Xamarin.Android: Temp. fix for vertical text alignment of the SearchBar (Issue #2936)

SearchBarAlignmentFixRenderer.cs

using System.Collections.Generic;
using System.Linq;
using Android.Content;
using Android.OS;
using Android.Views;
using Android.Widget;
using CloudMatic.Controls;
using CloudMatic.Droid.ControlsRenderer;
using Xamarin.Forms;
using Xamarin.Forms.Platform.Android;
using AView = Android.Views.View;
using AViewGroup = Android.Views.ViewGroup;

[assembly: ExportRenderer(typeof(SearchBar), typeof(SearchBarAlignmentFixRenderer))]
namespace CloudMatic.Droid.ControlsRenderer
{
    public class SearchBarAlignmentFixRenderer : SearchBarRenderer
    {
        public SearchBarAlignmentFixRenderer(Context context) : base(context)
        {
        }

        protected override void OnElementChanged(ElementChangedEventArgs<SearchBar> e)
        {
            base.OnElementChanged(e);
            if (Control == null)
                return;

            var editText = GetChildrenOfType<EditText>(Control).FirstOrDefault();
            if (editText == null)
                return;

            UpdateHorizontalAlignment(editText, Element.HorizontalTextAlignment, Context.HasRtlSupport(), ToVerticalGravityFlags(Xamarin.Forms.TextAlignment.Center));        
        }

        static void UpdateHorizontalAlignment(EditText view, Xamarin.Forms.TextAlignment alignment, bool hasRtlSupport, GravityFlags orMask = GravityFlags.NoGravity)
        {
            if ((int)Build.VERSION.SdkInt < 17 || !hasRtlSupport)
                view.Gravity = ToHorizontalGravityFlags(alignment) | orMask;
 			else
 				view.TextAlignment = ToTextAlignment(alignment);
        }

        IEnumerable<T> GetChildrenOfType<T>(AViewGroup self) where T : AView
        {
            for (var i = 0; i < self.ChildCount; i++)
            {
                AView child = self.GetChildAt(i);
                var typedChild = child as T;
                if (typedChild != null)
                    yield return typedChild;

                if (child is AViewGroup)
                {
                    IEnumerable<T> myChildren = GetChildrenOfType<T>((child as AViewGroup));
                    foreach (T nextChild in myChildren)
                        yield return nextChild;
                }
            }
        }

        static Android.Views.TextAlignment ToTextAlignment(Xamarin.Forms.TextAlignment alignment)
        {
            switch (alignment)
            {
                case Xamarin.Forms.TextAlignment.Center:
                    return Android.Views.TextAlignment.Center;
                case Xamarin.Forms.TextAlignment.End:
                    return Android.Views.TextAlignment.ViewEnd;
                default:
                    return Android.Views.TextAlignment.ViewStart;
            }
        }

        static GravityFlags ToVerticalGravityFlags(Xamarin.Forms.TextAlignment alignment)
        {
            switch (alignment)
            {
                case Xamarin.Forms.TextAlignment.Start:
                    return GravityFlags.Top;
                case Xamarin.Forms.TextAlignment.End:
                    return GravityFlags.Bottom;
                default:
                    return GravityFlags.CenterVertical;
            }
        }

        static GravityFlags ToHorizontalGravityFlags(Xamarin.Forms.TextAlignment alignment)
        {
            switch (alignment)
            {
                case Xamarin.Forms.TextAlignment.Center:
                    return GravityFlags.CenterHorizontal;
                case Xamarin.Forms.TextAlignment.End:
                    return GravityFlags.End;
                default:
                    return GravityFlags.Start;
            }
        }
    }
}