CustomButtonRenderer.cs

using Android.Content;
using Android.Graphics;
using Android.Views;
using SampleCode.Custom;
using SampleCode.Droid.Custom;
using Xamarin.Forms;
using Xamarin.Forms.Platform.Android;

[assembly: ExportRenderer(typeof(CustomButton), typeof(CustomButtonRenderer))]
namespace SampleCode.Droid.Custom
{
    public class CustomButtonRenderer : ButtonRenderer
    {
        Rect rect;

        public CustomButtonRenderer(Context context) : base(context) { }

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

            if (Control != null)
            {
                //Flat design button
                //Set the button state color on your button_background_style.xml
                Control.SetBackgroundResource(Resource.Drawable.button_background_style);
                Control.StateListAnimator = null;
                Control.Elevation = 0;
            }
        }

        public override bool OnInterceptTouchEvent(MotionEvent e)
        {
            if (e.ActionMasked == MotionEventActions.Down)
            {
                Control.SetTextColor(Android.Graphics.Color.ParseColor("#2679F9"));
            }
            else if (e.ActionMasked == MotionEventActions.Up || e.ActionMasked == MotionEventActions.Cancel)
            {
                Control.SetTextColor(Android.Graphics.Color.White);
            }
            else if (e.ActionMasked == MotionEventActions.Move)
            {
                //Change to default textcolor if the user tap, hold and drag on button
                rect = new Rect(Left, Top, Right, Bottom);
                if (!rect.Contains(Left + (int)e.GetX(), Top + (int)e.GetY()))
                {
                    Control.SetTextColor(Android.Graphics.Color.White);
                }
            }
            return false;
        }
    }
}