C# 读取和绘制 Shapefile (SHP) 文件的详细过程

shapefileviewer/
├── shapefileviewer.sln
├── shapefileviewer/
│   ├── app.config
│   ├── form1.cs
│   ├── form1.designer.cs
│   ├── form1.resx
│   ├── program.cs
│   ├── shpreader.cs
│   ├── maprenderer.cs
│   └── properties/
│       ├── assemblyinfo.cs
│       └── resources.designer.cs
└── packages.config

using system;
using system.collections.generic;
using system.drawing;
using system.drawing.drawing2d;
using system.io;
using system.windows.forms;
using dotspatial.data;
using dotspatial.symbology;
using dotspatial.topology;
namespace shapefileviewer
{
    public partial class form1 : form
    {
        private shpreader shpreader;
        private maprenderer maprenderer;
        private featureset currentlayer;
        private scalebar scalebar;
        private northarrow northarrow;
        private bool showscalebar = true;
        private bool shownortharrow = true;
        private bool showgrid = true;
        private float zoomfactor = 1.0f;
        private pointf panoffset = new pointf(0, 0);
        private point lastmouseposition;
        private bool ispanning = false;
        public form1()
        {
            initializecomponent();
            initializemapcomponents();
            initializeui();
        }
        private void initializemapcomponents()
        {
            shpreader = new shpreader();
            maprenderer = new maprenderer();
            scalebar = new scalebar();
            northarrow = new northarrow();
        }
        private void initializeui()
        {
            // 窗体设置
            this.text = "shapefile 查看器";
            this.size = new size(1200, 800);
            this.backcolor = color.lightgray;
            this.doublebuffered = true;
            // 创建地图控件
            mappanel = new panel
            {
                location = new point(10, 10),
                size = new size(880, 700),
                borderstyle = borderstyle.fixedsingle,
                backcolor = color.white,
                anchor = anchorstyles.top | anchorstyles.bottom | anchorstyles.left | anchorstyles.right
            };
            mappanel.paint += mappanel_paint;
            mappanel.mousewheel += mappanel_mousewheel;
            mappanel.mousedown += mappanel_mousedown;
            mappanel.mousemove += mappanel_mousemove;
            mappanel.mouseup += mappanel_mouseup;
            // 创建控制面板
            controlpanel = new panel
            {
                location = new point(900, 10),
                size = new size(280, 700),
                borderstyle = borderstyle.fixedsingle,
                backcolor = color.fromargb(240, 240, 240),
                anchor = anchorstyles.top | anchorstyles.bottom | anchorstyles.right
            };
            // 添加控件
            int ypos = 20;
            int labelwidth = 80;
            int controlwidth = 170;
            int rowheight = 30;
            // 打开文件按钮
            btnopen = new button
            {
                text = "打开 shapefile",
                location = new point(20, ypos),
                size = new size(controlwidth, 30),
                backcolor = color.steelblue,
                forecolor = color.white,
                flatstyle = flatstyle.flat
            };
            btnopen.flatappearance.bordersize = 0;
            btnopen.click += btnopen_click;
            controlpanel.controls.add(btnopen);
            // 缩放控制
            ypos += rowheight + 10;
            lblzoom = new label { text = "缩放:", location = new point(20, ypos), size = new size(labelwidth, 20) };
            controlpanel.controls.add(lblzoom);
            tbzoom = new trackbar
            {
                minimum = 10,
                maximum = 500,
                value = 100,
                tickfrequency = 10,
                location = new point(20, ypos + 25),
                size = new size(controlwidth, 45)
            };
            tbzoom.valuechanged += tbzoom_valuechanged;
            controlpanel.controls.add(tbzoom);
            lblzoomvalue = new label { text = "100%", location = new point(controlwidth + 30, ypos + 40), size = new size(50, 20) };
            controlpanel.controls.add(lblzoomvalue);
            // 平移控制
            ypos += rowheight + 60;
            btnpan = new button
            {
                text = "平移模式",
                location = new point(20, ypos),
                size = new size(controlwidth, 30),
                backcolor = color.forestgreen,
                forecolor = color.white,
                flatstyle = flatstyle.flat
            };
            btnpan.flatappearance.bordersize = 0;
            btnpan.click += btnpan_click;
            controlpanel.controls.add(btnpan);
            btnresetview = new button
            {
                text = "重置视图",
                location = new point(20, ypos + 40),
                size = new size(controlwidth, 30),
                backcolor = color.orange,
                forecolor = color.white,
                flatstyle = flatstyle.flat
            };
            btnresetview.flatappearance.bordersize = 0;
            btnresetview.click += btnresetview_click;
            controlpanel.controls.add(btnresetview);
            // 图层控制
            ypos += rowheight + 90;
