Avalonia/samples/ControlCatalog/Pages/HomePage.xaml.cs

using System;
using Avalonia;
using Avalonia.Animation;
using Avalonia.Controls;
using Avalonia.Controls.Primitives;
using Avalonia.Media;
using Avalonia.Styling;

namespace ControlCatalog.Pages;

public partial class HomePage : ContentPage
{
    public HomePage()
    {
        InitializeComponent();
    }

    protected override void OnAttachedToVisualTree(VisualTreeAttachmentEventArgs e)
    {
        base.OnAttachedToVisualTree(e);

        StartFloatingAnimation(BannerLogo1, 12, 8, TimeSpan.FromSeconds(12));
        StartFloatingAnimation(BannerLogo2, -14, 8, TimeSpan.FromSeconds(10));
        StartFloatingAnimation(BannerLogo3, -12, -12, TimeSpan.FromSeconds(14));
        StartFloatingAnimation(BannerLogo4, 12, -8, TimeSpan.FromSeconds(11));
    }

    private static void StartFloatingAnimation(Control target, double dx, double dy, TimeSpan duration)
    {
        var transform = new TranslateTransform();
        target.RenderTransform = transform;

        var animation = new Animation
        {
            Duration = duration,
            IterationCount = IterationCount.Infinite,
            Children =
            {
                new KeyFrame
                {
                    Cue = new Cue(0d),
                    Setters =
                    {
                        new Setter(TranslateTransform.XProperty, 0d),
                        new Setter(TranslateTransform.YProperty, 0d),
                    }
                },
                new KeyFrame
                {
                    Cue = new Cue(0.5d),
                    Setters =
                    {
                        new Setter(TranslateTransform.XProperty, dx),
                        new Setter(TranslateTransform.YProperty, dy),
                    }
                },
                new KeyFrame
                {
                    Cue = new Cue(1d),
                    Setters =
                    {
                        new Setter(TranslateTransform.XProperty, 0d),
                        new Setter(TranslateTransform.YProperty, 0d),
                    }
                },
            }
        };

        _ = animation.RunAsync(target);
    }

    private void UniformGrid_OnSizeChanged(object? sender, SizeChangedEventArgs e)
    {
        if (sender is not UniformGrid grid)
            return;

        const int minItemWidth = 248;
        grid.Columns = Math.Max(
            1,
            (int)((e.NewSize.Width + grid.ColumnSpacing) / (minItemWidth + grid.ColumnSpacing)));
    }
}