第15章-扩展开发与插件集成

第15章：扩展开发与插件集成

15.1 SharpMap 扩展概述

SharpMap 提供了多种扩展机制：

数据提供者扩展：支持新的数据格式
图层扩展：自定义图层渲染
样式扩展：自定义符号和渲染
第三方库集成：GDAL、BruTile、ProjNet 等

15.2 GDAL 扩展

15.2.1 安装配置

Install-Package SharpMap.Extensions
Install-Package Gdal.Native

15.2.2 栅格图层

using SharpMap.Layers;

// 配置 GDAL
GdalConfiguration.ConfigureGdal();

// 创建 GDAL 栅格图层
var rasterLayer = new GdalRasterLayer("Satellite", "satellite.tif");
rasterLayer.Transparency = 0.8f;

map.Layers.Add(rasterLayer);

15.2.3 OGR 数据提供者

using SharpMap.Data.Providers;

// 支持 GeoJSON
var geoJsonProvider = new Ogr("data.geojson");

// 支持 KML
var kmlProvider = new Ogr("data.kml");

// 支持 FileGDB
var fgdbProvider = new Ogr("database.gdb", "layer_name");

var layer = new VectorLayer("GeoJSON Data", geoJsonProvider);

15.3 BruTile 扩展

15.3.1 自定义瓦片源

using BruTile;
using BruTile.Web;

public class CustomTileSource : HttpTileSource
{
    public CustomTileSource() : base(
        new GlobalSphericalMercator(0, 18),
        GetUrlFormatter(),
        GetServerNodes(),
        "CustomSource")
    {
    }
    
    private static Func<Uri, byte[]> GetUrlFormatter()
    {
        return (uri) =>
        {
            using (var client = new WebClient())
            {
                client.Headers.Add("User-Agent", "SharpMap/1.0");
                return client.DownloadData(uri);
            }
        };
    }
    
    private static IEnumerable<string> GetServerNodes()
    {
        return new[] { "a", "b", "c" };
    }
}

15.3.2 瓦片缓存策略

public class TwoLevelCache : ITileCache<byte[]>
{
    private readonly MemoryCache<byte[]> _memoryCache;
    private readonly FileCache _fileCache;
    
    public TwoLevelCache(string cachePath, int memoryCacheSize = 100)
    {
        _memoryCache = new MemoryCache<byte[]>(memoryCacheSize, memoryCacheSize * 2);
        _fileCache = new FileCache(cachePath, "png");
    }
    
    public void Add(TileIndex index, byte[] tile)
    {
        _memoryCache.Add(index, tile);
        _fileCache.Add(index, tile);
    }
    
    public byte[] Find(TileIndex index)
    {
        // 先查内存
        var tile = _memoryCache.Find(index);
        if (tile != null)
            return tile;
        
        // 再查文件
        tile = _fileCache.Find(index);
        if (tile != null)
        {
            _memoryCache.Add(index, tile);  // 加载到内存
        }
        
        return tile;
    }
    
    public void Remove(TileIndex index)
    {
        _memoryCache.Remove(index);
        _fileCache.Remove(index);
    }
}

15.4 NetTopologySuite 集成

15.4.1 几何操作

using NetTopologySuite.Geometries;
using NetTopologySuite.Operation.Buffer;
using NetTopologySuite.Operation.Union;

// 高级缓冲区
var bufferParams = new BufferParameters
{
    EndCapStyle = EndCapStyle.Round,
    JoinStyle = JoinStyle.Round,
    QuadrantSegments = 16
};
var buffer = BufferOp.Buffer(geometry, distance, bufferParams);

// 高性能合并
var geometries = new List<Geometry> { poly1, poly2, poly3 };
var union = CascadedPolygonUnion.Union(geometries);

// 简化
using NetTopologySuite.Simplify;
var simplified = TopologyPreservingSimplifier.Simplify(geometry, tolerance);

15.4.2 空间索引

using NetTopologySuite.Index.Strtree;
using NetTopologySuite.Index.KdTree;

// STRtree（适合静态数据）
var strTree = new STRtree<string>();
strTree.Insert(geometry.EnvelopeInternal, "feature1");
strTree.Build();

// KdTree（适合点数据）
var kdTree = new KdTree<string>();
foreach (var point in points)
{
    kdTree.Insert(point.Coordinate, "point");
}

15.5 ProjNet 扩展

15.5.1 坐标系统工厂

using ProjNet.CoordinateSystems;
using ProjNet.CoordinateSystems.Transformations;

public class CoordinateSystemService
{
    private readonly Dictionary<int, ICoordinateSystem> _systems;
    private readonly CoordinateSystemFactory _factory;
    private readonly CoordinateTransformationFactory _transformFactory;
    
    public CoordinateSystemService()
    {
        _systems = new Dictionary<int, ICoordinateSystem>();
        _factory = new CoordinateSystemFactory();
        _transformFactory = new CoordinateTransformationFactory();
        
