Use GDAL / OGR vector file read and write

Feeling GIS Vector relevant content was quite complex, and because of version iterations of data using GDAL / OGR read and write vector is also a bit different. This concludes the example of a read vector codes are as follows:

#include <iostream>

#include <gdal/ogrsf_frmts.h>

using namespace std;

bool ReadDXF(string filePath, vector<vector<OGRPoint>>& vertexPoint)
{   
    GDALDataset *poDS = (GDALDataset*)GDALOpenEx(filePath.c_str(), GDAL_OF_VECTOR, NULL, NULL, NULL);
    if (!poDS)
    {
        printf("无法读取该文件，试检查格式是否正确！");
        return false;
    }
    if (poDS->GetLayerCount()<1)
    {
        printf("该文件的层数小于1，试检查格式是否正确！");
        return false;
    }

    OGRLayer  *poLayer = poDS->GetLayer(0); //读取层
    poLayer->ResetReading();
    
    OGRFeature *poFeature;
    while ((poFeature = poLayer->GetNextFeature()) != NULL)
    {
        OGRGeometry *pGeo = poFeature->GetGeometryRef();
        OGRwkbGeometryType pGeoType = pGeo->getGeometryType();

        if (pGeoType == wkbLineString || pGeoType == wkbLineString25D)
        {
            OGRLinearRing  *pCurve = (OGRLinearRing*)pGeo;
            if (pCurve->getNumPoints() < 1)
            {
                continue;
            }

            vector<OGRPoint> pl;
            for (int i = 0; i<pCurve->getNumPoints(); i++)
            {
                OGRPoint point;
                pCurve->getPoint(i, &point);                        
                pl.push_back(point);
            }
            vertexPoint.push_back(pl);
        }

        ////        
        //OGRFeatureDefn *poFDefn = poLayer->GetLayerDefn();        
        //int n = poFDefn->GetFieldCount(); //获得字段的数目，不包括前两个字段（FID,Shape);
        //for (int iField = 0; iField <n; iField++)
        //{         
        //    //输出每个字段的值
        //    cout << poFeature->GetFieldAsString(iField) << "    ";            
        //}
        //cout << endl;   

        OGRFeature::DestroyFeature(poFeature);
    }

    GDALClose(poDS);
    poDS = nullptr;

    return true;
}

bool WriteShp(string filePath, vector<vector<OGRPoint>> vertexPoint)
{
    //创建
    GDALDriver* driver = GetGDALDriverManager()->GetDriverByName("ESRI Shapefile");
    if (!driver)
    {
        printf("Get Driver ESRI Shapefile Error！\n");
        return false;
    }
    
    GDALDataset* dataset = driver->Create(filePath.c_str(), 0, 0, 0, GDT_Unknown, NULL);
    OGRLayer* poLayer = dataset->CreateLayer("houseType", NULL, wkbPolygon, NULL);
    
    //创建属性字段
    {
        // 字符串
        OGRFieldDefn oField1("名称", OFTString);
        oField1.SetWidth(8);
        if (poLayer->CreateField(&oField1) != OGRERR_NONE) {
            printf("Creating Name field failed.\n"); return FALSE;
        }

        // 浮点数
        OGRFieldDefn oField2("面积", OFTReal);
        oField2.SetPrecision(3);
        if (poLayer->CreateField(&oField2) != OGRERR_NONE) {
            printf("Creating Name field failed.\n"); return FALSE;
        }

        // 整型
        OGRFieldDefn oField3("结点数", OFTInteger);
        if (poLayer->CreateField(&oField3) != OGRERR_NONE) {
            printf("Creating Name field failed.\n"); return FALSE;
        }
    }

    //创建特征
    for (auto& iter : vertexPoint)
    {
        OGRFeature *poFeature = new OGRFeature(poLayer->GetLayerDefn());
        
        OGRLinearRing ogrring;
        int pNum = (int)iter.size();
        ogrring.setNumPoints(pNum);
        for (int i = 0; i < iter.size(); i++)
        {
            ogrring.setPoint(i, iter[i].getX(), iter[i].getY(), iter[i].getZ());
            //cout << iter[i].x() << '\t' << iter[i].y() << '\t' << iter[i].z() << endl;
        }
        //cout << "-----------------------------\n";

        OGRPolygon polygon;
        polygon.addRing(&ogrring);
        poFeature->SetGeometry(&polygon);       

        poFeature->SetField("名称", "多边形");
        poFeature->SetField("面积", polygon.get_Area());
        poFeature->SetField("结点数", pNum);

        if (poLayer->CreateFeature(poFeature) != OGRERR_NONE)
        {
            printf("Failed to create feature in shapefile.\n");
            return false;
        }
    }
    
    //释放
    GDALClose(dataset);
    dataset = nullptr;
    //GDALDestroyDriverManager();

    return true;
}

int main()
{
    GDALAllRegister();
    CPLSetConfigOption("GDAL_FILENAME_IS_UTF8", "NO");  //支持中文路径
    CPLSetConfigOption("SHAPE_ENCODING", "");  //解决中文乱码问题
        
    string filePath = "D:/2.dxf";
    vector<vector<OGRPoint>> vertexPoint;
    if (!ReadDXF(filePath, vertexPoint))
    {
        return 1;
    }

    string newPath = "C:/Users/charlee/Desktop/SHP/dst.shp";
    WriteShp(newPath, vertexPoint);

    return 0;
}

In this example, a DXF file read line (loop) characteristics, converts it into the surface, and then stored in one of the SHP. Meanwhile, the file is written back to the SHP corresponding attribute field.

DXF file reads:

Create and save a SHP file: