XF相对控件布局

using System;

using Xamarin.Forms;

using Xamarin.Forms.Xaml;

[assembly: XamlCompilation (XamlCompilationOptions.Compile)]

namespace App6

{

    public partial class App : Application

    {

        public App ()

        {

            InitializeComponent();

            BoxView bv = new BoxView { Color = Color.Red, WidthRequest = 150, HeightRequest = 150 };

            Label lbl = new Label { Text = "这是一个红色的方块", TextColor = Color.Red };

            RelativeLayout rl = new RelativeLayout();

            rl.Children.Add(bv,Constraint.RelativeToParent((parent)=>parent.Width/2),Constraint.RelativeToParent((parent)=>parent.Height/2));

            rl.Children.Add(lbl, Constraint.RelativeToView(bv, (parent, sibling) => sibling.X+bv.Width), Constraint.RelativeToView(bv, (parent, sibling) => sibling.Y));

MainPage = new ContentPage { Content=rl};

        }

protected override void OnStart ()

        {

            // Handle when your app starts

        }

protected override void OnSleep ()

        {

            // Handle when your app sleeps

        }

protected override void OnResume ()

        {

            // Handle when your app resumes

        }

    }

}