        LoadCommonSystems();
    }
    
    private void LoadCommonSystems()
    {
        // 从 EPSG 数据库或配置文件加载
        _systems[4326] = GeographicCoordinateSystem.WGS84;
        _systems[3857] = CreateWebMercator();
        // ...
    }
    
    public ICoordinateTransformation GetTransformation(int sourceSrid, int targetSrid)
    {
        var source = _systems[sourceSrid];
        var target = _systems[targetSrid];
        return _transformFactory.CreateFromCoordinateSystems(source, target);
    }
}

15.6 自定义数据提供者

15.6.1 实时数据提供者

public class RealtimeGpsProvider : IProvider
{
    private readonly Func<IEnumerable<GpsPoint>> _dataSource;
    private readonly GeometryFactory _factory;
    
    public RealtimeGpsProvider(Func<IEnumerable<GpsPoint>> dataSource)
    {
        _dataSource = dataSource;
        _factory = new GeometryFactory();
    }
    
    public Collection<Geometry> GetGeometriesInView(Envelope envelope)
    {
        var points = _dataSource()
            .Where(p => envelope.Contains(p.Longitude, p.Latitude))
            .Select(p => _factory.CreatePoint(new Coordinate(p.Longitude, p.Latitude)))
            .Cast<Geometry>()
            .ToList();
        
        return new Collection<Geometry>(points);
    }
    
    // 其他接口方法实现...
}

// 使用
var gpsProvider = new RealtimeGpsProvider(() => GetGpsPositions());
var gpsLayer = new VectorLayer("GPS", gpsProvider);
map.VariableLayers.Add(gpsLayer);  // 动态图层

15.6.2 数据库提供者

public class CustomDbProvider : IProvider
{
    private readonly string _connectionString;
    private readonly string _tableName;
    private readonly string _geometryColumn;
    
    public void ExecuteIntersectionQuery(Envelope envelope, FeatureDataSet ds)
    {
        using (var conn = new SqlConnection(_connectionString))
        {
            conn.Open();
            
            var sql = $@"
                SELECT * FROM {_tableName}
                WHERE {_geometryColumn}.STIntersects(
                    geometry::STGeomFromText('POLYGON(({envelope.MinX} {envelope.MinY}, 
                        {envelope.MaxX} {envelope.MinY}, {envelope.MaxX} {envelope.MaxY}, 
                        {envelope.MinX} {envelope.MaxY}, {envelope.MinX} {envelope.MinY}))', 
                        {SRID})) = 1";
            
            using (var cmd = new SqlCommand(sql, conn))
            using (var reader = cmd.ExecuteReader())
            {
                var table = CreateFeatureDataTable();
                
                while (reader.Read())
                {
                    var row = table.NewRow() as FeatureDataRow;
                    // 填充数据...
                    table.AddRow(row);
                }
                
                ds.Tables.Add(table);
            }
        }
    }
}

15.7 自定义图层

15.7.1 热力图图层

public class HeatmapLayer : Layer
{
    private readonly IProvider _dataSource;
    private readonly int _radius;
    private readonly Color[] _gradient;
    
    public HeatmapLayer(string name, IProvider dataSource, int radius = 20)
        : base(name)
    {
        _dataSource = dataSource;
        _radius = radius;
        _gradient = CreateGradient();
    }
    
    public override Envelope Envelope => _dataSource.GetExtents();
    
    public override void Render(Graphics g, Map map)
    {
        var points = _dataSource.GetGeometriesInView(map.Envelope)
            .OfType<Point>()
            .Select(p => map.WorldToImage(p.Coordinate))
            .ToList();
        
        // 创建热力图
        using (var heatmap = new Bitmap(map.Size.Width, map.Size.Height))
        {
            foreach (var point in points)
            {
                DrawHeatPoint(heatmap, point, _radius);
            }
            
            ApplyGradient(heatmap);
            g.DrawImage(heatmap, 0, 0);
        }
    }
    
    private void DrawHeatPoint(Bitmap bitmap, PointF center, int radius)
    {
        // 绘制热力点（高斯衰减）
        for (int x = -radius; x <= radius; x++)
        {
            for (int y = -radius; y <= radius; y++)
            {
                int px = (int)center.X + x;
                int py = (int)center.Y + y;
                
                if (px >= 0 && px < bitmap.Width && py >= 0 && py < bitmap.Height)
                {
                    double distance = Math.Sqrt(x * x + y * y);
                    if (distance <= radius)
                    {
                        double intensity = 1 - (distance / radius);
                        var currentColor = bitmap.GetPixel(px, py);
                        int newAlpha = Math.Min(255, currentColor.A + (int)(intensity * 50));
                        bitmap.SetPixel(px, py, Color.FromArgb(newAlpha, 255, 0, 0));
                    }
                }
            }
        }
    }
}

