SegmentedControlImplementation.cs

using System;
using Xamarin.Forms;
using SegmentedControl.FormsPlugin.Android;
using Xamarin.Forms.Platform.Android;
using Android.Widget;
using Android.Views;
using Android.Graphics.Drawables;
using Android.Content;

[assembly: ExportRenderer(typeof(SegmentedControl.FormsPlugin.Abstractions.SegmentedControl), typeof(SegmentedControlRenderer))]
namespace SegmentedControl.FormsPlugin.Android
{
	/// <summary>
	/// SegmentedControl Renderer
	/// </summary>
	public class SegmentedControlRenderer : ViewRenderer<Abstractions.SegmentedControl, RadioGroup>
	{
		RadioGroup nativeControl;
		RadioButton _rb;
        Context context;

        public SegmentedControlRenderer(Context context) : base(context)
        {
            this.context = context;
        }

		protected override void OnElementChanged(ElementChangedEventArgs<Abstractions.SegmentedControl> e)
		{
			base.OnElementChanged(e);

			if (Control == null)
			{
                // Instantiate the native control and assign it to the Control property with
                // the SetNativeControl method

                var layoutInflater = LayoutInflater.From(context);

                var view = layoutInflater.Inflate(Resource.Layout.RadioGroup, null);

                nativeControl = (RadioGroup)layoutInflater.Inflate(Resource.Layout.RadioGroup, null);

                for (var i = 0; i < Element.Children.Count; i++)
                {
                    var o = Element.Children[i];
                    var rb = (RadioButton)layoutInflater.Inflate(Resource.Layout.RadioButton, null);

                    rb.LayoutParameters = new RadioGroup.LayoutParams(0, LayoutParams.WrapContent, 1f);
                    rb.Text = o.Text;

                    if (i == 0)
                        rb.SetBackgroundResource(Resource.Drawable.segmented_control_first_background);
                    else if (i == Element.Children.Count - 1)
                        rb.SetBackgroundResource(Resource.Drawable.segmented_control_last_background);

                    ConfigureRadioButton(i, rb);

                    nativeControl.AddView(rb);
                }

                var option = (RadioButton)nativeControl.GetChildAt(Element.SelectedSegment);

                if (option != null)
                    option.Checked = true;

                SetNativeControl(nativeControl);
			}

			if (e.OldElement != null)
			{
				// Unsubscribe from event handlers and cleanup any resources

				if (nativeControl != null)
					nativeControl.CheckedChange -= NativeControl_ValueChanged;
			}

			if (e.NewElement != null)
			{
				// Configure the control and subscribe to event handlers

                nativeControl.CheckedChange += NativeControl_ValueChanged;
			}
		}

		protected override void OnElementPropertyChanged(object sender, System.ComponentModel.PropertyChangedEventArgs e)
		{
			base.OnElementPropertyChanged(sender, e);

            if (nativeControl == null || Element == null) return;

			switch (e.PropertyName)
			{
				case "Renderer":
                    Element?.SendValueChanged();
					break;
				case "SelectedSegment":
                    var option = (RadioButton)nativeControl.GetChildAt(Element.SelectedSegment);
						
                    if (option != null)
						option.Checked = true;

                    if (Element.SelectedSegment < 0)
                    {
                        var layoutInflater = LayoutInflater.From(context);

						nativeControl = (RadioGroup)layoutInflater.Inflate(Resource.Layout.RadioGroup, null);

						for (var i = 0; i < Element.Children.Count; i++)
						{
							var o = Element.Children[i];
                            var rb = (RadioButton)layoutInflater.Inflate(Resource.Layout.RadioButton, null);

							rb.LayoutParameters = new RadioGroup.LayoutParams(0, LayoutParams.WrapContent, 1f);
							rb.Text = o.Text;

							if (i == 0)
								rb.SetBackgroundResource(Resource.Drawable.segmented_control_first_background);
							else if (i == Element.Children.Count - 1)
								rb.SetBackgroundResource(Resource.Drawable.segmented_control_last_background);

							ConfigureRadioButton(i, rb);

							nativeControl.AddView(rb);
						}

						nativeControl.CheckedChange += NativeControl_ValueChanged;

						SetNativeControl(nativeControl);
                    }

					Element.SendValueChanged();
					break;
				case "TintColor":
                    OnPropertyChanged();
					break;
				case "IsEnabled":
					OnPropertyChanged();
					break;
				case "SelectedTextColor":
                    var v = (RadioButton)nativeControl.GetChildAt(Element.SelectedSegment);
                    v.SetTextColor(Element.SelectedTextColor.ToAndroid());
					break;
			}
		}

		void OnPropertyChanged()
		{
            if (nativeControl != null && Element != null)
            {
                for (var i = 0; i < Element.Children.Count; i++)
                {
                    var rb = (RadioButton)nativeControl.GetChildAt(i);

                    ConfigureRadioButton(i, rb);
                }
            }
		}

		void ConfigureRadioButton(int i, RadioButton rb)
		{
			if (i == Element.SelectedSegment)
			{
                rb.SetTextColor(Element.SelectedTextColor.ToAndroid());
				_rb = rb;
			}
			else
			{
                var textColor = Element.IsEnabled ? Element.TintColor.ToAndroid() : Element.DisabledColor.ToAndroid();
				rb.SetTextColor(textColor);
			}

			GradientDrawable selectedShape;
			GradientDrawable unselectedShape;

			var gradientDrawable = (StateListDrawable)rb.Background;
			var drawableContainerState = (DrawableContainer.DrawableContainerState)gradientDrawable.GetConstantState();
			var children = drawableContainerState.GetChildren();

			// Doesnt works on API < 18
			selectedShape = children[0] is GradientDrawable? (GradientDrawable)children[0] : (GradientDrawable)((InsetDrawable)children[0]).Drawable;
			unselectedShape = children[1] is GradientDrawable? (GradientDrawable)children[1] : (GradientDrawable)((InsetDrawable)children[1]).Drawable;

            var color = Element.IsEnabled ? Element.TintColor.ToAndroid() : Element.DisabledColor.ToAndroid();

			selectedShape.SetStroke(3, color);
			selectedShape.SetColor(color);
			unselectedShape.SetStroke(3, color);

			rb.Enabled = Element.IsEnabled;
		}

		void NativeControl_ValueChanged(object sender, RadioGroup.CheckedChangeEventArgs e)
		{
			var rg = (RadioGroup)sender;
			if (rg.CheckedRadioButtonId != -1)
			{
				var id = rg.CheckedRadioButtonId;
				var radioButton = rg.FindViewById(id);
				var radioId = rg.IndexOfChild(radioButton);

                var rb = (RadioButton)rg.GetChildAt(radioId);

                var color = Element.IsEnabled ? Element.TintColor.ToAndroid() : Element.DisabledColor.ToAndroid();
				_rb?.SetTextColor(color);
				rb.SetTextColor(Element.SelectedTextColor.ToAndroid());
                _rb = rb;

				Element.SelectedSegment = radioId;
			}
		}

		protected override void Dispose(bool disposing)
		{
			if (nativeControl != null)
			{
				nativeControl.CheckedChange -= NativeControl_ValueChanged;
				nativeControl.Dispose();
				nativeControl = null;
				_rb = null;
			}

			try
			{
				base.Dispose(disposing);
			}
			catch (Exception ex)
			{
				return;
			}
		}
        /// <summary>
        /// Used for registration with dependency service
        /// </summary>
        public static void Init() {
			var temp = DateTime.Now;
		}
    }
}