            chkshowscalebar = new checkbox { text = "显示比例尺", location = new point(20, ypos), checked = true, autosize = true };
            chkshowscalebar.checkedchanged += chkshowscalebar_checkedchanged;
            controlpanel.controls.add(chkshowscalebar);
            chkshownortharrow = new checkbox { text = "显示指北针", location = new point(20, ypos + 30), checked = true, autosize = true };
            chkshownortharrow.checkedchanged += chkshownortharrow_checkedchanged;
            controlpanel.controls.add(chkshownortharrow);
            chkshowgrid = new checkbox { text = "显示网格", location = new point(20, ypos + 60), checked = true, autosize = true };
            chkshowgrid.checkedchanged += chkshowgrid_checkedchanged;
            controlpanel.controls.add(chkshowgrid);
            // 图层列表
            ypos += rowheight + 100;
            lbllayers = new label { text = "图层:", location = new point(20, ypos), autosize = true };
            controlpanel.controls.add(lbllayers);
            lstlayers = new listbox
            {
                location = new point(20, ypos + 25),
                size = new size(controlwidth, 150),
                selectionmode = selectionmode.one
            };
            lstlayers.selectedindexchanged += lstlayers_selectedindexchanged;
            controlpanel.controls.add(lstlayers);
            // 状态标签
            statuslabel = new label
            {
                text = "就绪",
                location = new point(10, 720),
                size = new size(1160, 20),
                anchor = anchorstyles.bottom | anchorstyles.left
            };
            this.controls.add(statuslabel);
            // 添加控件到窗体
            this.controls.add(mappanel);
            this.controls.add(controlpanel);
        }
        #region 控件声明
        private panel mappanel;
        private panel controlpanel;
        private button btnopen;
        private button btnpan;
        private button btnresetview;
        private trackbar tbzoom;
        private label lblzoom;
        private label lblzoomvalue;
        private checkbox chkshowscalebar;
        private checkbox chkshownortharrow;
        private checkbox chkshowgrid;
        private label lbllayers;
        private listbox lstlayers;
        private label statuslabel;
        #endregion
        #region 事件处理
        private void btnopen_click(object sender, eventargs e)
        {
            using (openfiledialog openfiledialog = new openfiledialog())
            {
                openfiledialog.filter = "shapefile 文件 (*.shp)|*.shp|所有文件 (*.*)|*.*";
                openfiledialog.title = "选择 shapefile 文件";
                if (openfiledialog.showdialog() == dialogresult.ok)
                {
                    try
                    {
                        statuslabel.text = $"正在加载: {path.getfilename(openfiledialog.filename)}...";
                        application.doevents();
                        // 加载 shapefile
                        currentlayer = shpreader.loadshapefile(openfiledialog.filename);
                        if (currentlayer != null)
                        {
                            // 添加到图层列表
                            lstlayers.items.add(path.getfilenamewithoutextension(openfiledialog.filename));
                            lstlayers.selectedindex = lstlayers.items.count - 1;
                            // 重置视图
                            zoomfactor = 1.0f;
                            panoffset = new pointf(0, 0);
                            tbzoom.value = 100;
                            lblzoomvalue.text = "100%";
                            statuslabel.text = $"已加载: {path.getfilename(openfiledialog.filename)} | 要素数: {currentlayer.features.count}";
                        }
                        else
                        {
                            statuslabel.text = "加载失败: 无效的文件格式";
                        }
                    }
                    catch (exception ex)
                    {
                        statuslabel.text = $"错误: {ex.message}";
                        messagebox.show($"加载 shapefile 失败: {ex.message}", "错误", messageboxbuttons.ok, messageboxicon.error);
                    }
                    finally
                    {
                        mappanel.invalidate();
                    }
                }
            }
        }
        private void mappanel_paint(object sender, painteventargs e)
        {
            graphics g = e.graphics;
            g.smoothingmode = smoothingmode.antialias;
            g.clear(color.white);
            if (currentlayer == null) return;
            // 应用变换
            g.translatetransform(panoffset.x, panoffset.y);
            g.scaletransform(zoomfactor, zoomfactor);
            // 绘制地图内容
            maprenderer.render(g, currentlayer, mappanel.clientsize);
            // 绘制网格
            if (showgrid)
            {
                maprenderer.drawgrid(g, mappanel.clientsize, zoomfactor);
            }
            // 绘制指北针
            if (shownortharrow)
            {
                northarrow.draw(g, new pointf(mappanel.clientsize.width - 50, 50), 30);
            }
            // 绘制比例尺
            if (showscalebar)
            {