15.7.2 轨迹图层

public class TrackLayer : Layer
{
    private readonly List<TrackPoint> _trackPoints;
    
    public TrackLayer(string name) : base(name)
    {
        _trackPoints = new List<TrackPoint>();
    }
    
    public void AddPoint(TrackPoint point)
    {
        _trackPoints.Add(point);
    }
    
    public override void Render(Graphics g, Map map)
    {
        if (_trackPoints.Count < 2)
            return;
        
        var screenPoints = _trackPoints
            .Select(p => map.WorldToImage(new Coordinate(p.Longitude, p.Latitude)))
            .ToArray();
        
        // 渐变轨迹
        for (int i = 1; i < screenPoints.Length; i++)
        {
            float progress = (float)i / screenPoints.Length;
            var color = InterpolateColor(Color.Blue, Color.Red, progress);
            
            using (var pen = new Pen(color, 3))
            {
                g.DrawLine(pen, screenPoints[i - 1], screenPoints[i]);
            }
        }
        
        // 绘制终点
        var lastPoint = screenPoints.Last();
        using (var brush = new SolidBrush(Color.Red))
        {
            g.FillEllipse(brush, lastPoint.X - 6, lastPoint.Y - 6, 12, 12);
        }
    }
}

15.8 插件架构

15.8.1 插件接口

public interface IMapPlugin
{
    string Name { get; }
    string Description { get; }
    void Initialize(Map map, MapBox mapBox);
    void Dispose();
}

public interface IToolPlugin : IMapPlugin
{
    Cursor Cursor { get; }
    void OnMouseDown(MouseEventArgs e);
    void OnMouseMove(MouseEventArgs e);
    void OnMouseUp(MouseEventArgs e);
}

15.8.2 插件管理器

public class PluginManager
{
    private readonly List<IMapPlugin> _plugins;
    private readonly Map _map;
    private readonly MapBox _mapBox;
    
    public PluginManager(Map map, MapBox mapBox)
    {
        _plugins = new List<IMapPlugin>();
        _map = map;
        _mapBox = mapBox;
    }
    
    public void LoadPlugins(string pluginPath)
    {
        var dlls = Directory.GetFiles(pluginPath, "*.dll");
        
        foreach (var dll in dlls)
        {
            try
            {
                var assembly = Assembly.LoadFrom(dll);
                var pluginTypes = assembly.GetTypes()
                    .Where(t => typeof(IMapPlugin).IsAssignableFrom(t) && !t.IsInterface);
                
                foreach (var type in pluginTypes)
                {
                    var plugin = Activator.CreateInstance(type) as IMapPlugin;
                    if (plugin != null)
                    {
                        plugin.Initialize(_map, _mapBox);
                        _plugins.Add(plugin);
                    }
                }
            }
            catch (Exception ex)
            {
                Console.WriteLine($"加载插件失败: {dll} - {ex.Message}");
            }
        }
    }
    
    public IEnumerable<IMapPlugin> GetPlugins() => _plugins;
    
    public T GetPlugin<T>() where T : IMapPlugin
    {
        return _plugins.OfType<T>().FirstOrDefault();
    }
}

15.9 本章小结

本章介绍了 SharpMap 的扩展开发：

GDAL 扩展：栅格数据和 OGR 数据支持
BruTile 扩展：自定义瓦片源和缓存
NTS 集成：高级几何操作
ProjNet 扩展：坐标系统服务
自定义提供者：实时数据和数据库数据
自定义图层：热力图和轨迹图层
插件架构：可扩展的插件系统

下一章预告：第16章将介绍性能优化与最佳实践。

posted @ 2026-01-08 14:09 我才是银古阅读(3) 评论(0) 收藏举报

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第15章-扩展开发与插件集成

第15章：扩展开发与插件集成

15.1 SharpMap 扩展概述

15.2 GDAL 扩展

15.2.1 安装配置

15.2.2 栅格图层

15.2.3 OGR 数据提供者

15.3 BruTile 扩展

15.3.1 自定义瓦片源

15.3.2 瓦片缓存策略

15.4 NetTopologySuite 集成

15.4.1 几何操作

15.4.2 空间索引

15.5 ProjNet 扩展

15.5.1 坐标系统工厂

15.6 自定义数据提供者

15.6.1 实时数据提供者

15.6.2 数据库提供者

15.7 自定义图层

15.7.1 热力图图层

15.7.2 轨迹图层

15.8 插件架构

15.8.1 插件接口

15.8.2 插件管理器

15.9 本章小结

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