C# DXF文件解析与交互式显示含缩放拖拽

一、核心功能实现原理

二、完整代码实现（含详细注释）

1. 环境配置

// 安装依赖库
Install-Package netDxf
Install-Package System.Numerics.Vectors

2. 主窗体设计（WinForm）

using System;
using System.Drawing;
using System.Numerics;
using System.Windows.Forms;
using netDxf;
using netDxf.Entities;

namespace DXFViewer
{
    public partial class MainForm : Form
    {
        private DxfDocument dxf;
        private Vector2 offset = Vector2.Zero;  // 平移偏移量
        private float zoom = 1.0f;              // 缩放系数
        private Point lastMousePos;

        public MainForm()
        {
            InitializeComponent();
            this.DoubleBuffered = true;          // 防闪烁
            hScroll.Maximum = 10000;
            vScroll.Maximum = 10000;
        }
    }
}

3. DXF加载与解析

// 加载DXF文件
private void LoadDxf(string path)
{
    try
    {
        dxf = DxfDocument.Load(path);
        UpdateView();
    }
    catch (Exception ex)
    {
        MessageBox.Show($"加载失败: {ex.Message}");
    }
}

// 解析实体数据
private void ParseEntities()
{
    entities.Clear();
    foreach (Entity entity in dxf.Entities)
    {
        if (entity.Type == EntityType.Line)
        {
            var line = (Line)entity;
            entities.Add(new DxfEntity
            {
                Type = EntityType.Line,
                Points = new[] { line.StartPoint, line.EndPoint }
            });
        }
        else if (entity.Type == EntityType.Circle)
        {
            var circle = (Circle)entity;
            entities.Add(new DxfEntity
            {
                Type = EntityType.Circle,
                Center = circle.Center,
                Radius = circle.Radius
            });
        }
        // 其他实体类型处理...
    }
}

4. 自定义绘图引擎

// 绘制所有实体
private void DrawEntities(Graphics g)
{
    foreach (var entity in entities)
    {
        Matrix3x2 transform = GetTransformMatrix();
        switch (entity.Type)
        {
            case EntityType.Line:
                DrawLine(g, (LineEntity)entity, transform);
                break;
            case EntityType.Circle:
                DrawCircle(g, (CircleEntity)entity, transform);
                break;
        }
    }
}

// 坐标变换矩阵
private Matrix3x2 GetTransformMatrix()
{
    return Matrix3x2.CreateTranslation(-offset.X, -offset.Y) *
           Matrix3x2.CreateScale(zoom, zoom) *
           Matrix3x2.CreateTranslation(ClientSize.Width / 2, ClientSize.Height / 2);
}

5. 交互事件处理

// 鼠标滚轮缩放
private void MainForm_MouseWheel(object sender, MouseEventArgs e)
{
    float delta = e.Delta > 0 ? 1.1f : 0.9f;
    zoom *= delta;
    UpdateScrollBars();
    Invalidate();
}

// 鼠标拖拽平移
private void MainForm_MouseDown(object sender, MouseEventArgs e)
{
    lastMousePos = e.Location;
}

private void MainForm_MouseMove(object sender, MouseEventArgs e)
{
    if (e.Button == MouseButtons.Left)
    {
        Vector2 delta = new Vector2(e.X - lastMousePos.X, e.Y - lastMousePos.Y);
        offset += delta;
        lastMousePos = e.Location;
        UpdateScrollBars();
        Invalidate();
    }
}

// 更新滚动条
private void UpdateScrollBars()
{
    hScroll.Maximum = (int)(dxf?.BoundingRectangle.Width * zoom ?? 10000);
    vScroll.Maximum = (int)(dxf?.BoundingRectangle.Height * zoom ?? 10000);
    hScroll.Value = (int)offset.X;
    vScroll.Value = (int)offset.Y;
}