                scalebar.draw(g, new pointf(20, mappanel.clientsize.height - 40), zoomfactor);
            }
        }
        private void tbzoom_valuechanged(object sender, eventargs e)
        {
            zoomfactor = tbzoom.value / 100.0f;
            lblzoomvalue.text = $"{tbzoom.value}%";
            mappanel.invalidate();
        }
        private void btnpan_click(object sender, eventargs e)
        {
            ispanning = !ispanning;
            btnpan.backcolor = ispanning ? color.orangered : color.forestgreen;
            mappanel.cursor = ispanning ? cursors.hand : cursors.default;
        }
        private void btnresetview_click(object sender, eventargs e)
        {
            zoomfactor = 1.0f;
            panoffset = new pointf(0, 0);
            tbzoom.value = 100;
            lblzoomvalue.text = "100%";
            mappanel.invalidate();
        }
        private void chkshowscalebar_checkedchanged(object sender, eventargs e)
        {
            showscalebar = chkshowscalebar.checked;
            mappanel.invalidate();
        }
        private void chkshownortharrow_checkedchanged(object sender, eventargs e)
        {
            shownortharrow = chkshownortharrow.checked;
            mappanel.invalidate();
        }
        private void chkshowgrid_checkedchanged(object sender, eventargs e)
        {
            showgrid = chkshowgrid.checked;
            mappanel.invalidate();
        }
        private void lstlayers_selectedindexchanged(object sender, eventargs e)
        {
            if (lstlayers.selectedindex >= 0)
            {
                // 在实际应用中，这里应该加载选中的图层
                // 本示例中只显示当前加载的图层
                mappanel.invalidate();
            }
        }
        private void mappanel_mousewheel(object sender, mouseeventargs e)
        {
            // 缩放功能
            int zoomdelta = e.delta > 0 ? 10 : -10;
            tbzoom.value = math.min(math.max(tbzoom.minimum, tbzoom.value + zoomdelta), tbzoom.maximum);
        }
        private void mappanel_mousedown(object sender, mouseeventargs e)
        {
            if (ispanning && e.button == mousebuttons.left)
            {
                lastmouseposition = e.location;
                mappanel.capture = true;
            }
        }
        private void mappanel_mousemove(object sender, mouseeventargs e)
        {
            if (ispanning && e.button == mousebuttons.left)
            {
                panoffset.x += e.x - lastmouseposition.x;
                panoffset.y += e.y - lastmouseposition.y;
                lastmouseposition = e.location;
                mappanel.invalidate();
            }
        }
        private void mappanel_mouseup(object sender, mouseeventargs e)
        {
            if (ispanning && e.button == mousebuttons.left)
            {
                mappanel.capture = false;
            }
        }
        #endregion
    }
    #region 辅助类
    public class shpreader
    {
        public featureset loadshapefile(string filepath)
        {
            if (!file.exists(filepath))
                throw new filenotfoundexception("shapefile 文件不存在", filepath);
            // 检查是否存在同名的 .shx 文件
            string shxpath = path.changeextension(filepath, ".shx");
            string dbfpath = path.changeextension(filepath, ".dbf");
            if (!file.exists(shxpath))
                throw new filenotfoundexception("找不到关联的 .shx 文件", shxpath);
            if (!file.exists(dbfpath))
                throw new filenotfoundexception("找不到关联的 .dbf 文件", dbfpath);
            // 使用 dotspatial 加载 shapefile
            return featureset.open(filepath);
        }
    }
    public class maprenderer
    {
        private readonly font labelfont = new font("arial", 8);
        private readonly brush labelbrush = brushes.black;
        private readonly pen gridpen = new pen(color.lightgray, 1);
        public void render(graphics g, featureset featureset, size panelsize)
        {
            if (featureset == null || featureset.features.count == 0)
                return;
            // 计算边界框
            extent extent = featureset.extent;
            double width = extent.width;
            double height = extent.height;
            // 计算缩放比例
            float scalex = (float)(panelsize.width / width);
            float scaley = (float)(panelsize.height / height);
            float scale = math.min(scalex, scaley) * 0.9f; // 留出一些边距
            // 计算偏移量以居中显示
            float offsetx = (float)(-extent.minx * scale) + (panelsize.width - (float)width * scale) / 2;
            float offsety = (float)(extent.maxy * scale) + (panelsize.height - (float)height * scale) / 2;
            // 绘制每个要素
            foreach (ifeature feature in featureset.features)
            {
                igeometry geometry = feature.basicgeometry;
                drawgeometry(g, geometry, scale, offsetx, offsety);
            }
        }
        private void drawgeometry(graphics g, igeometry geometry, float scale, float offsetx, float offsety)
        {
            if (geometry is point point)
            {
                drawpoint(g, point, scale, offsetx, offsety);
            }
            else if (geometry is linestring linestring)
            {
                drawlinestring(g, linestring, scale, offsetx, offsety);
