第十五章：插件系统与扩展开发

15.1 插件系统概述

15.1.1 Weikio Plugin Framework

LightCAD的插件系统基于Weikio Plugin Framework构建，这是一个.NET平台的轻量级插件加载框架，支持运行时动态加载和卸载程序集。

15.1.2 内置行业插件

LightCAD预置了五个行业插件：

插件	文件	大小	功能领域
QdArch	QdArch.dll	591KB	建筑设计
QdElectric	QdElectric.dll	45KB	电气设计
QdHvac	QdHvac.dll	95KB	暖通设计
QdStruct	QdStruct.dll	173KB	结构设计
QdWater	QdWater.dll	201KB	给排水设计

15.2 插件加载机制

15.2.1 插件管理器

public class PluginManager
{
    private static List<IPlugin> loadedPlugins = new();
    private static string pluginDirectory;

    /// <summary>
    /// 加载指定目录下的所有插件
    /// </summary>
    public static void LoadPlugins(string directory)
    {
        pluginDirectory = directory;

        if (!Directory.Exists(directory))
        {
            Directory.CreateDirectory(directory);
            return;
        }

        var pluginFiles = Directory.GetFiles(directory, "*.dll");

        foreach (var pluginFile in pluginFiles)
        {
            try
            {
                LoadPlugin(pluginFile);
            }
            catch (Exception ex)
            {
                Console.WriteLine(
                    $"加载插件失败 {Path.GetFileName(pluginFile)}: {ex.Message}");
            }
        }
    }

    /// <summary>
    /// 加载单个插件
    /// </summary>
    private static void LoadPlugin(string pluginPath)
    {
        // 使用Weikio Plugin Framework加载
        var assembly = Assembly.LoadFrom(pluginPath);

        // 查找实现IPlugin接口的类型
        var pluginTypes = assembly.GetTypes()
            .Where(t => typeof(IPlugin).IsAssignableFrom(t)
                && !t.IsAbstract && !t.IsInterface);

        foreach (var pluginType in pluginTypes)
        {
            var plugin = (IPlugin)Activator.CreateInstance(pluginType);
            plugin.Initialize();
            loadedPlugins.Add(plugin);

            Console.WriteLine($"已加载插件：{plugin.Name} v{plugin.Version}");
        }
    }

    /// <summary>
    /// 获取所有已加载的插件
    /// </summary>
    public static IReadOnlyList<IPlugin> LoadedPlugins => loadedPlugins;

    /// <summary>
    /// 卸载所有插件
    /// </summary>
    public static void UnloadAll()
    {
        foreach (var plugin in loadedPlugins)
        {
            plugin.Shutdown();
        }
        loadedPlugins.Clear();
    }
}

15.2.2 插件接口

/// <summary>
/// 插件基础接口
/// </summary>
public interface IPlugin
{
    /// <summary>
    /// 插件名称
    /// </summary>
    string Name { get; }

    /// <summary>
    /// 插件版本
    /// </summary>
    string Version { get; }

    /// <summary>
    /// 插件描述
    /// </summary>
    string Description { get; }

    /// <summary>
    /// 插件作者
    /// </summary>
    string Author { get; }

    /// <summary>
    /// 初始化插件
    /// </summary>
    void Initialize();

    /// <summary>
    /// 关闭插件
    /// </summary>
    void Shutdown();
}

/// <summary>
/// 带命令注册能力的插件
/// </summary>
public interface ICommandPlugin : IPlugin
{
    /// <summary>
    /// 注册插件命令
    /// </summary>
    void RegisterCommands(CommandRegistry registry);
}

/// <summary>
/// 带UI扩展能力的插件
/// </summary>
public interface IUIPlugin : IPlugin
{
    /// <summary>
    /// 注册菜单项
    /// </summary>
    void RegisterMenuItems(MenuRegistry registry);

    /// <summary>
    /// 注册工具栏按钮
    /// </summary>
    void RegisterToolbarItems(ToolbarRegistry registry);

    /// <summary>
    /// 注册面板
    /// </summary>
    void RegisterPanels(PanelRegistry registry);
}

