Colours

Main.axaml

<UserControl xmlns="https://github.com/avaloniaui">


 <StackPanel HorizontalAlignment="Center" VerticalAlignment="Center">
 	<Canvas Width="120" Height="120">
 		<Rectangle Name="One" Height="44" Width="44" />
 		<Rectangle Name="Two" Height="44" Width="44" Canvas.Left="20" Canvas.Top="20" />
 		<Rectangle Name="Three" Height="44" Width="44" Canvas.Left="40" Canvas.Top="40" />
 		<Rectangle Name="Four" Height="44" Width="44" Canvas.Left="60" Canvas.Top="60" />
 	</Canvas>
 	
	<Button Name="Button" HorizontalAlignment="Stretch" HorizontalContentAlignment="Center">
		Click Me
	</Button>
 </StackPanel>

</UserControl>

Main.axaml.cs

using Avalonia;
using Avalonia.Controls;
using Avalonia.Markup.Xaml;
using Avalonia.Controls.Shapes;
using Avalonia.Media;

namespace XamlPlayground.Views
{
    public class SampleView : UserControl
    {
    	private Rectangle _one;
    	private Rectangle _two;
    	private Rectangle _three;
    	private Rectangle _four;
    	
        protected override void OnAttachedToVisualTree(VisualTreeAttachmentEventArgs e)
        {
            _one = this.Find<Rectangle>("One");
            _two = this.Find<Rectangle>("Two");
            _three = this.Find<Rectangle>("Three");
            _four = this.Find<Rectangle>("Four");
            
            _one.Fill = Brushes.Blue;
            _two.Fill = Brushes.Green;
            _three.Fill = Brushes.Orange;
            _four.Fill = Brushes.Red;
            
            var button = this.Find<Button>("Button");
            
            button.Click += (sender, e) => 
            {
                var one = _one.Fill;
                var two = _two.Fill;
                var three = _three.Fill;
                var four = _four.Fill;
                
                _one.Fill = four;
                _two.Fill = one;
                _three.Fill = two;
                _four.Fill = three;
            };
            
            base.OnAttachedToVisualTree(e);
        }
    }
}