            }
            else if (geometry is polygon polygon)
            {
                drawpolygon(g, polygon, scale, offsetx, offsety);
            }
            else if (geometry is multipoint multipoint)
            {
                foreach (point pt in multipoint.geometries)
                {
                    drawpoint(g, pt, scale, offsetx, offsety);
                }
            }
            else if (geometry is multilinestring multilinestring)
            {
                foreach (linestring ls in multilinestring.geometries)
                {
                    drawlinestring(g, ls, scale, offsetx, offsety);
                }
            }
            else if (geometry is multipolygon multipolygon)
            {
                foreach (polygon poly in multipolygon.geometries)
                {
                    drawpolygon(g, poly, scale, offsetx, offsety);
                }
            }
        }
        private void drawpoint(graphics g, point point, float scale, float offsetx, float offsety)
        {
            float x = (float)(point.x * scale + offsetx);
            float y = (float)(-point.y * scale + offsety); // y坐标反转
            // 绘制点符号
            g.fillellipse(brushes.red, x - 3, y - 3, 6, 6);
            g.drawellipse(pens.black, x - 3, y - 3, 6, 6);
        }
        private void drawlinestring(graphics g, linestring linestring, float scale, float offsetx, float offsety)
        {
            pointf[] points = new pointf[linestring.coordinates.count];
            for (int i = 0; i < linestring.coordinates.count; i++)
            {
                coordinate coord = linestring.coordinates[i];
                float x = (float)(coord.x * scale + offsetx);
                float y = (float)(-coord.y * scale + offsety); // y坐标反转
                points[i] = new pointf(x, y);
            }
            // 绘制线
            g.drawlines(pens.blue, points);
        }
        private void drawpolygon(graphics g, polygon polygon, float scale, float offsetx, float offsety)
        {
            // 绘制外环
            drawring(g, polygon.shell, scale, offsetx, offsety, pens.green, brushes.lightgreen);
            // 绘制内环（孔洞）
            foreach (linearring hole in polygon.holes)
            {
                drawring(g, hole, scale, offsetx, offsety, pens.red, brushes.lightpink);
            }
        }
        private void drawring(graphics g, linearring ring, float scale, float offsetx, float offsety, pen pen, brush brush)
        {
            pointf[] points = new pointf[ring.coordinates.count];
            for (int i = 0; i < ring.coordinates.count; i++)
            {
                coordinate coord = ring.coordinates[i];
                float x = (float)(coord.x * scale + offsetx);
                float y = (float)(-coord.y * scale + offsety); // y坐标反转
                points[i] = new pointf(x, y);
            }
            // 填充多边形
            if (brush != null)
                g.fillpolygon(brush, points);
            // 绘制边界
            g.drawpolygon(pen, points);
        }
        public void drawgrid(graphics g, size panelsize, float zoomfactor)
        {
            float gridsize = 50 * zoomfactor;
            float offsetx = panelsize.width % gridsize / 2;
            float offsety = panelsize.height % gridsize / 2;
            for (float x = offsetx; x < panelsize.width; x += gridsize)
            {
                g.drawline(gridpen, x, 0, x, panelsize.height);
            }
            for (float y = offsety; y < panelsize.height; y += gridsize)
            {
                g.drawline(gridpen, 0, y, panelsize.width, y);
            }
        }
    }
    public class scalebar
    {
        public void draw(graphics g, pointf location, float zoomfactor)
        {
            float barlength = 100 * zoomfactor;
            float barheight = 10;
            // 绘制比例尺条
            g.fillrectangle(brushes.white, location.x, location.y, barlength, barheight);
            g.drawrectangle(pens.black, location.x, location.y, barlength, barheight);
            // 绘制刻度
            g.drawline(pens.black, location.x, location.y - 5, location.x, location.y + barheight + 5);
            g.drawline(pens.black, location.x + barlength, location.y - 5, location.x + barlength, location.y + barheight + 5);
            // 绘制标签
            font font = new font("arial", 8);
            string label = $"{barlength / 100 * 10} km"; // 简化计算
            g.drawstring(label, font, brushes.black, location.x, location.y + barheight + 5);
        }
    }
    public class northarrow
    {
        public void draw(graphics g, pointf location, float size)
        {
            // 绘制箭头
            pointf[] arrowpoints =
            {
                new pointf(location.x, location.y - size / 2),
                new pointf(location.x + size / 2, location.y + size / 2),
                new pointf(location.x - size / 2, location.y + size / 2)
            };
            g.fillpolygon(brushes.white, arrowpoints);
            g.drawpolygon(pens.black, arrowpoints);
            // 绘制文字
            font font = new font("arial", 10, fontstyle.bold);
            g.drawstring("n", font, brushes.black, location.x - 5, location.y - size / 2 - 15);
        }
    }
    #endregion
}

