ShrlAlgoToolkit/Melskin/Controls/Toast/ScreenHost.cs

using System.Diagnostics;
using System.Windows.Media.Animation;


namespace Melskin.Controls;
#region Internal Implementation
internal class ScreenHost : IToastHost
{
    private readonly List<Window> toastWindows = [];
    private readonly object obj = new();
    private const double Spacing = 15;

    public void AddToast(ToastControl toast)
    {
        //空出空间，显示阴影
        toast.Margin = new Thickness(4);
        var window = new Window
        {
            Content = toast,
            WindowStyle = WindowStyle.None,
            AllowsTransparency = true,
            Background = Brushes.Transparent,
            ShowInTaskbar = false,
            Topmost = true,
            Owner = null,
            SizeToContent = SizeToContent.WidthAndHeight,
            Left = -9999
        };

        window.Loaded += (_, _) =>
        {
            lock (obj)
            {
                toastWindows.Add(window);
                RepositionToasts();
            }
        };

        window.Closed += (_, _) =>
        {
            lock (obj)
            {
                toastWindows.Remove(window);
                RepositionToasts();
            }
        };

        window.Show();
    }

    public void RemoveToast(ToastControl toast)
    {
        Debug.Assert(toastWindows != null, nameof(toastWindows) + " != null");
        var window = toastWindows.FirstOrDefault(w => Equals(w.Content, toast));
        window?.Close();
    }

    private void RepositionToasts()
    {
        var workArea = SystemParameters.WorkArea;
        var currentTop = Spacing; // 从顶部开始，有间距。

        foreach (var window in toastWindows)
        {
            // 将窗口水平居中。
            var left = workArea.Left + (workArea.Width - window.ActualWidth) / 2;

            var moveAnim = new DoubleAnimation(currentTop, TimeSpan.FromMilliseconds(350))
            { EasingFunction = new QuinticEase { EasingMode = EasingMode.EaseOut } };

            window.Left = left; //直接设置水平位置。
            window.BeginAnimation(Window.TopProperty, moveAnim); // Animate vertical position.

            // 更新下一次 Toast 的顶部位置。
            currentTop += window.ActualHeight + Spacing;
        }
    }
}
#endregion