/// <summary>
/// 带元素类型扩展能力的插件
/// </summary>
public interface IElementPlugin : IPlugin
{
    /// <summary>
    /// 注册自定义元素类型
    /// </summary>
    void RegisterElementTypes(ElementTypeRegistry registry);
}

15.3 开发自定义插件

15.3.1 创建插件项目

# 创建类库项目
dotnet new classlib -n MyLightCADPlugin -f net8.0-windows

# 添加LightCAD核心引用
cd MyLightCADPlugin
dotnet add reference ../LightCAD.Core/LightCAD.Core.csproj
dotnet add reference ../LightCAD.Runtime/LightCAD.Runtime.csproj

15.3.2 实现插件

// MyPlugin.cs
public class MyPlugin : IPlugin, ICommandPlugin, IElementPlugin
{
    public string Name => "我的自定义插件";
    public string Version => "1.0.0";
    public string Description => "LightCAD自定义插件示例";
    public string Author => "开发者";

    public void Initialize()
    {
        Console.WriteLine("我的插件已初始化");
    }

    public void Shutdown()
    {
        Console.WriteLine("我的插件已关闭");
    }

    public void RegisterCommands(CommandRegistry registry)
    {
        registry.Register(new CommandInfo
        {
            Name = "MYCOMMAND",
            DisplayName = "我的命令",
            Description = "执行自定义操作",
            Action = ExecuteMyCommand
        });

        registry.Register(new CommandInfo
        {
            Name = "DRAWSTAR",
            DisplayName = "绘制星形",
            Description = "绘制一个正五角星",
            Action = DrawStar
        });
    }

    public void RegisterElementTypes(ElementTypeRegistry registry)
    {
        registry.Register(new ElementType
        {
            Guid = new LcGuid("my-plugin-star-element"),
            Name = "Star",
            DisplayName = "五角星",
            Category = "自定义图形",
            Is3D = false,
            Creator = () => new StarElement()
        });
    }

    private void ExecuteMyCommand()
    {
        // 自定义命令逻辑
        MessageBox.Show("执行自定义命令！");
    }

    private void DrawStar()
    {
        // 绘制五角星的逻辑
        var center = InputManager.GetPoint("指定五角星中心：");
        var radius = InputManager.GetDistance("指定外径：");

        var star = CreateStarPolyline(center, radius, 5);
        DocumentManager.Current.Entities.Add(star);
    }

    private LcPolyline CreateStarPolyline(Point2d center,
                                           double outerRadius, int points)
    {
        var polyline = new LcPolyline { IsClosed = true };
        var innerRadius = outerRadius * 0.382;

        for (int i = 0; i < points * 2; i++)
        {
            var angle = Math.PI / 2 + Math.PI * i / points;
            var r = (i % 2 == 0) ? outerRadius : innerRadius;
            polyline.AddVertex(new Point2d(
                center.X + r * Math.Cos(angle),
                center.Y + r * Math.Sin(angle)
            ));
        }

        return polyline;
    }
}

15.3.3 自定义元素类型

/// <summary>
/// 自定义五角星元素
/// </summary>
public class StarElement : LcEntity, IUpdateObject
{
    public Point2d Center { get; set; }
    public double OuterRadius { get; set; } = 50;
    public double InnerRadius { get; set; } = 19.1;
    public int Points { get; set; } = 5;
    public double Rotation { get; set; } = 0;

    public override string TypeName => "Star";

    public override BoundingBox2d Bounds
    {
        get
        {
            return new BoundingBox2d
            {
                Min = new Point2d(
                    Center.X - OuterRadius, Center.Y - OuterRadius),
                Max = new Point2d(
                    Center.X + OuterRadius, Center.Y + OuterRadius)
            };
        }
    }

    public override void TransformBy(Matrix4d matrix)
    {
        var p3d = new Point3d(Center.X, Center.Y, 0);
        var transformed = matrix.Transform(p3d);
        Center = new Point2d(transformed.X, transformed.Y);
    }

    public override LcEntity Clone()
    {
        return new StarElement
        {
            Center = Center,
            OuterRadius = OuterRadius,
            InnerRadius = InnerRadius,
            Points = Points,
            Rotation = Rotation,
            Color = Color,
            LayerName = LayerName
        };
    }

    public override double DistanceTo(Point2d point)
    {
        return point.DistanceTo(Center) - OuterRadius;
    }

