MainPage()
        {
            var ratingBar = new RatingBar
            {
                Rating = 3.5f,
                StepSize = 0.5f
            };

            Content = new StackLayout
            {
                Children = { ratingBar }
            };
        }
    }
}

using Android.App;
using Android.Content.PM;
using Android.OS;
using Xamarin.Forms;
using Xamarin.Forms.Platform.Android;

namespace YourNamespace.Droid
{
    [Activity(Label = "YourApp", Icon = "@mipmap/icon", Theme = "@style/MainTheme", MainLauncher = true, ConfigurationChanges = ConfigChanges.ScreenSize | ConfigChanges.Orientation)]
    public class MainActivity : FormsAppCompatActivity
    {
        protected override void OnCreate(Bundle savedInstanceState)
        {
            TabLayoutResource = Resource.Layout.Tabbar;
            ToolbarResource = Resource.Layout.Toolbar;

            base.OnCreate(savedInstanceState);

            Forms.Init(this, savedInstanceState);
            LoadApplication(new App());
        }
    }
}