C# Avalonia 16- Animation- SampleViewer - FollowExample

FollowExample.axaml代码

<UserControl xmlns="https://github.com/avaloniaui"
             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
             xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
             xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
             mc:Ignorable="d" d:DesignWidth="800" d:DesignHeight="450"
             x:Class="AvaloniaUI.FollowExample">
    <Canvas x:Name="containerCanvas" Background="transparent" PointerMoved="OnPointerMoved">
        <Rectangle x:Name="followRectangle" Canvas.Left="0" Canvas.Top="0" Fill="red" Width="50" Height="50" />
    </Canvas>
</UserControl>

FollowExample.axaml.cs代码

using Avalonia;
using Avalonia.Controls;
using Avalonia.Input;
using Avalonia.Markup.Xaml;
using Shares.Avalonia;
using System;

namespace AvaloniaUI;

public partial class FollowExample : UserControl
{
    private readonly AnimationPlayer animation = new AnimationPlayer();
    private Point lastMousePosition = new Point(300, 200);
    private Vector rectangleVelocity = new Vector(0, 0);
    public FollowExample()
    {
        InitializeComponent();
        // 初始位置
        Canvas.SetLeft(followRectangle, lastMousePosition.X);
        Canvas.SetTop(followRectangle, lastMousePosition.Y);

        // 配置 AnimationPlayer
        animation.Duration = double.MaxValue; // 无限播放
        animation.Loop = true;
        animation.Fps = 60;

        // 每帧执行“跟随逻辑”
        animation.At(0).PlayGlobal(UpdateRectangle);

        animation.Start();
    }
    private void OnPointerMoved(object? sender, PointerEventArgs e)
    {
        lastMousePosition = e.GetPosition(containerCanvas);
    }
    private void UpdateRectangle(double globalProgress)
    {
        // 当前矩形位置
        var location = new Point(
            Canvas.GetLeft(followRectangle),
            Canvas.GetTop(followRectangle));

        // 指向鼠标的向量
        Vector toMouse = lastMousePosition - location;

        // 施加“跟随力”
        double followForce = 0.01;
        rectangleVelocity += toMouse * followForce;

        // 阻尼系数（防止发散）
        double drag = 0.8;
        rectangleVelocity *= drag;

        // 更新位置
        location += rectangleVelocity;

        Canvas.SetLeft(followRectangle, location.X);
        Canvas.SetTop(followRectangle, location.Y);
    }
}

运行效果