MyAvaloniaDemo/AuroraDesk.Presentation/Controls/ConnectorColumnPanel.cs

using System;
using Avalonia;
using Avalonia.Controls;

namespace AuroraDesk.Presentation.Controls;

/// <summary>
/// 垂直均匀分布子元素的面板，用于渲染节点左右侧连接点。
/// </summary>
public class ConnectorColumnPanel : Panel
{
    public static readonly StyledProperty<ConnectorColumnSide> SideProperty =
        AvaloniaProperty.Register<ConnectorColumnPanel, ConnectorColumnSide>(nameof(Side), ConnectorColumnSide.Center);

    public ConnectorColumnSide Side
    {
        get => GetValue(SideProperty);
        set => SetValue(SideProperty, value);
    }

    protected override Size MeasureOverride(Size availableSize)
    {
        var maxWidth = 0d;
        var totalHeight = 0d;

        foreach (var child in Children)
        {
            child.Measure(new Size(double.PositiveInfinity, double.PositiveInfinity));
            var desired = child.DesiredSize;
            var margin = (child as Control)?.Margin ?? new Thickness(0);

            var horizontalMargin = Math.Abs(margin.Left) + Math.Abs(margin.Right);
            var verticalMargin = Math.Max(0, margin.Top) + Math.Max(0, margin.Bottom);

            maxWidth = Math.Max(maxWidth, desired.Width + horizontalMargin);
            totalHeight += desired.Height + verticalMargin;
        }

        var height = double.IsInfinity(availableSize.Height) ? totalHeight : availableSize.Height;
        return new Size(maxWidth, height);
    }

    protected override Size ArrangeOverride(Size finalSize)
    {
        var count = Children.Count;
        if (count == 0)
        {
            return finalSize;
        }

        var totalHeight = 0d;
        foreach (var child in Children)
        {
            var margin = (child as Control)?.Margin ?? new Thickness(0);
            totalHeight += child.DesiredSize.Height + Math.Max(0, margin.Top) + Math.Max(0, margin.Bottom);
        }

        var availableHeight = finalSize.Height;
        var spacing = count > 0
            ? Math.Max(0, (availableHeight - totalHeight) / (count + 1))
            : 0;

        var currentY = spacing;
        foreach (var child in Children)
        {
            var childHeight = child.DesiredSize.Height;
            var childWidth = child.DesiredSize.Width;
            var margin = (child as Control)?.Margin ?? new Thickness(0);

            double x = Side switch
            {
                ConnectorColumnSide.Left => margin.Left,
                ConnectorColumnSide.Right => finalSize.Width - childWidth + margin.Left,
                _ => (finalSize.Width - childWidth) / 2 + (margin.Left - margin.Right) / 2
            };

            var y = currentY + Math.Max(0, margin.Top);
            child.Arrange(new Rect(x, y, childWidth, childHeight));
            currentY += Math.Max(0, margin.Top) + childHeight + Math.Max(0, margin.Bottom) + spacing;
        }

        return finalSize;
    }
}

public enum ConnectorColumnSide
{
    Center,
    Left,
    Right
}