using system;
using system.windows.forms;
namespace shapefileviewer
{
    static class program
    {
        [stathread]
        static void main()
        {
            application.enablevisualstyles();
            application.setcompatibletextrenderingdefault(false);
            application.run(new form1());
        }
    }
}

<?xml version="1.0" encoding="utf-8"?>
<configuration>
  <startup>
    <supportedruntime version="v4.0" sku=".netframework,version=v4.7.2"/>
  </startup>
</configuration>

<?xml version="1.0" encoding="utf-8"?>
<packages>
  <package id="dotspatial.core" version="1.9.0" targetframework="net472" />
  <package id="dotspatial.data" version="1.9.0" targetframework="net472" />
  <package id="dotspatial.symbology" version="1.9.0" targetframework="net472" />
  <package id="dotspatial.topology" version="1.9.0" targetframework="net472" />
  <package id="nettopologysuite" version="1.15.3" targetframework="net472" />
</packages>

install-package dotspatial.core
install-package dotspatial.data
install-package dotspatial.symbology
install-package dotspatial.topology
install-package nettopologysuite

public featureset loadshapefile(string filepath)
{
    // 检查文件存在性
    if (!file.exists(filepath)) throw new filenotfoundexception(...);
    // 检查关联文件
    string shxpath = path.changeextension(filepath, ".shx");
    string dbfpath = path.changeextension(filepath, ".dbf");
    if (!file.exists(shxpath) || !file.exists(dbfpath)) 
        throw new filenotfoundexception(...);
    // 使用 dotspatial 加载
    return featureset.open(filepath);
}

