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**Code Explanation:** The code provides an implementation of smooth dragging for a control named `DragControls`. **Key Concepts:** * **UserControl**: A custom control that inherits functionality from the `UserControl` class. * **DispatcherTimer**: An object that triggers a callback after a specified interval. * **Target Position**: The final destination point for the control's position. * **PointerPressed and PointerReleased Events**: Event handlers for when the mouse button is pressed and released on the control. * **OnTimerTick Event**: A callback triggered every 10 milliseconds to update the control's position. * **InitializeComponent()**: Method for initializing the control. * **OnPointerPressed()**: Method called when the mouse button is pressed. It starts dragging, records the initial position, and starts the timer. * **OnPointerReleased()**: Method called when the mouse button is released. It stops dragging, sets the target position, and stops the timer. * **OnPointerMoved()**: Method called when the mouse pointer moves. It updates the target position based on the current and previous positions. **Usage:** 1. Create an instance of `DragControls` control. 2. Set the target position of the control using the `_targetPosition` variable. 3. Set any other desired properties of the control. **Benefits:** * Smooth and natural dragging experience. * Event-driven handling for mouse press, move, and release events. * Adjustable target position. **Additional Notes:** * The code assumes the control has a `Window` as its root container. * The `_targetPosition` variable should be initialized with the desired target position of the control. * The animation and visual feedback should be implemented separately.

正文

Avalonia 实现平滑拖动指定控件

1.创建一个UserControl控件，并且添加以下代码

using System;
using Avalonia;
using Avalonia.Controls;
using Avalonia.Input;
using Avalonia.Markup.Xaml;
using Avalonia.Media;
using Avalonia.Media.Imaging;
using Avalonia.Platform;
using Avalonia.Threading;
using Avalonia.VisualTree;

namespace Token;

/// <summary>
/// 实现拖动的控件
/// </summary>
public partial class DragControls : UserControl
{
    /// <summary>
    /// 记录上一次鼠标位置
    /// </summary>
    private Point lastMousePosition;

    /// <summary>
    /// 用于平滑更新坐标的计时器
    /// </summary>
    private DispatcherTimer _timer;

    /// <summary>
    /// 标记是否先启动了拖动
    /// </summary>
    private bool isDragging = false;

    /// <summary>
    /// 需要更新的坐标点
    /// </summary>
    private PixelPoint _targetPosition;

    public LoginStackPanelRight()
    {
        InitializeComponent();

        // 添加当前控件的事件监听
        PointerPressed += OnPointerPressed;
        PointerMoved += OnPointerMoved;
        PointerReleased += OnPointerReleased;

        // 初始化计时器
        _timer = new DispatcherTimer
        {
            Interval = TimeSpan.FromMilliseconds(10)
        };
        _timer.Tick += OnTimerTick;
    }

    /// <summary>
    /// 计时器事件
    /// </summary>
    /// <param name="sender"></param>
    /// <param name="e"></param>
    private void OnTimerTick(object sender, EventArgs e)
    {
        var window = this.FindAncestorOfType<Window>();
        if (window != null && window.Position != _targetPosition)
        {
            // 更新坐标
            window.Position = _targetPosition;
        }
    }

    private void InitializeComponent()
    {
        AvaloniaXamlLoader.Load(this);
    }

    private void OnPointerPressed(object sender, PointerPressedEventArgs e)
    {
        if (!e.GetCurrentPoint(this).Properties.IsLeftButtonPressed) return;
        // 启动拖动
        isDragging = true;
        // 记录当前坐标
        lastMousePosition = e.GetPosition(this);
        e.Handled = true;
        // 启动计时器
        _timer.Start();
    }

    private void OnPointerReleased(object sender, PointerReleasedEventArgs e)
    {
        if (!isDragging) return;
        // 停止拖动
        isDragging = false;
        e.Handled = true;
        // 停止计时器
        _timer.Stop();
    }

    private void OnPointerMoved(object sender, PointerEventArgs e)
    {
        if (!e.GetCurrentPoint(this).Properties.IsLeftButtonPressed) return;
        
        // 如果没有启动拖动，则不执行
        if (!isDragging) return;

        var currentMousePosition = e.GetPosition(this);
        var offset = currentMousePosition - lastMousePosition;
        var window = this.FindAncestorOfType<Window>();
        if (window != null)
        {
            // 记录当前坐标
            _targetPosition = new PixelPoint(window.Position.X + (int)offset.X,
                window.Position.Y + (int)offset.Y);
        }
    }
}

通过以上组件可以实现平滑拖动
效果如图

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