    /// <summary>
    /// 获取五角星的顶点
    /// </summary>
    public List<Point2d> GetVertices()
    {
        var vertices = new List<Point2d>();
        for (int i = 0; i < Points * 2; i++)
        {
            var angle = Rotation + Math.PI / 2 + Math.PI * i / Points;
            var r = (i % 2 == 0) ? OuterRadius : InnerRadius;
            vertices.Add(new Point2d(
                Center.X + r * Math.Cos(angle),
                Center.Y + r * Math.Sin(angle)
            ));
        }
        return vertices;
    }

    public bool NeedsUpdate { get; private set; }
    public void OnUpdate(UpdateContext context)
    {
        NeedsUpdate = false;
    }
}

15.4 插件部署

15.4.1 编译和部署

# 编译插件
dotnet build -c Release

# 将编译输出复制到LightCAD的Plugins目录
copy bin/Release/net8.0-windows/MyLightCADPlugin.dll \
     ../LightCAD.WinForm/bin/Debug/net8.0-windows/Plugins/

15.4.2 插件清单文件

为了更好地管理插件信息，可以创建清单文件：

{
    "name": "MyLightCADPlugin",
    "version": "1.0.0",
    "author": "开发者",
    "description": "LightCAD自定义插件示例",
    "assembly": "MyLightCADPlugin.dll",
    "dependencies": [],
    "minimumLightCADVersion": "1.0.0"
}

15.5 ComponentActionLoader

15.5.1 操作加载器

ComponentActionLoader是LightCAD中专门用于加载建模操作的插件加载器：

public class ComponentActionLoader
{
    private Dictionary<string, IComponentAction> actions = new();

    /// <summary>
    /// 从程序集加载操作
    /// </summary>
    public void LoadActionsFromAssembly(Assembly assembly)
    {
        var actionTypes = assembly.GetTypes()
            .Where(t => typeof(IComponentAction).IsAssignableFrom(t)
                && !t.IsAbstract);

        foreach (var type in actionTypes)
        {
            var action = (IComponentAction)Activator.CreateInstance(type);
            actions[action.Name] = action;
        }
    }

    /// <summary>
    /// 获取操作
    /// </summary>
    public IComponentAction GetAction(string name)
    {
        return actions.TryGetValue(name, out var action) ? action : null;
    }

    /// <summary>
    /// 获取所有操作
    /// </summary>
    public IEnumerable<IComponentAction> GetAllActions()
    {
        return actions.Values;
    }

    /// <summary>
    /// 获取某个类别的操作
    /// </summary>
    public IEnumerable<IComponentAction> GetActionsByCategory(string category)
    {
        return actions.Values.Where(a => a.Category == category);
    }
}

public interface IComponentAction
{
    string Name { get; }
    string DisplayName { get; }
    string Category { get; }
    LcSolid3d Execute(ActionContext context);
}

15.6 扩展点总结

15.6.1 LightCAD可扩展的维度

扩展维度	接口/机制	说明
元素类型	IElementPlugin / ElementTypeRegistry	定义新的图元类型
命令	ICommandPlugin / CommandRegistry	添加新的用户命令
建模操作	IComponentAction / ComponentActionLoader	添加3D建模操作
UI菜单	IUIPlugin / MenuRegistry	扩展菜单系统
UI工具栏	IUIPlugin / ToolbarRegistry	添加工具栏按钮
UI面板	IUIPlugin / PanelRegistry	添加侧边面板
文件格式	IFormatPlugin / FormatConverter	支持新的文件格式
捕捉类型	ISnapProvider / SnapManager	自定义捕捉行为

15.7 本章小结

本章详细介绍了LightCAD的插件系统和扩展开发方法。LightCAD基于Weikio Plugin Framework提供了灵活的插件加载机制，支持运行时动态加载插件。通过IPlugin及其扩展接口（ICommandPlugin、IElementPlugin、IUIPlugin），开发者可以在多个维度上扩展LightCAD的功能。内置的五个行业插件展示了实际的插件应用场景。ComponentActionLoader专门用于加载3D建模操作，是建模扩展的核心入口。

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