三、高级功能扩展

1. 多图层支持

// 图层过滤显示
private void UpdateLayerVisibility()
{
    var activeLayers = dxf.Layers
        .Where(l => l.IsVisible)
        .Select(l => l.Name)
        .ToList();
    
    entities = entities.Where(e => activeLayers.Contains(e.Layer)).ToList();
}

2. 选择高亮

// 鼠标点击检测
private void CheckSelection(Point clientPos)
{
    Vector2 pos = Vector2.Transform(
        new Vector2(clientPos.X, clientPos.Y),
        Matrix3x2.Invert(GetTransformMatrix())
    );

    foreach (var entity in entities)
    {
        if (entity.Type == EntityType.Line)
        {
            var line = (LineEntity)entity;
            if (IsPointNearLine(pos, line.StartPoint, line.EndPoint))
            {
                selectedEntity = entity;
                Invalidate();
                break;
            }
        }
    }
}

3. 性能优化方案

// 分块加载实现
private void LoadLargeDxf(string path)
{
    using (var stream = new FileStream(path, FileMode.Open))
    {
        var reader = new DxfReader(stream);
        while (reader.ReadNextSection())
        {
            if (reader.SectionName == "ENTITIES")
            {
                while (!reader.EndOfSection)
                {
                    var entity = reader.ReadEntity();
                    if (entity != null)
                    {
                        entities.Add(ParseEntity(entity));
                        if (entities.Count % 100 == 0) // 每100个刷新界面
                        {
                            this.Invoke((MethodInvoker)delegate { Invalidate(); });
                        }
                    }
                }
            }
        }
    }
}

四、界面设计示例

+---------------------------------+
| 文件操作栏 [打开] [保存] [退出]   |
+---------------------------------+
| 图层控制面板                    |
| [可见图层列表]                  |
+---------------------------------+
| 图形显示区 (PictureBox)         |
| 缩放: 100% 平移: (0,0)          |
+---------------------------------+
| 状态栏                        |
| 坐标: (X:0,Y:0) 选中实体: 无    |
+---------------------------------+

五、完整项目结构

DXFViewer/
├── Controls/
│   ├── LayerControl.cs      # 图层管理控件
│   └── EntitySelector.cs    # 实体选择器
├── Forms/
│   ├── MainForm.cs          # 主界面
│   └── AboutForm.cs         # 关于窗口
├── Models/
│   ├── DxfEntity.cs         # 实体基类
│   └── LayerInfo.cs         # 图层信息
└── Resources/
    ├── icons/
    └── styles/

六、调试与测试

1. 坐标调试工具

// 实时坐标显示
private void UpdateStatusBar(Point clientPos)
{
    Vector2 worldPos = Vector2.Transform(
        new Vector2(clientPos.X, clientPos.Y),
        Matrix3x2.Invert(GetTransformMatrix())
    );
    statusBar.Text = $"世界坐标: ({worldPos.X:F3}, {worldPos.Y:F3})";
}

2. 内存泄漏检测

// 使用WeakReference管理实体
private List<WeakReference<DxfEntity>> weakEntities = new();

// 添加实体时
weakEntities.Add(new WeakReference<DxfEntity>(entity));

七、扩展学习资源

1. 官方网页
   • netDxf GitHub仓库 github.com/haplokuon/netDxf
   • DXF文件格式规范 www.autodesk.com/education/free-software/autocad
   • 源码 C#读取并显示DXF文件（含缩放、拖放）示例源码 youwenfan.com/contentcsc/93690.html
2. 进阶功能参考
   • 三维实体解析（netDxf.Entities.Solid）
   • 块参照处理（netDxf.Entities.BlockReference）
   • 自定义着色器（使用OpenTK实现OpenGL渲染）

通过上述方案，开发者可以构建专业级DXF查看器，支持从基础文件解析到复杂交互操作的全流程需求。建议结合具体应用场景优化渲染管线，并定期进行内存分析（使用dotMemory等工具）。