// 计算缩放比例
float scalex = (float)(panelsize.width / width);
float scaley = (float)(panelsize.height / height);
float scale = math.min(scalex, scaley) * 0.9f;
// 计算偏移量
float offsetx = (float)(-extent.minx * scale) + (panelsize.width - (float)width * scale) / 2;
float offsety = (float)(extent.maxy * scale) + (panelsize.height - (float)height * scale) / 2;
// 应用变换
float x = (float)(coord.x * scale + offsetx);
float y = (float)(-coord.y * scale + offsety); // y坐标反转

// 点绘制
g.fillellipse(brushes.red, x - 3, y - 3, 6, 6);
g.drawellipse(pens.black, x - 3, y - 3, 6, 6);
// 线绘制
g.drawlines(pens.blue, points);
// 面绘制
g.fillpolygon(brush, points);
g.drawpolygon(pen, points);

// 在 form1 类中添加
private void lstlayers_mousedoubleclick(object sender, mouseeventargs e)
{
    if (lstlayers.selectedindex >= 0 && currentlayer != null)
    {
        // 显示属性表
        showattributetable(currentlayer);
    }
}
private void showattributetable(featureset layer)
{
    form attrform = new form();
    attrform.text = "属性表 - " + layer.name;
    attrform.size = new size(800, 600);
    datagridview grid = new datagridview();
    grid.dock = dockstyle.fill;
    grid.readonly = true;
    grid.datasource = layer.datatable;
    attrform.controls.add(grid);
    attrform.showdialog();
}

// 在 maprenderer 类中添加
public ifeature selectfeature(pointf clickpoint, featureset layer, float scale, float offsetx, float offsety)
{
    // 将屏幕坐标转换为地图坐标
    double mapx = (clickpoint.x - offsetx) / scale;
    double mapy = -(clickpoint.y - offsety) / scale;
    // 查找最近的要素
    ifeature closestfeature = null;
    double mindistance = double.maxvalue;
    foreach (ifeature feature in layer.features)
    {
        double distance = feature.geometry.distance(new coordinate(mapx, mapy));
        if (distance < mindistance)
        {
            mindistance = distance;
            closestfeature = feature;
        }
    }
    // 检查是否在容差范围内
    if (mindistance < 10.0 / scale) // 10像素容差
        return closestfeature;
    return null;
}

// 在 form1 类中添加
private void lstlayers_mouseclick(object sender, mouseeventargs e)
{
    if (e.button == mousebuttons.right && lstlayers.selectedindex >= 0)
    {
        contextmenustrip menu = new contextmenustrip();
        toolstripmenuitem coloritem = new toolstripmenuitem("更改颜色");
        coloritem.click += (s, args) => changelayercolor();
        menu.items.add(coloritem);
        toolstripmenuitem widthitem = new toolstripmenuitem("更改线宽");
        widthitem.click += (s, args) => changelinewidth();
        menu.items.add(widthitem);
        menu.show(lstlayers, e.location);
    }
}
private void changelayercolor()
{
    if (currentlayer != null)
    {
        colordialog dialog = new colordialog();
        if (dialog.showdialog() == dialogresult.ok)
        {
            // 在实际应用中，更新图层样式
            mappanel.invalidate();
        }
    }
}

// 在 form1 类中添加
private void btnexport_click(object sender, eventargs e)
{
    using (savefiledialog savedialog = new savefiledialog())
    {
        savedialog.filter = "png 图片 (*.png)|*.png|jpeg 图片 (*.jpg)|*.jpg|bmp 图片 (*.bmp)|*.bmp";
        savedialog.title = "导出地图";
        if (savedialog.showdialog() == dialogresult.ok)
        {
            bitmap bmp = new bitmap(mappanel.width, mappanel.height);
            mappanel.drawtobitmap(bmp, new rectangle(0, 0, mappanel.width, mappanel.height));
            bmp.save(savedialog.filename);
            statuslabel.text = $"地图已导出到: {savedialog.filename}";
        }
    }
}

// 在 shpreader 类中添加
featureset.encoding = encoding.getencoding("gb2312"); // 或 utf-8