GradientColorStackRenderer.cs

using System;  
using GradientColorDemo.Droid;  
using GradientColorDemo.CustomControls;  
using Xamarin.Forms;  
using Xamarin.Forms.Platform.Android;  
[assembly: ExportRenderer(typeof(GradientColorStack), typeof(GradientColorStackRenderer))]  
namespaceDroid {  
    public class GradientColorStackRenderer: VisualElementRenderer < StackLayout > {  
        private Color StartColor {  
            get;  
            set;  
        }  
        private Color EndColor {  
            get;  
            set;  
        }  
        protected override void DispatchDraw(global::Android.Graphics.Canvas canvas)   
        {  
            #region for Vertical Gradient  
            //var gradient = new Android.Graphics.LinearGradient(0, 0, 0, Height,      
            # endregion
            # region  for Horizontal Gradient  
            var gradient = newGraphics.LinearGradient(0, 0, Width, 0,   
            #endregion 
            this.StartColor.ToAndroid(), 
            this.EndColor.ToAndroid(), 
            Android.Graphics.Shader.TileMode.Mirror);  
            var paint = new Android.Graphics.Paint() {  
                Dither = true,  
            };  
            paint.SetShader(gradient);  
            canvas.DrawPaint(paint);  
            base.DispatchDraw(canvas);  
        }  
        protected override void OnElementChanged(ElementChangedEventArgs<StackLayout> e) {  
            base.OnElementChanged(e);  
            if (e.OldElement != null || Element == null) {  
                return;  
            }  
            try {  
                var stack = e.NewElement as GradientColorStack;  
                this.StartColor = stack.StartColor;  
                this.EndColor = stack.EndColor;  
            } catch (Exception ex) {  
                Syatem.Diagnostics.Debug.WriteLine(@ "ERROR:", ex.Message);  
            }  
        }  
    }  
}